Dynamic Light Scattering Studies Research Articles

Thin Film Formation of HSA in the Presence of CTAB-Capped Gold Nanorods through Phase Separation.

Phase behavior in protein-nanoparticle systems in light of protein corona formation has been investigated. We report the formation of HSA thin films following the addition of a solid protein to a solution of CTAB-capped gold nanorods (AuNRs) via phase separation. The phase separation behavior was observed through UV-vis spectroscopy, turbidity assays, and DLS studies. UV-vis spectra for the protein-AuNR solution indicated a possible self-assembly formation by CTAB-HSA complexes and AuNR-HSA conjugates. The turbidity was found to increase linearly up to 30-50% v/v for each component. The growth phase slope is proportional to the concentration of the components, AuNRs, and HSA, with no lag phase. Dynamic light scattering (DLS) shows the formation of larger aggregates with time, implying a segregated phase of AuNR-HSA and a CTAB-HSA-AuNR network. ζ-potential values confirm surface modification, implying protein corona formation on nanorods. The thin films were also characterized using SEM, AFM, SAXS, XPS, FTIR, and TGA studies. SEM images show a smooth surface with a reduced number of pores, indicating the compactness of the deposited structure. AFM shows two different structural pattern formations with the deposition, indicating possible self-assembly of the protein-conjugated nanoparticles. FTIR studies indicate a change in the hydrogen bonding network and confirm the CTAB-HSA-AuNR complex network formation. The XPS studies indicate Au-S bond formation, along with Au-S-S-Au interactions. SAXS studies indicate the formation of aggregates (oligomers), as well as the presence of dominant attractive intermolecular interactions in the thin films.

Incorporating Kappa-carrageenan in Liposomes Facilitates Development of Lipopolysaccharide Hybrid Nanoplatform

Sulfated polysaccharides (kappa-carrageenan) integration in lipids provides diverse structural and physicochemical properties in nanotechnology. Such a lipopolysaccharide hybrid (LPHS) system offers superior applications in the food and pharmaceutical industry. This study investigates the synthesis and characterization of sulfated polysaccharide (kappa-carrageenan: κ-CG) integrated smart liposomes (cubosomes) for establishing cubic tendency in the LPHS system. The κ-CG integrated smart liposomes were prepared using the modified thin film hydration approach. Characterization studies (liposomes and smart liposomes) were performed using dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). DLS studies confirmed the nano-range of both delivery systems. The SEM and TEM investigation revealed the formation of classical cubic morphology of the smart liposomes. Sulfated polysaccharide (κ-CG) integrated smart liposomes exhibited an enhanced κ-CG release profile compared to the liposome-free κ-CG alone. This was due to improved entrapment efficiency (68%) and better overall stability established by the κ-CG incorporation.

Incorporating Kappa-carrageenan in Liposomes Facilitates Development of Lipopolysaccharide Hybrid Nanoplatform

Sulfated polysaccharides (kappa-carrageenan) integration in lipids provides diverse structural and physicochemical properties in nanotechnology. Such a lipopolysaccharide hybrid (LPHS) system offers superior applications in the food and pharmaceutical industry. This study investigates the synthesis and characterization of sulfated polysaccharide (kappa-carrageenan: κ-CG) integrated smart liposomes (cubosomes) for establishing cubic tendency in the LPHS system. The κ-CG integrated smart liposomes were prepared using the modified thin film hydration approach. Characterization studies (liposomes and smart liposomes) were performed using dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). DLS studies confirmed the nano-range of both delivery systems. The SEM and TEM investigation revealed the formation of classical cubic morphology of the smart liposomes. Sulfated polysaccharide (κ-CG) integrated smart liposomes exhibited an enhanced κ-CG release profile compared to the liposome-free κ-CG alone. This was due to improved entrapment efficiency (68%) and better overall stability established by the κ-CG incorporation.

BSA Binding and Aggregate Formation of a Synthetic Amino Acid with Potential for Promoting Fibroblast Proliferation: An In Silico, CD Spectroscopic, DLS, and Cellular Study.

