Colloids and Surfaces B: Biointerfaces

BackgroundThe development of nanocarriers with precise control over drug release is crucial for targeted therapy. This study focuses on the design and optimization of pH-sensitive gelatin/perfluorohexane (PFH) nanodroplets loaded with berberine chloride, a model drug relevant to traditional Chinese medicine. Subjects and MethodsNanodroplets were prepared using an emulsion technique, with optimization of parameters including homogenization rate, polymer concentration, surfactant, drug, and perfluorocarbon conte nt. ResultsThe optimized formulation resulted in nanodroplets with a mean particle size of 281.7 nm and a drug encapsulation efficiency of 66.8 {+/-} 1.7%. Characterization studies confirmed successful encapsulation and pH-responsive behavior. Ultrasound stimulation significantly enhanced drug release, with 150 kHz frequency proving more effective than 1 MHz. Stability studies demonstrated prolonged stability over one month at 4{degrees}C. Following 10 minutes of ultrasound irradiation, the nanodroplets exhibited 89.4% cumulative drug release. ConclusionsIn conclusion, these pH-sensitive nanodroplets show potential for delivering berberine chloride in a controlled manner, connecting traditional Chinese medicine with contemporary drug delivery methods.

Formation of extracellular polymeric substances (EPS) is a crucial step for bacterial biofilm growth. Dependence of EPS composition on the growth substrate and the conditioning of the latter is thus of primary importance. Here, we present results of studies on the growth of biofilms of two different strains each, of the Gram negative bacteria Escherichia coli and Klebsiella pneumoniae, on four polymers used commonly in indwelling medical devices - Polyethene, Polypropylene, Polycarbonate, and Polytetrafluoroethylene immersed in Bovine Serum Albumin (BSA) for 24 hrs. The polymer substrates are studied before and after immersing in BSA for 9 hrs and 24 hrs, using contact angle measurement (CAM) and Field Emission Scanning Electron Microscopy (FE-SEM) to extract, respectively, the philicity (defined as{phi} {equiv} sin ({theta}-90{degrees}), where{theta} is contact angle of the liquid on the solid at a particular temperature and ambient pressure) and spatial Hirsch parameter H (defined from the relation, F(r) ~ r2H, where F(r) is the mean squared density fluctuation at the sample surface). H =, <0.5 or >0.5 signifies no correlation, anti-correlation, and correlation, respectively. The substrates are seen to transform from large hydrophobicity to near amphiphilicity with the formation of BSA conditioning surface layer, and the H-values distinguish the length scales of ~ 100 nm, 500 nm, and 2000 nm, with the anti-correlation increasing with length scale. Biofilms grown on the BSA-covered surfaces are studied with CAM, FE-SEM, Fourier Transform Infrared (FTIR) and Surface Enhanced Raman Spectroscopy (SERS). Most notably, the{phi} -values are independent of the bacterial species and strain but dependent on the polymer, as is also shown strikingly by both types of spectra, while H-values show some bacterial variation. Thus, the EPS composition and consequently the wetting properties of the corresponding bacterial biofilms seems to be decided by the interaction of the conditioning BSA layer with a specific polymer used as the growth substrate.

We introduce a method for conjugating antigens to gold nanoparticles (GNPs) while synthesizing them using gas plasma, which eliminates the need for chemical linkers intended to facilitate the conjugation procedure for immunotherapy purposes. We report a physical approach to conjugate antigen Nestin (NES) as a marker in malignant tumors to GNPs. Two approaches were used to perform the conjugation of GNPs and NES. The first method involved using citrate to synthesize GNPs, and then NES was conjugated onto the GNPs surface by plasma. In the second method, GNPs were simultaneously synthesized and linker-freely conjugated to NES by plasma treatment. Enzyme-linked immunosorbent assay with the protocol defined in this study, Zeta-sizer, Ultraviolet-visible spectroscopy, and Transmission Electron Microscopy results confirmed NES conjugation to GNPs. In addition, the toxicity of the prepared samples was investigated in vitro using peripheral blood mononuclear cells (PBMCs) and flow cytometry, which proved the non-toxicity of the samples. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/570950v2_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1bffa43org.highwire.dtl.DTLVardef@c75811org.highwire.dtl.DTLVardef@166f4b3org.highwire.dtl.DTLVardef@4b4def_HPS_FORMAT_FIGEXP M_FIG C_FIG

