Chemistry

Point of Care Devices for Clinical Use
As a part of the ongoing projects on perinatal depression, neonatal jaundice, early detection of cardiac malfunction and dengue detection, more than 700 patients from Sri Sathya Sai General Hospital (SSSGH), Prasanthi Nilayam, Sri Sathya Sai Institute of Higher Medical Sciences (SSSIHMS), Prasanthigram and SSSIHMS, Whitefield have been enrolled. The blood, saliva and urine samples from these patients were collected after obtaining informed consent. These samples were processed and stored appropriately. These samples were analysed using standard hospital protocol/equipment and gold standard- HPLC to know the actual value to be compared with that from our proposed devices.

Dengue and heart disease detection devices underwent testing of their alpha models. The feedback was noted and appropriate modifications have been implemented in the fabrication of the beta version. The neonatal device was deployed at SSSGH, Prasanthi Nilayam for field trials. The device for monitoring depression is under fabrication and is planned to be deployed for field trials by the end of this year. In addition, new novel materials for SPCE emission enhancements were studied and the mobile phone-SPCE platform was optimized for the detection of Tannic acid in water sources. Simple, candle soot-based fractal nano carbon islands were coated and shown to be better spacer layers than other nanomaterials that are less eco-friendly due to their synthesis protocol.

Work on novel materials, such as photonic crystals and soret nanoparticle assemblies for the detection of femtomolar aluminum ions, spermidine, iodide & glutathione and zeptomolar cortisol, is also underway.

Synthesis of Small Molecules with Potent Biological Activity
Natural products have afforded a rich source of compounds and made a huge contribution to human health.

Andrographis paniculata is an Ayurvedic herb known as Kalmegh (Nelavemu in Telugu). Andrographolide, the main constituent of Andrographis paniculata and its analogues, possess anti-cancer, anti-inflammatory, anti-bacterial, anti-diabetic, anti-HIV, FXR antagonists and hepato-protective properties. In this regard we have synthesized a number of derivatives of andrographolide and extensively studied their anti-cancer properties. Further studies are under progress, as we found that Androgragholide possesses very good anti-venom properties through PLA2 inhibition.

Spirobibenzopyans and pyrilium salts are two classes of novel synthetic compounds explored extensively by us. A library of over sixty compounds have been synthesized and characterized for various biological properties. They were found to have potent anti-cancer, anti-inflammatory, anti-bacterial and anti-venom properties as first in class therapeutic agents.

Azole antifungals, commonly known as conazoles, have been used for the topical treatment of superficial fungal infections and oral treatment of deep mycoses. In the current work, a series of oxiconazole analogs are being synthesized with chromones as the core moiety and modified azole rings as the substituents. Biological activity (antifungal and antibacterial activity) of the synthesized compounds is being investigated. Molecular docking studies of the synthesized compounds against lanosterol-14-demethylase are being done to understand the mechanism of inhibition.

Chromones are well-known for their ability to scavenge hydroxyl radicals, superoxide anion radicals and lipid peroxy-radicals, which are important for prevention of diseases associated with an oxidative damage of membranes, proteins and DNA. One step synthesis of novel chromone compounds having basic flavonoid skeleton using aldol condensation was done.

Selective Fluoride Removal by Metal Ion Complexed Polymer Films
User-friendly and biodegradable, Zirconium-Lanthanum (ZLPC) and Zirconium- Cerium (ZCPC) complexed polyvinyl alcohol (PVA) films were synthesized for effective defluoridation of water. These films adsorbed 95-97% fluoride from water at pH 7, with 85% removal by ZLPC and 93% removal by ZCPC within the first 45minutes of the adsorption process. Ab-initio calculations were performed to understand the mechanism of adsorption. The films were reusable and showed ~85% removal of fluoride even after the fifth regeneration cycle. These handy films have a scope to be developed into a prototype for defluoridation of ground water.

Moreover, polymer blend-metal ion cross-linked composites of polyvinyl alcohol with polyethylene glycol, polyvinyl pyrrolidone, polyethyleneimine and polyacrylic acid have also shown promising results, which could be used as a water filtration membrane due to its water permeability. The composites based on PVA-polymer blends with Zirconium ion showed maximum adsorption of 99% fluoride in the pH range of 5 to 7. The composites could be utilized to design and develop promising defluoridating device for the fluoride endemic villages of the Rayalaseema region of Andhra Pradesh, India.

Environment: Anti-Corrosion Studies
The effects of thioureidobenzheteroazoles, namely 2-thioureidobenzoxazole (BOT), 2-thioureidobenzimidazole (BIT), 2-thioureidobenzothiazole (BTT) and isoperthiocyanic acid derivatives on the corrosion behaviour of mild steel in 2.0 M solution of HCl have been investigated by electrochemical and quantum chemical methods. Based on these findings, 2-thioureidobenzheteroazoles were found to exhibit very good corrosion inhibitory characteristics. Quantum chemical calculations revealed that sulphur and nitrogen heteroatoms serve as reactive centres for the adsorption of inhibitors.

Computational Investigation of Adsorption of Metal Ions on Biopolymers
A comparative study on the adsorption of metal ions on naturally occurring polymers, chitin, chitosan and cellulose has been done computationally. Desalination of seawater has been explored as a useful alternative to solve the problem of shortage of freshwater. 93.5% of the dissolved salts are constituted by Na, K, Mg, Ca, Br, S and Cl. Here, a theoretical investigation of biopolymers, chitosan, chitin and cellulose, as potential adsorbents of alkali and alkali earth metal ions has been carried out using Density Functional Theory (DFT) calculations.

Synthesis of Novel Chemosensors for Sensing Applications
Considerable attention has been focused on the design of chemosensors which have the ability to selectively recognize and sense analytes through the naked eye, electrochemical, and optical responses. The present research work is focused on design and synthesis of some chemosensors for sensing harmful anions such as fluoride and cyanide and some toxic metal ions in aqueous media. Water soluble curcumin glycoside was synthesized and the aluminium complex of curcumin glycoside was used for fluoride ion detection in water. The present detection concept is further explored to develop a low cost, reusable F- detection kit, which showed its ability to detect Fluoride ions in aqueous medium at a very low concentration. Several derivatives of 2-benzoxazolylimino thiazolidinone were synthesized for sensing toxic metal ions such as mercury, cadmium, lead, etc.

Nanomaterials for Electro Catalytic Applications
Electrocatalysis by nanomaterials and nanocomposites has generated immense research interest as they exhibit very high surface area and unique electron conducting ability. Our research work focuses on the synthesis of novel nanocomposites for application as electrochemical sensors and fuel cells. Several silver and gold based nanocomposites were synthesised and used for electrochemical detection of neurotransmitters such as dopamine and serotonin and also the interfering molecules like uric acid and ascorbic acid. Novel gold and palladium based nanocomposites have been synthesised and used as electro catalysts that can oxidize methanol and ethanol and reduce hydrogen ions to release energy. Apart from that, we are also investigating oxygen evolution reaction and oxygen reduction reaction that would enhance the sluggish kinetics in Li-ion cells.

Metal Complexes for Hydrogen Fuel Cell Applications
Researchers have shown great deal of attention on transition metal complexes with varying ligands due to their potential uses as catalysts, biological processes and inorganic materials. In this context, hydrogen as the future energy currency is widely considered as the solution to the energy crisis. Metal ions can be framed in special position by using appropriate ligands. In the current study, the electrocatalytic behaviour of palladium (II) metal complexes of sulphur based ligands have been investigated for efficient hydrogen evolution reaction (HER).