Kim, Eleonora E

Kim E.E., Belova A.S., Filimonova L.V., Khanin D.A., Nikiforova G.G., Kononevich Y.N., Shchegolikhina O.I., Muzafarov A.M.

Kim E.E., Ershova T.O., Belova A.S., Khanin D.A., Bashkova E.V., Nikiforova G.G., Kononevich Y.N., Anisimov A.A., Shchegolikhina O.I., Muzafarov A.M.

Kim E.E., Il’ina T.M., Kononevich Y.N., Ionov D.S., Khanin D.A., Nikiforova G.G., Muzafarov A.M.

Crosslinked polysiloxanes with boron bis(dibenzoylmethanate) complexes used as crosslink junctions of polymer networks are first synthesized, and their physicochemical, mechanical, thermal, and fluorescent properties are studied. It is shown that the polymers under study feature the elastic behavior, possess high thermal and thermo-oxidative stability, and exhibit intense fluorescence in a wide wavelength range (400‒700 nm).

Semenov A.N., Gvozdev D.A., Zlenko D.V., Protasova E.A., Khashimova A.R., Parshina E.Y., Baizhumanov A.A., Lotosh N.Y., Kim E.E., Kononevich Y.N., Pakhomov A.A., Selishcheva A.A., Sluchanko N.N., Shirshin E.A., Maksimov E.G.

Carotenoids are potent antioxidants with a wide range of biomedical applications. However, their delivery into human cells is challenging and relatively inefficient. While the use of natural water-soluble carotenoproteins capable to reversibly bind carotenoids and transfer them into membranes is promising, the quantitative estimation of the delivery remains unclear. In the present work, we studied echinenone (ECN) delivery by cyanobacterial carotenoprotein AnaCTDH (C-terminal domain homolog of the Orange Carotenoid Protein from Anabaena), into liposome membranes labelled with BODIPY fluorescent probe. We observed that addition of AnaCTDH-ECN to liposomes led to the significant changes in the fast-kinetic component of the fluorescence decay curve, pointing on the dipole-dipole interactions between the probe and ECN within the membrane. It may serve as an indirect evidence of ECN delivery into membrane. To study the delivery in detail, we carried out molecular dynamics modeling of the localization of ECN within the lipid bilayer and calculate its orientation factor. Next, we exploited FRET to assess concentration of ECN delivered by AnaCTDH. Finally, we used time-resolved fluorescence anisotropy to assess changes in microviscosity of liposomal membranes. Incorporation of liposomes with β-carotene increased membrane microviscosity while the effect of astaxanthin and its mono- and diester forms was less pronounced. At temperatures below 30 °C addition of AnaCTDH-ECN increased membrane microviscosity in a concentration-dependent manner, supporting the protein-mediated carotenoid delivery mechanism. Combining all data, we propose FRET-based analysis and assessment of membrane microviscosity as potent approaches to characterize the efficiency of carotenoids delivery into membranes.

Lokteva D.A., Kononevich Y.N., Temnikov M.N., Nezhnyy P.A., Kim E.E., Khanin D.A., Nikiforova G.G., Muzafarov A.M.

A series of new cross-linked polysiloxane polymers based on functionalized cyclo- and oligosiloxane precursors was prepared by UV-induced hydrothiolation “click”-reaction using DMPA as the initiator and their physico-mechanical properties were studied. The study of a morphology of prepared polymers by scanning electron microscopy (SEM) shows that the microstructure of all samples is homogenous. The mechanical properties of all the samples were studied by the tension and compression tests. It was shown that mechanical properties of studied materials, which significantly depends on precursors nature, can be fine-tuned by changing the structure of the initial vinyl precursor. The Young's modulus varies in the range of 4.5–117 MPa in the tension test and in the rage of 6.3–209 MPa in the compression test. The tensile strength varies in the range of 0.3–3.9 MPa in the tension test and in the rage of 2.3–28 MPa in the compression test. The thermal stability of the samples was evaluated by thermal gravimetric analysis (TGA). The weight loss was observed in the range of 275–333 °C in air and 322–370 °C in argon for prepared samples. All samples were characterized by DSC method. It was shown that only DSC curves for polymers 1 and 3 contain transitions related to glass formation (−78 and −35 °C, respectively). All polymer samples have a similar water contact angle in the range of 90–102°. • A series of new cross-linked polysiloxanes was prepared and fully characterized. • Physicochemical, mechanical, and thermal properties of polymers are studied. • Mechanical properties of studied polymers significantly depend on precursors nature.

Pakhomov A.A., Kim E.E., Kononevich Y.N., Ionov D.S., Maksimova M.A., Khalchenia V.B., Maksimov E.G., Anisimov A.A., Shchegolikhina O.I., Martynov V.I., Muzafarov A.M.

