Lysozyme adsorption on carbonaceous nanoparticles probed by second harmonic light scattering.

The first hyperpolarizability () of two different sizes (15 and 35 nm) of carbonaceous nanoparticle (CNP) is reported for the first time using second harmonic light scattering (SHLS). The values of the CNPs were found to be larger than those of organic molecules like pNA but lower than those of plasmonic nanoparticles like gold and silver. SHLS was further used to investigate the adsorption of a model protein Lysozyme (Lyz) on these CNPs, which is crucial for the design of safe and effective CNP-based therapeutics.

Thermodynamics of multilayer protein adsorption on a gold nanoparticle surface.

We report the thermodynamics of protein adsorption on negatively charged colloidal gold nanoparticles (GNPs) of 16 nm to 69 nm at pH 7.0. Three biologically important proteins of varying size, namely tetrameric alcohol dehydrogenase (ADH) from , bovine serum albumin (BSA), and insulin from the porcine pancreas were taken and their adsorption on the GNP surface was investigated by dynamic light scattering (DLS), absorption spectroscopy and zeta potential measurements.

Probing Polymer Chain Folding in Solution Using Second Harmonic Light Scattering.

Periodically grafted amphiphilic copolymers (PGACs) were earlier shown by us to adopt a zigzag folded conformation in the solid state, which enabled the backbone and pendant segments to segregate and occupy alternate layers in a lamellar structure. The conformational transition from a random coil to a zigzag folded chain in solution is an interesting problem, which is largely unexplored. To examine this, an orthogonally clickable parent polyester was sequentially clicked with two types of poly(ethylene glycol) (PEG) segments: one is a simple PEG and the other is a PEG that carries a dipolar chromophore.

Linear and Nonlinear Optical Properties of Tricyanopropylidene-Based Merocyanine Dyes: Synergistic Experimental and Theoretical Investigations.

New merocyanines dyes with tricyanopropylidene-based acceptor units connected to dihexylaminophenyl or dihexylaminothiophenyl donor moieties through polyenic bridges of different lengths have been designed. All derivatives exhibited a strong dipolar character and showed a typical intramolecular charge transfer (ICT) transition. NMR spectroscopy experiments combined with DFT calculations demonstrated that both the nature of the donor-acceptor pair and the length of the conjugated linker strongly impact the electronic structure of the dyes and induce alteration in the bond-length alternation (BLA) and marked shifts in the ICT absorption bands.

Combination of Cyanine Behaviour and Giant Hyperpolarisability in Novel Merocyanine Dyes: Beyond the Bond Length Alternation (BLA) Paradigm.

Merocyanine dyes that exhibit antithetic cyanine-like behaviour and giant first-order hyperpolarisability (β) values have been designed. These cyanine-type dyes open up an intriguing route towards molecular-based electro-optic materials as well as new second-harmonic generation dyes for imaging.

Chemical applications of hyper-Rayleigh scattering in solution.

Hyper-Rayleigh or second harmonic Rayleigh scattering (HRS or SHLS) has been employed to measure equilibrium physical properties of molecules in solution. It has been utilized in our laboratory to obtain the dissociation constants of weak organic acids such as substituted benzoic and cinnamic acids in solution. Partition coefficient, supramolecular structure formation and stoichiometry, critical micelle concentration, and binding or association constant of a molecule with another molecule have all been measured by the HRS technique by us.