FT-IR Spectroscopy for the Identification of Binding Sites and Measurements of the Binding Interactions of Important Metal Ions with Bovine Serum Albumin

Inhibition of SARS-CoV-2 spike protein entry using biologically modified polyacrylonitrile nanofibers: in vitro study towards specific antiviral masks

With the increase in the contagiousness rates of Coronavirus disease (COVID-19), new strategies are needed to protect people and to halt the from the spread of viruses.

Mummified embalmed head skin: SR-FTIR microspectroscopic exploration

This case report details the examination of the skin of an Egyptian mummified head with a possible skin disorder. The head, thought to be dated in the first half of the 18th Dynasty, New Kingdom (1570-1400 BCE) belongs to the Museum of Forensic Anthropology, University of Madrid. Initial histological examination demonstrated evidence of chronic inflammation, which was confirmed by immunohistochemistry and Transmission Electron Microscopy (TEM). However, confirmation of pathology could be confounded by both the age of the specimen and the process of preservation by mummification. In this case report, Synchrotron Radiation Fourier Transform Microspectroscopy (SR-µFTIR) was used to add novel insights into embalmed mummified tissue. More precisely, FTIR is used for the first time on the specific specimens, while no other similar studies have been performed on these samples priorly. Additionally, modern skin tissue was examined too, in order to compare the amount of degradation to the mummified one. Whilst the FTIR results confirmed the results from the initial histological study, they also showed a biochemical modification of the mummified skin that could be indicative of tissue degradation. The latter was supported by comparing it to FTIR results of the modern tissue used.

Revealing the complexity of distinct manganese species-protein interactions through multi-spectroscopy

The effect of manganese (Mn) on protein conformation is closely related to its chemical species. To further realize the behavior of different species of Mn in vivo, this study is designed to analyze the separate and simultaneous interactions of Mn(ii) and Mn(iii) with bovine serum albumin (BSA) using multi-spectroscopy. The results demonstrated that the interaction of Mn(ii) or Mn(iii) with BSA is a process of static quenching and Mn(iii) formed a more stable complex. The binding constants and thermodynamic constants indicated that a 1:1 complex was formed between Mn(ii)/Mn(iii) and BSA through a moderate binding force, and hydrophobic interaction played an important role in the binding. UV-Vis spectroscopy, synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy results revealed that the conformation changes in BSA induced by Mn(ii)/Mn(iii) binding. The results of the ternary systems suggested that both Mn species interfered the interaction of the other with BSA. The conformation of BSA may change more to adapt to the simultaneous binding to Mn (ii) and Mn (iii) when two Mn species coexist.

Hybrid hydrogels for bacteriocin delivery to infected wounds

Superficial infections in chronic wounds can prevent the wound healing process by the development of persistent infections and drug-resistant biofilms. Topically applied antimicrobial formulations with stabilized and controlled release offer significant benefits for the effective treatment of wound infections. Bacteriocins are the antimicrobial peptides (AMPs) produced by bacteria that are viable alternatives to antibiotics owing to their natural origin and low propensity for resistance development. Herein, we developed a hybrid hydrogel composed of Pluronic F127 (PF127), ethylenediaminetetraacetic acid (EDTA) loaded liposomes, glutathione (GSH), and the bacteriocin Garvicin KS (GarKS) referred to as "GarKS gel". The GarKS gel exhibited suitable viscosity and rheological properties along with controlled release behavior (up to 9 days) for effective peptide delivery following topical application. Potent in vitro antibacterial and anti-biofilm effects of GarKS gel were evident against the Gram-positive bacterium Staphylococcus aureus. The in vivo treatment of methicillin resistant S. aureus (MRSA) infected mouse wounds suggested potent antibacterial effects of the GarKS gel following multiple applications of once-a-day application for three consecutive days. Altogether, these results provide proof-of-concept for the successful development of AMP loaded topical formulation for effective treatment of wound infections.