PURPOSEBenzalkonium chloride (BAK), a common preservative in eye drops, has a major side effect of dry eye. The mechanisms are typically attributed to BAK cytotoxicity. However, due to its surfactant properties, BAK can disrupt the tear film lipid layer (TFLL), leading to dry eye. This study examined the stability and compressibility of the TFLL and the impact of the presence of BAK. METHODSMeibomian gland secretion (meibum, source of the TFLL) was collected from sacrificed cows eyelids. Lipids were extracted by dissolving meibum in chloroform to a final concentration of 1 mg/mL, with one solution additionally containing 0.1 mg/mL BAK. Each solution was overlaid on a water subphase in a Langmuir Trough-Blodgett trough. The changes of surface pressure ({pi}) with area (A) for the lipid film upon compression were monitored, and the corresponding compression modulus (Cs-1) at each data point was determined. RESULTSThe {pi}-A isotherms for meibum lipid monolayers exhibited near-reversible behavior with a smooth profile with a maximum {pi} of approximately 32 mN/m. The Cs-1-{pi} isotherms of the meibum lipid monolayer show that the films are gel-like with a constant compressive modulus of 24-32 mN/m within the surface pressure range of 8-30 mN/m. In contrast, adding BAK dramatically decreased the maximum surface pressure to only 10 mN/m and the compressive modulus to only 2-10 mN/m. CONCLUSIONSThis study demonstrated that BAK disrupts the meibum lipid layer by forming a monolayer with decreased stability and reduced compressive resistance, a mechanism that may underlie its dry-eye side effect yet has largely been neglected.

In the current work, biosynthesis of silver nanoparticle (Ag NPs) and interaction study between alpha amylase and Ag NPs/nanocluster has been performed via wet-lab as well as in silico approach. We have synthesized Ag NPs using alpha amylase enzyme which reduces the silver nitrate precursor forming the stable Ag NPs. UV-Visible spectroscopy and fluorescence spectroscopies were performed for optical characterization of Ag NPs. UV-Vis spectra showed the wide absorption band centered around 475 nm due to surface plasmon resonance. We have also observed gradual decrease in fluorescence intensity with the increase in incubation time. Also, shift in {lambda}max of the emission spectra was recorded which clearly suggested the formation of nano-bio-conjugate. Circular dichroism spectra show the initial decrease in the ellipticity, when we added the silver nitrate, but after incubating for different time, there are no major changes in secondary structure of protein. In computational study we have modelled ground state configuration of (Ag)24 nanocluster using in silico approach. Further docking of the modelled optimized nanocluster with alpha amylase was performed and found that Ag-nanocluster showing non-covalent interaction with alpha amylase and forming stable docking complex.

Advances in molecular medicine related to the treatment of genetic disorders and cancer require finding new pathways for gene transfer. Nonviral delivery methods rely on the application of polymers, liposomes and cationic lipid systems used as vehicle. Among these systems, there is increasing interest in surfactants, which, due to their ability to complex with nucleic acids can deliver into cell DNA or RNA molecules of almost any size, which is unattainable with viral gene delivery systems.The main aim of this study was to determine the effect of the concentration of lactose-based surfactants (zwitterionic derivatives of sulfobetaine with carbohydrate moieties) on the structure of DNA/RNA as well as to explore their abilities of nucleic acid complexation. Structural studies of DNA or RNA in complexes with surfactants of two types at various concentrations were conducted using circular dichroism (CD) spectroscopy, gel electrophoresis (GE) and synchrotron radiation small angle X-ray scattering (SR-SAXS). Our studies showed that the examined surfactants have excellent properties of forming complexes with DNA and RNA. Additionally, to determine the cytotoxicity and transfection abilities of the studied lipoplexes, preliminary tests were performed in HeLa and fibroblast cells. The obtained results suggest that these systems have relatively low toxicity; however, further research is needed in this area.

