Intriguingly, 13-mer frog-peptide, temporin L (TempL) contains 50% aromatic residues within its first eight residues. Considering the role of aromatic residues in self-assembly of peptides and the potential of such peptides in biomedical applications, we envisaged to identify new short self-assembling peptides from the amino-terminus of TempL and characterize their structural and biological properties. Thus, starting from the eighth to the first residue of TempL, we synthesized five 4 to 8 residue peptides (T-4mer to T-8mer). Different ultrastructural studies suggested nano-spherical/nano-fibrillar structures of these peptides. Remarkably, T-6mer, T-7mer and T-8mer exhibited polyproline type-II circular dichroism spectra of collagen-like triple-helical structure and sigmoidal melting curves like that we observed with rat-tail type-I collagen. Amazingly, the T-8mer peptide at 1.5% (w/v) forms hydrogel within an hour indicating its ability to form supramolecular assembly, saturated with water. We further studied collagen-mimetic nature of these TempL-derived peptides. HepG2 cells showed significant adhesions onto the coatings of T-6mer, T-7mer, T-8mer peptides and rat-tail type-I collagen which got compromised when these cells were pre-treated with antibody of collagen receptor, integrin α2β1. Interestingly, following the adhesions onto the surface of these TempL-derived peptides, cytoskeletal organization was induced in HepG2 cells like that observed in the presence of a collagen protein. Overall, the current results demonstrated the dissection of a frog-peptide, TempL with revelation of collagen-mimetic peptides from its aromatic-residue rich amino-terminus.

Bioelectrodes with low carbon footprint can provide an innovative solution to the surmounting levels of e-waste. Biodegradable polymers offer green and sustainable alternatives to synthetic materials. Here, a chitosan-carbon nanofiber (CNF) based membrane has been developed and functionalized for electrochemical sensing application. The surface characterization of the membrane revealed crystalline structure with uniform particle distribution, and surface area of 25.52 m2/g and pore volume of 0.0233 cm3/g. The membrane was functionalized to develop a bioelectrode for the detection of exogenous oxytocin in milk. Electrochemical impedance spectroscopy was employed to determine oxytocin in a linear concentration range of 10 to 105 ng/mL. The developed bioelectrode showed an LOD of 24.98 ± 11.37 pg/mL and sensitivity of 2.77 × 10-10 Ω / log ng mL-1/mm2 for oxytocin in milk samples with 90.85-113.34 percent recovery. The chitosan-CNF membrane is ecologically safe and opens new avenues for environment-friendly disposable materials for sensing applications.

With the advancement of technology, the use of new and improved materials starting from macro- to micro- and nano-range in varied fields has increased exponentially. Although the scientific community has been interested in nanomaterials due to their unique properties, the use of these innovative materials has given rise to concern regarding their potential toxicity to living beings as well as the environment. This chapter elaborates on how emerging nanomaterials behave in relation to dynamic microenvironments at the nano–bio–eco interface level and how this affects their toxicity, fate, and exposure potential. In addition, a brief account of the exposure pathways and different models used for toxicity evaluation is also discussed, vis-à-vis the ongoing research work on toxicity, the role of contributing factors, and the probable alternatives developed to attenuate related hazards, challenges, and future outlook.