Rapid synthesis of manganese dioxide nanoparticles for enhanced biocompatibility and theranostic applications

Manganese dioxide (MnO₂), lauded for its biocompatibility and distinctive optical and physical characteristics, has become an indispensable material in the biomedical field, showing immense potential in disease detection, treatment, and prevention. Particularly, the ability of MnO₂ nanoparticles to oxidize glutathione (GSH) to its oxidized form has positioned them as pivotal players in GSH sensing. However, conventional preparation methods, whether top-down or bottom-up, often result in nanoparticles that require multi-step processing and modification to achieve good dispersion in physiological conditions, which is both time-consuming and complex. To address this, a rapid and efficient method was developed for producing well-dispersed and stable MnO₂ nanoparticles using tannic acid to reduce potassium permanganate. The polyphenolic structure of tannic acid not only facilitates the reduction process but also enhances the dispersibility of the nanoparticles in biological environments. In addition, PEG could improve the stability of MnO₂ nanoparticles and also reduce their size. Moreover, we demonstrate the application of these nanoparticles in a colorimetric assay for GSH detection, leveraging their ability to react with GSH to produce Mn²⁺. Furthermore, these nanoparticles were utilized in a colorimetric assay for GSH detection, harnessing their reactivity with GSH to generate Mn²⁺. Beyond this, the MnO₂ nanoparticles exhibit potential for the loading of a spectrum of molecules, including small molecules, peptides, DNA, RNA, and proteins, through electrostatic interactions, π-π stacking, and the inherent reactivity of polyphenols. This groundbreaking strategy heralds a new era for MnO₂ in the realm of theranostic agent delivery, offering a promising avenue for enhancing diagnostic accuracy and therapeutic efficacy in biomedical applications.