This study presents the chemical synthesis, purification, and characterization of a novel non-natural synthetic amino acid. The compound was synthesized in solution, purified, and characterized using NMR spectroscopy, polarimetry, and melting point determination. Dynamic Light Scattering (DLS) analysis demonstrated its ability to form aggregates with an average size of 391 nm, extending to the low micrometric size range. Furthermore, cellular biological assays revealed its ability to enhance fibroblast cell growth, highlighting its potential for tissue regenerative applications. Circular dichroism (CD) spectroscopy showed the ability of the synthetic amino acid to bind serum albumins (using bovine serum albumin (BSA) as a model), and CD deconvolution provided insights into the changes in the secondary structures of BSA upon interaction with the amino acid ligand. Additionally, molecular docking using HDOCK software elucidated the most likely binding mode of the ligand inside the BSA structure. We also performed in silico oligomerization of the synthetic compound in order to obtain a model of aggregate to investigate computationally. In more detail, the dimer formation achieved by molecular self-docking showed two distinct poses, corresponding to the lowest and comparable energies, with one pose exhibiting a quasi-coplanar arrangement characterized by a close alignment of two aromatic rings from the synthetic amino acids within the dimer, suggesting the presence of π-π stacking interactions. In contrast, the second pose displayed a non-coplanar configuration, with the aromatic rings oriented in a staggered arrangement, indicating distinct modes of interaction. Both poses were further utilized in the self-docking procedure. Notably, iterative molecular docking of amino acid structures resulted in the formation of higher-order aggregates, with a model of a 512-mer aggregate obtained through self-docking procedures. This model of aggregate presented a cavity capable of hosting therapeutic cargoes and biomolecules, rendering it a potential scaffold for cell adhesion and growth in tissue regenerative applications. Overall, our findings highlight the potential of this synthetic amino acid for tissue regenerative therapeutics and provide valuable insights into its molecular interactions and aggregation behavior.

A novel photocatalytic activity of Bi2S3 nanoparticles for pharmaceutical and organic pollution removal in water remediation

In recent times, there has been a surge of interest in the unique characteristics and possible applications of nanoparticles in various fields, including environmental clean-up. The contamination of water sources with pharmaceutical and organic substances has emerged as a significant environmental concern. Semiconductor nanoparticles, particularly Bi2S3 nanoparticles, have garnered considerable attention due to their efficacy and environmentally friendly nature in advanced oxidation processes (AOPs). These nanoparticles have shown remarkable photocatalytic abilities in the destruction of pollutants when exposed to UV–visible light. This study covers the production, characterization, and degradation of Bi2S3 nanoparticles in relation to organic and pharmaceutical contaminants. By utilizing co-precipitate methods, it becomes possible to precisely manipulate the size, shape, and composition of the nanoparticles, which are crucial factors in determining their catalytic effectiveness. The created nanoparticles are then examined using various analytical techniques, such as Powder X-ray Diffraction (P-XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV-visible spectroscopy, Photoluminescence study (PL), colour chromaticity coordinates (CIE), and Dynamic light scattering study (DLS). The catalytic capability of the synthesised compounds was compared to the degradation of Picric acid and paracetamol as model pollutants. The observed photocatalytic activity of these nanoparticles indicates their potential in water purification and environmental clean-up. The findings suggest that incorporating these nanoparticles into practical systems for pollutant degradation is feasible and can be applied in diverse scenarios. The results shed light on the efficient utilization of Bi2S3 nanoparticles as photocatalysts for the oxidation of drugs and organic contaminants. By utilizing Bi2S3 nanoparticles, the elimination of pharmaceutical and organic pollutants from water sources becomes achievable, thereby contributing to the preservation and safeguarding of the environment and public health.

Rapid assessment of changes in phage bioactivity using dynamic light scattering.

Extensive efforts are underway to develop bacteriophages as therapies against antibiotic-resistant bacteria. However, these efforts are confounded by the instability of phage preparations and a lack of suitable tools to assess active phage concentrations over time. In this study, we use dynamic light scattering (DLS) to measure changes in phage physical state in response to environmental factors and time, finding that phages tend to decay and form aggregates and that the degree of aggregation can be used to predict phage bioactivity. We then use DLS to optimize phage storage conditions for phages from human clinical trials, predict bioactivity in 50-y-old archival stocks, and evaluate phage samples for use in a phage therapy/wound infection model. We also provide a web application (Phage-Estimator of Lytic Function) to facilitate DLS studies of phages. We conclude that DLS provides a rapid, convenient, and nondestructive tool for quality control of phage preparations in academic and commercial settings.