Molecular mechanism and thermodynamic study of Rosuvastatin interaction with human serum albumin using a surface plasmon resonance method combined with a multi-spectroscopic, and molecular modeling approach

Rosuvastatin (ROS) is an anti-cholesterol drug belonging to statin drugs. A multi-spectroscopic approach combined with a molecular modeling technique was used to assess ROS association with human serum albumin (HSA). Besides, an HSA immobilized surface plasmon resonance (SPR) chip was used to obtain kinetic parameters (ka, kd, and K_D). Fluorescence quenching titrations revealed that ROS interacts with HSA via a dynamic, exothermic, enthalpy-driven mechanism. Hydrogen bonds and van der Waals interactions as the most prevalent bonding forces contribute to ROS-HSA complex formation. ROS binding to HSA alters HSA conformation. The SPR results indicated that ROS and HSA have a strong interaction possessing an equilibrium constant (K_D) of 1.55 × 10^-8 M at 298 K. A competitive analysis of site markers showed that ROS has a higher tendency to bind to the warfarin binding site (site IIA), which may explain why warfarin has a higher anticoagulant effect in ROS users. FRET analysis indicated that non-radiation energy transfer occurred between ROS and HSA. According to molecular docking studies, ROS prefers binding sites IB and IIA while the ROS-HSA complex stabilizes due to the hydrogen bond and π-π interaction. The presence of hydrogen-bond donors and acceptors, as well as aromatic ROS moieties, facilitates such interactions.

Investigation of bovine serum albumin aggregation upon exposure to silver(i) and copper(ii) metal ions using Zetasizer

Depending upon the metal coordination capacity and the binding sites of proteins, interaction between metal and proteins leads to a number of changes in the protein molecule which may include the change in conformation, unfolding, overall charge, and aggregation in some cases. In this study, Cu(ii) and Ag(i) metal ions were selected to investigate aggregation of bovine serum albumin (BSA) molecule upon interaction by measuring the size and charge of the aggregates using nano-Zetasizer instrument. Two concentrations of metal ions were made to interact with a specific concentration of BSA and the size and zeta potential of BSA aggregates were measured from 0 min upto 18 h. The Cu(ii) and Ag(i) metal ions showed almost similar behavior in inducing the BSA aggregation and the intensity of peak corresponding to the normal-sized protein decreased with time, whereas the peak corresponding to the protein aggregate increased. However, the effect on zeta potential of the aggregates was observed to be different with both metal ions. The aggregation of protein due to interaction of different metal ions is important to study as it gives insight to the pathogenesis of many neurological disorders and would result in developing effective ways to limit their exposure.

Investigation of binding interaction behavior between antiemetic drugs and Trypsin by spectroscopy and molecular docking

Antiemetic drugs are used to control excessive vomiting and nausea and generally absorbed through gastrointestinal tract. In present study, the in-vitro binding interactions two of the antiemetic drugs (dimenhydrinate and ondansetron) between Trypsin (Tsn) secreted from pancreas to small intestine for protein digestion were investigated by fluorescence emission spectroscopy (FES), UV-VIS spectroscopy, synchronous fluorescence spectroscopy (SFS), FT-IR spectroscopy and molecular modeling methods. Also, the effect of these drugs on the catalytic activity of Tsn was determined. The fluorescence quenching experiments indicated that each drugs quenched the intrinsic fluorescence of Tsn with their increased concentrations. The results of SFS and UV-VIS spectra proved the interaction of dimenhydrinate and ondansetron with Tsn. FT-IR spectra showed that the secondary structure of enzyme was altered in the presence of the drugs. All these spectroscopy results were validated and explained by molecular docking studies. Both drugs have inhibition effect on the catalytic activity of Tsn and the IC₅₀ values were determined as 2.6 × 10^-4 M and 6.4 × 10^-4 M for dimenhydrinate and ondansetron, respectively. Docking results revealed that the hydrogen bond interaction of dimenhydrinate with active-site residue Ser195 and ondansetron with active-site residues His57 and Ser195 hydrogen bonds might be cause the inhibition of enzyme activity. The results of this study can provide valuable information in the field of pharmacokinetics and pharmacodynamics.

