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Background: It is crucial for the body to maintain a firm balance between the inducers and inhibitors of angiogenesis, the process of proliferation of blood vessels from pre-existing ones. Human angiogenin (hAng) is a potent inducer of angiogenesis and the search for inhibitors has become a vital research area. Aminoglycosides are linked ring systems consisting of amino sugars and an aminocyclitol ring and are in use in clinical practices for a long time. These compounds have found clinical uses as antibacterial agents that inhibit bacterial protein synthesis. Objective: Gentamycin C1, Kanamycin A, Neomycin B, Paromomycin I, and Streptomycin A are commonly used aminoglycoside antibiotics that have been used for the present study. Among these, Neomycin has reported inhibitory activity against angiogenin-induced angiogenesis on the chicken chorioallantoic membrane. This study focuses on the thermodynamic parameters involved in the interactions of these antibiotics with hAng. Main Findings: Anti-ribonucleolytic effect of the antibiotics was observed qualitatively using an agarose gel-based assay, which shows that Neomycin exhibits the most efficient inhibition of hAng. Fluorescence quenching studies at different temperatures, using Stern-Volmer and van’t Hoff equations provide information about the thermodynamics of binding, which furthermore highlights the higher binding constant of Neomycin. Docking studies provide an insight into the participation of specific amino acid residues with the aminoglycoside antibiotics. It was observed that the antibiotics preferably interact with the nuclear translocation site, except Streptomycin, which interacts with the ribonucleolytic site of the protein with low affinity.

Advanced glycation end products (AGEs) formed through nonenzymatic glycation results in diseases including diabetic complications, Alzheimer’s disease and atherosclerosis etc. The development of novel antiglycating agents has thus become an important area of research. In our present work, we have reported the inhibitory activity of morin loaded PLGA NPs (MPNPs) on the D-ribose induced glycation of human serum albumin (HSA) based on spectroscopic studies. MPNPs were characterized by spectroscopic and microscopic techniques. HSA was incubated with ribose at 37 °C for one month and the formation of AGEs was confirmed from fluorescence studies, the increase in absorbance and the measurement of free amino groups. Further HSA and ribose mixtures incubated with MPNPs showed significant reduction in the extent of advanced glycation end product formation that were confirmed by UV-Vis and fluorescence spectroscopy and matrix-assisted laser desorption/ionization time-of-flight (MALDI- ToF) techniques. The structural changes induced by MPNPs were further confirmed by circular dichroism studies. Our findings suggest that MPNPs have the potential to be used antiglycating agents.

Thin films prepared from protein sources are biodegradable, biocompatible and find application as biomaterials for slow-release drug carriers for skin treatment in burns, ulcers or infected wounds. Cataract eye lenses discarded after surgery have a significant protein content. Films have been prepared from the discarded cataract lens emulsions obtained after surgery. Sorbitol was used as a plasticizer to facilitate film formation that exhibited high water solubility. To enhance the mechanical properties and reduce the solubility of the films, cross-linking of the polypeptide chains was initiated using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) in presence of NHS (N-hydroxysuccinimide). As the effects of the cross-linker and plasticizer incorporate conflicting properties, an optimization was necessary. The plasticizer imparts flexibility to the film, while the cross-linker decreases solubility but increases hardness that imparts brittleness. A reduction in water solubility of the film for practical applicability was required in such a way that the flexibility was not compromised. The concentration of the cross-linker and the duration of cross-linking were varied to optimize the mechanical properties of the films. The films were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and optical microscopy. Physical properties like thickness and total soluble matter were measured. The mechanical properties of the films were evaluated by performing nano-indentation and nano-tribology (NINT) experiments.

Endometriosis is a debilitating gynecological disorder in women of reproductive age. Laparoscopy, a minimally invasive surgical procedure, provides a definitive diagnosis of the disease. Current treatments, including hormonal therapy and pain medication, are often associated with undesirable side effects limiting their long-term usage. This calls for exploring newer diagnostic and therapeutic options with minimal side effects. Curcumin is an established anti-endometriotic agent with inherent fluorescent properties; however, poor bioavailability limits its clinical utility. To address this shortcoming, various transition metals were conjugated with curcumin to improve its stability, specificity and pharmacological properties. The chemical stability, hemocompatibility and ability of the synthesized metallo-curcumin complexes (MCCs) to ameliorate endometriotic lesions were investigated. While all of the MCCs exhibited low hemolytic activity, their chemical and biological activities were largely dependent on the nature of the metal ion conjugated to the curcumin molecule. Copper-curcumin and nickel-curcumin complexes demonstrated superior therapeutic efficacy evidenced by enhanced antioxidant activity, selective cytotoxicity and increased accumulation in endometriotic cells mediated by an energy-dependent active transport process.

