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Emerging drug-delivery systems demand a controlled or programmable or sustained release of drug molecules to improve therapeutic efficacy and patient compliance. Such systems have been heavily investigated as they offer safe, accurate, and quality treatment for numerous diseases. Amongst newly developed drug-delivery systems, electrospun nanofibres have emerged as promising drug excipients and are coming up as promising biomaterials. The inimitable characteristics of electrospun nanofibres in terms of their high surface-to-volume ratio, high porosity, easy drug encapsulation, and programmable release make them an astounding drug-delivery vehicle.

Cellular hypoxia is a major cause of oxidative stress, culminating in neuronal damage in neurodegenerative diseases. Numerous ex vivo studies have implicated that hypoxia episodes leading to disruption of Ca2+ homeostasis and redox status contribute to the progression of various neuropathologies and cell death. Isolation and maintenance of primary cell culture being cost-intensive, the details of the time course relationship between Ca2+ overload, L-type Ca2+ channel function, and neurite retraction under chronic and long-term hypoxia remain undefined. In order to explore the effect of oxidative stress and Ca2+ overload on neurite length, first, we developed a 5-day-long neurite outgrowth model using N2a cell line. Second, we propose a chronic hypoxia model to investigate the modulation of the L-type Ca2+ channel (Cav1.2) and oxidative resistance gene (OXR1) expression level during the process of neurite retraction and neuronal damage over 32 h. Thirdly, we developed a framework for quantitative analysis of cytosolic Ca2+, superoxide formation, neurite length, and constriction formation in individual cells using live imaging that provides an understanding of molecular targets. Our findings suggest that an increase in cytosolic Ca2+ is a feature of an early phase of hypoxic stress. Further, we demonstrate that augmentation in the L-type channel leads to amplification in Ca2+ overload, ROS accumulation, and a reduction in neurite length during the late phase of hypoxic stress. Next, we demonstrated that non-prophylactic treatment of resveratrol leads to the reduction of calcium overloading under chronic hypoxia via lowering of L-type channel expression. Finally, we demonstrate that resveratrol-mediated reduction of Cav1.2 channel and STAT3 expression are associated with retention of neurite integrity. The proposed in vitro model assumes significance in the context of drug designing and testing that demands monitoring of neurite length and constriction formations by im

Alginate and gelatin are bio-polymers widely used in drug delivery. A range of salts can be used to achieve the required flexibility in biomaterial design. Hofmeister series gives an idea about the behaviour of salts with proteins. However, its application for the design of biomaterials and their specific effect on high-viscosity polymers and polymer mixtures has not quite been explored. Firstly, this work proposes a strategic interaction-based approach for designing a dual-drug ocular biomaterial. Secondly, the impact of different salt anions on gelatin and alginate mixture for the developed protocols is studied by a proposed method of determining shear-dependent general intrinsic viscosity. Thirdly, shear-dependent intrinsic viscosity is used to determine the interaction amongst the polymers in their mixture, which is then correlated to the release profiles and hydrodynamic radii of polymer mixtures. It is observed that Hofmeister anions behave reversely for high-viscosity negatively charged polymers and depends on the charge densities of the anions. For the polyelectrolyte/polyampholyte complex/mixture, the interactions depend on the addition sequence. It is inferred that the kosmotropes are preferred for protocols where salt is added between gelatin and alginate and chaotropes for protocols where salt is added to the gelatin and alginate complex/mixture in terms of release profiles.