Use of nitrogen-doped amorphous carbon nanodots (N-CNDs) as a fluorometric paper-based sensor: a new approach for sensitive determination of lead(ii) at a trace level in highly ionic matrices

This work reports a facile synthesis of nitrogen-doped amorphous carbon nanodots (N-CNDs) and their use as a fluorometric paper-based sensor for the determination of Pb²⁺ at a low concentration. Both solution-based and paper-based systems were developed. The results show that the linearity ranges for Pb²⁺ determination were 0.010-10 mg L^-1 (LOD = 0.008 mg L^-1) and 0.005-0.075 mg L^-1 (LOD = 0.004 mg L^-1) for the solution-based and the paper-based sensors, respectively. Furthermore, the developed sensors show relatively high selectivity toward Pb²⁺ over ten other metal cations of different charges including As³⁺, Hg²⁺, Cd²⁺, Mg²⁺, Ni²⁺, Zn²⁺, Fe³⁺, Cu²⁺, Ba²⁺, and Ag⁺. The mechanism of Pb²⁺ determination was also investigated. It was found that the sensors exploited the quenching of the fluorescence intensity of N-CNDs by Pb²⁺via the photo-induced electron transfer (PET) mechanism. When applied to real water and herbal medicine samples, the performance of the sensor exhibited no significant difference as compared to the results of the validation method (ICP-OES). Overall, the developed sensors, especially the paper-based one, are promising for the practical analysis of Pb²⁺ in pharmaceutical and environmental samples with a low Pb²⁺ concentration.

Iso-mukaadial acetate and ursolic acid acetate inhibit the chaperone activity of Plasmodium falciparum heat shock protein 70-1

Plasmodium falciparum is the most lethal malaria parasite. The present study investigates the interaction capabilities of select plant derivatives, iso-mukaadial acetate (IMA) and ursolic acid acetate (UAA), against P. falciparum Hsp70-1 (PfHsp70-1) using in vitro approaches. PfHsp70-1 facilitates protein folding in the parasite and is deemed a prospective antimalarial drug target. Recombinant PfHsp70-1 protein was expressed in E. coli BL21 cells and homogeneously purified by affinity chromatography. The interaction between the compounds and PfHsp70-1 was evaluated using malate dehydrogenase (MDH), and luciferase aggregation assay, ATPase activity assay, and Fourier transform infrared (FTIR). PfHsp70-1 prevented the heat-induced aggregation of MDH and luciferase. However, the PfHsp70-1 chaperone role was inhibited by IMA or UAA, leading to both MDH and luciferase's thermal aggregation. The basal ATPase activity of PfHsp70-1 (0.121 nmol/min/mg) was closer to UAA (0.131 nmol/min/mg) (p = 0.0675) at 5 mM compound concentration, suggesting that UAA has no effect on PfHsp70-1 ATPase activity. However, ATPase activity inhibition was similar between IMA (0.068 nmol/min/mg) (p < 0.0001) and polymyxin B (0.083 nmol/min/mg) (p < 0.0001). The lesser the Pi values, the lesser ATP hydrolysis observed due to compound binding to the ATPase domain. FTIR spectra analysis of IMA and UAA resulted in PfHsp70-1 structural alteration for β-sheets shifting the amide I band from 1637 cm-1 to 1639 cm-1, and for α-helix from 1650 cm-1 to 1652 cm-1, therefore depicting secondary structural changes with an increase in secondary structure percentage suggesting that these compounds interact with PfHsp70-1.

Biogenic Selenium Nanoparticles: A Fine Characterization to Unveil Their Thermodynamic Stability

Among the plethora of available metal(loid) nanomaterials (NMs), those containing selenium are interesting from an applicative perspective, due to their high biocompatibility. Microorganisms capable of coping with toxic Se-oxyanions generate mostly Se nanoparticles (SeNPs), representing an ideal and green alternative over the chemogenic synthesis to obtain thermodynamically stable NMs. However, their structural characterization, in terms of biomolecules and interactions stabilizing the biogenic colloidal solution, is still a black hole that impairs the exploitation of biogenic SeNP full potential. Here, spherical and thermodynamically stable SeNPs were produced by a metal(loid) tolerant Micrococcus sp. Structural characterization obtained by Scanning Electron Microscopy (SEM) revealed that these SeNPs were surrounded by an organic material that contributed the most to their electrosteric stabilization, as indicated by Zeta (ζ) potential measurements. Proteins were strongly adsorbed on the SeNP surface, while lipids, polysaccharides, and nucleic acids more loosely interacted with SeNMs as highlighted by Fourier Transform Infrared Spectroscopy (FTIR) and overall supported by multivariate statistical analysis. Nevertheless, all these contributors were fundamental to maintain SeNPs stable, as, upon washing, the NM-containing extract showed the arising of aggregated SeNPs alongside Se nanorods (SeNRs). Besides, Density Functional Theory (DFT) calculation unveiled how thiol-containing molecules appeared to play a role in SeO₃²⁻ bioreduction, stress oxidative response, and SeNP stabilization.