Biosynthesis of silver nanocatalyst and its application for the efficient hydrogenation of nitroarenes

The utilization of plant extracts for the synthesis of silver nanoparticles (Ag-NPs) has attracted attention from all over the world due to its unique physicochemical characteristics and significance in the field of environment. Here, Nepal pepper fruit extract was successfully employed to synthesize Ag-NPs. As obtained, Nepal pepper-mediated Ag-NPs were employed for the catalytic conversion of nitroarenes including 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 2-nitroaniline (2-NA), and 2,4,6-trinitrophenol (2,4,6-TNP), into their corresponding amino derivatives using sodium borohydride (NaBH4). The Ag-NPs were analyzed using UV–visible (UV-Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-rays (EDX), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), X-rays Diffraction (XRD), and Zeta potential. TEM micrographs revealed the prepared Ag-NPs were predominantly spherical, with an average diameter of 13.9 nm. DLS and zeta potential studies showed stable small-size Ag-NPs of an average size of 6.8 nm. Ag-NPs elucidate outstanding reduction efficiency against 4-NP, 2-NP, 2-NA, and 2,4,6-TNP with rate constants of 1.71 × 10−3 s−1, 2.32 × 10−3 s−1, 2.88 × 10−3 s−1, and 1.54 × 10−3 s−1, respectively. Additionally, stability and reusability of Ag-NPs revealed stability for up to 15 days and excellent recyclability with small activity loss. This study constittutes an environmentally friendly approach for the synthesis of Ag-NP nanoparticles and their applications in improved organic chemical reduction rates and transformations.

Rapid pH-dependent Photocatalytic Degradation of Methylene Blue by CdS Nanorods Synthesized through Hydrothermal Process

CdS nanorods were successfully synthesized using a hydrothermal method and their photocatalytic degradation activity was tested on methylene blue (MB) at different pH levels. The synthesis of CdS nanorods was confirmed using various techniques including UV–Vis and FTIR spectrometers, X-ray diffraction (XRD), dynamic light scattering (DLS), and high-resolution transmission electron microscope (HRTEM). UV–Vis analysis showed an absorption peak at 385 nm in the CdS nanorods suspension. FTIR spectroscopy revealed the presence of different functional groups responsible for stabilizing the nanorods. TEM analysis showed that the particles had a rod-like morphology with crystallite sizes ranging from 2 to 10 nm, consistent with the DLS studies. XRD analysis confirmed the crystalline nature of CdS. A photocatalytic reactor was used to degrade methylene blue at different pH values, and the residual concentration was monitored using UV–Vis spectroscopy. The photocatalytic activity of CdS nanorods was found to be improved by adjusting the pH of the solution. The nanorods showed high efficiency in degrading methylene blue, with degradation performance of approximately 32 % and 35 % after just 30 min under sunlight at pH 4 and pH 10, respectively. This research has potential applications in the photodegradation of harmful pollutants in both industrial wastewater and domestic water supplies.

Mitigation of the Deleterious Effect of Heavy Metals on the Conformational Stability of Ubiquitin through Osmoprotectants.