The rapid growth in the applications of nanoparticles (NPs) in biomedical and pharmaceutical fields requires an understanding of the interactions with the lipid bilayer membrane for further in vivo studies. Zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), negatively charged 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) and positively charged 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) have been used to prepare model lipid membranes and the ability of flavonoid loaded nanoparticles to cross the membranes investigated. The lipid vesicles have been prepared by a freeze-thaw method followed by an extrusion technique and characterised by dynamic light scattering (DLS) and high-resolution transmission electron microscopy (HRTEM). The synthesized model lipid membranes exhibited a bilayer spherical type of morphology with an average diameter of less than 150 nm. A calcein leakage assay and fluorescence anisotropy measurement indicated that the membranes are permeable to the flavonoid (fisetin/morin/epicatechin) loaded human serum albumin nanoparticles. This implies that drug/compound encapsulated nanoparticles are able to effectively cross the lipid bilayer thus permitting the design and development of new compounds that may be encapsulated for safe and potential use in biomedical applications.

The effects of non-enzymatic glycation on the structural and functional properties of human angiogenin (hAng) have been investigated with respect to the formation of advanced glycated end products (AGEs), on prolonged treatment with d-Glucose, d-Fructose and d-Ribose at 37 °C. Fluorescence studies show the formation of fluorescent AGEs which exhibit emission maxima at 406 nm and 435 nm. Glycation of hAng with ribose leads to the maximum loss of its functional characteristic properties, as compared to fructose and glucose, along with the formation of higher oligomers. An increase in the incubation time results in the formation of higher oligomers with a concomitant decrease in the ribonucleolytic activity. The increase in the hydrodynamic radii of the glycated samples compared to native hAng is indicative of structural perturbations. The ribonucleolytic activity and the DNA binding ability of glycated hAng has been investigated by an agarose gel-based assay. Glycated hAng was unable to bind with human placental ribonuclease inhibitor (hRI), otherwise known to form one of the strongest protein-protein interaction systems with an affinity in the femtomolar range.

Molecular docking of N-1,4-disubstituted-1,2,3-triazole tethered carboxymethylated thymidine and uridine with ribonuclease A, indicated their possible binding with the P

Flavonoids are a class of polyphenols that possess diverse properties. The structure-activity relationship of certain flavonoids and resveratrol with ribonuclease A (RNase A) has been investigated. The selected flavonoids have a similar skeleton and the positional preferences of the phenolic moieties toward inhibition of the catalytic activity of RNase A have been studied. The results obtained for RNase A inhibition by flavonoids suggest that the planarity of the molecules is necessary for effective inhibitory potency. Agarose gel electrophoresis and precipitation assay experiments along with kinetic studies reveal Ki values for the various flavonoids in the micromolar range. Minor secondary structural changes of RNase A were observed after interaction with the flavonoids. An insight into the specific amino acid involvement in the binding of the substrate using docking studies is also presented. The dipole moment of the flavonoids that depends on the orientation of the hydroxyl groups in the molecule bears direct correlation with the inhibitory potency against RNase A. The direct association of this molecular property with enzyme inhibition can be exploited for the design and development of inhibitors of proteins.

Ribonuclease A is used as a model enzyme system for the design of RNase inhibitors. Previous studies have established that the geometric nature of the active site cleft is an important feature for the accommodation of crescent-shaped compounds in the active site of RNase A. In the current research, benzene-based triazolylated semicircular hybrid molecules carrying different polar functionalities were synthesized and screened for their RNase A inhibitory potency. An additional carboxylic acid group at the C1-position of the 1,3,5-trisubstituted benzene ring enhanced the inhibitory properties significantly. Furthermore, the studies revealed that the reduced arm lengths of 3,5-substituents result in a better geometric complementarity that makes the molecules fit favorably in the semicircular cavity of the active site as visualized by docking studies. In a series of ten such new compounds, the 3,5-bis[4-(sulfomethyl)-1H-1,2,3-triazol-1-yl]benzoic acid exhibited, the highest inhibition efficiency with a K

Microwave radiations from various electronic devices are of serious health concern. In this article, using spectroscopic measurements, we show that the microwave radiation of strength 22 dBm and frequency 10 GHz facilitates protein fibrillation. However, this adverse effect of low-field radiation can be restricted by the presence of biocompatible citrate-capped gold nanoparticles. The dissipative field by metallic particles is able to disrupt the fibrillar network. We believe that the obtained results paved a way to find a therapeutic measure to combat fibrillation related diseases.