Reference materials (RM)-assisted Rayleigh-Gans-Debye approximation (rm-RGDA) has been developed and used to in situ determine the size and thickness of the adlayer on the particles in solution. The particle size determined by rm-RGDA is quite close to that measured by electron microscopy but significantly smaller than that measured by DLS. The BSA adlayer absorbed on PS50, PS100 and SiO2 NPs is 3.3, 0.9 and 1.2 nm, respectively, and close to those observed by SEM, which is 4.6, 1.3 and 3.8 nm, respectively. The FTIR analysis results show that the BSA absorbed on larger particles or hydroxyl-abundant surface, e.g. PS100 and SiO2 NPs can lose its secondary structure, e.g. -helix, to a great extent and that absorbed on a more curve surface, e.g. smaller PS50 particles can largely preserve its secondary structure as its free state. The measurement results show the curvature of the NPs is closely related to the structure change of the adsorbed protein. This method provide a facile and new approach to measure the size and its adlayer change of the hybrid and core-shell structured nanoparticles in a wide range of wavelength. SIGNIFICANCEQuantitative study on the adsorption of the protein on colloidal nanoparticles is an important approach to understand the biophysical effect, compared with other ex situ methods such as TEM and SEM, where the specimen are undergone pre-processing and no longer the original state in measurement. It is, therefore, a big challenge. In order to cope with this challenge, UV-vis based RGDA has been developed and applied to in situ measure the size of the dispersed colloidal nanoparticles and their protein adlayer thickness, where the protein adlayer thickness on the colloidal nanoparticles can be easily determined. We believe this method provide a facile and sensitive way to in situ measure the dimension change of hybrid colloidal nanoparticles.

Biofilms are multicellular communities of microbial cells that grow on natural and synthetic surfaces. They have become the major cause for hospital-acquired infections because once they form, they are very difficult to eradicate. Nanotechnology offers a new approach to fight biofilm-associated infections. Here, we report on the synthesis of silver nanoparticles (AgNPs) with antibacterial ligand epigallocatechin gallate (EGCG) and the formation of lysozyme protein corona on AgNPs as shown by UV-Vis, dynamic light scattering, and circular dichroism analyses. We further tested the activity of EGCG-AgNPs and their lysozyme bioconjugates on the viability of Bacillus subtilis cells and biofilm formation. Our results showed that, although EGCG-AgNPs presented no antibacterial activity on planktonic Bacillus subtilis cells, they inhibited B. subtilis biofilm formation at concentrations larger than 40 nM and EGCG-AgNP-lysozyme bioconjugates inhibited biofilms at concentrations above 80 nM. Cytotoxicity assays performed with human cells showed a reverse trend, where EGCG-AgNPs barely affected human cell viability, while EGCG-AgNP-lysozyme bioconjugates severely hampered viability. Our results therefore demonstrate that EGCG-AgNPs may be used as non-cytotoxic antibiofilm agents.

This study presents the first investigation of the adsorption behaviour of Afatinib on gold nanoparticle (AuNP) monolayers, employing a combination of AFM-SEIRA and SERS techniques. Two types of AuNPs with distinct sizes, synthesized using different reagents, were employed to elucidate the influence of surface type on drug adsorption. The first type of AuNPs was synthesized using sodium borohydride (SB), whereas the second type was obtained using hydroxylamine hydrochloride (HH) as the reducing agent. AFM-SEIRA revealed that Afatinib interacts to the AuNPs primarily through the quinazoline ring, amide group, and amino moiety, with adsorption geometry strongly dependent on nanoparticle type. Contributions from CH3 and CH2 moieties were also identified, indicating their role in stabilizing the molecule/metal interface. Time-resolved SERS studies demonstrated that the adsorption process is dynamic and involves molecular reorientation, followed by gradual desorption, which is accelerated at physiological temperature (37 {degrees}C). Competitive adsorption experiments with phenylboronic acid (PBA) showed that Afatinib exhibits higher affinity toward AuNPs, however, co-adsorption leads to reduced stability of both species on the surface. The results reveal molecular insights into drug/nanoparticle interactions and emphasize the role of surface functionalization in efficient nanocarrier design. This work deepens understanding of adsorption at plasmonic interfaces for biomedical use.

