Folate Receptor Targeting Mn(II) Complex Encapsulated Porous Silica Nanoparticle as an MRI Contrast Agent for Early‐State Detection of Cancer

Cancer is recognized as one of the major causes of mortality, however, early‐stage detection can increase the survival chance greatly. It is recognized that folate receptors are gradually overexpressed in the cellular membrane with the progress of cancer from stage 1 to stage 4. Utilizing the fact, herein, developed a porous silica nanoparticle system C1@SiO₂–FA–NP; A) impregnated with thermodynamically stable Mn(II) complex (1) molecules within the core of the nanoparticle, and B) surface functionalized with folate units. It exhibited a high longitudinal relaxivity value r₁ = 21.45 mM⁻¹s⁻¹ that substantially increased to r₁ = 40.97 mM⁻¹s⁻¹ in the presence of 0.67 mM concentration of BSA under the physiological condition. The in vitro fluorescent images after surface conjugation of C1@SiO₂–FA–NP with FITC (fluorescein isothiocyanate) buttressed the inclusion of the nanoparticle exclusively within the cancerous HeLa cells than that of healthy HEK293 cells. The importance of the surface‐bound folate unit in the nanoparticle is further established by comparing the fluorescent images of HeLa cells in the absence of the group. Finally, the applicability of C1@SiO₂–FA–NP as the T₁‐weighted MRI contrast agent for early‐stage cancer diagnosis is established within C57BL/6 mice after infecting the mice with HeLa cells.