Cancer photodynamic therapy: Silicon quantum dots as therapeutic nanomaterials

Cancer photodynamic therapy (PDT) is a minimally invasive cancer treatment that uses photosensitizers to generate reactive oxygen species (ROS) and induce selective tumor cell death. Conventional PDT agents, including organic dyes and metal-based nanoparticles, face significant limitations such as photobleaching, poor tissue penetration, toxicity, and limited photostability which restrict their clinical effectiveness. Silicon quantum dots (SiQDs) offer a new alternative of photosensitizers that can overcome these limitations. The nanomaterials have already shown strong potential in cancer detection and diagnostics. In addition, SiQDs are also ideal PDT agents because they are heavy-metal-free, non-toxic, biocompatible, photostable, and exhibit tunable optical properties with customizable surfaces for targeted delivery, enhanced precision and therapeutics. Applied Quantum Materials Inc. (AQM) synthesizes SiQDs that are highly-pure, have a narrow-size-distribution and showcase exquisite control over surface modifications (including biomolecule conjugation of 8-150 kDa). These nanomaterials display bright, size-dependent luminescence across the visible-NIR spectrum. Biocompatibility studies show >90% cell viability at concentrations up to 500 µg/mL after 24 h incubation, indicating SiQDs have great potential for clinical translation. AQM's recent advances have shown enhanced material uptake into cancer cells along with improved light-triggered therapeutic activity. Under low-level NIR laser irradiation, findings exhibited significantly reduced cancer cell viability, correlating with increased intracellular ROS generation. Initial results indicate cancer cells destruction in 10 minutes. These outcomes offer great potential for SiQDs as effective photosensitizers for PDT.