Glaucoma is one of the leading causes of loss of vision. The problems associated with the marketed formulations of anti-glaucoma drugs are low bioavailability, unwanted side effects, and low patient compliance. Hydrogels are an important class of soft materials that play a crucial role in developing an ocular drug delivery system. They assume a special significance in addressing the problems associated with the marketed formulations of eyedrops. An appropriate design of the hydrogel system capable of encapsulating single or multiple drugs for glaucoma has emerged in recent times to overcome such challenges. Although various modes of imaging play critical roles in assessing the efficacy of these formulations, evaluating hydrogels for drug permeation and retention remains challenging. Especially, the assessment of dual drugs in the hydrogel system is not straightforward due to the complexity in measuring drug penetration and retention for in vivo or ex vivo systems. There is a need to develop tools for the fabrication and validation of hydrogel-based systems that give insight into precorneal retention, biocompatibility, cellular uptake, and cell permeation. The current review highlights some of the complexities in formulating hydrogel and benchmarking technologies, including confocal laser scanning microscopy, fluorescent microscopy, slit-lamp biomicroscopy, and camera-based imaging. This review also summarizes recent evaluations of various hydrogel formulations using in vitro and in vivo models. Further the article will help researchers from various disciplines, including formulation scientists and biologists, set up preclinical protocols for evaluating polymeric hydrogels. © 2022 American Chemical Society. All rights reserved.

Surface functionalization and cross-linking have been adopted extensively by researchers to customize hydrogel properties, especially in the last decade. The clinical translation of such biomaterials is in a poor state due to long-term toxicity, often beyond the periphery of the short-term animal studies. We endeavor to relook at the material development strategy with all FDA-approved biopolymers in their native states, like gelatin and sodium alginate, without using any functionalization and cross-linking. The fabrication of a cross-linker-free hydrogel has remained one of the main challenges in biomaterial design and requires multiscale structuring of the hydrogels. The physical properties of these hydrogels were enhanced by plasticizers (PEG and glycerol) and a monovalent salt (NaCl). An in-depth analysis suggested that PEG forms a plasticizing layer at the sodium alginate and gelatin interface and glycerol alters the overall polymer structure. The results were further complemented by different characterization methods (scattering techniques and infrared spectroscopy) and molecular dynamics simulations. The detailed microstructural analysis surfaced the enthralling integrated swelling mechanism in gelatin chains that led to high-performing hydrogels. © 2022 The Royal Society of Chemistry

The depolymerization of lignin to produce renewable value-added building block chemicals has received increased attention from both industry and academia, as its facilitation is a key in the development of future biorefinery technologies. The main challenge in lignin depolymerization relies on its complex structure. Numerous efforts have shown that catalysts, solvents, reaction parameters, and physiochemical properties of lignin significantly affect the depolymerization reaction of lignin. Solvents are crucial components of the reaction system and affect the performance of the lignin depolymerization process. A good solvent can promote the solubility of lignin and enhance the catalyst–lignin interactions, and could also stabilize the reactive intermediates. However, the relationship and dependence of the molecular structure of lignins with its solubility and reactivity in different solvents are poorly understood. Thus, it is important to understand the influence of solvents on the reaction mechanism, the thermodynamic state of lignin, intermediates, products, and catalysts’ stability. In this article, various solvents used in the depolymerization of different types of lignin reactions are extensively overviewed. Special attention is paid to comparing the conversion of lignin, yield of bio-oil, and yield of monomers in the presence of different polarity-categorized solvents and binary solvents. Graphical abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Since coal washeries generate huge quantities of high-ash rejects as waste, effective utilization of coal rejects help in sustainable coal preparation. Out of different coal rejects, tailings from froth-flotation process can be a potential material for the extraction of clean coal due to its fine size, availability in the slurry form, presence of good carbon values, and better liberation properties. In the present study, three different methodologies i.e., chemical method, chemico-physical method, and physical method are explored to separate clean coal with >49.8% yield for their utilization in coke making process. The chemical method of demineralization by alkali-acid leaching shows a high clean coal yield of 65.4%; however, the alteration of vitrinite-group macerals makes it unsuitable for coke making process. Chemico-physical method of clean coal separation by hydrothermal extraction followed by density separation results in clean coal at 49.8% yield with an increase in vitrinite group macerals, which shows a positive impact on rheological and coking properties. The physical separation method by ultrafine grinding followed by density-gradient-centrifugation resulted in 58.2% of clean coal yield with coking properties similar to the clean coal obtained in conventional coal beneficiation plants. By adopting chemico-physical method and physical method of coal cleaning, the overall clean coal yield of the washery can be improved by >5.1%. Also, there is no deterioration in coke properties such as coke strength after reaction and coke reactivity index by using the prepared clean coal in coal blend.