Surfactants and film-forming polymers are common ingredients in consumer spray products such as cleaning products, hair care products, and anti-perspirants. Spraying eases application by creating aerosolised droplets of the product that can distribute evenly over the treated surface. However, these aerosols can potentially be inhaled during their normal application. Droplets that reach the alveoli can interact with the pulmonary surfactant; a complex mixture of phospholipids and proteins that regulates the surface tension at the air-liquid interface. This interaction could elevate the minimum surface tension at maximum compression and change the surface rheology of the pulmonary surfactant at the interface. We tested four surfactants and seven polymers for their ability to inhibit pulmonary surfactant function in vitro and investigated if the inhibition is dose-rate dependent i.e., the product of the concentration (mg/mL) and aerosolisation rate (mL/min). We found that independent of chemical class (surfactant or polymer) there was a clear dose-rate dependent inhibition of pulmonary surfactant function and that different chemicals inhibited function at different dose-rates. We compared the points of departure of inhibitory chemicals to a polymer with known dose-rate dependent lung toxicity. When assessing the risk of chemicals that might be inhaled, it is essential to ensure normal use would not inhibit pulmonary surfactant function leading to immediate effects on the lungs. Lay summarySpray products create a cloud of tiny droplets in the air when they are used. This cloud can be inhaled, and if it reaches the deepest parts of the lungs, it can interact with the thin layer of liquid, called pulmonary surfactant, that covers the cells. It protects the lung tissue during the constant movement of breathing. Droplets can sometimes disrupt the pulmonary surfactant function, making breathing difficult. Chemicals that are used in spray products must be tested to assess if they are harmful if inhaled. In this project we studied the effect of chemicals that are commonly found in spray products on the functioning of the pulmonary surfactant in vitro. The results can be combined with other in vitro methods to test if chemicals are harmful to inhale without testing on animals.

In dermatology, chelates play a significant role in skin care and treatment of skin diseases. Chelates involve coordination bonding between metal ions and organic molecules such as flavonoids. Quercetin (Q) is an extensively studied natural flavonoid with proven safety and anti-inflammatory properties. This study shows the role of two biocompatible metal ions, Iron (Fe2+) and Copper (Cu2+) in coordination bonding with Q in 2-Propanol 50% and 80% at 1:1 stoichiometry. Our results show that chelation involves the hydroxyl groups and occurs by coordination of Cu2+ to Q for the Ring A-B (Benzoyl group) resulting in a fluorescence emission peak at 530nm from the Ring B-C (Cinnamoyl group). This chelates Q+Cu2+ reduces mechanically induced erythema in the skin (Tanned type). A similar effect was observed in the chelate Q+Fe2+ where the coordination of Fe2+ to Q occurs for the cinnamoyl group resulting in an emission peak at 425nm from Benzoyl group of Q. The statistical analysis shows significant differences in the effects of Q+Cu2+ (p-value = 0.00001), Q+Fe2+ (p-value = 0.0003) respect to Q as well as between them (p-value =0.0029). Our results suggest that the interaction between Q and metal ions plays a central role in the inflammatory pathway. We conclude that the anti-inflammatory properties of Q were enhanced by both Q+Fe2+ and Q+Cu2+ chelates, highlighting the effect of Q+Fe2+ where the hydroxyl groups available in the cinnamoyl group of the Q molecule are the main intermediates to interact with Fe2+, which is a requirement to trigger the anti-inflammatory molecular events of Q molecules.

