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A lysine based peptide amphiphile (PA) is designed and synthesized for efficient water immobilization. The PA with a minimum gelation concentration (MGC) of 1% w/v in water shows prolonged stability and can also efficiently immobilize aqueous mixtures of some other organic solvents. The presence of a free amine induced pH dependency of the gelation as the PA could form hydrogel at a pH range of 1-8 but failed to do so above that pH. Various spectroscopic and microscopic experiments such as steady state fluorescence, NMR, IR, CD, and FESEM reveal the presence of hydrophobic interaction, hydrogen bond, and π-π stacking interaction in the self-assembly process. The self-aggregation has been correlated with the design of the molecule to show the involvement of supramolecular forces and the hierarchical pathway. While the L analogue formed left-handed helical nanofibers, the other enantiomer showed opposite helicity. Interestingly the equimolar mixture of the isomers failed to form any fibrous aggregate. Although fibers formed at a subgel concentration, no helical nature was observed at this stage. The length and thickness of the fibers increased with increase in the gelator concentration. The nanofibers formed by the gelator are used as a template to prepare mesoporous single wall silica nanotubes (SWSNTs) in situ in plain water without the requirement of any organic solvent as well as any external hydrolyzing agent. The SWSNTs formed are open at both ends, are few micrometers in length, and have an average diameter of ~10 nm. The BET isotherm showed a type IV hysteresis loop suggesting mesoporous nature of the nanotubes.

Metal oxide nanoparticles (NPs) have shown enhanced antibacterial effects against many bacteria. Thus, understanding the potential antibacterial effects of nickel oxide nanoparticles (NiO NPs) against Grampositive and Gram-negative pathogenic bacteria is an urgent need to enable the exploration of NiO NP use in biomedical sciences. To this end, NiO NPs were synthesized by microwave assisted hydrothermal synthesis method. The synthesized NPs were characterized by X-ray diffraction (XRD) and Fourier Transfer Infrared (FT-IR) and UV-visible spectroscopy. The morphological features of the synthesized NiO NPs were analysed using Transmission Electron Microscopy (TEM) and FE-SEM analysis. The antibacterial activity of NiO NP was explored using different antimicrobial and biophysical studies. The obtained data reveals that the NiO NP has stronger antibacterial activity against Gram-positive bacteria compared to Gram-negative bacteria. The mechanism behind the antibacterial activity of the NiO NP was explored by evaluating the amount of ROS generation at the NiO NP interface. The effect of ROS generation on the bacterial membrane was evaluated by BacLight assay and morphological analysis of the bacterial membrane using FE-SEM. The data altogether suggested that the oxidative stress generated at the NiO NP interface resulted in membrane damage leading to bacterial cell death.