Adsorption of an amphiphilic penicillin onto human serum albumin: characterisation of the complex

Unraveling the Compositional and Molecular Features Involved in Lysozyme-Benzothiazole Derivative Interactions

In this work we present a computational analysis together with experimental studies, focusing on the interaction between a benzothiazole (BTS) and lysozyme. Results obtained from isothermal titration calorimetry, UV-vis, and fluorescence were contrasted and complemented with molecular docking and machine learning techniques. The free energy values obtained both experimentally and theoretically showed excellent similarity. Calorimetry, UV-vis, and 3D/2D-lig-plot analysis revealed that the most relevant interactions between BTS and lysozyme are based on a predominance of aromatic, hydrophobic Van der Waals interactions, mainly aromatic edge-to-face (T-shaped) π-π stacking interactions between the benzene ring belonging to the 2-(methylthio)-benzothiazole moiety of BTS and the aromatic amino acid residue TRP108 of the lysozyme receptor. Next, conventional hydrogen bonding interactions contribute to the stability of the BTS-lysozyme coupling complex. In addition, mechanistic approaches performed using elastic network models revealed that the BTS ligand theoretically induces propagation of allosteric signals, suggesting non-physiological conformational flexing in large blocks of lysozyme affecting α-helices. Likewise, the BTS ligand interacts directly with allosteric residues, inducing perturbations in the conformational dynamics expressed as a moderate conformational softening in the α-helices H1, H2, and their corresponding β-loop in the lysozyme receptor, in contrast to the unbound state of lysozyme.

Advanced Materials Based on Nanosized Hydroxyapatite

The development of new materials based on hydroxyapatite has undergone a great evolution in recent decades due to technological advances and development of computational techniques. The focus of this review is the various attempts to improve new hydroxyapatite-based materials. First, we comment on the most used processing routes, highlighting their advantages and disadvantages. We will now focus on other routes, less common due to their specificity and/or recent development. We also include a block dedicated to the impact of computational techniques in the development of these new systems, including: QSAR, DFT, Finite Elements of Machine Learning. In the following part we focus on the most innovative applications of these materials, ranging from medicine to new disciplines such as catalysis, environment, filtration, or energy. The review concludes with an outlook for possible new research directions.

Influence of the Surfactant Structure on Photoluminescent π-Conjugated Polymer Nanoparticles: Interfacial Properties and Protein Binding

π-Conjugated polymer nanoparticles (CPNs) are under investigation as photoluminescent agents for diagnostics and bioimaging. To determine whether the choice of surfactant can improve CPN properties and prevent protein adsorption, five nonionic polyethylene glycol alkyl ether surfactants were used to produce CPNs from three representative π-conjugated polymers. The surfactant structure did not influence size or yield, which was dependent on the nature of the conjugated polymer. Hydrophobic interaction chromatography, contact angle, quartz crystal microbalance, and neutron reflectivity studies were used to assess the affinity of the surfactant to the conjugated polymer surface and indicated that all surfactants were displaced by the addition of a model serum protein. In summary, CPN preparation methods which rely on surface coating of a conjugated polymer core with amphiphilic surfactants may produce systems with good yields and colloidal stability in vitro, but may be susceptible to significant surface alterations in physiological fluids.

EHS matrix incubated in media containing penicillin retains sufficient concentrations of antibiotic to inhibit growth of susceptible microorganisms

In studying the interaction between bacteria and host cells in vitro, the latter are frequently cultured on commercially available biotic matrices such as Matrigel® or Geltrex®. To avoid contamination, host cells are commonly grown in the presence of antibiotics. However, we present here the finding that cell culture on such a matrix in the presence of antibiotics interferes with the outcome of subsequent infection experiments by virtue of diminished bacterial survival. By comparing outcomes for penicillin-susceptible and resistant strains of Staphylococcus aureus, we show that residual penicillin remains in the matrix despite the antibiotics' withdrawal from culture. Hence, the use of antibiotics should be avoided in this context.

Human serum albumin encapsulated gold nanoclusters: effects of cluster synthesis on natural protein characteristics

The differences in the physiochemical properties between native Human Serum Albumin (HSA) and HSA encapsulated gold nanoclusters (HSA-AuNCs) are characterised.

Exploring the thermodynamics and conformational aspects of nicotinic acid binding with bovine serum albumin: a detailed calorimetric, spectroscopic and molecular docking study

An attempt to obtain a physicochemical and conformational outlook on the binding interaction of vitamin B₃ (NA) with a model transport protein BSA using calorimetry, light scattering, molecular docking, and spectroscopic techniques.

Interaction of curcumin nanoformulations with human plasma proteins and erythrocytes

Background

Recent studies report curcumin nanoformulation(s) based on polylactic-co-glycolic acid (PLGA), β-cyclodextrin, cellulose, nanogel, and dendrimers to have anticancer potential. However, no comparative data are currently available for the interaction of curcumin nanoformulations with blood proteins and erythrocytes. The objective of this study was to examine the interaction of curcumin nanoformulations with cancer cells, serum proteins, and human red blood cells, and to assess their potential application for in vivo preclinical and clinical studies.