The present study utilizes the novel combination of Gum tragacanth (GT) and sodium alginate (SA) to reinforce SA hydrogel beads. The composite hydrogel beads were encapsulated with phenolic compounds extracted from Basella sps. The rheological studies conferred increased elastic property of GT incorporated formulations. Higher swelling behavior was observed in simulated intestinal fluid (SIF) with increasing GT content in SA formulations. SA-GT composite hydrogels revealed increased encapsulation efficiency with sustained release of phenolic compounds in SIF. GT incorporated hydrogel beads exhibited increased biodegradation (up to 82% weight loss) in biodegradation media (in vitro). FTIR study found no molecular interaction between SA and GT. TGA analysis revealed that GT incorporation did not affect the thermal behavior of SA. Furthermore, SA-GT encapsulated hydrogels showed remarkable cytotoxicity against osteosarcoma cells. Thus our findings suggest SA-GT gel formulation could be used as a promising delivery system for drugs and nutraceutical compounds.

Protein nitration can occur as a result of peroxynitrite-mediated oxidative stress. Excess production of peroxynitrite (PN) within the cellular medium can cause oxidative damage to biomolecules. The in vitro nitration of Ribonuclease A (RNase A) results in nitrotyrosine (NT) formation with a strong dependence on the pH of the medium. In order to mimic the cellular environment in this study, PN-mediated RNase A nitration has been carried out in a crowded medium. The degree of nitration is higher at pH 7.4 (physiological pH) compared to pH 6.0 (tumor cell pH). The extent of nitration increases significantly when PN is added to RNase A in the presence of crowding agents PEG 400 and PEG 6000. PEG has been found to stabilize PN over a prolonged period, thereby increasing the degree of nitration. NT formation in RNase A also results in a significant loss in enzymatic activity.

Nanoencapsulation has emerged as a promising approach for the effective delivery of poorly aqueous soluble compounds. The current study focuses on the preparation of human serum albumin (HSA)-based nanoparticles (NPs) and poly lactic

Angiogenin (Ang), is a ribonucleolytic protein that is associated with angiogenesis, the formation of blood vessels. The involvement of Ang in vascularisation makes it a potential target for the identification of compounds that have the potential to inhibit the process. The compounds may be assessed for their ability to inhibit the ribonucleolytic activity of the protein and subsequently blood vessel formation, a crucial requirement for tumor formation. We report an inhibition of the ribonucleolytic activity of Ang with the gallate containing green tea polyphenols, ECG and EGCG that exhibits an increased efficacy upon forming polyphenol-capped gold nanoparticles (ECG-AuNPs and EGCG-AuNPs). The extent of inhibition was confirmed using an agarose gel-based assay followed by fluorescence titration studies that indicated a hundred fold stronger binding of polyphenol-capped gold nanoparticles (GTP-AuNPs) compared to the bare polyphenols. Interestingly, we found a change in the mode of inhibition from a noncompetitive type to a competitive mode of inhibition in case of the GTP-AuNPs, which is in agreement with the 'n' values obtained from the fluorescence quenching studies. The effect on angiogenesis has also been assessed by the chorioallantoic membrane (CAM) assay. We find an increase in the inhibition potency of GTP-AuNPs that could find applications in the development of anti-angiogenic compounds.