Efficacy Assessment of Biosynthesized Copper Oxide Nanoparticles (CuO-NPs) on Stored Grain Insects and Their Impacts on Morphological and Physiological Traits of Wheat (Triticum aestivum L.) Plant

Herein, CuO-NPs were fabricated by harnessing metabolites of Aspergillus niger strain (G3-1) and characterized using UV-vis spectroscopy, XRD, TEM, SEM-EDX, FT-IR, and XPS. Spherical, crystallographic CuO-NPs were synthesized in sizes ranging from 14.0 to 47.4 nm, as indicated by TEM and XRD. EDX and XPS confirmed the presence of Cu and O with weight percentages of 62.96% and 22.93%, respectively, at varied bending energies. FT-IR spectra identified functional groups of metabolites that could act as reducing, capping, and stabilizing agents to the CuO-NPs. The insecticidal activity of CuO-NPs against wheat grain insects Sitophilus granarius and Rhyzopertha dominica was dose- and time-dependent. The mortality percentages due to NP treatment were 55-94.4% (S. granarius) and 70-90% (R. dominica). A botanical experiment was done in a randomized block design. Low CuO-NP concentration (50 ppm) caused significant increases in growth characteristics (shoot and root length, fresh and dry weight of shoot and root, and leaves number), photosynthetic pigments (total chlorophylls and carotenoids), and antioxidant enzymes of wheat plants. There was no significant change in carbohydrate or protein content. The use of CuO-NPs is a promising tool to control grain insects and enhance wheat growth performance.

Biodegradation of malachite green by a novel laccase-mimicking multicopper BSA-Cu complex: Performance optimization, intermediates identification and artificial neural network modeling

In this work, a soluble biopolymer was prepared by conjugating the bovine serum albumin (BSA) with transition metal ion (Cu²⁺). BSA-Cu complex was synthesized and characterized using UV-vis absorption, fluorescence and ATR-FTIR spectroscopies. A colorimetric guaiacol oxidation based method, was used to study the catalytic activity of complex and the results indicated its laccase-like activity. Compared with laccase, BSA-Cu complex showed a higher K_m value and a similar V_max value at the same mass concentration. Also, the ability of the BSA-Cu complex to decolorize malachite green (MG) was tested and the results showed that the complex was able to complete the decolorization process of MG within 30 min. Using gas chromatography/mass spectrometry (GC-MS) the resultant metabolites of MG degradation were analyzed and the toxicity of degradation products was assessed against Escherichia coli and Bacillus subtilis. The results confirmed the formation of less toxic products after degradation of MG by BSA-Cu complex. To predict the decolorization efficiency (DE%) of MG, an artificial neural network (ANN) was designed with five, five and one neurons in the input, hidden and output layers, respectively. The obtained results showed the ability of the designed ANN to predict MG removal successfully.

Effects of temperature and relative humidity in D2O on solid-state hydrogen deuterium exchange mass spectrometry (ssHDX-MS)

Lyophilized powders containing myoglobin and various excipients were subjected to ssHDX-MS at different temperatures and D₂O vapor activity (RH). Deuterium incorporation was fitted to a bi-exponential association model for each formulation and the dependence of regression parameters on temperature and RH was evaluated. Data fitted best to a simplified model in which the slow exponential term was considered invariant with temperature and RH while the fast exponential term retained its temperature and RH dependence. This suggests that rapid rate processes such as water vapor sorption and initial deuterium labeling may be more dependent on temperature and RH than slower processes such as sequential exchange and transport in the solid matrix.