The Ubiquitin-Proteasome System (UPS) is important in protein homeostasis and is involved in many cell processes. UPS's wide range of regulatory activities is based on the unique and diverse signals transmitted through all-encompassing processes. Cells need a fully functional UPP to cope with oxidative stress, so cellular redox status modulates ubiquitin activity. However, these protein quality control systems are compromised under adverse conditions such as heavy metal stress, resulting in pathological conditions. Heavy metals disrupt the physiological action of sensitive proteins by forming complexes with side-chain functional groups or by dislocating critical metal ions in metalloproteins. In addition, perturbation in the structure of Ubiquitin may affect the ubiquitin-proteasome pathway. In this study, it has been investigated the effects of heavy metals likewise chromium (Cr), cadmium (Cd), and mercury chloride (HgCl2) on the conformational stability of Ubiquitin as well as overcome their hazardous effect, the interaction of osmo-protectants such as Sesamol, gallic acid, Glycine, and ascorbic acid have also been explored in the study. The near and far UV-circular dichroism measurements deduced the secondary and tertiary structural changes. The size of the Ubiquitin before and after exposure to heavy metals was measured by DLS (dynamic light scattering). Docking research was also used to investigate the interaction of Ubiquitin with various heavy metals. Near and far UV-circular dichroism (CD) measurements revealed that mercury, chromium, and cadmium disrupt Ubiquitin's secondary and tertiary structure. The effect of chromium, even at low concentrations, was significantly deleterious compared to cadmium and mercury chloride. Ubiquitin's far-UV circular dichroism spectra subjected to heavy metals were recorded in several osmo-protectants, such as ascorbic acid, Glycine, gallic acid, and Sesamol, which offset the adverse effects of heavy metals. DLS studies revealed a noteworthy change in the hydrodynamic radius of Ubiquitin in the presence of heavy metals. Docking analysis revealed a significant binding affinity of mercury and cadmium ions with Ubiquitin. This study can infer the heavy metals' disruption of Ubiquitin's secondary and tertiary structure. Osmo-protectants produced by animal cells are more effective against heavy metals than plant antioxidants.

Biogenic Synthesis of Zinc Oxide Nanoparticles Mediated by the Extract of Terminalia catappa Fruit Pericarp and Its Multifaceted Applications.

Zinc oxide nanoparticles (ZnO-NPs) were biosynthesized by using the pericarp aqueous extract from Terminalia catappa Linn. These NPs were characterized using various analytical techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet (UV) spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM), and XRD studies of the nanoparticles reported mean size as 12.58 nm nanocrystals with highest purity. Further SEM analysis emphasized the nanoparticles to be spherical in shape. The functional groups responsible for capping and stabilizing the NPs were identified with FTIR studies. DLS studies of the synthesized NPs reported ζ potential as -10.1 mV and exhibited stable colloidal solution. These characterized ZnO-NPs were evaluated for various biological applications such as antibacterial, antifungal, antioxidant, genotoxic, biocompatibility, and larvicidal studies. To explore its multidimensional application in the field of medicine. NPs reported a potential antimicrobial activity at a concentration of 200 μg/mL against bacterial strains in the decreasing order of Streptococcus pyogenes > Streptococcus aureus > Streptococcus typhi > Streptococcus aeruginosa and against the fungi Candida albicans. In vitro studies of RBC hemolysis with varying concentrations of NPs confirm their biocompatibility with IC50 value of 211.4 μg/mL. The synthesized NPs' DPPH free radical scavenging activity was examined to extend their antioxidant applications. The antiproliferation and genetic toxicity were studied with meristematic cells of Allium cepa reported with mitotic index (MI index) of 1.2% at the concentration of 1000 μg/mL. NPs exhibited excellent Larvicidal activity against Culex quinquefasciatus larvae with the highest mortality rate as 98% at 4 mg/L. Our findings elicit the therapeutic potentials of the synthesized zinc oxide NPs.

Characterization of the effect of chromium salts on tropocollagen molecules and molecular aggregates

Though the capability of chromium treatment to improve the stability and mechanical properties of collagen fibrils is well-known, the influence of different chromium salts on collagen molecules (tropocollagen) is not well characterized. In this study, the effect of Cr3+ treatment on the conformation and hydrodynamic properties of collagen was studied using atomic force microscopy (AFM) and dynamic light scattering (DLS). Statistical analysis of contours of adsorbed tropocollagen molecules using the two-dimensional worm-like chain model revealed a reduction of the persistence length (i.e., the increase of flexibility) from ≈72 nm in water to ≈56–57 nm in chromium (III) salt solutions. DLS studies demonstrated an increase of the hydrodynamic radius from ≈140 nm in water to ≈190 nm in chromium (III) salt solutions, which is associated with protein aggregation. The kinetics of collagen aggregation was shown to be ionic strength dependent. Collagen molecules treated with three different chromium (III) salts demonstrated similar properties such as flexibility, aggregation kinetics, and susceptibility to enzymatic cleavage. The observed effects are explained by a model that considers the formation of chromium-associated intra- and intermolecular crosslinks. The obtained results provide novel insights into the effect of chromium salts on the conformation and properties of tropocollagen molecules.

