Ultra-high stable chitosan functionalized gold nanoparticles (GNPs) of desired biopolymeric corona are synthesized without adding conventional hazardous reducing agents. The inherent unique set of properties like reducing ability, stabilizing effect, and mucoadhesiveness of chitosan is exhibited in the present work. Morphologies and ultra-stability of the synthesized materials are characterized by standard techniques. The mucoadhesiveness of the synthesized materials are well documented through the biological potency of the synthesized GNPs. The prominent bioactivity is evident from the antifilarial activity. The cellular and molecular level studies on the induction of oxidative stress, DNA damage, and undesirable protein expression clearly explain the antifilarial activities. Interestingly, the developed nanoparticle shows no detectable sign of toxicity when evaluated in vitro (rat peritoneal MФ) or in vivo (Wistar rat). Therefore, the synthesized green GNPs appear to be a substantial promise as an efficacious broad-spectrum nanotherapeutic agent with safe outcome for clinical attempt.

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Allylamine-functionalized silicon quantum dots (ASQDs) of high photostability are synthesized by a robust inverse micelle method to use the material as a fluorescent probe for selective recognition of thiocyanate (a biomarker of a smoker and a nonsmoker). The synthesized ASQDs were characterized by absorption, emission, and Fourier transform infrared spectroscopy. Surface morphology is studied by transmission electron microscopy and dynamic light scattering. The synthesized material exhibits desirable fluorescence behavior with a high quantum yield. A selective and accurate (up to 10–10 M) method of sensing of thiocyanate anion is developed based on fluorescence amplification and quenching of ASQDs. The sensing mechanism is investigated and interpreted with a crystal clear mechanistic approach through the modified Stern–Volmer plot. The developed material and the method is applied to recognize the anion in the human blood sample for identification of the degree of smoking. The material deserves high potentiality in the field of bio-medical science.

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: Gold nanoparticles (GNPs) have diverse optical and photo-thermal properties. It is used for diagnostic imaging because of their ability to absorb near infrared (NIR) and X-rays, and their surface enhanced Raman scattering properties. Recently they are used for drug delivery and more particularly photothermal treatment. Their ability to absorb NIR energy and convert it to heat by a Surface Plasmon Resonance mechanism has made these materials promising for the treatment of tumors. GNPs having diameter higher than 1.4–1.5 nm is found nontoxic to the environment. In the present work, polymer anchored GNPs are synthesized by reducing AuIII to Au0 in presence of either chitosan or polyvinyl alcohol, which act as in situ reducers cum stabilizers. Microscopic techniques (TEM, SEM and DLS) are used to analyse the size, surface morphology and size distribution respectively. The unique mucoadhesive properties of chitosan particularly make the system promising with respect to antimicrobial (anti-bacteria as well as anti-fungus) activities. An attempt has been made to understand the mechanistic path involved in antimicrobial activities. Antimicrobial potential of chitosan anchored gold nanoparticles (GNPc) are noticed even at very low dose. The results of bio-chemical analysis (MDA, NBT, DNA fragmentation and over-expression of heat shock protein) clearly explain antimicrobial activities. Additionally, gold chitosan systems interact with microbial DNA and inhibit the action of DNA repair enzyme. Interestingly, in vitro (rat peritoneal MФ) or in vivo (Wistar rat) analysis exhibits negligible cytotoxicy. Thus the synthesized material (particularly GNPc) is promising as an effective nano therapeutic agent.

The present study illustrates a clear functionalization chemistry for the synthesis of guanidine functionalized reduced graphene oxide (GfG) for sorption of Cr(VI).

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