Interaction study of monoisoamyl dimercaptosuccinic acid with bovine serum albumin using biophysical and molecular docking approaches

Monoisoamyl 2,3-dimercaptosuccinic acid (MiADMSA), a lipophilic chelator has been evaluated for its potential use as an antidote in arsenic poisoning. The pharmacokinetics and pharmacodynamics properties of a drug could be understood via study its mechanism of interaction with bovine serum albumin protein (BSA). Therefore, the interaction between MiADMSA with BSA was investigated using various spectroscopic techniques and computational methods. Linear quenching of BSA intrinsic fluorescence intensity with the increasing concentration of MiADMSA was observed in the fluorescence study. Furthermore, synchronous results revealed that MiADMSA slightly changed the conformation of BSA. The binding constant value of the BSA-MiADMSA complex was found 1.60 × 104 M-1 at 298 K. The value of thermodynamic parameters ΔG, ΔH, and ΔS described that the process is spontaneous, endothermic, and hydrophobic forces are involved in the interaction of MiADMSA with BSA. Competitive site marker experiments showed that MiADMSA binds to site-II of BSA. Conformational changes of BSA with the interaction of MiADMSA were apparent by CD, UV-Visible, FT-IR, and 3D fluorescence spectroscopy. To strengthen the experimental findings we have also performed a theoretical study on the BSA-MiADMSA complex. Two sites were identified with docking score of - 6.642 kcal/mol at site IIa and - 3.80 kcal/mol for site IIb via molecular docking study. Molecular dynamics simulation study inferred the stability of the BSA-MiADMSA complex which was analyzed in a long simulation run. The experimental and computational studies have shown the effective binding of MiADMSA with BSA which is essential for the transportation and elimination of a drug from the body.

Difference in the binding mechanism of distinct antimony forms in bovine serum albumin

The toxicity of antimony (Sb) is closely related to its chemical forms. To further realize the toxicity risk of different forms of Sb, the separate and simultaneous binding mechanisms of antimony potassium tartrate/potassium pyroantimonate with bovine serum albumin (BSA) were investigated with muti-spectroscopic methods. Fluorescence quenching result and UV-vis absorption spectra showed that a 1:1 complex was formed between antimony potassium tartrate/potassium pyroantimonate and BSA through a modest binding force. The results revealed that the binding of antimony potassium tartrate/potassium pyroantimonate to BSA caused changes in the secondary structure of BSA. Both Sb forms (antimony potassium tartrate and potassium pyroantimonate) were able to interact with BSA when coexisting but there was a binding influence on their interacting with the BSA. Both Sb forms interfere with the binding of the other to protein.

Effects of Ionic Liquids on Metalloproteins

In the past decade, innovative protein therapies and bio-similar industries have grown rapidly. Additionally, ionic liquids (ILs) have been an area of great interest and rapid development in industrial processes over a similar timeline. Therefore, there is a pressing need to understand the structure and function of proteins in novel environments with ILs. Understanding the short-term and long-term stability of protein molecules in IL formulations will be key to using ILs for protein technologies. Similarly, ILs have been investigated as part of therapeutic delivery systems and implicated in numerous studies in which ILs impact the activity and/or stability of protein molecules. Notably, many of the proteins used in industrial applications are involved in redox chemistry, and thus often contain metal ions or metal-associated cofactors. In this review article, we focus on the current understanding of protein structure-function relationship in the presence of ILs, specifically focusing on the effect of ILs on metal containing proteins.

Contribution to the Understanding of the Interaction between a Polydopamine Molecular Imprint and a Protein Model: Ionic Strength and pH Effect Investigation

Several studies were devoted to the design of molecularly imprinted polymer (MIP)-based sensors for the detection of a given protein. Here, we bring elements that could contribute to the understanding of the interaction mechanism involved in the recognition of a protein by an imprint. For this purpose, a polydopamine (PDA)-MIP was designed for bovine serum albumin (BSA) recognition. Prior to BSA grafting, the gold surfaces were functionalized with mixed self-assembled monolayers of (MUDA)/(MHOH) (1/9, v/v). The MIP was then elaborated by dopamine electropolymerization and further extraction of BSA templates by incubating the electrode in proteinase K solution. Three complementary techniques, electrochemistry, zetametry, and Fourier-transform infrared spectrometry, were used to investigate pH and ionic strength effects on a MIP's design and the further recognition process of the analytes by the imprints. Several MIPs were thus designed in acidic, neutral, and basic media and at various ionic strength values. Results indicate that the most appropriate conditions, to achieve a successful MIPs, were an ionic strength of 167 mM and a pH of 7.4. Sensitivity and dissociation constant of the designed sensor were of order of (3.36 ± 0.13) µA·cm-2·mg-1·mL and (8.56 ± 6.09) × 10-11 mg/mL, respectively.