Flavonoids like quercetin and myricetin serve as naturally occurring antioxidants but their bioactivity is limited due to low aqueous solubility and oxidation under physiological conditions. In this current study, the antioxidant activity of quercetin and myricetin loaded chitosan nanoparticles during the induced oxidation of Ribonuclease A (RNase A) has been compared with the corresponding free flavonoids. Oxidation of RNase A leads to intermolecular dityrosine (DT) bond formation which shows a characteristic fluorescence emission around 405 nm. Although both quercetin and myricetin loaded nanoparticles initially exhibit lower antioxidant property compared to the free flavonoids, however, with increase in oxidant concentration over time the DT fluorescence showed greater increase for free flavonoids in comparison to the nanoparticles. The polyphenol loaded nanoparticles are also found to be effective in preventing bacterial cell damage in oxidizing medium. The slow release of flavonoids from the nanoparticles is responsible for their prolonged antioxidant effect in the oxidizing medium unlike the free flavonoids which are exhausted almost completely in the initial phase.

The dinuclear copper(II) complex [Cu2(µ–L2NH)2(OH2)2](ClO4)4 (1) was obtained following one imine side arm hydrolysis of HL1 (2,6-bis-[{3-(diethylamino)propylimino}methyl]-4-methylphenol). Introduction of carboxylates inhibited the hydrolysis and resulted in two tetranuclear copper(II) complexes [Cu4(µ4–O)(µ–L1)2(µ1,3–O2CCH3)4]·H2O (2a) and [Cu4(µ4–O)(µ–L1)2(µ1,3–O2CC2H5)4]·H2O (2b). Use of perchlorate and carboxylate salts of copper(II) for the reactions under study with HL1 has directed these reactions. Perchlorate anions in presence of H2O molecules, as hydrolytic nucleophiles, triggered imine arm hydrolysis and bridging carboxylate anions allowed transformation of copper(II) bound H2O molecule to μ4-oxido central nucleating group via hydroxido-bridge. The complexes were obtained from simultaneous chelation and bridging by the hydrolyzed and as used ligand anions L2NH− and HL1− respectively. These complexes have been characterized in the solid state by X-ray crystallography and FT-IR spectroscopy. Solution phase stability of Cu2-based fragments was studied by UV–vis absorption spectroscopy. Solution properties have been examined for substrate binding in catechol oxidase activity and binding affinity for biomacromolecules like DNA and Human Serum Albumin.

Seven new carbohydrate–bistriazole hybrid molecules were designed taking into consideration the crescent shaped active site of ribonuclease A (RNase A). In this case, the β-D-ribofuranose structure was used as the basic building unit; both the C1 and C4 arms protruding out towards the β-face of the tetrahydrofuran moiety of the ribose sugar provided an overall “U” shape to the basic building block. Several combinations of bistriazole moieties were constructed on the two arms of this basic building block. These mono- and/or bis-substituted 1,2,3-triazole units were linked to acidic functional groups because of the overall basic nature of the hydrolytic site of RNase A. All these compounds were efficient competitive inhibitors of RNase A with inhibition constants (Ki) in the micromolar range. In contrast to the carboxylic acid-modified hybrid molecules, molecules carrying sulfonic acids were found to be more potent because of the stronger interactions with the positively charged active site. The most efficient inhibitor of the series was the disulfonic acid-functionalized carbohydrate-bis-triazole hybrid molecule. Docking studies disclosed that the molecule, because of its well defined “U” shape with flexible arms, fits effectively in the active site; moreover, in all cases, besides the acid groups, the triazole and sugar rings also actively participated in creating the hydrogen bonding network in the cavity of the enzyme active site.

Fullerene-protein interaction studies have been a key topic of investigation in recent times, but the lower water solubility of fullerene somewhat limits its application in the biological system. In this work, we have compared the activities of fullerene and its water-soluble hydrated form, that is fullerenol, on ribonuclease A (RNase A) under physiological conditions (pH 7.4). The interaction studies of fullerene and fullerenol with protein suggest that the binding depends on the hydrophobic interactions between the protein and the ligand. In addition, fullerene and fullerenol slow down the ribonucleolytic activity of RNase A through noncompetitive and mixed types of inhibition, respectively. This precisely gives the idea about the ligand-binding sites in RNase A, which has further been explored using docking studies. Both these nanoparticles show a reduction in dityrosine formation in RNase A caused due to oxidative stress and also prevent RNase A dimer formation to different extents depending on their concentration.

