Visible Bioinspired Nanodots

Nanoscale optical labeling is the advanced bioimaging tool that is based on fluorescence phenomena and enables visualization of bacteria, viruses and biological tissues, provide monitoring of functional biosystems in-vitro and in-vivo and imaging-guided transportation of drug molecules conjugated to fluorescence biomarkers. There is a variety of fluorescence biolabels such as organic molecular dyes, genetically encoded fluorescent proteins such as green fluorescent protein, semiconductor quantum dots and carbon nanodots.

In this work we propose a novel class of visible bioinspired nanodots (VBNDs) possessing unique intrinsic photon emission. These biocompatible nanodots are nanoparticles self-assembled from chemically synthesized ultrashort peptide biomolecules. Developed new technology allows transforming the originally non-fluorescent dots into visible nanoparticles by modification of their peptide secondary structure. We show that after heating of bionanodots to elevated temperature a full refolding of peptide secondary structure from native α-helix like structure to thermally-induced β-sheets occur. Such a spatial transformation of peptide secondary structure leads to a deep modification of bionanodot electronic structure resulting in appearance of two new wide spectral bands of optical absorption and photon emission in blue and green regions. The physical origin of the fluorescence found in VBNDs is completely differed from inorganic counterpart quantum dots and can potentially lead to a new physics and wide biomedical applications.

The main advantages of the proposed VBNDs with respect to existing bioimagers are their highly homogenous ultrasmall size of several nanometers, original biocompatibility and intensive visible fluorescence. The novel visible nanodots of biological origin can be widely used in nanobiotechnology for medical diagnostics and therapy, and can dramatically impact additional nanotechnological fields such as image sensors, light emitting devices, display technology and more.

The authors appreciate support of Ministry of Science, Technology and Space of Israel.