Immobilization of protein on Fe3O4 nanoparticles for magnetic hyperthermia application

We report a facile approach for the preparation of protein conjugated glutaric acid functionalized Fe₃O₄ magnetic nanoparticles (Pro-Glu-MNPs), having improved colloidal stability and heating efficacy. The Pro-Glu-MNPs were prepared by covalent conjugation of BSA protein onto the surface of glutaric acid functionalized Fe₃O₄ magnetic nanoparticles (Glu-MNPs) obtained through thermal decomposition. XRD and TEM analyses confirmed the formation of crystalline Fe₃O₄ nanoparticles of average size ~5 nm, whereas the conjugation of BSA protein to them was evident from XPS, FTIR, TGA, DLS and zeta-potential measurements. These Pro-Glu-MNPs showed good colloidal stability in different media (water, phosphate buffer saline, cell culture medium) and exhibited room temperature superparamagnetism with good magnetic field responsivity towards the external magnet. The induction heating studies revealed that the heating efficacy of these Pro-Glu-MNPs was strongly reliant on the particle concentration and their stabilizing media. In addition, they showed enhanced heating efficacy over Glu-MNPs as surface passivation by protein offers colloidal stability to them as well as prevents their aggregation under AC magnetic field. Further, Pro-Glu-MNPs are biocompatible towards normal cells and showed substantial cellular internalization in cancerous cells, suggesting their potential application in hyperthermia therapy.

Laccase-catalyzed cross-linking of BSA mediated by tyrosine

Tyrosine was explored as a cross-linking agent to form cross-linked bovine serum albumin (BSA) using laccase as a catalyst. Liquid chromatography-mass spectrometry (LC-MS) and fluorescence spectra indicated that tyrosine can be mainly oxidized to be dityrosine. Spectra analysis and molecular weight were used to characterize the BSA treated with tyrosine and laccase. Both SDS-PAGE and size exclusion chromatography confirmed the formation of cross-linked BSA, while most of the protein products existed as BSA-tyrosine conjugates. The MALDI-TOF analysis revealed that five tyrosine units were grafted on one BSA monomer, however one cross-linked BSA consists of two BSA monomers and 18 tyrosine. Furthermore, the content of the amino acid of BSA was identified using amino acid analysis, among those the percentage of lysine presented a visible decline from 12.36% to 11.43%, corresponding to 4-5 lysine residues. The pure and modified BSA were hydrolyzed by trypsin and the corresponding peptides were obtained. Different mass of five peptides from LC-MS spectra after hydrolysis indicated that tyrosine could react with Lys-136, Lys-204, Lys-224, Lys-322 and Lys-537 in BSA, promoting the formation of BSA-tyrosine conjugates and cross-linked BSA.

Transport of Tl(I) in water-saturated porous media: Role of carbonate, phosphate and macromolecular organic matter

Understanding the transport behaviors of thallium (Tl) in porous media is of considerable interest for both natural soils and artificial filtration removal of Tl. In this context, the transport behaviors of Tl(I) in water-saturated sand columns under different conditions were systematically investigated. It was found that, in addition to the effects of pH and ionic strength (IS), the transport of Tl(I) depended on the carbonate, phosphate and macromolecular organic matter as well. Tl(I) broken the columns more difficultly under higher pH and lower IS conditions. Moreover, the adsorption of carbonate and phosphate on sand surfaces may increase the retention of Tl(I) in columns. As for macromolecular organic matter, humic acid (HA) facilitated Tl(I) transport, especially under neutral and alkaline conditions (7.0 and 9.8), which was possibly associated with Tl-complexes formation and competed adsorption between Tl(I) and HA. However, bovine serum albumin (BSA) impeded Tl(I) transport for the reason that deposited BSA might provide more adsorption sites for Tl(I), though Tl(I) had a slight effect on BSA transport. In order to evaluate the mechanisms of transport, a dual-sites non-equilibrium model was applied to fit the breakthrough curves of Tl(I). Retardation factor (R) values of individual Tl(I) transport from model calculations were found to be higher than that of Tl(I) transport with HA and lower than that of Tl(I) transport with BSA. The fraction of instantaneous sorption sites (β) was found to decrease with increasing pH, implying nonequilibrium sorption is a main sorption mechanism of Tl(I) with pH increasing. The fundamental data obtained herein demonstrated that carbonate, phosphate and macromolecular organic matter significantly influenced the Tl(I) migration and could lead to the leaking or bindings of Tl(I) at Tl-occurring sites.