BackgroundEmerging antimicrobial resistance poses serious threat to human well-being. Current therapeutics often fail to treat bacterial infections as pathogenic bacteria often attach to various surfaces and form biofilm. One such pathogen, Pseudomonas aeruginosa, can form biofilm for its survival in the presence of antibacterial agents. This study aimed to evaluate the antibacterial, antibiofilm, and mechanistic activities of Lantana camara leaf extract mediated silver nanoparticles (LCLE-Ag NPs) against Pseudomonas aeruginosa, where the extract contributes for the reduction of Ag+ to Ag0. MethodsLCLE-Ag NPs were synthesized and characterized by using UV visible spectroscopy, dynamic light scattering, and electron microscopy. Antibacterial and antibiofilm activities of the synthesized NPs were assessed against P. aeruginosa isolates KPW.1-S1 and HRW.1-S3. Extracellular polysaccharides (EPS), and extracellular DNA (eDNA) and reactive oxygen species (ROS) generation were visualized using epifluorescence microscopy. The ability of the nanoparticles to eradicate preformed biofilm was also evaluated. The expressions of quorum-sensing genes were analyzed using semi quantitative polymerase chain reaction. Cytotoxicity was tested on human kidney epithelial-like cells. ResultsThe synthesized LCLE-Ag NPs displayed an absorption peak at 416 nm and a size range of 30 to 35 nm. They exhibited significant antibacterial and antibiofilm activities correlating with decreased EPS and eDNA levels. LCLE-Ag NPs effectively disrupted both preformed and antibiotic-induced biofilms and such activities were found to be associated with increased ROS levels and decrease in lasI and pqsA expression. Cytotoxicity assays indicated no significant toxicity at effective concentrations. ConclusionsLCLE-Ag NPs displayed promising antibacterial and antibiofilm activities against P. aeruginosa, acting through biofilm matrix disruption, ROS generation, and quorum-sensing inhibition.

The top layer of skin, the stratum corneum, provides a formidable barrier to the skin. Nanoparticles are utilized and further explored for personal and health care applications related to the skin. In past years several researchers have studied the translocation and permeation of nanoparticles of various shapes, sizes, and surface chemistry through the cell membranes. Most of these studies focused on a single nanoparticle and a simple bilayer system, whereas skin has a highly complex lipid membrane architecture. Moreover, it is highly unlikely that a nanoparticle formulation applied on the skin will not have multiple nanoparticle-nanoparticle and skin-nanoparticle interactions. In this study, we have utilized coarse-grained MARTINI molecular dynamics simulations to assess the interactions of two types (bare and dodecane-thiol coated) of nanoparticles with two models (single bilayer and double bilayer) of skin lipid membranes. The nanoparticles were found to be partitioned from the water layer to the lipid membrane as an individual entity as well as in the cluster form. It was discovered that each nanoparticle reached the interior of both single bilayer and double bilayer membrane irrespective of nanoparticle type and concentration, though coated particles were observed to efficiently traverse across bilayer when compared with bare particles. The coated nanoparticles also created a single large cluster inside the membrane, whereas bare nanoparticles were found in small clusters. Both the nanoparticles exhibited preferential interactions with cholesterol molecules present in the lipid membrane as compared to other lipid components of the membrane. We have also observed that the single membrane model exhibited unrealistic instability at moderate to the higher concentration of nanoparticles, and hence for translocation study, at minimum double bilayer model should be employed.

