Mesoporous Bioactive Glass Nanoparticles with Dopants Bismuth and Iron as Magnetic Photothermal Agents for Biomedical Applications

The nanosized 45S5 bioactive glass (BG) containing iron (Fe) and bismuth (Bi) as magnetic photothermal agent (PTA) (B_F_FABG) was first time synthesized by bio-inspired route using folic acid (FA) template. Similarly, for comparative analysis, BGs doped with Fe²⁺/Fe³⁺ or Bi³⁺ separately (F_FABG and B_FABG) were also synthesized. XPS and FTIR analysis of B_F_FABG revealed the presence of FA and dopants Fe²⁺/Fe³⁺ and Bi³⁺ in the BG network. Based on the XRD pattern, B_F_FABG was semi-crystalline in nature, with an average crystallite size of 0.2 ± 0.04 nm. Fe²⁺/Fe³⁺ ions and FA molecules have a lower affinity for the BG network than the heaviest and most polarizable Bi³⁺ ions, according to TGA analysis. An increase of Q⁴ species in the B_F_FABG network was revealed by ²⁹Si NMR investigation due to the presence of Fe²⁺/Fe³⁺ and Bi³⁺ ions. For B_F_FABG, there was also a rise in Q³ and Q² species due to the dual dopants. B_F_FABG is nano-crystalline, with an average diameter of 12.8 ± 0.3 nm, according to HR-TEM and SAED pattern. The BG samples, both doped and undoped, were found to be mesoporous, with pore diameters ranging from 2 to 50 nm. Due to the presence of Bi³⁺ ions, B_F_FABG showed remarkable photoluminescence along with bone-bonding ability during excitation in the range of ~1092 nm. The magnetic characteristics were also induced in B_F_FABG due to Fe²⁺/Fe³⁺ doping. The novel B_F_FABG NPs reported the least toxicity through in-vitro hemolysis assay and is an ultimate multifunctional material to treat bone abnormalities.