Metal halide perovskite nanocrystals for biomedical engineering: Recent advances, challenges, and future perspectives

Halide perovskites (HaPs) quantum dots (QDs) have emerged as appealing optoelectronic components for a wide range of applications in photovoltaics, lightning, sensing, and bioimaging technology. However, the practical advantages of all HaPs QDs solutions are highly curtailed attributable to the presence of toxic lead ion and easy structural breakdown upon light irradiation, thermal heating, and polar solvents, limiting their biomedical applicability. In this review, for the first time, the significance of HaPs QDs in biomedical applications, such as bioimaging, light-activated therapeutics, and biosensing technologies have been systematically summarized. The optoelectronic properties, structural studies, and synthesis methodologies of HaPs QDs, as well as their structural intolerance to polar environments and light exposure, were highlighted. Importantly, various encapsulation strategies for strengthening the structural and luminescence stability of HaPs QDs in aqueous solvents and under light illumination was thoroughly evaluated. The clear advancement of HaPs QDs in cancer cell imaging, biomolecule sensing, photodynamic aspects, and photocatalytic cancer therapy application was also briefly introduced. The improvements in the stability of HaPs QDs against moisture, light, and the polar environment was assessed and compared across several publications. The prospects for employing HaPs QDs in the assembly of biomaterial for effective anti-cancer therapy via imaging modalities, including single-photon and multi-photon imaging abilities; and therapeutic platforms, such as photodynamic and photocatalytic therapy was comprehensively explored. The current technological advancements are addressed in terms of progress and limitations, followed by an optimistic view of their future potential application.