In this work, the hydrogen bonding interaction of water and ethanol with Polysorbate 80 (P-80, Tween 80) is simulated, in relation to its role in oil upgrading and recovery, using real theoretical and experimental studies. The theoretical physicochemical results obtained were compared with other experimental results derived from the treatment of improved and recovered oil after mixing Biocompatible Pharmaceutical Formulations (BPF) of these three compounds and oil produced in Venezuela. The Spartan 16 program was used to build the molecular structures and simulate the interactions with the semi-empirical PM3 method, to compare them with two real experiments. These two experiments were performed as follows: in the first, the mixture consists of a surfactant, (Z)-Sorbitan mono-9-octadecenoate poly(oxy-1,2-ethanediyl) or polyoxoethylene (20) sorbitan mono-oleate (Polysorbate 80), which is mixed with the hydrocarbon, and then completely fluidized with the addition of ethyl alcohol or ethanol.Water and ions (<100 ppm) present in this experiment are contained in oil and ethanol as contaminants (approximately 1.73-1.30% of total water). In the second experiment, the BPF ratios were 10:5:0.1:0.01 for oil:water with 17,800 ppm NaCl:P-80:ethanol (approximately 33.09% of total water and 1.78% w/v NaCl). The simulations were performed taking into account both real experiments. The simulated interactive products were characterized by the following parameters: energy, minimum conformational energy, solvation energy, aqueous energy, HOMO energy, LUMO energy, {Delta}E, dipole moment, polarizability, electrostatic potential map (EPM) and electron density.A theoretical parametric relationship (sio Index, "stability in oil Index") is developed to evaluate the stability of the molecular forms generated within the hydrocarbon. The following theoretical experiments were performed: First, successive interactions of water with P-80 from position 1 to position 21. Second, successive interactions from position 1 to position 21 of P-80 of water and ethanol, 1 to 1. Third, successive interactions with P-80 of 21 ethanol molecules on the final product of the first experiment. These theoretical results were compared with some experimental results obtained using Oil Mixtures. The results obtained and compared in both experimental series (theoretical and real) allow to distinguish the role of P-80, Ethanol, Water and ions for the improvement and recovery of the treated oil. It is concluded that the formulation that does not contain added water and sodium chloride is supposed to use the contaminating water present in the petroleum and the water contained in the ethanol (<5%).This formulation has very little effect on the resulting Density of the improved Oil, but it greatly decreases the resulting Viscosity in the Crude Oil. The formulation that contains more than 30% added Water decreases the Density while the Viscosity of the Crude Oil responds proportionally to the Water retained in it. This difference in the results could be interpreted as a different proportion and chemical composition as a consequence of a different structural relationship between these components and a different conformation of the nanoparticle generated within the Oil, in each case. In this sense, the hypothesis is established that there would be an intermediate molecular form that could improve both Viscosity and Density.

The objective of the present study was to synthesize Cu doped ZnS nanocore crosslinked with lignocellulose (represented as Cu:ZnS-lignocellulose nanocomposite) for antifungal action against the devastating tea blister blight pathogen Exobasidium vexans. The characteristic features of the nanocomposite were analyzed via different physicochemical techniques like FTIR, XRD, XPS, SEM, SEM-EDX, Elemental mapping, PCS, and UV-PL studies. The FTIR and XPS investigations revealed the crosslinking between lignocellulose and the Cu:ZnS. The presence of lignocellulose was seen to attribute a potent antifungal efficacy, also enhancing the stability of the resulting nanocomposite in aqueous suspensions. The antifungal efficacy confirmed through disk diffusion and broth dilution assays have a maximum zone of inhibition of 1.75 cm2 and a MIC50 of 0.05 mg/ml against E. vexans. Additionally, the antisporulant activity was evident as the basidiospores failed to germinate in presence of the Cu:ZnS-lignocellulose nanocomposites. This shows potential for stemming the rapid infectivity of E. vexans by achieving disease inhibition at the early stage. Finally, the comparison with two commonly used commercial fungicides (copper oxychloride and fluconazole) demonstrated >10-fold higher antifungal activity for Cu:ZnS-lignocellulose nanocomposites.

Respiratory infections by RNA viruses are one of the major burdens upon global health and economy. Viruses like influenza or coronaviruses can be transmitted through respiratory droplets or contaminated surfaces. An effective antiviral coating can decrease the viability of the virus particles in the outside environment significantly, hence reducing their transmission rate. In this work, we have screened a series of nanoparticles and their composites for antiviral activity using Nano Luciferase based highly sensitive influenza A reporter virus. Using this screening system, we have identified copper-graphene (Cu-Gr) nanocomposite shows strong antiviral activity. Extensive material and biological characterization of the nanocomposite suggested a unique metal oxide embedded graphene sheet architecture that can inactivate the virion particles only within 30 minutes of pre-incubation and subsequently interferes with the entry of these virion particles into the host cell. This ultimately results in reduced viral gene expression, replication and production of progeny virus particles, slowing down the overall pace of progression of infection. Using PVA as a capping agent, we have been able to generate a Cu-Gr nanocomposite based highly transparent coating that retains its original antiviral activity in the solid form.