A series of multifluorophore compounds with two, four, six and eight BODIPY residues linked to a siloxane core via a flexible spacer was synthesized. An increasing number of BODIPY units caused an enhanced propensity to chromophore aggregation with characteristic photophysical effects evoked by the aggregation. The increase in the number of fluorophores additionally resulted in considerable increase in molar extinction coefficient . Meanwhile, a slight drop of the extinction coefficient as calculated per a single chromophore was detected. Multifluorophore conjugates showed a significant broadening of fluorescence emission bands in polar solvents and a substantial decrease in the fluorescence quantum yield due to the aggregation-caused quenching. Time resolved fluorescence measurements of multifluorophore compounds in different solvents showed that the fluorescence decays have a multiexponential character and strongly depend on the number of fluorophores in the conjugate, polarity/viscosity of the solvent and the detection wavelength. • A series of BODIPY-siloxane conjugates with 2,4,6, and 8 fluorophores in a single molecule was synthesized. • The dyes showed a pronounced solvatochromic behavior. • A moderate quenching of fluorescence. • Decrease of specific extinction coefficient calculated per a single chromophore. • Fluorescence lifetimes depend on the detection wavelength and solvent.

Kim E.E., Kononevich Y.N., Dyuzhikova Y.S., Ionov D.S., Khanin D.A., Nikiforova G.G., Shchegolikhina O.I., Vasil’ev V.G., Muzafarov A.M.

Nowadays, luminescent materials attract wide attention due to their valuable characteristics and broad area of potential application. Luminescent silicone-based polymers possess unique properties, such as flexibility, hydrophobicity, thermal and chemical stabilities, etc., which allow them to be utilized in various fields, such as optoelectronics, solid-state lasers, luminescent solar concentrators, sensors, and others. In the present work, a metal-ligand interaction approach was applied to obtain new cross-linked luminescent polymers based on multiligand polysiloxanes with grafted β-diketone fragments and organoeuropiumsiloxanes containing various organic substituents. Organoeuropiumsiloxanes were utilized as a source of Eu3+ ions due to their compatibility with the silicon matrix. All synthesized polymers were fully characterized and their physicochemical, mechanical, self-healing, optical, and thermal properties were studied.

Kim E.E., Kononevich Y.N., Anisimov A.A., Buzin M.I., Vasil'ev V.G., Korlyukov A.A., Ionov D.S., Khanin D.A., Shtykova E.V., Volkov V.V., Muzafarov A.M.

Elastic cross-linked by metal-ligand interaction networks based on polysiloxanes have attracted wide attention in the field of materials science as materials with self-healing, shape-memory and recyclable elastomeric properties. A series of novel cross-linked polymers based on linear polysiloxane and metal β -diketonate precursors by the reaction of multiligand PDMS with grafted β -diketonate fragments and Nickel (II) acetate have been successfully prepared and fully characterized. Physicochemical, mechanical, rheological and thermal properties of all polymers are studied. The proposed approach to preparation coordination polysiloxane polymers can be usefully utilized at the design and development of new smart materials with unique properties and easy recyclability. • A series of novel cross-linked polymers have been prepared and fully characterized. • β -Diketonate fragments grafted on PDMS and Ni 2+ ion were used for cross-linking. • Physicochemical, mechanical, rheological, thermal properties of polymers are studied.

Kim E.E., Kononevich Y.N., Volodin A.D., Khanin D.A., Korlyukov A.A., Muzafarov A.M.

In this work, a series of novel macrocycles and helicates based on organosilicon bis-dibenzoylmethane ligand have been synthesized and characterized as well as their structures have been determined by X-ray analysis, MS, NMR and UV–Vis spectroscopy. The thermal stability of the complexes was estimated by thermal gravimetric analysis (TGA).

Kim E.E., Belova A.S., Filimonova L.V., Khanin D.A., Nikiforova G.G., Kononevich Y.N., Shchegolikhina O.I., Muzafarov A.M.

Makarov G.I., Makarova T.M.

As a supplement to the widely used general AMBER force field, a set of parameters is proposed for molecular dynamics modeling of the structure and properties of polymer chains in polyalkylsiloxane matrices of materials capable of selfhealing after stress loads.

Efimova A.S., Ustimova M.A., Frolova A.Y., Martynov V.I., Deyev S.M., Fedorov Y.V., Fedorova O.A., Pakhomov A.A.

Makarov G.I., Deriabin K.V., Islamova R.M., Bartashevich E.V.

Polymer–metal complexes of polydimethylsiloxanes are especially promising materials because of their self–healing ability. The structural models of the copolymer of $$\alpha $$ , $$\omega $$ –(3–aminopropyl)polydimethylsiloxane and 2,6–pyridinedicarboxamide coordinating Ni(II) ions in various proportions were constructed using the molecular dynamics simulation methods and fragment condensation approach. The glass transition temperature, isothermal compressibility coefficient, and volumetric coefficient of thermal expansion were estimated. For the developed structural models those characteristics did not have an apparent dependence on the Ni(II) content. The analysis of structural organization of copolymeric models revealed that the water molecules were aggregated in clusters in proximity to the Ni(II) 2,6–pyridinedicarboxamide homoleptic complexes. The geometrical characteristics of the copolymer chains coiled into irregular helices were determined. The methodology of the chain twisting estimation was proposed.