The Oral route of administration forms the heartwood of the ever-growing tree of drug delivery technology. It is one of the most preferred dosage forms among patients and controlled release community. Despite the high patient compliance, the deliveries of anti-cancerous drugs, vaccines, proteins, etc. via the oral route are limited and have recorded a very low bioavailability. The oral administration must overcome the physiological barriers (low solubility, permeation and early degradation) to achieve efficient and sustained delivery. This review aims at highlighting the conventional and modern-age strategies that address some of these physiological barriers. The modern age designs include the 3D printed devices and formulations. The superiority of 3D dosage forms over conventional cargos is summarized with a focus on long-acting designs. The innovations in Pharmaceutical organizations (Lyndra, Assertio and Intec) that have taken giant steps towards commercialization of long-acting vehicles are discussed. The recent advancements made in the arena of oral peptide delivery are also highlighted. The review represents a comprehensive journey from Nano-formulations to micro-fabricated oral implants aiming at specific patient-centric designs

Coke plant wastewater contains many toxic pollutants such as phenol, cyanide, and ammonia, etc., handling and disposal of which has a significant impact on the environment and human health. A novel adsorbent based on lignite extraction waste was prepared and its effect on the removal of simulated methylene blue, phenol and colour (ortho, para-benzo quinone) from real coking wastewater was investigated. Lignite waste (residue) after humic acid separation has a significant quantity of oxidized functional groups along with residual KOH, which makes it suitable for the preparation of activated carbon with high surface area. Since hydrothermal extraction breaks coal-mineral-pore aggregate, the separation efficiency of ash-bearing minerals improved, 11 % ash coal prepared from the residue with 81.6 % yield. Prepared activated carbon from low ash residue has a mesoporous surface (49.8 nm pore size), 0.554 cm3/g of total pore volume, and 980 m2/gram BET surface area. The adsorption kinetics followed pseudo-second order (R2 = 0.984) for methylene blue, pseudo-second-order (R2 = 0.978) for phenol, and pseudo-first-order (R2 = 0.935) for colour adsorption. Adsorption isotherm at equilibrium shows a maximum adsorption capacity of 120 mg/g for methylene blue, 20.49 mg/g for phenol and 588.23 PtCo/g for colour. The adsorption isotherm was in good agreement with Langmuir isotherm (R2 = 0.989-0.994) compared to Freundlich model (R2 = 0.924-0.982). The presence of negatively charged surface favours the uptake of cationic groups. Apart from phenol and colour, the adsorbent can remove total organic carbon (TOC) by 93.6 % and thiocyanide by 6.7 %. Adsorbent reutilization studies show that, the regenerated adsorbent by thermal treatment can be used for 3 cycles.

We explore the chemotaxis of an elliptical double-faced Janus motor (Janusbot) stimulated by a second-order chemical reaction on the surfaces, aA + bB → cC + dD, inside a microfluidic channel. The self-propulsions are modeled considering the full descriptions of hydrodynamic governing equations coupled with reaction-diffusion equations and fluid-structure interaction. The simulations, employing a finite element framework, uncover that the differential rate kinetics of the reactions on the dissimilar faces of the Janusbot help in building up enough osmotic pressure gradient for the motion as a result of non-uniform spatiotemporal variations in the concentrations of the reactants and products around the particle. The simulations uncover that the mass diffusivities of the reactants and products along with the rates of forward and backward reactions play crucial roles in determining the speed and direction of the propulsions. Importantly, we observe that the motor can move even when there is no difference in the total stoichiometry of the reactants and products, (a + b) = (c + d). In such a scenario, while the reaction triggers the motion, the difference in net-diffusivities of the reactants and products develops adequate osmotic thrust for the propulsion. In contrast, for the situations with a + b ≠c + d, the particle can exhibit propulsion even without any difference in net-diffusivities of the reactants and products. The direction and speed of the motion are dependent on difference in mass diffusivities and reaction rate constants at different surfaces.