Histidine-Functionalized Diblock Copolymer Nanoparticles Exhibit Enhanced Adsorption onto Planar Stainless Steel.

RAFT aqueous emulsion polymerization of isopropylideneglycerol monomethacrylate (IPGMA) is used to prepare a series of PGEO5MA46 -PIPGMAy nanoparticles, where PGEO5MA is a hydrophilic methacrylic steric stabilizer block bearing pendent cis-diol groups. TEM studies confirm a spherical morphology while dynamic light scattering (DLS) analysis indicated that the z-average particle diameter can be adjusted by varying the target degree of polymerization for the core-forming PIPGMA block. Periodate oxidation is used to convert the cis-diol groups on PGEO5MA46 -PIPGMA500 and PGEO5MA46 -PIPGMA1000 nanoparticles into the analogous aldehyde-functionalized nanoparticles, which are then reacted with histidine via reductive amination. In each case, the extent of functionalization is more than 99% as determined by 1 HNMR spectroscopy. Aqueous electrophoresis studies indicate that such derivatization converts initially neutral nanoparticles into zwitterionic nanoparticles with an isoelectric point at pH 7. DLS studies confirm that such histidine-derivatized nanoparticles remain colloidally stable over a wide pH range. A quartz crystal microbalance is employed at 25°C to assess the adsorption of both the cis-diol- and histidine-functionalized nanoparticles onto planar stainless steel at pH 6. The histidine-bearing nanoparticles adsorb much more strongly than their cis-diol counterparts. For the highest adsorbed amount of 70.5mgm-2 , SEM indicates a fractional surface coverage of 0.23 for the adsorbed nanoparticles.

Investigation of structural, optical and photoluminescence properties of non-essential amino acid capped zinc sulfide nanoparticles for optoelectronic applications

The objective of the study is to synthesize Zinc Sulphide nanoparticles (ZnS) with different amino acid capping agents in aqueous solution by a simple and cost effective facile chemical co precipitation method and analyze their optoelectronic features. Bio compatibility with less toxic amino acids such as l-Glutamic acid, l-Alanine and l-Asparagine were used as capping agents. These amino acids are from Non-essential amino acid group and its capping behavior suitable for semiconducting nanoparticles like ZnS. The role of non essential amino acids were to stabilize the nanoparticle against agglomeration and also to provide chemical passivation that leads to a significant influence on the improved structural, optical and photoluminescence properties of ZnS nanoparticles. The detailed structural analysis of Zinc Sulphide nano particles revealed by X-ray diffraction method (XRD). From this analysis observed the formation of Cubic ZnS nanoparticles with an average crystallite size in the range of 2.08–2.22 nm.The morphology of the nano particles studied by Field emission scanning electron microscope (FESEM). Particle size examined by Dynamic Light scattering studies (DLS) and which revealed that particle size ranges are below 50 nm. The functional groups of nanoparticles were identified by Fourier transform Infrared spectroscopy (FT-IR) studies. Photoluminescence studies attributed that the considerable emission bands. The UV–Vis analysis disclosed the optical band gap range from 3.77 eV to 3.95 eV.

Purification and Structural Characterization of N-Terminal 190 Amino Acid Deleted Essential Mammalian Protein; Transcription Termination Factor 1.

The mammalian transcription termination factor 1 (TTF1) is an essential protein that plays diverse cellular physiological functions like transcription regulation (both initiation and termination), replication fork blockage, chromatin remodeling, and DNA damage repair. Hence, understanding the structure and mechanism conferred by its variable conformations is important. However, so far, almost nothing is known about the structure of either the full-length protein or any of its domains in isolation. Since the full-length protein even after multiple attempts could not be purified in soluble form, we have codon optimized, expressed, and purified the N-terminal 190 amino acid deleted TTF1 (ΔN190TTF1) protein. In this study, we characterized this essential protein by studying its homogeneity, molecular size, and secondary structure using tools like dynamic light scattering (DLS), circular dichroism (CD) spectroscopy, Raman spectroscopy, and atomic force microscopy (AFM). By CD spectroscopy and DLS, we confirmed that the purified protein is homogeneous and soluble. CD spectroscopy also revealed that ΔN190TTF1 is a helical protein, which was further established by analysis of Raman spectra and amide I region deconvolution studies. The DLS study estimated the size of a single protein molecule to be 17.2 nm (in aqueous solution). Our structural and biophysical characterization of this essential protein will open avenues toward solving the structure to atomic resolution and will also encourage researchers to investigate the mechanism behind its diverse functions attributed to its various domains.