Wang J., Ding H., Bi Z., Liu L., Sun N., Wang W., Wang C., He H., Zhou K., Yu B.

Mohanty S., Parameswaran B., Sarkar S., Kumar A., Behera P.K., Singha N.K., Gupta V.K.

Click chemistry is an innovative approach to synthesizing new molecules by connecting two or more chemical entities having complementary “spring-loaded” reactive functional groups. Click reactions such as thiol–ene reactions, azide–alkyne reactions, Diels–Alder (DA) reactions, and retro Diels–Alder (rDA) reactions are useful in the synthesis of a single product with high yield and purity. Due to the high selectivity and good yield, these click reactions have become practical and reliable methods to develop new grades of polymer products with improved properties via post-synthetic structural modifications. Polyolefin elastomers having diversified structures and properties are widely used in various industries like the automotive, construction, medical, military and defense sectors. The major consumption of elastomers is mainly in tires, shoe soles, sports equipment, construction sealant, building materials, and toys. Due to the inhomogeneous structure and low functionality of the polymers used in elastomers, the tuning of properties and structural modifications are challenging. To overcome these challenges click reactions are considered as a simple and efficient way to tune the structure and achieve the desired properties by post-synthetic structural modification of the polymer chains. In this chapter, we will discuss the post-synthetic modifications of elastomers such as natural rubber (NR), polybutadiene rubber (PBR), styrene–butadiene rubber (SBR), isobutylene isoprene rubber (IIR), ethylene propylene diene monomer (EPDM), silicone rubber, and other specialty elastomers by various click reactions, including DA, rDA, azide–alkyne, and thiol–ene reactions, and the effect of such chemical modifications on the properties of the elastomers.

Yagafarov N., Kuang J., Takeda N., Liu Y., Ouali A., Unno M.

A mild and highly selective hydrosilylation method was employed to synthesize five novel well-defined Janus ring siloxanes bearing terpenes and terpenoids, which are the main bioactive components of essential oils. The characterization of these new bio-sourced molecular materials, derived from hydrosilyl-substituted all-cis-cyclotetrasiloxane, was conducted through comprehensive analyses using multinuclear NMR, infrared spectroscopy, elemental analysis, and mass spectroscopy. The thermal stability of the newly synthesized Janus rings was investigated, and the siloxane skeleton was shown to confer an enhanced thermal stability compared with free terpenes and terpenoids.

Kim E.E., Ershova T.O., Belova A.S., Khanin D.A., Bashkova E.V., Nikiforova G.G., Kononevich Y.N., Anisimov A.A., Shchegolikhina O.I., Muzafarov A.M.

Likkei K., Moldenhauer M., Tavraz N.N., Egorkin N.A., Slonimskiy Y.B., Maksimov E.G., Sluchanko N.N., Friedrich T.

Carotenoids perform multifaceted roles in life ranging from coloration over light harvesting to photoprotection. The Orange Carotenoid Protein (OCP), a light-driven photoswitch involved in cyanobacterial photoprotection, accommodates a ketocarotenoid vital for its function. OCP extracts its ketocarotenoid directly from membranes, or accepts it from homologs of its C-terminal domain (CTDH). The CTDH from Anabaena (AnaCTDH) was shown to be important for carotenoid transfer and delivery from/to membranes. The C-terminal tail of AnaCTDH is a critical structural element likely serving as a gatekeeper and facilitator of carotenoid uptake from membranes. We investigated the impact of amino acid substitutions within the AnaCTDH-CTT on echinenone and canthaxanthin uptake from DOPC and DMPG liposomes. The transfer rate was uniformly reduced for substitutions of Arg-137 and Arg-138 to Gln or Ala, and depended on the lipid type, indicating a weaker interaction particularly with the lipid head group. Our results further suggest that Glu-132 has a membrane-anchoring effect on the PC lipids, specifically at the choline motif as inferred from the strongly different effects of the CTT variants on the extraction from the two liposome types. The substitution of Pro-130 by Gly suggests that the CTT is perpendicular to both the membrane and the main AnaCTDH protein during carotenoid extraction. Finally, the simultaneous mutation of Leu-133, Leu-134 and Leu-136 for alanines showed that the hydrophobicity of the CTT is crucial for carotenoid uptake. Since some substitutions accelerated carotenoid transfer into AnaCTDH while others slowed it down, carotenoprotein properties can be engineered toward the requirements of applications.

Parshina E.K., Deriabin K.V., Kolesnikov I.E., Novikov A.S., Kocheva A.N., Golovenko E.A., Islamova R.M.