Oral administration of Amphotericin B (AmB) is abstained due to its poor bioavailability and high toxicity. Current intravenous lipid formulations are delivered as 3-5 mg AmB/kg of body weight, due to its dose dependent nephrotoxicity. In this work, we engineer the electrospun gelatin nanofibers to enable their use for controlled release of AmB in the form of oral tablets while focusing on loading realistic drug doses of AmB as per the clinical guidelines for the treatment of Visceral Leishmaniasis. A detailed study is carried out to understand the effect of different crosslinking strategies, drug concentrations, compressive loading (to form tablets) and additional protective layer of sodium alginate on release kinetics. Based on the outcome of these studies, we developed a systematic protocol to achieve the controlled release and minimizing the frequency of dosing in order to attain less toxicity at realistic body pH condition. The swelling and enzymatic degradation studies further infer the realistic stability of the tablet and its correlation with the in-vitro release kinetics of drug.

Polymers have a wide range of applications in everyday life. They are also essential components of biological systems. Molecular dynamics simulation is a technique to study the properties of the polymers. In this thesis, we use molecular dynamics simulations to understand the statics and dynamics of three different polymers. First, we study chromosome structure and dynamics in E. coli. Recent experiments on live cells grown in micro-confinements, study the morphology and segregation of chromosomes with a combination of genetic and biochemical manipulations. The antibiotic-treated bacteria do not undergo cell division, and using DNAc, the replication of DNA can be switched off at high temperatures. In the absence of replication, chromosome size shows non-linear growth and a subsequent gradual saturation as cell length increases. When replication is allowed, chromosome segregation takes place in the undivided cell approximately to its 1/4-th and 3/4-th positions lengthwise. To explain these fascinating results, we used a model where the chromosome is treated as a polymer with side loops and cytosol as passive crowders. The entropic effect due to confinement and crowders captures the observed morphology, localization, and segregation of chromosomes successfully. However, experiments show higher positional fluctuations of the chromosome than the equilibrium estimate. This could be because of the presence of active forces in the cell. Next, we use molecular dynamics simulation to study the pH-responsive behavior of gelatin, a polymer frequently used in biomedical applications. We look at the static properties of gelatin in aqueous salt solutions at three different pH, 1.2, 7, and 10. At the isoelectric point (pH=7), we observe a monotonic increase in the size of the polymer with an increase in salt concentration. At pH=1.2, the addition of salt leads to a collapse of the polymer. In the negative polyelectrolyte regime (pH=10), we observe a “collapse-reexpansion” behavior

In recent years, lignin, the third fraction of lignocellulosic biomass, has evolved as one of the most prominent renewable resources for value-added aromatic chemicals. Lignin constitutes around 10-30% of the total lignocellulosic biomass. It is made up of aromatic monomers (coniferyl, sinapyl, and p-coumaryl), which brands it as the most abundant renewable source of aromatic chemicals. The removal of aromatic entities from lignin is a big challenge to date, mainly due to its heterogeneous nature and tendency of the polymer to repolymerize a more condensed structure. While working in a similar area in the last few years, we have narrowed down the specific needs and targets in this area of interest. The early and recent advancement has always given a strong focus on the development and screening of efficient catalysts for lignin depolymerization. Although the catalyst is a crucial component for the lignin depolymerization to monomeric products, significant attention is also required on the catalyst-to-lignin interactions and collision possibility of inter-unit linkages with the catalyst. An appropriate solvent might regulate the collision possibility of inter-unit linkages with active site of the catalyst. The use of a suitable solvent can also reduce the formation of char and restrain the repolymerization reactions. Therefore, Hansen solubility parameters (HSP) were utilized for selecting a suitable solvent for the lignin polymer. A mixture of water and THF was observed to have higher thermodynamic compatibility for lignin and guaiacol with a RED ~ 1. The beneficial effect of water and THF mixture was also observed in the depolymerization reactions of Kraft lignin using HZSM as a catalyst and NaOH as co-catalyst. A higher lignin conversion of 77% and 79% selectivity towards guaiacols with negligle char could be attained at the optimal reaction conditions from statistical analysis - Response Surface Methodology (RSM). The water-THF ratio was also found as the major i