Pattern formation during evaporation of biofluids has numerous biomedical applications, e.g., in disease identification. The drying of a bidisperse colloidal droplet involves formation of coffee ring patterns owing to the deposition of constituent particles. In the present study, we examine the distinctly different pattern formations during the drying of a colloidal solution depending on the nature of the constituent proteins. The pattern formations of two oppositely charged proteins, namely HSA and lysozyme, have been studied in the presence of fluorescence polystyrene beads of two different sizes (providing better image contrast for further analysis). The variation of pattern formation has been studied by varying the concentrations of the proteins as well as the particles. Furthermore, using image analysis, the patterns are segmented into different regions for quantification. To explain the variations in the patterns, we delve into the interplay of the interactions, especially the capillary and the DLVO forces (between the particles and the substrate). The developed methodology based on the coffee ring effect may be used to identify individual proteins.

Basella is an important green leafy vegetable species of Chenopodiaceae family and is known for its medicinal properties. Hydroxy-benzoic acids, hydroxy-cinnamic acids and flavones groups were identified and characterized from the aqueous stem extracts of B. alba and B. rubra species. Higher values of phenolics as well as antioxidant activity were noted from B. alba species extracts. The evaluation of the cytoxicity of these extracts on A431 (epidermoid carcinoma), Hep G2 (hepatocellular carcinoma) and MG 63 (osteosarcoma) cells indicated anti-proliferative activity against all the cell lines. B. alba extract showed higher anti-proliferative activity (37.95–84.86%). Chick embryo chorioallantoic membrane (CAM) assay revealed inhibition of neo-vessels formation. Significant suppression was found with extracts of B. alba at 7 mg/ml compared to that of B. rubra. This is the first study to report the anti-angiogenic activity of Basella species. These studies indicate that Basella sps can be used as a source of natural antioxidants and can be of high significance in pharmaceutical and nutraceutical industries.

The formation of specific patterns during evaporation of biofluids e.g. blood, serum etc. can be analyzed for quick identification of several diseases. Human Serum Albumin (HSA) is frequently used as the model protein to study amyloid fibril formation that is responsible for numerous neurodegenerative diseases like Parkinson’s disease, Alzheimer’s disease etc. In the present study the fibril growth of HSA is characterized by analyzing the drying patterns of the protein solution. The fibril formation of HSA is confirmed by spectrofluorimetry and the β-sheet content is quantified by far-UV Circular Dichroism spectrometry. Examinations of the drying patterns of HSA, in presence of fluorescent nanoparticles, reveals distinctive pattern transformations with increase in the β-sheet content visualized through fluorescence microscopy and FESEM. The fluorescence images of the dried droplet are analyzed using image processing by the color thresholding method. A rapid quantification methodology of the β-sheet content of HSA and the fraction of unfolded protein has been developed by comparing the results of the image analysis with those of the far-UV CD data.

1,5-Regioisomeric triazole linked disaccharides have been synthesized and screened for their inhibitory properties against ribonuclease A (RNase A). The angular constraint-driven 'crescent shaped' inhibitors accommodated themselves into the enzyme active site. An improved enzyme inhibition was observed with increased H-bonding ability of polar functional groups in the modified disaccharides. In this series, introduction of two carboxyl groups in the furanose rings elicited the best result with an inhibition constant of 50 ± 3 µM. This is the first ever report on the use of disaccharides as RNase A inhibitors.

In order to demonstrate the influence of the surface chirality of the nanoparticles on amyloid fibrillation, the inhibiting effectiveness of the chiral gold nanoparticles, synthesized using the two enantiomeric forms (i.e., d- and l-) of glutamic acid, toward the fibrillation of human serum albumin (HSA) has been investigated. Here the enantiomers of glutamic acid are used as both reducing and stabilizing/capping agents. It is found that the surface chirality is the only major difference between the d-glutamic acid mediated gold (DGAu) and l-glutamic acid mediated gold (LGAu) nanoparticles. The fibrillation process has been monitored using various biophysical techniques, e.g., turbidity assay, Thioflavin T fluorescence kinetics, Congo red binding study, circular dichroism spectroscopy, fluorescence microscopy, and transmission electron microscopy. The experimental results illustrate that DGAu is more effective in inhibiting the formation of HSA fibrils than LGAu. Furthermore, the differential inhibiting e...