AbstractPolymer‐metal complexes (PMCs) based on poly(2,2′‐bipyridine‐4,4′‐dicarboxamide‐co‐polydimethylsiloxanes) with cyclometalated di(2‐phenylpyridinato‐C2,N')iridium(III) fragments and cross‐linked by Zn2+ (Zn[Ir]‐BipyPDMSs) or Ir3+ (Ir[Ir]‐BipyPDMSs) represent flexible, stretchable, phosphorescent, and self‐healing molecular oxygen sensors. PMCs provide strong phosphorescence at λem = 595–605 nm. Zn[Ir]‐BipyPDMS with PDMS chain length of Mn = 5000 has the highest quantum yield of 9.3% and is a molecular oxygen sensor at different O2 concentrations (0–100 vol%) compared to Ir[Ir]‐BipyPDMSs. A Stern−Volmer constant is determined for Zn[Ir]‐BipyPDMS as KSV = 0.014%−1, which is similar to the reported oxygen‐sensitive iridium(III) complexes. All synthesized PMCs exhibit high elongation at break (up to 1100%) and self‐healing efficiency (up to 99%).

Pasenkiewicz-Gierula M., Hryc J., Markiewicz M.

In contrast to plants, humans are unable to synthesise carotenoids and have to obtain them from diet. Carotenoids fulfil several crucial biological functions in the organism; however, due to poor solubility in water, their bioavailability from plant-based food is low. The processes of carotenoid absorption and availability in the human body have been intensively studied. The recent experimental findings concerning these processes are briefly presented in the introductory part of this review, together with a summary of such topics as carotenoid carriers, body transport and tissue delivery, to finally report on molecular-level studies of carotenoid binding by membrane receptors. The main message of the review is contained in the section describing computational investigations of carotenoid intercalation and dynamic behaviour in lipid bilayers. The relevance of these computational studies lies in showing the direct link between the microscopic behaviour of molecules and the characteristics of their macroscopic ensembles. Furthermore, studying the interactions between carotenoids and lipid bilayers, and certainly proteins, on the molecular- and atomic-level using computational methods facilitates the interpretation and explanation of their macroscopic properties and, hopefully, helps to better understand the biological functions of carotenoids.

Minyaylo E.O., Kudryavtseva A., Anisimov A., Zaitsev A.V., Khanin D., Ol'shevskaya V.A., Buzin M.I., Peregudov A.S., Shchegolikhina O., Muzafarov A.

The synthesis of novel stereoregular carborane-containing phenylcyclosiloxanes (4, 5, 6, 8, 12 -SiO- units in the ring) has been developed. The structures of all compounds were confirmed by a complex...

Frolova A.Y., Kutyakov S.V., Martynov V.I., Deyev S.M., Pakhomov A.A.

In this work, we synthesized a green fluorescent dye derivative, 1,3,5,7-tetramethyl-BODIPY, with a heptyl substituent at the 8-position. The obtained highly hydrophobic compound was able to rapidly and irreversibly bind to eukaryotic cells. Incubation of cells with the dye over different periods of time or at different concentrations allowed us to control the degree of cell labeling and the level of fluorescence. This made it possible to modulate the fluorescence level of different eukaryotic cell cultures and then distinguish them by their level of fluorescence signal in the green channel in cytometric experiments. The labeled cells can be combined and further analyzed in the same test tube under identical conditions using the channels in which the dye does not fluoresce. This approach has been tested on a number of tumor cell cultures containing the HER2 receptor on their surface. The representation of the receptor in these cells was analyzed in one test tube in one run using a HER2-specific ligand based on the hybrid protein DARPin9_29-mCherry, which fluoresces in the red region of the spectrum.

Chen L., Hu J.

Likkei K., Moldenhauer M., Tavraz N.N., Maksimov E.G., Sluchanko N.N., Friedrich T.

Carotenoids are pigments of diverse functions ranging from coloration over light-harvesting to photoprotection. Yet, the number of carotenoid-binding proteins, which mobilize these pigments in physiological media, is limited, and the mechanisms of carotenoid mobilization are still not well understood. The same applies for the determinants of carotenoid uptake from membranes into carotenoproteins, especially regarding the dependence on the chemical properties of membrane lipids. Here, we investigate xanthophyll uptake capacity and kinetics of a paradigmatic carotenoid-binding protein, the homolog of the Orange Carotenoid Protein's C-terminal domain from Anabaena sp. PCC 7120 (AnaCTDH), using liposomes formed from defined lipid species and loaded with canthaxanthin (CAN) and echinenone (ECN), respectively. Phospholipids with different chain length and degree of saturation were investigated. The composition of carotenoid-loaded liposomes directly affected the incorporation yield and storage ratio of CAN and ECN as well as the rate of carotenoid uptake by AnaCTDH. Generally, saturated PC lipids were identified as unsuitable, and a high phase transition temperature of the lipids negatively affected the carotenoid incorporation and storage yield. For efficient carotenoid transfer, the velocity increases with increasing chain length or membrane thickness. An average transfer yield of 93 % and 43 % were obtained for the formation of AnaCTDH(CAN) and AnaCTDH(ECN) holoproteins, respectively. In summary, the most suitable lipids for the formation of AnaCTDH(CAN/ECN) holoproteins by carotenoid transfer from artificial liposomes are phosphatidylcholine (18:1) and phosphatidylglycerol (14:0). Thus, these two lipids provide the best conditions for further investigation of lipid-protein interaction and the carotenoid uptake process.

