Sandalwood-derived carbon quantum dots as bioimaging tools to investigate the toxicological effects of malachite green in model organisms.

Malachite green is an N-methylated diaminophenylmethane dye that has generated much concern over its suggestive carcinogenic nature. After its excessive use in aquaculture industry as an effective ectoparasitide, much debate was raised over its toxicological effects leading to scientific studies conducted on animal models. Even after several bans, malachite green is still easily available in many parts of the world and unscrupulously even used to give green vegetables a fresher look. This study aims to address this concern by systematically studying the toxicological effects of malachite green through bioimaging in plant and animal cell and tissue. Sandalwood-derived carbon quantum dots have been used as a bioimaging tool since they are non-cytotoxic and show excellent fluorescence properties. Onion tissues demonstrate the translocation of the dye inside cells having high affinity for the nuclei and cell walls. Toxicological effects on the growth of Vigna radiata (mung beans) have been studied methodically. Bioimaging of the transverse cross-section of the dye-treated plant root shows a significant difference from the control. In animal cells, dose-dependent decrease in cell viability of MG-63 cells was observed with MG. CQD showed good fluorescence in both cytoplasm and nucleus of MG63 cells. In addition, CQDs were employed as a great tool for bioimaging of the histopathologically adverse effects of MG in Golden hamster animal model. This study showed CQDs could be used as an alternative non-site specific fluorescent probe for cell and tissue imaging for better visualization of cell and tissue architectural changes.

Characterization of Self-Assembled Protein Scaffolds from Collagen-Mimetic Peptides.

Collagen-mimetic peptides have been utilized to form structures of different morphology for various biomedical and nanotechnology applications. This chapter describes the characterization of collagen-mimetic peptide self-assembled structures formed by tuning the interactions between peptides. Inclusion of varying hydrophobicity, electrostatic forces, and stereoselectivity was mainly employed in CMP designs discussed herein. The role of these forces can be assessed using multiple characterization techniques. Light scattering techniques have been employed to study the aggregation kinetics of self-assembled nanostructures and to investigate the net charge distribution of peptides. Spectroscopy techniques like circular dichroism, fluorescence, and absorption spectroscopy have been utilized to decipher the secondary structures of peptide and binding of the peptides with dyes. Imaging techniques helped in resolving the morphology of the self-assembled structures. Confocal fluorescence microscopy and differential scanning calorimetry helped in indirect assessment of hydrophobicity and X-ray studies to determine the inter-helical spacing between the triple helical peptides of the higher order structures.