Indian Institute of Technology Hyderabad Researchers has developed a method to produce controlled-release oral tablets for treating fungal infections and leishmaniasis (kala azar or black fever) that are prevalent in the country. Their tablets were found to release the drug Amphotericin B in a sustained and controlled manner over a period of 10 days.

Lignin is recognized as a renewable and rich source of aromatics, which could be an alternative to fossil fuel-based petrochemicals. However, the development of an efficient catalyst and industrially scalable process for lignin depolymerization remains a challenge. The present work is therefore dedicated towards a one-pot approach for depolymerization of commercial kraft lignin in a batch reactor with higher loading using the water-THF solvent mixture over the HZSM-5 and NaOH catalytic system. Process parameters such as time, temperature, lignin-to-solvent (w/v), water-to-THF (v/v), NaOH-to-lignin (w/w), catalyst-to-lignin (w/w), and Si/Al mole ratios of HZSM5 were chosen carefully and optimized using statistical analysis-response surface methodology (RSM). A significant yield of 61% for a particular single ring aromatic compound (i.e. guaiacols) was obtained under the optimized reaction conditions: reaction time = 2 h, temperature = 533 K, lignin-to-solvent ratio = 0.060 (1:16.6), water-to-THF ratio = 0.86:1, catalyst-to-lignin ratio = 1:6 (0.16), NaOH-to-lignin ratio = 0.1 and Si/Al ratio = 280. Around 77% of lignin was selectively converted to guaiacols (79%) with minimal char formation (7.7%). The Hansen solubility parameter and RSM studies indicate that the obtained results were significantly related to the solubility of lignin and guaiacol at different water-THF ratios. FT-IR and 1H-NMR studies were also performed to correlate the process outcome with the presence of functional groups in identified EtOAc soluble products. A plausible mechanism for catalytic depolymerization of lignin has been proposed considering the product distribution obtained under varying process parameters.

The effect of salt on the static properties of aqueous solution of gelatin is studied by molecular dynamics simulation at pH = 1.2, 7, and 10. At the isoelectric point (pH = 7), a monotonic increase in size of the polymer is obtained with the addition of sodium chloride ions. In the positive polyelectrolyte regime (pH = 1.2), collapse of gelatin is observed with increase in salt concentration. In the negative polyelectrolyte regime, we observe an interesting collapse–reexpansion behavior. This is due to the screening of repulsion between the excess charges followed by the screening of attraction of oppositely charged ions as the salt concentration is increased. This mechanism is very different from the charge inversion mechanism which causes the reexpansion in the presence of multivalent ions. The location of salt concentration corresponding to the minimum size of the chain is comparable to the theoretical estimate. The shift in the peak of radial distribution function calculated between monomers and salt ions confirms this spatial reorganization. The predictions from the simulation are verified by dynamic light scattering(DLS) and small-angle X-ray scattering (SAXS) experiments. The size of the hydrodynamic “clusters” obtained from DLS confirms the simulation predictions. Persistence length of the gelatin is calculated from SAXS to get single chain statistics, which also agrees well with the simulation results.

Amphotericin B (AmB) is one of the potent antimycotic drugs used to cure invasive fungal infections and Leishmaniasis. However, it’s appalling collateral toxicity restricts its applicability for only parenteral administration with frequent dosing. Further, AmB is amphipathic and exhibits negligible absorption during oral administration due to its poor solubility. Current research unfolds the possibility to deliver AmB in a controlled way through oral route. First, homogeneous solution of gelatin-AmB was successfully electrospun into the nanofibers followed by crosslinking and compression to form compressed nanofibrous oral tablet (CNOT) containing 20 mg AmB in a 500 mg tablet. In-vitro biodegradation and thermal stability were investigated followed by studying the drug release kinetics. Antifungal activity was also examined up to seven days. AmB loaded CNOT showed zero order release profile with prominent antifungal activity up to seven days against Candida albicans. This study paves the way for a safe, yet effective oral administration of AmB while still maintaining the therapeutic efficacy for treating life-threatening fungal infections.