Anokhina T.S., Ershova T.O., Anisimov A.A., Temnikov M.N., Grushevenko E.A., Borisov I.L., Volkov A.V., Muzafarov A.M.

This paper presents the results of studies on the pervaporation properties (for benzene/hexane mixtures) and gas permeability (for He, H2, N2, O2, CO2, CH4, C2H6, and C4H10) of ladder-like polyphenylsesquioxanes (L-PPSQ) with improved physical and chemical properties. These polymers were obtained by condensation of cis-tetraphenylcyclotetrasiloxanetetraol in ammonia medium. The structure of L-PPSQ was fully confirmed by a combination of physicochemical analysis methods: 1H, 29Si NMR, IR spectroscopy, HPLC, powder XRD, and viscometry in solution. For the first time, a high molecular weight of the polymer (Mn = 238 kDa, Mw = 540 kDa) was achieved, which determines its improved mechanical properties and high potential for use in membrane separation. Using TGA and mechanical analysis methods, it was found that this polymer has high thermal (Td5% = 537 °C) and thermal-oxidative stability (Td5% = 587 °C) and good mechanical properties (Young’s module (E) = 1700 MPa, ultimate tensile stress (σ) = 44 MPa, elongation at break (ε) = 6%), which is important for making membranes workable under various conditions. The polymer showed a high separation factor for a mixture of 10% wt. benzene in n-hexane (126) at a benzene flow of 33 g/(m2h).

Pol'shchikova N.V., Sergienko N.V., Belova A.S., Kononevich Y.N., Ionov D.S., Khanin D.A., Buzin M.I., Nikiforova G.G., Shchegolikhina O.I., Muzafarov A.M.

In the present work, a method for the preparation of the new luminescent polymer compositions was described. A series of polymer films based on organosilicon dimethylsiloxane-phenylsilsesquioxane block-copolymer containing flexible linear dimethylsiloxane and rigid polycyclic phenylsilsesquioxane blocks in the structure of the macromolecule and polyfunctional phenyleuropiumethoxysiloxane [C6H5Si(OC2H5)2O]3Eu, as a molecular luminescent filler, was prepared and fully characterized. Physicochemical, mechanical, optical, and thermal properties all the polymer films were investigated. The polymer films form stable 3D networks and demonstrate a high thermal and thermo-oxidative stability. The study of mechanical properties showed that the tensile strength is in the range of 14–19 MPa, elongation at break is in the range of 5–8% and the Young's modulus is in the range of 380–560 MPa for the investigated polymers. The optical properties of the polymers were studied in the solid state at room temperature. It was shown, that upon excitation with 310 nm UV light the emission spectra of all samples show the five emission peaks that are characteristic for the Eu3+ ion arising from the 5D0→7FJ (J = 0–4) transitions.

Yue X., Zeng S., Sun R., Li Y., Lu A., Kang M., Yu F.

Xie G., Wang Y., Zhou X., He L., Li H.

Developing a contactless ratiometric luminescent thermometry with high sensitivity, widely available temperature range, and reliable performance is still a challenge in materials science. Herein, we adopted an in-situ formation strategy to synthesize luminescent lanthanide complexes in siloxane-polyether matrix by the reaction between 4′-(4-carboxyphenyl)- 2,2′:6′,2″- terpyridine (Hcptpy) ligand and lanthanide ions (Eu 3+ /Tb 3+ ) to realize a ratiometric luminescent thermometer. The unique energy cascade from Hcptpy → Tb 3+ → Eu 3+ in siloxane-polyether enables the luminescent films to be not only the multi-color emission, but also provide highly temperature-sensitive over the wide temperature range. The EuTb 15 @SP film for luminescent thermometry performance is fine-tuned to reach a maximum relative sensitivity of 7.26% K −1 at 397 K and shows repeated utilization without sensitivity loss. Furthermore, the multi-color emission ranging from red through yellow to green can be achieved by tuning the Eu 3+ /Tb 3+ molar ratio. Consequently, utilizing siloxane-polyether as matrix has been proven to be an effective strategy for constructing lanthanide-based hybrid films with temperature sensor properties. We believe that the reported strategies for preparing a bimetallic complex-doped siloxane-polyether hybrid film will broaden potential applications. • Transparent hybrid films with high sensing performance were synthesized by simple sol-gel method. • The hybrid films exhibit excellent optical properties and show remarkable increase in PLQY. • Multi-color hybrid films can be obtained by adjusting the temperature or the lanthanide ions molar ratio. • Because of the energy transfer between the bimetallic emission centers, the film can be used as a luminescent thermometer. • The hybrid films display excellent temperature detecting performance in the range of 77–397 K with a maximum relative sensitivity of 7.26% K −1 .