The effect of oscillation induced by a frequency-dependent alternating current (AC) electric field to dissociate preformed amyloid fibrils has been investigated. An electrowetting-on-dielectric type setup has been used to apply the AC field of varying frequencies on preformed fibrils of human serum albumin (HSA). The disintegration potency has been monitored by a combination of spectroscopic and microscopic techniques. The experimental results suggest that the frequency of the applied AC field plays a crucial role in the disruption of preformed HSA fibrils. The extent of stress generated inside the droplet due to the application of the AC field at different frequencies has been monitored as a function of the input frequency of the applied AC voltage. This has been accomplished by assessing the morphology deformation of the oscillating HSA fibril droplets. The shape deformation of the oscillating droplets is characterized using image analysis by measuring the dynamic changes in the shape dependent parameters such as contact angle and droplet footprint radius and the amplitude. It is suggested that the cumulative effects of the stress generated inside the HSA fibril droplets due to the shape deformation induced hydrodynamic flows and the torque induced by the intrinsic electric dipoles of protein due to their continuous periodic realignment in presence of the AC electric field results in the destruction of the fibrillar species.

The formation and deposition of amyloid fibrils have been linked to the pathogenesis of numerous debilitating neurodegenerative disorders. Serum albumins serve as good model proteins for understanding the molecular mechanisms of protein aggregation and fibril formation. Graphene-based nanotherapeutics appear to be promising candidates for designing inhibitors of protein fibrillation. The inhibitory effect of graphene oxide (GO) nanoparticles on the fibrillation of human serum albumin (HSA) in an in vitro mixed solvent system has been investigated. The methods used include ThT fluorescence, ANS binding, Trp fluorescence, circular dichroism, fluorescence microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. It was observed that GO inhibits HSA fibrillation and forms agglomerates with β-sheet rich prefibrillar species. Binding of GO prevents the formation of mature fibrils with characteristic cross-β sheet but does not promote refolding to the native state.

The capillary driven flow of water inside a microchannel with altered wettabilities is experimentally investigated and modeled theoretically. The surfaces of the PDMS made microchannel are exposed to oxygen plasma, rendering the surfaces increasingly hydrophilic, which provides the driving force for the flow. The plasma treated surfaces are characterized using topography and phase imaging of AFM scanning, as well as nano-indentation, to correlate the distinct structural changes to the hydrodynamic profiles of the advancing meniscus. The experimental results are further analyzed using a newly proposed slip velocity model. The aim is to obtain a qualitative relationship between the surface properties and the flow parameters, namely the advancing meniscus velocity and pressure drop inside the channel. The insights are of fundamental importance in diverse fields, such as enhanced oil recovery, microfluidic devices, cell separation, and pathology. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4616–4627, 2017

Glycation of ocular lens proteins plays a vital role in the development of diabetic cataract. In order to investigate the role of glycation in cataractogenesis, the extent of glycation of human γB-crystallin was determined by an in vitro glycation study in a solution of high glucose content for upto 28days. The glycated protein has been purified and the formation of advanced glycation end products (AGEs) has been monitored spectroscopically. Size exclusion chromatographic studies showed that the covalent intermolecular crosslinking in the dimer formed was not due to disulfide bond formation. MALDI-TOF spectroscopy was employed to determine the number of glucose moieties attached to the protein due to glycation.

Understanding the interaction of proteins with nanoparticles has become an important area of research in biomedical and pharmaceutical fields. Morin is a flavonol which shows several properties including antioxidant, anticancer, and anti-inflammatory activities. However, the major limitation is its poor aqueous solubility. Therefore, morin-loaded polylactic-co-glycolic acid (PLGA) nanoparticles (MPNPs) were prepared to improve the solubility of morin. The resulting MPNPs were characterized by spectroscopic and microscopic techniques. The nanoparticles were spherical with an average size of 237 ± 17 nm. UV-visible, fluorescence, and circular dichroism (CD) spectroscopy were employed to study the interaction of the MPNPs with human serum albumin (HSA). Our study revealed that a static fluorescence quenching mechanism was involved in the interaction between HSA and MPNPs. Hydrophobic interactions also play an important role in stabilizing the HSA-MPNP complex. CD results suggest that there is an alteration of the secondary structure of HSA in the presence of MPNPs. MPNPs exhibit antioxidant properties which are supported by the DPPH assay. We have further checked the effect of HSA on the antioxidant property of morin and MPNPs. HSA binding with MPNPs was also found to influence the in vitro release property of morin from MPNPs wherein a delayed release response is observed.