Comparison of Gold Nanoparticles Deposition Methods and Their Influence on Electrochemical and Adsorption Properties of Titanium Dioxide Nanotubes

The increasing interest of attachment of gold nanoparticles (AuNPs) on titanium dioxide nanotubes (TNTs) has been devoted to obtaining tremendous properties suitable for biosensor applications. Achieving precise control of the attachment and shape of AuNPs by methods described in the literature are far from satisfactory. This work shows the comparison of physical adsorption (PA), cyclic voltammetry (CV) and chronoamperometry (CA) methods and the parameters of these methods on TNTs properties. The structural, chemical, phase and electrochemical characterizations of TNTs, Au/TNTs, AuNPs/TNTs are carried out using scanning electron microscopy (SEM), electrochemical impedance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy. The use of PA methods does not allow the deposition of AuNPs on TNTs. CV allows easily obtaining spherical nanoparticles, for which the diameter increases from 20.3 ± 2.9 nm to 182.3 ± 51.7 nm as a concentration of tetrachloroauric acid solution increase from 0.1 mM to 10 mM. Increasing the AuNPs deposition time in the CA method increases the amount of gold, but the AuNPs diameter does not change (35.0 ± 5 nm). Importantly, the CA method also causes the dissolution of the nanotubes layer from 1000 ± 10.0 nm to 823 ± 15.3 nm. Modification of titanium dioxide nanotubes with gold nanoparticles improved the electron transfer and increased the corrosion resistance, as well as promoted the protein adsorption. Importantly, after the deposition of bovine serum albumin, an almost 5.5-fold (324%) increase in real impedance, compared to TNTs (59%) was observed. We found that the Au nanoparticles-especially those with smaller diameter-promoted the stability of bovine serum albumin binding to the TNTs platform. It confirms that the modification of TNTs with gold nanoparticles allows the development of the best platform for biosensing applications.

Flame-Made Calcium Phosphate Nanoparticles with High Drug Loading for Delivery of Biologics

Nanoparticles exhibit potential as drug carriers in biomedicine due to their high surface-to-volume ratio that allows for facile drug loading. Nanosized drug delivery systems have been proposed for the delivery of biologics facilitating their transport across epithelial layers and maintaining their stability against proteolytic degradation. Here, we capitalize on a nanomanufacturing process famous for its scalability and reproducibility, flame spray pyrolysis, and produce calcium phosphate (CaP) nanoparticles with tailored properties. The as-prepared nanoparticles are loaded with bovine serum albumin (model protein) and bradykinin (model peptide) by physisorption and the physicochemical parameters influencing their loading capacity are investigated. Furthermore, we implement the developed protocol by formulating CaP nanoparticles loaded with the LL-37 antimicrobial peptide, which is a biological drug currently involved in clinical trials. High loading values along with high reproducibility are achieved. Moreover, it is shown that CaP nanoparticles protect LL-37 from proteolysis in vitro. We also demonstrate that LL-37 retains its antimicrobial activity against Escherichia coli and Streptococcus pneumoniae when loaded on nanoparticles in vitro. Therefore, we highlight the potential of nanocarriers for optimization of the therapeutic profile of existing and emerging biological drugs.

Two-dimensional infrared spectral explorations into bilayer and monolayer self-assemblies of amphiphilic polypeptides

Poly(2-(3-((2-hydroxyethyl)amino)-3-oxopropyl)ethyleneamido) (PHAOE) is an amphiphilic polypeptide. The self-assembly is significant, but the ultrafast dynamic analyses of the peptide self-assembly are exiguous and worth further exploring. In this investigation, the temporal dynamic characteristics of the aggregates and unaggregated PHAOEs are mined by the two-dimensional infrared (2D IR) spectroscopy. The homogeneous and inhomogeneous diffusion processes of the carbonyl stretching modes of the unaggregated PHAOEs are slower than those of the self-assemblies. The inhomogeneous spectral diffusion proportion of the biopolymer PHAOE in methanol is greater than that in dimethyl sulfoxide (DMSO). The solvation shells surround the aggregates and unaggregated PHAOEs in the protic solvent methanol, but there are not any solvation shells around the aggregates or unaggregated PHAOEs in the dipolar solvent DMSO. The massive hydrogen-bonded monolayer self-assembly has merely an aggregate of PHAOEs and no solvation shell in DMSO. But the hydrogen-bonded bilayer self-assembly has a self-assembled methanol shell and an interior aggregate of PHAOEs in methanol. The self-assemblies of PHAOEs motivate the methanols to self-assemble. The large delocalized amide structure results in the fast spectral diffusion of the carbonyl stretching mode.Communicated by Ramaswamy H. Sarma.