Zou W., Ramanathan R., Urban S., Sinclair C., King K., Tinker R., Bansal V.

Sunscreens have become a mainstream consumer product for protection against the damaging ultraviolet (UV) radiation in sunlight. Before a sunscreen is released to the market, it must undergo a set of safety and efficacy tests established by a government or relevant regulatory authority. Regulatory bodies rely on access to appropriate analytical methods to ensure product compliance. The current sunscreen testing standards, particularly those to evaluate the sunscreen efficacy, are far from ideal from both a regulatory and an ethical perspective. For instance, some tests mandate unwarranted exposure of UV radiation to humans and cannot be reliably replicated. This article aims to provide a comprehensive review of the existing sunscreen testing standards, while providing a critical perspective on associated challenges, demands and opportunities in improving analytical methods for sunscreen testing. This review will provide a roadmap for those interested in sunscreen testing, including manufacturers, regulatory bodies, policy makers and academic researchers. • Multiple historical and current sunscreen testing methods comprehensively reviewed. • Sunscreen regulations across key global jurisdictions compared. • Issues and challenges associated with sunscreen testing critically discussed. • Future roadmap and directions for the development of analytical methods for sunscreen testing provided.

Belova A.S., Khchoyan A.G., Il’ina T.M., Kononevich Y.N., Ionov D.S., Sazhnikov V.A., Khanin D.A., Nikiforova G.G., Vasil’ev V.G., Muzafarov A.M.

A method for the preparation of polydimethylsiloxanes with grafted methoxy-substituted dibenzoylmethanatoboron difluoride has been described. The structures of prepared polymers were confirmed using NMR, IR spectroscopy and gel permeation chromatography methods. Their thermal properties were investigated using thermal gravimetric analysis, differential scanning calorimetry and thermomechanical analysis. The prepared polymers had good thermal (Td5% up to 393 °C) and thermo-oxidative (Td5% = 413 °C) stability. The polymers started to transit in a viscous flow state at about 40 °C (for 3 a) and at about 20 °C (for 3 b). The viscoelastic characteristics of prepared polymers were determined in the sinusoidal oscillating vibrations mode. It was shown that the studied polymers at low frequencies at room temperature are viscoelastic fluids (G′ < G″). Increasing the frequency led to inversion (crossover) of dependences G′ and G″, which indicated the transition of polymers from viscous to elastomeric behavior characteristics, and the beginning of the formation of a physical network. Optical properties were studied using electron absorption, steady-state and time-resolved fluorescence spectroscopy. It was shown that intramolecular H-dimers exist in the ground state. The polymers studied had a bright fluorescence in the solution and in the solid state, consisting of bands of monomer and excimer emission. Thermally-activated delayed fluorescence was observed in the solution and the solid state. The prepared polymers possess intriguing properties that make them useful as optical materials, sensors or imaging agents.

Birchall L., Foerster A., Rance G.A., Terry A., Wildman R.D., Tuck C.J.

The drive towards device miniaturisation in fields such as microfluidics or microelectronics has established a need for non-intrusive, in situ temperature sensing, which is difficult to implement and manufacture in devices. Inkjet printing is a non-contact, maskless deposition method which is compatible with a wide range of materials and may enable the economical design and production of such devices. However, current inkjet-printed thermal sensors are predominantly based on resistance across printed circuits and do not meet the requirements for miniaturised devices. In this paper, an inkjet-printable material for luminescence-based temperature sensing is presented. Two-part reactive inks are developed using CdSe/ZnS quantum dots immobilised in an addition cure silicone matrix. Further platinum catalyst is added to resolve issues with catalyst poisoning by labile QD ligands, with the effect of catalyst loading on the degree of conversion and QD emission probed using Raman microscopy and well-plate reading, respectively. A mechanism for platinum-induced quenching is proposed. The inkjet printing of a bulk QD-silicone composite is successfully demonstrated for the first time, enabling a new route for devices with embedded luminescence thermometry. Confocal laser scanning microscopy is used to characterise the temperature response of the material, demonstrating sensing with a thermal coefficient of emission intensity of − 0.68 to − 0.93 % °C −1 between 30 and 60 °C. We anticipate that this material has application for in situ thermal analysis and calibration within the fields of microfluidics. • Fluorescent CdSe/ZnS quantum dots/silicone composite inks are formulated for RIP • A thermal coefficient of emission intensity of − 0.68 to − 0.93 % °C −1 between 30 and 60 °C is observed. • RIP is demonstrated with an average drop diameter of 37.5 µm.

Khrebtov A.A., Fedorenko E.V., Mirochnik A.G.