Biomaterials are enriched with characteristics that have transformed them into numerous therapeutic modalities. Oral drug delivery has advanced quickly and has offered many polymeric vehicles for control release of drug molecules. Some of them have very poor mechanical stability and they lack in material tunability, which causes an early degradation, or the burst release of drug molecules in the initial hours. To overcome these defects, crosslinkers have been introduced; however, they add potential toxicity to the system. In order to improve these shortcomings, we introduce strategies to design cross-linker free drug delivery vehicles. Sodium alginate and gelatin are the two FDA approved biodegradable polymers used extensively in this research. Throughout the investigation, these polymers were neither cross-linked or chemically functionalized to alter their native state. The aim was to maximize the potential of physical forces like hydrogen bonding, van der Waal’s force, electrostatic interaction in stabilizing these polymers against rapid dissolution. Sodium alginate and gelatin are charged polymers and their association led to the formation of pH responsive hydrogels with tunable properties. The physiochemical features of these hydrogels were studied in detail. The effects of plasticizers (PEG and glycerol) and monovalent salt (NaCl) were investigated in depth to understand their role in designing an ideal drug carrier.

In this work, we report a low‐cost, less energy intensive, and an innovative way of recycling thermoplastic polystyrene (PS) waste objects into submicron, aligned fibers using extract from citrus peel, an agricultural waste. As‐fabricated recycled PS fabric is then structurally characterized and tested as an oil sorbent material. The hydrophobic‐oleophilic PS fabric is found to absorb 40.5 ± 3.6 g/g of oil, with 77.3% oil retention within 1 h. To investigate the practical application of recycled PS fabric for oil spills remediation, we tested its buoyancy properties in oil‐over‐water static and dynamic system besides examining their reusability. The as‐fabricated fabric floats on water after oil sorption indicating its high buoyancy and therefore can be collected easily after soaking the oil. This work is a simple illustration of systematic analysis of recycling two different waste materials (thermoplastic polystyrene and citrus peels) and reusing them into a more valuable product

Oral drug delivery has advanced at a brisk pace and has offered many polymeric cargos to have control release of drug molecules. Despite the towering success in this arena, few shortcomings need to be addressed. Critical ones are the lack of material tunability that causes an early degradation, or the high expulsion of drug molecules in the initial hours. To overcome these defects, cross-linkers like glutaraldehyde, have been introduced, however, they add potential toxicity to the system. Alternatives like biodegradable cross-linkers like genipin have a prohibitively high cost. In order to improve these shortcomings, we introduce strategies to design cross-linker free drug delivery vehicles. Sodium alginate and gelatin are the two FDA approved biodegradable polymers used extensively in this research. Throughout the investigation, these polymers were neither cross-linked (few test cases were crosslinked) or chemically functionalized to alter their native state. The goal was to maximize the potential of physical forces (hydrogen bonding and polymer entanglements) in stabilizing these polymers against rapid dissolution. Sodium alginate and gelatin are charged polymers and their association led to the formation of polyelectrolyte hydrogels. The physiochemical properties of these hydrogels were studied in detail. The effect of plasticizers (PEG and glycerol) and monovalent salt (NaCl) was investigated in depth to understand their role in designing an ideal drug carrier. The hydrogels inspired us to investigate the potential of few naturally occurring materials (soya nuggets and cardamom husk) as drug carriers. Soya nuggets are protein-rich and consumed heavily worldwide. Similar to hydrogels it possesses porosity and swells in an aqueous medium. These properties were further scrutinized which led to the transformation of soya nuggets into drug carriers. However, soya nuggets were limited by their low loading efficiency and stability against proteindigesting enzymes. In o

