Natural rubber latex assisted shape-attuned synthesis of intrinsically radiopaque and magnetic bioceramic nanocomposite with hyperthermia potential for cancer therapeutics

Abstract

Shape-attuned design plays a remarkable role in modulating the hyperthermia potential of magnetic nanomaterials intended for targeted cancer therapy by tuning the saturation magnetization (M_s) together with the time required to achieve hyperthermia temperature. In light of this, a customized approach has been adopted to synthesize a magnetic bioceramic nanocomposite comprising maghemite, hydroxyapatite (HAP) and silica nanoparticles by the sol–gel method, wherein biosynthesized natural rubber latex (NRL) served as a colloidal sacrificial hard template to modulate its ultrastructure via a controlled sintering process. TEM micrographs of the magnetic nanocomposite sintered at 600 °C for 6 h (LMN6) exhibited a comprehensive morphology consisting of hollow silica quasi-nanospheres adjoined to hydroxyapatite nanorods and nearly spherical maghemite nanoparticles. LMN6 has a saturation magnetization of 18 emu g⁻¹ and achieved a hyperthermia temperature (42 °C) within a very short time interval of 6.2 min. Digital X-ray radiography proved its attenuation efficacy with a grey value of 113 and a contrast enhancement of 121.5% compared with its adjacent black background, while micro-CT analysis validated the radiopacity of LMN6 with a CT number of 1353 HU, enabling live monitoring of the bioceramic system in the biological milieu. Moreover, LMN6 with embedded silica nanospheres having a hollow core of ∼80 nm and a non-porous shell of ∼12 nm offered a favourable drug loading efficiency (60.5%) with a sustained and targeted release of 76% of the chemotherapeutic drug ‘doxorubicin’ at the slightly acidic tumour pH of 6.5 within 7 days. Besides, MTT assay and F-actin staining authenticate its biocompatibility, presenting this biomedically relevant system for its utility in combinatorial cancer therapy.