Aggregation of Enveloped Viruses By Platelet Factor 4 (PF4) and Neutrophil Extracellular Traps (NETs): Implications for the Anti-Viral Properties of NETs

As part of the innate immune response, neutrophils release neutrophil extracellular traps (NETs), webs of DNA coated with histones that ensnare and kill bacteria. A growing body of literature suggests that NETs can also capture and inactivate enveloped viruses. The ability of NETs to limit the systemic spread of pathogens occurs at the expense of collateral organ damage induced when high concentrations of NETs are digested by DNases to release toxic NET degradation products (NDPs) including cell free DNA and histones. Our group has shown that the positively charged platelet-specific chemokine (PF4, CXCL4), compacts NETs by forming tetramers that electrostatically cross-bind two polyanionic fragments of DNA, similarly to the way it aggregates heparans. PF4 complexed to NETs induces NET resistance to nuclease digestion, preventing the release of toxic NDPs while enhancing NET-bacterial capture by bridging anionic DNA to the negatively charged microbial surface. PF4 has also been shown limit pulmonary injury and enhance survival in mice infected with PR8, a mouse-adapted H1N1 influenza virus. Our group and others have found that both PF4 and NETs are elevated in the setting of SARS-CoV-2, leading us to hypothesize that they may act synergistically to combat the proliferation of enveloped viruses. To investigate the effect of PF4 on the pathogenicity of enveloped viruses, we studied PR8 and murine hepatitis virus (MHV)-1, a betacoronavirus that induces severe pulmonary disease. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) were used to assess the ability of PF4 and human-derived NETs to aggregate MHV-1 and PR8 virions. ChAdOx1, a replication-deficient adenovirus was used as a non-enveloped viral control. The DLS and SEM studies showed that PF4 (5-20 µg/ml) aggregated MHV-1 and PR8, forming complexes with an average diameter of 500nm, the width of 4-5 virions (Figure 1). In contrast, PF4 did not aggregate non-enveloped adenovirus. DLS studies showed that PF4 does not form complexes with coronavirus spike protein. However, the anti-PF4-polyanion antibody KKO, bound to PF4-viral complexes, leading to an additional 50% increase in viral aggregate size, an effect not seen with an isotype control antibody TRA (Figure A). These results suggest that PF4 binds to polyanions on the viral envelop via electrostatic interaction, much in the same way that it binds to heparans and DNA. We preformed subsequent DLS studies in which MHV-1 virions were incubated with both intact and digested NETs, and viral-NET aggregation was only observed in the presence of PF4. To determine if PF4 aggregates virus in vivo, IHC studies were performed on lungs harvested from MHV-1-infected A/J mice inoculated intranasally with 5 x 103 PFU of virus and sacrificed at 48h. The lungs were prepared for immunohistochemistry (IHC), and labeled with antibodies directed against PF4 and the MHV-1 nucleocapsid protein. We calculated the average Pearson's coefficient in 4 randomly selected 20x confocal images of the lungs of MHV-1 infected animals (n=4 mice, 16 images analyzed) using the FIJI JaCoP colocalization plugin. We observed co-localization of PF4 and MHV-1 within the cytoplasm of a subset of cells (r= 0.70225, p<0.0001), suggesting that PF4-MHV-1 aggregation occurs in vivo (Figure B) Lastly, the plaque forming unit assay was used to measure the effect of PF4 on MHV-1 infectivity of L2 cells. We found that incubating MHV-1 with PF4 (0-100µg/ml), leads to a 50% decrease in infectivity(n=5, p=0.023). Our studies demonstrate that PF4 binds to and aggregates MHV-1 and PR8 in vitro likely through electrostatic interactions with the viral envelop rather than adhesion to the viral spike protein. These results also suggest that PF4-mediated aggregation enhances viral capture by NETs to form NETs:PF4:viral complexes that may limit viral spread. IHC studies of lungs from MHV-1 infected mice demonstrate that PF4 colocalizes with the virus, suggesting that aggregation also occurs in vivo. In ongoing studies, we are investigating whether PF4 and NETs act synergistically to reduce coronavirus and influenza infectivity and enhance immune recognition and subsequent clearance of viral aggregates. These findings will help to define the anti-viral properties of NETs and may generate insights relevant to the treatment of coronavirus, influenza, and other enveloped viruses. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A novel pyrene-based aggregation induced enhanced emission active Schiff base fluorophore as a selective “turn-on” sensor for Sn2+ ions and its application in lung adenocarcinoma cells

