Raja Summe Ullah

Chemical modification of starch and its application as an adsorbent material

Starch is a biopolymer of plant origin which is cheap abundant and has many applications in food and non-food industries. However, in the native form, its applications are limited due to shortcomings, such as loss of viscosity and thickening power upon cooking and storage, retrogradation characteristics and absence of certain groups responsible for a particular function, etc. So, in order to reduce its limitations and improve its applications, modification of starch is necessary. It can be modified by several ways like chemical modification, physical modification and genetic modification but the most important one is the chemical modification. In this review, we selected the published data related to the chemical modification like grafting, cross-linking, esterification, etherification and dual modification of starch and application of modified starch for the adsorption of organic dyes and heavy metals from water.

Synthesis of polyphosphazenes with different side groups and various tactics for drug delivery

Polyphosphazenes (PPZs) are hybrid polymers comprising a main chain containing nitrogen and phosphorous linked through interchanging single and double bonds, and side chains. The two chlorine atoms attached to the phosphorous of polydichlorophosphazene, which is produced by thermal ring-opening and living-cationic polymerization, are significant in the importance of polyphosphazene, as they can be easily replaced by an uncountable number of nucleophiles, resulting in hundreds of different PPZs with different properties ranging from hydrophobic to hydrophilic, fast to slow degradation, and burst to sustained drug release. More than seven hundred types of PPZs are synthesized as a result of different combinations of side groups. For applications in drug delivery, PPZs can be treated in various ways and converted into different vehicles of nano/micro size to load and release drugs. This review covers the synthesis of PPZs and their different modifications, especially focusing on the side groups and different vehicles, including microspheres, micelles, films and hydrogels, that are involved in drug-delivery applications.

Synthesis of carboxymethyl starch- g -polyvinylpyrolidones and their properties for the adsorption of Rhodamine 6G and ammonia

Carboxymethyl starch-g-polyvinylpyrolidones (CMS-g-PVPs) were prepared by grafting of carboxymethyl starch (CMS) with N-vinylpyrolidone (NVP) using different initiators. The grafting percentage of all the modified starches was determined and the modified starch (CMS-g-PVP-5) with maximum grafting percentage was characterized by elemental analysis, 1H NMR and FT-IR spectroscopy. Crystallinity and thermal properties of CMS-g-PVP-5 were analysed by XRD and TGA, respectively. CMS-g-PVP-5 was then utilized for the adsorption of Rhodamine 6G (dye) from water under different pH, temperature, adsorbate doze and adsorbent concentration. This modified starch showed good adsorption ability towards Rhodamine 6G. CMS-g-PVP-5 was also applied for the adsorption of ammonia gas and proved an exciting adsorbent for ammonia.

Synthesis of amphiphilic block copolymers containing ferrocene–boronic acid and their micellization, redox-responsive properties and glucose sensing

AbstractAmphiphilic block copolymer PMAEFc-b-PMVAPBA was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. The hydrophobic and hydrophilic blocks of copolymers self-assembled into spherical micelles in aqueous solution. The redox behaviour of ferrocene was studied by using water-soluble (NH4)2Ce(NO3)6 and NaHSO3 as the oxidizing agent and reducing agent, respectively. The change in polarity and swelling of micelles increased the hydrodynamic diameter due to the oxidation of ferrocene, while glucose binding with boronic acid hydroxyls leads to unimers or smaller aggregates. TEM and DLS were used to investigate the redox-controlled behaviour of micelles. This redox-responsive behaviour would provide a prerequisite for detection/binding of biological analytes study and redox-controlled release of drug. Graphical abstractGaphical representation of micellization and redox responsive mechanism of ferrocene boronic acid based amphiphilic block copolymers.

Synthesis of ferrocene-based saccharides and their anti-migration and burning rate catalytic properties

In the search for ferrocene-based burning rate catalysts (BRCs) with good burning rate catalytic properties and low migration, we synthesized four ferrocene-based saccharides (S-Fcs). The synthesis of S-Fcs was confirmed by energy-dispersive X-ray (EDX), nuclear magnetic resonance (1H NMR), Fourier transform infra-red (FT-IR) and ultraviolet-visible (UV-Vis) spectroscopy. The electrochemical behavior of ferrocene-based BRCs is important to investigate the electron transfer burning rate catalytic mechanism. Therefore, the electrochemical behavior of the S-Fcs was investigated by cyclic voltammetry. The burning rate catalytic properties of the S-Fcs on thermal disintegration of ammonium perchlorate (AP) were determined by TG and DTG techniques. Thermal analysis results showed that the S-Fcs were thermally stable and showed good burning rate catalytic effects on thermal disintegration of AP. The S-Fcs were also analyzed in anti-migration studies in comparison with the most commonly used ferrocene-based burning rate catalyst (catocene) and ferrocene. It was found that S-Fcs showed excellent anti-migration behavior in AP-based propellant as compared to catocene and ferrocene.