Gelatin has been the biomaterial of choice for decades now. Its low cost, renewable, nontoxic and biodegradable properties make it one of the most desirable materials for controlled release applications. However, the usage of gelatin is limited by its poor mechanical/thermal stability and high water solubility. Chemical cross-linkers and hydrophobic modifications of gelatin have solved this problem but they lead to the problem of toxicity and/ or high processing cost. This research attempts to employ a nontoxic hydrophobic drug molecule to curb early degradation of gelatin in an aqueous environment. We report the design of non-cross-linked gelatin capsules with high dissolution resistance in an aqueous medium. Piperine, a hydrophobic drug (Solubility: 40mg/L in water) was coated on the gelatin capsules to enhance its stability in an aqueous environment. The hydrophobic piperine molecules repelled the water molecules to intensify its dissolution resistance. This stabilization was used to control the release of naproxen sodium, encapsulated inside the gelatin matrix. Piperine, in this case, acts as a placebo i.e it has zero therapeutic effect but its presence was necessary to control the early degradation of gelatin matrix. The deposition of piperine was done using the solvent evaporation method where ethanol was used as the solvent. The wettability studies revealed the hydrophobic nature of surface after the deposition of piperine while SEM analysis showed the presence of long cylindrical (fiber-like) structures over the gelatin surface. Further investigation (FTIR/ATR and molecular dynamics) revealed that the long fiber structures were due to the crystallization of piperine over the surface of gelatin. This crystallization was triggered by the intermolecular association (hydrogen bond) of ethanol and piperine. These observations enabled us to optimize the piperine loading protocol over the gelatin capsules that helped in achieving a zero order naproxen release for 3

The thermochemical conversion of lignocellulosic biomass including lignin leads to the generation of a complex mixture of oxygenated aromatic monomers. Further processing of this mixture is essential for the production of value-added chemicals. The present investigation is therefore dedicated to the hydrodeoxygenation (HDO) of guaiacol as model compound over molybdenum (Mo), tungsten (W) and tantalum (Ta) modified nickel catalysts supported on Al2O3 ZrO2, TiO2 and SiO2 in a batch reactor. All the catalysts were prepared by co-impregnation method and characterized by several techniques such as BET, powder-XRD, H2-TPR, UV–vis, FTIR and pyridine-FTIR to understand the interaction of nickel and modifier and their role in activity and product selectivity. Among the various catalysts studied, molybdenum modified nickel catalyst (Ni-Mo) supported on zirconia exhibits superior activity and selectivity. Detail characterization results revealed that various reducible surface species were formed depending on nickel to molybdenum mole ratio, total metal loading, reduction temperature and supports. The Ni-Mo/Zr catalysts are associated with metallic nickel and partially reduced Mo4+ species which acts as Lewis acid sites. The proportion of Ni/Mo4+ varies with the nickel to molybdenum mole ratio and reduction temperature. The Ni-Mo/Zr catalyst of equimolar Ni-Mo composition showed higher HDO activity of guaiacol and selectivity of phenol due to the presence of optimum proportion of Ni and Mo4+ species. During HDO of guaiacol, phenol, catechol, anisole, cresols, cyclohexanol, cyclohexanone, cyclohexene and cyclohexane were identified as products and phenol was the primary product with higher selectivity. A possible reaction pathway is proposed based on the product distribution obtained under wide range of process parameters and using different catalysts. The structural informations of catalysts obtained from various characterization studies are co-related with the HDO activity and

Sodium Alginate and Gelatin blends showed strong response towards the external stimuli of pH and ionic strengths. Molecular dynamics simulations were used to study the hydrogen bonding interactions in these blends when subjected to different pH and different ionic strength medium. The effect of plasticizers viz. glycerol and polyethylene glycols of different molecular weights on the blend were also studied. In addition, the effect of external stimuli and plasticizers upon the individual constituents of the blend viz. Sodium Alginate and Gelatin were also studied in order to understand their combined effect in the properties shown by the Sodium Alginate and Gelatin blend. Polyelectrolytic properties of sodium alginate and polyampholytic properties of gelatin were explored both in presence and absence of salt. Finally, the simulation results for gelatin in salt medium were verified using theoretical expressions and experimental analysis of the same system.

