Polymer-Functionalized NIR-Emitting Nanoparticles: Applications in Cancer Theranostics and Treatment of Bacterial Infections

In recent years, there has been tremendous excitement over the development of new classes of applications for NIR-emitting nanoparticles. These materials have found application in fields diverse as early diagnosis of metastatic cancers, imaging-guided drug delivery and biodistribution studies, photothermal or photodynamic therapy of tumors, non-invasive detection and monitoring of deep-tissue pathogenic infections, and potentiating the antibiotic strength against antibiotic-resistant bacterial infections, to name a few. However, the cornerstone of these applications rests on the successful functionalization of these nanoparticles, in order to render them biocompatible, increase circulation and residence time, and to provide them the necessary targeting capability and enhance the functionality of the imaging agent. Here, we present an in-depth review of the methods used for polymer functionalization of the most common classes of NIR-emitting nanoparticles: organic dyes and small-molecule probes, inorganic quantum dots, gold nanoparticles, carbon dots, carbon nanotubes, graphene and their derivatives, and upconversion or downconversion nanoparticles. By exploring the preclinical studies and the clinical trials (wherever applicable), we investigate the strategies which have been successfully deployed till date, as well as comment on the potential concerns of toxicity arising from the biomedical applications of these nanoparticles.