Methods

The cellular uptake of curcumin nanoformulations was assessed by measuring curcumin levels in cancer cells using ultraviolet-visible spectrophotometry. Protein interaction studies were conducted using particle size analysis, zeta potential, and Western blot techniques. Curcumin nanoformulations were incubated with human red blood cells to evaluate their acute toxicity and hemocompatibility.

Results

Cellular uptake of curcumin nanoformulations by cancer cells demonstrated preferential uptake versus free curcumin. Particle sizes and zeta potentials of curucumin nanoformulations were varied after human serum albumin adsorption. A remarkable capacity of the dendrimer curcumin nanoformulation to bind to plasma protein was observed, while the other formulations showed minimal binding capacity. Dendrimer curcumin nanoformulations also showed higher toxicity to red blood cells compared with the other curcumin nanoformulations.

Conclusion

PLGA and nanogel curcumin nanoformulations appear to be very compatible with erythrocytes and have low serum protein binding characteristics, which suggests that they may be suitable for application in the treatment of malignancy. These findings advance our understanding of the characteristics of curcumin nanoformulations, a necessary component in harnessing and implementing improved in vivo effects of curcumin.

Ligand binding strategies of human serum albumin: how can the cargo be utilized?

Human serum albumin (HSA), being the most abundant carrier protein in blood and a modern day clinical tool for drug delivery, attracts high attention among biologists. Hence, its unfolding/refolding strategies and exogenous/endogenous ligand binding preference are of immense use in therapeutics and clinical biochemistry. Among its fellow proteins albumin is known to carry almost every small molecule. Thus, it is a potential contender for being a molecular cargo/or nanovehicle for clinical, biophysical and industrial purposes. Nonetheless, its structure and function are largely regulated by various chemical and physical factors to accommodate HSA to its functional purpose. This multifunctional protein also possesses enzymatic properties which may be used to convert prodrugs to active therapeutics. This review aims to highlight current overview on the binding strategies of protein to various ligands that may be expected to lead to significant clinical applications.

Mesoporous silicon: a platform for the delivery of therapeutics

Nanostructuring materials can radically change their properties. Two interesting examples highlighted here are nanoscale porosity inducing biodegradability, and nanoscale confinement affecting the physical form of an entrapped drug. Mesoporous silicon is under increasing study for drug-delivery applications, and is the topic of this review. The authors focus on those properties of most relevance to this application, as well as those recent studies published on small molecule and peptide/protein delivery.

Albumin binds self-assembling dyes as specific polymolecular ligands

Self-assembling dyes with a structure related to Congo red (e.g. Evans blue) form polymolecular complexes with albumin. The dyes, which are lacking a self-assembling property (Trypan blue, ANS) bind as single molecules. The supramolecular character of dye ligands bound to albumin was demonstrated by indicating the complexation of dye molecules outnumbering the binding sites in albumin and by measuring the hydrodynamic radius of albumin which is growing upon complexation of self-assembling dye in contrast to dyes lacking this property. The self-assembled character of Congo red was also proved using it as a carrier introducing to albumin the intercalated nonbonding foreign compounds. Supramolecular, ordered character of the dye in the complex with albumin was also revealed by finding that self-assembling dyes become chiral upon complexation. Congo red complexation makes albumin less resistant to low pH as concluded from the facilitated N-F transition, observed in studies based on the measurement of hydrodynamic radius. This particular interference with protein stability and the specific changes in digestion resulted from binding of Congo red suggest that the self-assembled dye penetrates the central crevice of albumin.

Effects of the molecular structure of two amphiphilic antidepressant drugs on the formation of complexes with human serum albumin

Interactions of two amphiphilic antidepressant drugs, imipramine and desipramine hydrochlorides, with the blood protein human serum albumin (HSA) were investigated to gain an understanding of the effects of drug molecular structure on the complex formation of drug-protein molecules. To elucidate the mechanisms of such effects, the protein-antidepressant interactions in aqueous buffered solutions of pH 3.0 and 5.5 (isoelectric point of HSA = 4.9) were investigated using conductivity, zeta potential, and dynamic light scattering. An increase of the critical micelle concentration of both antidepressants was detected as a consequence of extensive binding to the protein. From zeta-potential measurements, the Gibbs energies of adsorption of the drugs onto the protein were derived using the proposed models of Kayes and Ottewill and Watanabe. Measurements of the hydrodynamic radii of HSA-antidepressant complexes as a function of the drug concentration have shown a gradual increase of size of a saturation rather than a denaturation process of the protein. A larger drug adsorption at pH 5.5 than at pH 3.0 was also observed, as a consequence of a more important specific binding at the former pH.