Great potential has been discovered in the development of materials with a long afterglow (phosphorescence at room temperature and delayed fluorescence) for the purposes of luminescent sensing, bioimaging, information encryption and OLED. Here, we report the long-lived (lifetime up to 1.5 s) laser-induced room-temperature excimer delayed fluorescence (RTEDF) of difluoroboron β-diketonate complexes (BF 2 bdks) already at concentrations of 0.05% in solution cast polymer films. The emission centers of RTEDF of BF 2 bdks can retain for a long time in the polycarbonate matrix (>3 months) and can be repeatedly re-excited with a low-intensity ultraviolet light source. These results provide a foundation for the design of materials with applications in optical information storage and data encryption and decryption. • Difluoroboron β-diketonates form excimers in polymer films under laser irradiation. • Bright room-temperature excimer delayed fluorescence in polymers was revealed. • Lifetime of excimer delayed fluorescence is up to 1.5 s. • Excimer delayed fluorescence can retain for a long time (>3 months). • This phenomenon can be used for optical information storage and data encryption.

Slonimskiy Y.B., Egorkin N.A., Ashikhmin A.A., Friedrich T., Maksimov E.G., Sluchanko N.N.

Natural water-soluble carotenoproteins are promising antioxidant nanocarriers for biomedical applications. The Carotenoid-Binding Protein from silkworm Bombyx mori (BmCBP) is responsible for depositing carotenoids in cocoons. This determines the silk coloration, which is relevant for sericulture for four thousand years. While BmCBP function is well-characterized by molecular genetics, its structure and carotenoid-binding mechanism remain to be studied. To facilitate this, here we report on successful production of soluble BmCBP in Escherichia coli , its purification and characterization. According to CD spectroscopy and SEC-MALS, this protein folds into a ~ 27-kDa monomer capable of dose-dependent binding of lutein, a natural BmCBP ligand, in vitro. Binding leads to a >10 nm red-shift of the carotenoid absorbance and quenches tryptophan fluorescence of BmCBP. Using zeaxanthin, a close lutein isomer that can be stably produced in engineered E.coli strains, we successfully reconstitute the BmCBP holoform and characterize its properties. While BmCBP successfully matures into the holoform, BmCBP-zeaxanthin complexes are contaminated by the apoform. We demonstrate that the yield of the holoform can be increased by adding bovine serum albumin during cell lysis and that the remaining BmCBP apoform is efficiently removed using hydroxyapatite chromatography. Bacterial production of BmCBP paves the way for its structural studies and applications.

Darvin M.E., Lademann J., von Hagen J., Lohan S.B., Kolmar H., Meinke M.C., Jung S.

The antioxidant system of the human body plays a crucial role in maintaining redox homeostasis and has an important protective function. Carotenoids have pronounced antioxidant properties in the neutralization of free radicals. In human skin, carotenoids have a high concentration in the stratum corneum (SC)—the horny outermost layer of the epidermis, where they accumulate within lipid lamellae. Resonance Raman spectroscopy and diffuse reflectance spectroscopy are optical methods that are used to non-invasively determine the carotenoid concentration in the human SC in vivo. It was shown by electron paramagnetic resonance spectroscopy that carotenoids support the entire antioxidant status of the human SC in vivo by neutralizing free radicals and thus, counteracting the development of oxidative stress. This review is devoted to assembling the kinetics of the carotenoids in the human SC in vivo using non-invasive optical and spectroscopic methods. Factors contributing to the changes of the carotenoid concentration in the human SC and their influence on the antioxidant status of the SC in vivo are summarized. The effect of chemotherapy on the carotenoid concentration of the SC in cancer patients is presented. A potential antioxidant-based pathomechanism of chemotherapy-induced hand-foot syndrome and a method to reduce its frequency and severity are discussed.

Magalingam K.B., Somanath S.D., Haleagrahara N., Selvaduray K.R., Radhakrishnan A.K.

Carotenoids, fat-soluble pigments found ubiquitously in plants and fruits, have been reported to exert significant neuroprotective effects against free radicals. However, the neuroprotective effects of total mixed carotenes complex (TMC) derived from virgin crude palm oil have not been studied extensively. Therefore, the present study was designed to establish the neuroprotective role of TMC on differentiated human neural cells against 6-hydroxydopamine (6-OHDA)-induced cytotoxicity. The human neural cells were differentiated using retinoic acid for six days. Then, the differentiated neural cells were pre-treated for 24 hr with TMC before exposure to 6-OHDA. TMC pre-treated neurons showed significant alleviation of 6-OHDA-induced cytotoxicity as evidenced by enhanced activity of the superoxide dismutase (SOD) and catalase (CAT) enzymes. Furthermore, TMC elevated the levels of intra-neuronal dopamine and tyrosine hydroxylase (TH) in differentiated neural cells. The 6-OHDA induced overexpression of α-synuclein was significantly hindered in neural cells pre-treated with TMC. In proteomic analysis, TMC altered the expression of ribosomal proteins, α/β isotypes of tubulins, protein disulphide isomerases (PDI) and heat shock proteins (HSP) in differentiated human neural cells. The natural palm phytonutrient TMC is a potent antioxidant with significant neuroprotective effects against free radical-induced oxidative stress.