Schiff bases are an important class of compounds that are highly instrumental in complex formation as well as act as sensors for various metal ions. Herein, 1-aminopyrene was reacted with 5-bromo-2-thiophene carboxaldehyde to synthesize a designed Schiff base, PY-SB (N-((5-bromothiophen-2-yl) methylene) pyrene-2-amine) as a condensation product. The authenticity of the synthesized Schiff base compound was established using 1H NMR, 13C NMR, IR and HRMS techniques. Among the optoelectronic investigations, the AIEE (Aggregation Induced enhanced emission) property of PY-SB was explored and it showed 24 folds enhancement in fluorescence intensity in tetrahydrofuran (THF) and water mixtures (50:50). AIEE results were further supported by DLS (Dynamic Light scattering) study. In addition, PY-SB was found to be a highly selective and sensitive tool for the “turn-on” detection of Sn2+ ion. The turn–on fluorescence of PY-SB is due to the PET-OFF process. The electron transfer from nitrogen to the pyrene ring is completely blocked due to the formation of a complex of PY-SB with insitu generated Sn2 species(PY-SB + Sn2), which causes PET-OFF. The detection limit and binding constant of PY-SB towards Sn2+ ion were found to be 5.4 µM, and 2 × 104 M−1, respectively. The stoichiometric study through Job’s plot reveals the development of 2:1 ratio (Sn2: PY-SB) of complexation which is further confirmed by DFT, ES-MS, 1H NMR and 13C NMR, SEM-EDX. To verify the sensing behavior of PY-SB in a biological system, in vitro studies on lung adenocarcinoma cells were successfully carried out and they showed similar behavior as seen in the cuvette study.

Characterization of outcomes of amino acid modifications using a combinatorial approach to reveal physical and structural perturbations: A case study using trastuzumab biosimilar

Biopharmaceuticals, such as monoclonal antibodies, are considered as life-saving drugs for autoimmune diseases, cancer and infectious diseases. However, biotherapeutics tend to undergo chemical degradation during various stages of manufacturing. The conditions of chemical degradation, along with the physical degradation pathways, have a direct influence on the overall stability, safety and efficacy of these therapeutics. While site-specific chemical changes have been well-explored and investigated using various analytical approaches, the resulting conformational and structural changes have not been much studied. Thus, we explored various biophysical techniques for assessing the influence of three representatives forced degradation conditions viz. oxidation, deamidation, and glycation, in a model therapeutic trastuzumab biosimilar. The site-specific modifications caused by these stress conditions were analysed using high resolution mass spectrometry. While their thermodynamic and conformational consequences were investigated by using differential scanning colorimetry (Nano-DSC), circular dichroism (CD) spectroscopy, analytical ultracentrifugation (AUC), and dynamic light scattering (DLS). The investigated stress conditions resulted in reduced thermodynamic stability of mAb, as confirmed using Nano-DSC. Secondary structure analysis performed with CD spectroscopy indicated detectable structural alterations in the beta sheets of stressed samples. DLS and SV-AUC studies demonstrated an enhanced level of aggregation and fragmentation in presence of all stress conditions. Thus, the biophysical analytical toolkits, when used simultaneously, could offer deeper insights into the subtle conformational changes that result from site-specific chemical modifications in mAbs. Hence, these analytical approaches may serve as significant additions to the battery of techniques used for forced degradation analysis of biopharmaceuticals.

Synthesis, Self-Aggregation, Surface Characteristics, Electrochemical Property, Micelle Size, and Antimicrobial Activity of a Halogen-Free Picoline-Based Surface-Active Ionic Liquid.