Many biochemical processes are dependent on the presence or absence of molecular oxygen (O2). Palladium-tetrapyrrol derivatives can be used to measure O2-concentrations and O2-turnover during biochemical reactions and microbial growth in standard microtiter plates (MTPs). Palladium(II)-5,10,15,20-(tetrapentafluorophenyl)-porphyrin (1; CAS 72076-09-6) and Palladium(II)-5,10,15,20-(tetraphenyl)tetrabenzoporphyrin (2; CAS 119654-64-7) are introduced with this study. Spectral analyses of both compounds revealed that fluorescence quenching by O2 is not evenly distributed throughout all wavelengths and can therefore be used ratiometrically. Experimentally determined fluorescence lifetimes are around 500 {micro}s and 300 {micro}s for 1 and 2, respectively. A simple protocol is disclosed, how to immobilize the indicators on the bottom of MTP wells to give clear transparent dye doped polymer layers. We propose a straightforward procedure of how fluorescence data can be processed and calibrated in terms of O2 concentrations. Diverse applications are demonstrated and discussed, which include oxygen consumption and production by microorganisms as well as by enzymatically catalysed biochemical reactions. Various aspects are critically considered, as there are e.g. the dependence of O2 solubility on temperature and salinity, the diffusion of O2 across diverse phase boundaries, the unwanted O2 ingress into the reaction volume, the oxygen binding capacity of the MTP plastic material and the pH-dependence of the sensor layer. The findings and methods presented here open up a broad variety of high throughput assays involving changes of dissolved O2 as measurands for biochemical and biological activity. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/718663v1_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@4daa4dorg.highwire.dtl.DTLVardef@e7ab8aorg.highwire.dtl.DTLVardef@1af1149org.highwire.dtl.DTLVardef@97fea5_HPS_FORMAT_FIGEXP M_FIG C_FIG

Interactions between amino acid (dl-phenylalanine) and surfactant (cetyltrimethyl ammonium bromide) was investigated using density and density data was utilized to calculate apparent molar volume [Formula], and partial molar volume also known as limiting molar volume [Formula] to find out solute-solvent interactions between amino acid and surfactant.

Binding of a tetracationic porphyrin (TMPyP4+) to poly(rA) has been studied in neutral buffered solution of low ionic strength in a wide range of molar phosphate-to-dye ratios (P/D) using absorption spectroscopy, polarized fluorescence and fluorimetric titration. Two competitive binding modes were identified: partial intercalation of porphyrin chromophores between adenine bases prevailing at P/D > 20 and its outside binding to poly(rA) backbone dominating at P/D < 6. Both of them were accompanied by enhancement of the porphyrin emission. Absence of the emission quenching near stoichiometric P/D ratios allowed us to assume that external binding occurs without the self-stacking of the porphyrin chromophores.

We here report a study of aggregation of Semaglutide at different temperatures, using resonance light scattering (RLS), fluorescence polarization and back-scattering techniques. Fluorescence emission spectra were obtained by exciting the samples at 275 nm and 295 nm, revealing a peak emission at 600 nm associated with the aggregation process. The size of the aggregates is around 100 nm according to back-scattering measurements. Two distinct thermal transitions were observed by RLS: the first melting point (Tm1) at 30{degrees}C and the second (Tm2) at 91{degrees}C, indicating changes in aggregation state. The fluorescence polarization revealed a fast rotational dynamics of the aggregates at Tm2, leading to greater depolarization of the emitted light. The structural organization of the Ozempic aggregates was studied using two dyes, Laurdan for lipid components and 1,8-ANS for protein component (GLP1). Thus, revealing a stable PEG-lipid core which hold the GLP1, increasing their exposition to the solvent. An enhanced FRET event inside the aggregates in presence of Fe2+ and Fe3+ was observed. We conclude that the PEG-lipid core plays a significant role in the aggregates structure stability, being a key to improve the biological activity of Ozempic. This methodology can be used to study similar aggregation constructs in the pharmaceutical industry.