Fluorescence imaging is used widely to visualize biological processes, as well as cells (in-vivo and in-vitro) and has revolutionized the field of biomedical research. Semiconductor quantum dots have become a critical diagnostic tool for discerning cellular function at the molecular level. Their high brightness, long-lasting, size-dependent, tunability, and narrow luminescence set them apart from conventional fluorescent dyes. Quantum dots are being developed for a variety of biologically oriented applications, including fluorescent assays for drug discovery, disease detection, single protein tracking, and intracellular reporting. Despite these advantages, there are several challenges that QD imaging suppliers face, including heavy metal toxicity, elimination of reagents from the body, and auto-fluorescence from biological chromophores.
AQM has addressed each of the aforementioned challenges with the development of its silicon nanoparticles. Silicon holds considerable potential for in-vivo bioimaging applications due to its intrinsic tunable photoluminescence, non-toxicity, biodegradability and its large specific capacity for drug loading. SiQDs are small, elemental and are biocompatible with the human body. SiQDs will eventually dissolve to form silicic acid, a positive therapeutic and biological compound easily processed through the renal system.
As silicon is an indirect bandgap semiconductor, it has a much longer-lived excited-state than direct bandgap semiconductors such as CdS or CdSe. This property translates to nanoscale silicon and thereby displays photoluminescent lifetimes on the order of 100 ns to several microseconds. By taking advantage of this property, we see the potential for the application of our patented SiQDs for fluorescence in-vivo bioimaging. The remarkably long emission lifetime (5-130 μs) of photoluminescent porous silicon nanoparticles allows time-gated imaging of tissues in-vivo, completely eliminating shorter-lived (<10 ns) emission signals from organic chromophores or tissue auto-fluorescence.