Bovine Serum Albumin Protein-Based Liquid Crystal Biosensors for Optical Detection of Toxic Heavy Metals in Water

A new methodology involving the use of Bovine Serum Albumin (BSA) as a probe and liquid crystal (LC) as a signal reporter for the detection of heavy metal ions in water at neutral pH was developed. BSA acted as a multi-dentate ligand for the detection of multiple metal ions. The LC sensor was fabricated by immobilizing 3 µg mL-1 BSA solution on dimethyloctadecyl-[3-(trimethoxysilyl)propyl]ammonium chloride (DMOAP)-coated glass slides. In the absence of heavy metal ions, a dark optical image was observed, while in their presence, a dark optical image turned to bright. The optical response was characterized by using a polarized optical microscope (POM). The BSA based LC sensor selectively detected toxic metal ions as compared to s block metal ions and ammonium ions in water. Moreover, the limit of detection was found to be very low (i.e., 1 nM) for the developed new biosensor in comparison to reported biosensors.

Calcium-Induced Activity and Folding of a Repeat in Toxin Lipase from Antarctic Pseudomonas fluorescens Strain AMS8

It is hypothesized that the Ca²⁺ ions were involved in the activity, folding and stabilization of many protein structures. Many of these proteins contain repeat in toxin (RTX) motifs. AMS8 lipase from Antarctic Pseudomonas fluorescens strain AMS8 was found to have three RTX motifs. So, this research aimed to examine the influence of Ca²⁺ ion towards the activity and folding of AMS8 lipase through various biophysical characterizations. The results showed that CaCl₂ increased lipase activity. The far-UV circular dichroism (CD) and Fourier-transform infrared (FTIR) analysis suggested that the secondary structure content was improved with the addition of CaCl₂. Fluorescence spectroscopy analysis showed that the presence of CaCl₂ increased protein folding and compactness. Dynamic light scattering (DLS) analysis suggested that AMS8 lipase became aggregated at a high concentration of CaCl₂.The binding constant (K_d) value from the isothermal titration calorimetry (ITC) analysis proved that the Ca²⁺ ion was tightly bound to the AMS8 lipase. In conclusion, Ca²⁺ ions play crucial roles in the activity and folding of the AMS8 lipase. Calcium binding to RTX nonapeptide repeats sequences will induced the formation and folding of the RTX parallel β-roll motif repeat structure.

Ketoprofen-Based Ionic Liquids: Synthesis and Interactions with Bovine Serum Albumin

The development of ionic liquids based on active pharmaceutical ingredients (API-ILs) is a possible solution to some of the problems of solid and/or hydrophobic drugs such as low solubility and bioavailability, polymorphism and an alternative route of administration could be suggested as compared to the classical drug. Here, we report for the first time the synthesis and detailed characterization of a series of ILs containing a cation amino acid esters and anion ketoprofen (KETO-ILs). The affinity and the binding mode of the KETO-ILs to bovine serum albumin (BSA) were assessed using fluorescence spectroscopy. All compounds bind in a distance not longer than 6.14 nm to the BSA fluorophores. The estimated binding constants (KA) are in order of 10⁵ L mol⁻¹, which is indicative of strong drug or IL-BSA interactions. With respect to the ketoprofen-BSA system, a stronger affinity of the ILs containing l-LeuOEt, l-ValOBu, and l-ValOEt cation towards BSA is clearly seen. Fourier transformed infrared spectroscopy experiments have shown that all studied compounds induced a rearrangement of the protein molecule upon binding, which is consistent with the suggested static mechanism of BSA fluorescence quenching and formation of complexes between BSA and the drugs. All tested compounds were safe for macrophages.