Controlled drug delivery systems (DDS) have gained a lot of attention recently due to their added advantages such as improving therapeutic efficacy in delivering the drug molecules at a predetermined rate to the targeted site for a prolonged period. Designing a polymer based DDS involves an in-depth understanding of drug-carrier interactions, and good control over the parameters that can modulate transportation of drug molecules according to the therapeutic requirement. Delivering less soluble drug molecules encapsulated in hydrophilic polymer matrix in zero-order manner is usually a challenge. To counter this challenge, we used Piperine, a model hydrophobic drug and Amphotericin B (Amp-B), a model amphiphilic drug in order to develop a polymer based DDS. We also used FDA approved natural polymer gelatin (type A) as an excipient because of its biocompatibility, biodegradability, muco-adhesiveness and easy availability. Despite of all the advantages of gelatin, it is extremely hydrophilic and has poor mechanical stability in an aqueous solution that limits its application and long-term usage. To overcome this challenge, we used Glutaraldehyde (GTA) as a crosslinker to modify gelatin. Although GTA is widely used as a crosslinker because of its excellent efficiency in stabilizing collagenous material, higher concentration of GTA solution (25 % v/v) and longer exposure in saturated vapor of GTA (more than 24 h as reported in literature) may have adverse cytotoxic effects. We successfully used a highly diluted concentration of GTA solution (0.01-0.25 % v/v) and reduced the exposure time to only 6 minute to saturated GTA vapor for crosslinking to achieve the desired stability of the fabric. In summary, this thesis investigates the full potential of natural polymer (gelatin, type A) based cast-film (GCF) and electrospun nanofiber film (GNF) as DDS, particularly for less soluble drug molecules.

The aim of this study is to develop electrospun gelatin nanofibers based drug delivery carrier to achieve controlled and sustainable release of hydrophobic drug (piperine) for prolonged time. To accomplish this, we devised some strategies such as sandwiching the drug loaded gelatin nanofiber mesh with another gelatin nanofiber matrix without drug (acting as diffusion barrier), sequential crosslinking and finally, a combination of both. As fabricated multilayered electrospun nanofibers mesh was first characterized in terms of degradation study, morphology, drug-polymer interactions, thermal stability followed by studying their release kinetics in different physiological pH as per the gastrointestinal tract. Our results show that with optimized diffusional barrier support and sequential crosslinking together, a zero order sustained drug release up to 48 h may be achieved with a flexibility to vary the drug loading as per the therapeutic requirements. This work lays out the possibility of systematic design of multilayer nano-fiber mesh of a biopolymer as a drug delivery vehicle for hydrophobic drugs with a desired signature of zero order release for prolonged duration.

Recent years have witnessed growing demand for cost-effective natural bioproducts for therapeutic applications. In this work, cardamom husk was processed and turned into a protective shield for the hydrogel-drug conjugate. The seedless cardamom husk comprises of crude fibers and offers effective protection to the encapsulated hydrogel-drug matrix against degradation. Sodium alginate (SA) and gelatin were the biodegradable polymers utilized, while naproxen sodium (hydrophilic) and piperine (hydrophobic) were used as model drugs. The polymer-drug blend encased in this husk was engineered to give a long hour, zero-order release kinetics for both types of drugs. The hydrogel-drug conjugate was carefully optimized to achieve a controlled release with minimal or no use of cross-linkers. The viscosity of sodium alginate was used in such a way that the synthesis of a cross-linker free hydrogel-drug blend can be a reality. The husk was also found to be stable near sterilization temperatures. This research not only focusses on an available resource in nature but also showcases the role of modern methodology to convert this resource (cardamom husk) into a protective shield for a polymeric blend carrying drug molecules.