Pakhomov A.A., Kim E.E., Kononevich Y.N., Ionov D.S., Maksimova M.A., Khalchenia V.B., Maksimov E.G., Anisimov A.A., Shchegolikhina O.I., Martynov V.I., Muzafarov A.M.

A series of multifluorophore compounds with two, four, six and eight BODIPY residues linked to a siloxane core via a flexible spacer was synthesized. An increasing number of BODIPY units caused an enhanced propensity to chromophore aggregation with characteristic photophysical effects evoked by the aggregation. The increase in the number of fluorophores additionally resulted in considerable increase in molar extinction coefficient . Meanwhile, a slight drop of the extinction coefficient as calculated per a single chromophore was detected. Multifluorophore conjugates showed a significant broadening of fluorescence emission bands in polar solvents and a substantial decrease in the fluorescence quantum yield due to the aggregation-caused quenching. Time resolved fluorescence measurements of multifluorophore compounds in different solvents showed that the fluorescence decays have a multiexponential character and strongly depend on the number of fluorophores in the conjugate, polarity/viscosity of the solvent and the detection wavelength. • A series of BODIPY-siloxane conjugates with 2,4,6, and 8 fluorophores in a single molecule was synthesized. • The dyes showed a pronounced solvatochromic behavior. • A moderate quenching of fluorescence. • Decrease of specific extinction coefficient calculated per a single chromophore. • Fluorescence lifetimes depend on the detection wavelength and solvent.

Sluchanko N.N., Slonimskiy Y.B., Egorkin N.A., Varfolomeeva L.A., Kleymenov S.Y., Minyaev M.E., Moysenovich A.M., Parshina E.Y., Friedrich T., Maksimov E.G., Boyko K.M., Popov V.O.

AbstractFound in many organisms, soluble carotenoproteins are considered as antioxidant nanocarriers for biomedical applications, although the structural basis for their carotenoid transfer function, a prerequisite for rational bioengineering, is largely unknown. We report crystal structures of the Carotenoid-Binding Protein from Bombyx mori (BmCBP) in apo- and zeaxanthin (ZEA)-bound forms. We use spectroscopy and calorimetry to characterize how ZEA and BmCBP mutually affect each other in the complex, identify key carotenoid-binding residues, confirm their roles by crystallography and carotenoid-binding capacity of BmCBP mutants and reconstitute BmCBP complexes with biomedically-relevant xanthophylls lutein, zeaxanthin, canthaxanthin and astaxanthin. By cost-effectively and scalably solubilizing xanthophylls from various crude herbal extracts, His-tagged BmCBP remains monomeric and forms a dynamic nanocontainer delivering carotenoids to liposomes and to other carotenoid-binding proteins, which in particular makes the Orange Carotenoid Protein, a promising optogenetic tool, photoactive. Furthermore, BmCBP(ZEA) administration stimulates fibroblast growth, which paves the way for its biomedical applications.

Kim E.E., Kononevich Y.N., Dyuzhikova Y.S., Ionov D.S., Khanin D.A., Nikiforova G.G., Shchegolikhina O.I., Vasil’ev V.G., Muzafarov A.M.

Nowadays, luminescent materials attract wide attention due to their valuable characteristics and broad area of potential application. Luminescent silicone-based polymers possess unique properties, such as flexibility, hydrophobicity, thermal and chemical stabilities, etc., which allow them to be utilized in various fields, such as optoelectronics, solid-state lasers, luminescent solar concentrators, sensors, and others. In the present work, a metal-ligand interaction approach was applied to obtain new cross-linked luminescent polymers based on multiligand polysiloxanes with grafted β-diketone fragments and organoeuropiumsiloxanes containing various organic substituents. Organoeuropiumsiloxanes were utilized as a source of Eu3+ ions due to their compatibility with the silicon matrix. All synthesized polymers were fully characterized and their physicochemical, mechanical, self-healing, optical, and thermal properties were studied.

Feng M., Wang N., Li J., Feng S., Xu X.

In this work, in order to improve the low solubility and expand the applications of porphyrins in polysiloxanes, a series of designed siloxane-modified porphyrin derivatives was fabricated based on the Piers-Rubinsztajn reaction. The solubility of the porphyrin derivatives in polysiloxanes could be controlled by adjusting the siloxane chain length. Furthermore, the silicone-modified porphyrin derivatives were doped into a silicone elastomer prepolymer to obtain luminescent elastomers, which also showed good transparency and interfacial stability. In addition, the thermal stability and mechanical properties were well preserved compared with the original elastomer. Finally, based on the above-mentioned properties, an organosilicon elastomer doped with porphyrin showed good processability and plasticity, and could be fabricated into various complex three-dimensional models. The designed siloxane-modified porphyrin derivatives were fabricated using the Piers-Rubinsztajn reaction. Doping them into a silicone prepolymer produced homogeneous luminescent elastomers for the processing of 3D materials.