Synthesis of polyphosphazene and preparation of microspheres from polyphosphazene blends with PMMA for drug combination therapy

Drug combination therapy is an emerging technology to treat the diseases which are still annoyance to human being. Combination of two or more drugs can deal with diseases in a better way. Various different techniques have been introduced which can deliver combination of drugs in a safe and more controlled manner. In our research, we prepared polyphosphazene-based blend microspheres which can deliver two different drugs in a much sustained manner for long time. “Acetamidophenol,” commonly used drug, was attached to the polyphosphazene main chain to produce drug–polymer conjugates, and these were then blended with PMMA in different ratios to fabricate the microspheres of variable and controlled size. Another anticancer drug “camptothecin” was loaded in these microspheres to fabricate dual-drug-loaded microsphere. Furthermore, in vitro drug release behaviors of fabricated microspheres were also demonstrated.

Recent progress in the electron paramagnetic resonance study of polymers

This review article provides an overview of the contemporary research based on a tailor-made technique to understand the paramagnetic behavior of different polymer classes. The ubiquity of free radicals, including biradicals, triplet states, and point defects in polymer systems, has made EPR spectroscopy an indispensable tool in polymer science among other mainstream analytical techniques. The scope of EPR spectroscopy has broadened particularly due to the growing impulse to produce polymers with enhanced stability, to follow the charge transfer process in conducting polymers, to decipher the complex nanoscale dynamics of polymers, to fathom out the reaction mechanisms and kinetics of complex polymer reactions in a more facile way, and to carry out comprehensive structural and conformational analyses. Recent studies have hinted at the effectiveness of EPR spectroscopy in collecting data with sub-nanometer spatial resolution to decipher intrinsic intricacies, while keeping the pristine geometry unperturbed, a task yet not achievable with other conventional techniques. EPR spectroscopy is being applied in polymer science in multifarious ways, including, but not limited to, exploring the structure, conformation, and dynamics of polymer chain segments, degradation or defect studies, charge transfer properties, kinetics and reaction mechanisms especially of free radical polymerization reactions, and EPR imaging of the polymer matrix. A recent surge in its applications indicates that EPR spectroscopy is going to make a profound impact in the field of polymer science in upcoming years.

Recent progress in the modification of carbon materials and their application in composites for electromagnetic interference shielding

With the development in the modern technologies such as telecommunication instruments and scientific electronic devices, large amount of the electromagnetic radiations are produced, which lead to harmful effect on the highly sensitive electronic devices as well as on the health of human beings. To minimize the effect of electromagnetic radiations produced by different technologies, more efficient shielding materials are required which must be cost-effective, lightweight and good corrosion resistive. In this review, we focused on the shielding materials based on composites of carbon nanotubes and graphene. The typical surface modification of carbon nanotubes and graphene to optimize their interactions with polymers matrix has also summarized. It was found that the composites based on these carbon fillers were more efficient for electromagnetic interference shielding due to their unique properties (i.e., superior electrical, mechanical and thermal) together with lightweight, easy processing. Hence, the carbon nanotubes and graphene-based composites are excellent shielding materials against the electromagnetic radiations.

Recent progress in the synthesis of silver nanowires and their role as conducting materials

Synthesis of silver nanowires got much attention of researchers due to their promising applications in various fields of nanoelectronic devices. Many research articles focusing on silver nanowires synthesis have been reported since past decade. A number of techniques have been applied for successful synthesis of silver nanowires. Solution-based polyol process was proved as a dominant approach to the fabrication of silver nanowires with homogeneity and high aspect ratio. Various inorganic salts have been used in solution-based polyol synthesis of silver nanowires which play a key role in controlling the final morphology of silver nanowires and lead to uniform growth of silver nanowires. The different experimental parameters have been studied, which directly influence the final morphology of silver nanowires. The research on the development of an efficient synthesis approach of silver nanowires is still in progress to accomplish the need of advanced technology for controlled morphology and highest aspect ratio of silver nanowires. Moreover, the unique applications of silver nanowires in conducting polymers composites were discussed.

Synthesis of hydrogel-bearing phenylboronic acid moieties and their applications in glucose sensing and insulin delivery

In past few years, phenylboronic acids (PBAs) have attracted researchers attention due to their unique responsiveness towards diol-containing molecules such as glucose. This property allows hydrogel-bearing PBAs potentially to serve as an alternative for glucose-sensing and insulin-delivery systems. This review provides an outlook on the binding mechanism of PBA moieties with diols and the approaches to increase their binding selectivity and response for glucose molecules. The preparation methods and strategies of hydrogel-bearing PBA moieties along with their properties are discussed. In the last section, their applications in glucose-sensing and insulin-regulatory systems are described.