Steady state fluorescence and time resolved fluorescence studies at 298 K and low temperature phosphorescence (LTP) studies at 77 K of the interaction of bovine serum albumin (BSA) and human serum albumin (HSA) with ligand 4-azido-2H-chromen-2-one or 4-azidocoumarin (4-AC) have been carried out to visualize the location of the binding site and perturbation of the binding site of the tryptophan (Trp)/tyrosine (Tyr) of the protein(s) by monitoring the emission maxima of Trp residue(s) in proteins. The fluorescence quenching study of Trp estimated that the binding constant for both protein–ligand complexes is in the order of ∼106 with binding site 1. Perturbation in the secondary structures of serum albumins due to binding of 4-AC is also observed from circular dichroism (CD) studies. An energy transfer (ET) study further demonstrated that the non-radiative singlet–singlet ET that takes place from the Trp singlet states of proteins to the singlet state of ligands is greater in the case of BSA. This is supported by the distance and orientation of the donor–acceptor pair obtained from molecular docking studies. The molecular docking studies were also fruitfully exploited to understand the involvement of Trp213 in BSA and Trp214 in HSA in the ET process along with the perturbation of the residues around 5 A from the ligand 4-AC. Phosphorescence spectra at 77 K of the Trp residues in the free proteins (BSA/HSA) and in the complexes of BSA/HSA have also been utilized to specify the role of Trp residues in ET and the binding process.

Sulfonic nucleic acids were identified as inhibitors of ribonuclease A (RNase A). The incorporation of a strongly acidic group (sulfonic, –SO3H) at the 3′-end of pyrimidine nucleosides thymidine and uridine was prompted by the low inhibition constant (Ki) values recorded for carboxymethylsulfonyl (–SO2CH2CO2H) and –CO2H functionalized nucleosides. It was envisaged that the sulfonic acid-modified pyrimidines would bind effectively with the positively charged P1 site of ribonuclease A. Typical harsh conditions used for SO3H incorporation were replaced with milder reaction conditions. The uridine analogue showing a Ki value of 0.96 μM elicited a better result than the thymidine-modified inhibitor. Notably, it was also the best result among all modified non-phosphate acidic nucleosides reported and screened so far as RNase A inhibitors.

Films derived from natural sources such as proteins provide an advantage over synthetic films due to their noncytotoxicity, biodegradability, and vast functionality. A new protein source gained from the cataractous eye protein isolate (CEPI) obtained after surgery has been investigated for this purpose. Glycerol has been employed as the plasticizer and glutaraldehyde (GD) as a cross-linker. Fourier transform infrared spectroscopy was employed to characterize the films. Nanoindentation and thermogravimetric analyses reveal improved mechanical and thermal properties of the cross-linked films. The films with 20% (w/w) GD exhibited properties such as the highest modulus and low water solubility. It is possible to tune the properties based on the extent of cross-linking. All the films were completely degraded by the enzyme trypsin. The similarity of these films was checked by using the prepared films as a delivery vehicle for a model compound, ampicillin sodium. The encapsulation efficiency was found to be 74%, and in vitro release studies showed significant amounts of drug release at physiological pH. This study will help us understand how the properties of protein films can be tuned to obtain the desired physicochemical properties. These biodegradable protein films could find use in pharmaceutical industries as delivery carriers.

Films have been prepared from the natural antioxidant gallic acid and a proteinaceous source, the discarded emulsion obtained after cataract surgery referred to as the cataractous eye protein isolate (CEPI). Fourier transform spectroscopy (FTIR) and SDS PAGE studies confirmed the crosslinking of gallic acid with CEPI. The cross-section and surface of films were further characterized by scanning electron microscopy (SEM). The decrease in crystallinity of the films was confirmed by X-ray diffraction studies. The thermal property of the films is enhanced by the addition of gallic acid as evidenced from the Thermogravimetric analysis (TGA) studies. Films having 2% (w/w) gallic acid exhibited the maximum tensile strength of 2.88 ± 0.32 MPa comparable to other cross-linked films such as soy, casein, canola based protein films. The light barrier property of the films improved with incorporation of gallic acid. The cross-linked films were degraded by the application of the enzyme trypsin. The films also showed good antioxidant properties as determined from the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. The gallic acid incorporated nontoxic CEPI films are biodegradable and possess appreciable mechanical properties and could find use in diverse applications including pharmaceuticals.