We present a new approach toward the design of a halogen-free picoline-based surface-active ionic liquid (SAIL) (1-octyl-4-methyl pyridinium dodecyl sulfate) [C8γPic]DS consisting of long dodecyl sulfate (DS) as an anion. The surface properties, micellization behavior, and antimicrobial activity in an aqueous solution were investigated using tensiometry, conductometry, and ultraviolet (UV) spectroscopy. Incorporating the DS group in SAIL leads to lower critical micellar concentration (CMC) and enhanced adsorption at the air/water interface of the functionalized ionic liquid compared to the C8-alkyl chain-substituted pyridine ionic liquids. The antimicrobial activity was evaluated against a representative Gram-negative and Gram-positive bacteria panel. Antibacterial activities increased with the alkyl chain length, C8 being the homologous most effective antimicrobial agent. The micelle size of [C8γPic]DS was determined by the dynamic light-scattering (DLS) study. Cyclic voltammetry (CV) measurements have been employed to evaluate the interaction between the SAIL micelle and working electrode, diffusion coefficient, and micelle size of the SAIL solution. The diffusion coefficient explored the correlation of surface properties and the antimicrobial activity of [C8γPic]DS. This halogen-free SAIL is the future of wetting agents and emulsion studies in agriculture due to its small micelle size and surface characteristics.

Prediction of in vitro drug dissolution into fasted-state biorelevant media: Contributions of solubility enhancement and relatively low colloid diffusivity

A previously developed model showed good predictability for in vitro drug dissolution into FeSSGF and FeSSIF-V2, where biorelevant media-mediated enhanced drug dissolution by only about one-tenth as much as it enhanced solubility, due to drug-loaded fat globules and mixed micelles exhibiting far slower diffusivity than free drug. The present objective was to quantitatively assess the contributions of fasted biorelevant media-mediated solubility and diffusivity on enhanced drug dissolution in FaSSGF and FaSSIF-V2. Griseofulvin, ketoconazole, and ibuprofen were subjected to dissolution into FaSSGF and FaSSIF-V2, as well as their corresponding “surfactant-free” media. Solubility and dynamic light-scattering studies (DLS) of drug in FaSSGF and FaSSIF-V2 were conducted. Results showed that FaSSGF and FaSSIF-V2 mixed micelles were large and slowly diffusing (diffusivities about 2 × 10−8 cm2/s and 12×10−8 cm2/s, respectively), compared to free drug (about 7 × 10−6 cm2/s), although were smaller and more rapidly diffusing compared to drug-bound fat globules and mixed micelles from FeSSGF and FeSSIF-V2 (about 1 × 10−9 cm2/s and 7 × 10−8 cm2/s, respectively). Dissolution enhancement in FaSSGF and FaSSIF-V2 was the same as solubility enhancement, which was minimal. FaSSGF and FaSSIF-V2 practically did not enhance drug dissolution, since solubility was at best minimally increased, but also since micelles were relatively slowly diffusing relative to free drug diffusivity.

Enhancement in chaperone activity of human αA-crystallin by nanochaperone gold nanoparticles: Multispectroscopic studies on their molecular interactions

The chaperone activity of human αA-crystallin (HAA) against aggregation of human γD-crystallin (HGD) was enhanced by gold nanoparticles (AuNPs). Chaperone activity of HAA was almost doubled in the presence of 5.5 nM gold nanoparticles (AuNPs). To decipher this effect at molecular level, interactions between HAA and AuNPs were studied using fluorescence and circular dichroism spectroscopic techniques. The nanoparticles were synthesized and characterized by using TEM and dynamic light scattering (DLS). TEM and DLS studies revealed that bioconjugation of AuNPs with HAA did not cause any significant change in the size of the nanoparticles. AuNPs had caused static quenching of tryptophan (Trp) fluorescence, which was confirmed through determination of excited state lifetime of Trp residue of HAA in absence and the presence of AuNPs. The association and quenching constant for HAA-AuNPs conjugation were ∼ 109 M−1. Hydrogen bonding and van der Waals interactions were found to be involved in HAA-AuNPs complex. Polarity of Trp microenvironment in HAA was not perturbed by AuNPs as supported by synchronous and three-dimensional fluorescence spectroscopy. Far-UV CD spectra suggested that the secondary structure of HAA was not significantly affected by AuNPs.