Amide modes and protein conformation

Encapsulation of melatonin in zein/pectin composite nanoparticles: Fabrication, characterization, and in vitro release property

In this study, the encapsulation of melatonin (MT) in zein nanoparticles was investigated via anti-solvent co-precipitation method with pectin stabilization. Compared with MT-loaded zein nanoparticles (MT-Z NPs), 1.0 mg/mL pectin led to a 92.1 % of MT encapsulation efficiency, a 5.4 % of MT loading, a particle size growth from 111.3 to 294.8 nm, a ζ-potential reduction from +4.8 to -41.4 mV, and an irregular surface shape. Moreover, the hypsochromic and redshifts of the OH and amide I bands, and undetected MT crystalline characteristic peaks in MT-loaded zein/pectin nanoparticles (MT-Z/P NPs) revealed successful MT embedment governed by hydrogen and hydrophobic forces. The binding energies of zein with MT and pectin (-6.89 and - 7.01 kcal/mol) confirmed the stability of complex. MT-Z/P NPs prolonged MT release from 92.3 % to 63.6 % at 6 h in gastrointestinal tract (GIT) compared with MT-Z NPs, which could be a desirable MT delivery material in food industry.

Cobalt-induced oxidative stress and defense responses of Adhatoda vasica proliferated shoots

BACKGROUND

Levels of heavy metal pollution are increasing due to industrial activities and urban expansion. While cobalt (Co) can be toxic to plants at high levels and isn't considered essential, it plays a beneficial role in many enzymes and is critical for various biological functions. We conducted experiments to determine how Adhatoda vasica proliferated shoots react to exposure to various Co concentrations (50-1000 µM). We employed physiological and biochemical markers to elucidate the response mechanisms of this medicinal plant. The experiment was conducted in two replicates per treatment. The statistical analysis was based on data from four biological replicates per treatment.

RESULTS

Interestingly, the lowest Co concentration (50 µM) increased proliferated shoot growth by 41.45%. In contrast, higher Co concentrations (100-1000 µM) had detrimental effects on proliferated shoot development, water content, and photosynthetic pigment concentrations. As Co concentration increased, proliferated shoots produced excessive concentrations of reactive oxygen species (ROS). This ROS overproduction is believed to be the primary cause of oxidative damage, as evidenced by the elevated concentrations (18.46%-72.84%) of malondialdehyde (MDA) detected. In response to Co stress, non-enzymatic antioxidants were activated in a concentration-dependent manner. Co administration significantly increased the concentrations of different stress-protective compounds in shoots, including total antioxidants (133.18%), ascorbic acids (217.94%), free and bound phenolics (97.70% and 69.72%, respectively), proline (218.59%), free amino acids (206.96%), soluble proteins (65.97%), and soluble carbohydrates (18.52%). FTIR analysis further corroborated changes in the chemical composition of proliferated shoots. The analysis revealed variations in the peaks associated with major macromolecules, including phenolic compounds, lipids, proteins, carbohydrates, cellulose, hemicellulose, and sugars.

CONCLUSIONS

Our study offers the first comprehensive investigation into mechanisms by which Co stress triggers oxidative damage and alters functional groups in the medicinal plant, Adhatoda vasica.

Use of FTIR to study secondary structure of texturized plant proteins by high moisture extrusion cooking, a comprehensive review

Fourier-Transform Infrared spectroscopy (FTIR) is often used by researchers to understand the texturization mechanisms of plant proteins. High Moisture Extrusion-Cooking (HMEC) is the main process used for their texturization by heating, mechanical shearing, and subsequent cooling of a high-moisture mixture, which causes denaturation and restructuration of proteins, resulting in an anisotropic product, commonly called "meat analog". Researchers try to link the properties of extrudates to the secondary conformation of proteins, which are supposed to aggregate and align in the flow direction within the die. This review will attempt to show the reasons for studying the secondary structures of plant proteins in HMEC-textured products, and compare and discuss the different methods applied to prepare samples and analyze them by FTIR. A focus will be put on the different methods of spectra analysis (i.e., peak deconvolution, and reference tables used), for which a total of around 60 scientific papers have been carefully analyzed to illustrate the disparity of reference tables used in the literature. A discussion will summarize the various hypotheses currently found in the literature, and provided by FTIR to explain the texturization mechanisms of plant proteins through HMEC. Finally, advice such as comparing results with other amide bands and other analysis methods and following published procedures, are provided as an outlook for future improvements in FTIR data quality, processing and interpretation.

Relationship Between Cryoprotectant Potential and Protein Hydration in Aqueous Zwitterionic Solutions

The cryoprotectant potential of 3-(1-(2-(2-methoxyethoxy)ethyl)imidazol-3-io)butane-1-carboxylate (OE2imC3C) for proteins necessitates assessment to elucidate its relationship with protein hydration. To reveal this relationship, we assessed the protein stability (pre-freezing and post-thawing) and melting behavior in dilute aqueous protein-OE2imC3C solutions containing varying mole fractions (x) of OE2imC3C (x = 0, 7.7 × 10-3, and 1.7 × 10-2) using Fourier-transform infrared (FTIR) and near-UV circular dichroism (near-UV CD) spectroscopy and differential scanning calorimetry (DSC) techniques. Following freezing/thawing using a deep freezer, protein stability in aqueous OE2imC3C solutions (x = 1.7 × 10-2) preserved the folded state owing to the protein-OE2imC3C interaction, whereas stability at x = 7.7 × 10-3 was reduced. These results indicate that the protein cryoprotectant potential in aqueous OE2imC3C solutions at x = 1.7 × 10-2 is higher than that at x = 7.7 × 10-3, owing to the preferential binding of OE2imC3C with proteins.

Atmospheric cold plasma pretreatment for effective enhancement of covalent crosslinking between coconut globulin and tannic acid: Improving interfacial activity and emulsifying properties

Atmospheric cold plasma (ACP) represents a promising approach for enhancing covalent interactions between proteins and polyphenols, circumventing the drawbacks associated with traditional methods. This study aims to investigate the enhancement of covalent interactions between coconut globulin (CG) and tannic acid (TA) facilitated by ACP at varying pH levels. At acidic pH, ACP treatment was found to promote free radical-induced covalent cross-linking between CG and TA, whereas at pH 7.0 and 9.0, ACP treatment enhanced quinone-induced covalent cross-linking. In contrast, the covalent crosslinking induced by quinone significantly disrupted the protein structure, leading to greater exposure of hydrophobic groups. At pH 9.0, the CG-TA complex treated with ACP exhibited the highest interfacial activity, with an interfacial adsorption mass of 5292 ng/cm2. This was accompanied by improvements in droplet size, viscosity, and stability of the CG-TA-stabilized emulsion. These findings offer novel insights into the covalent modification of proteins and polyphenols, thereby broadening the potential applications of food protein.

Second-Order Mass-Weighting Scheme for Atom-Centered Density Matrix Propagation Molecular Dynamics

The atom-centered density matrix propagation (ADMP) method is an extended Lagrangian approach to ab initio molecular dynamics, which includes the density matrix in an orthonormalized atom-centered Gaussian basis as additional, fictitious, electronic degrees of freedom, classically propagated along with the nuclear ones. A high adiabaticity between the nuclear and electronic subsystems is mandatory in order to keep the trajectory close to the Born-Oppenheimer (BO) surface. In this regard, the fictitious electronic mass μ, being a symmetric, nondiagonal matrix in its most general form, represents a free parameter, exploitable to optimize the propagation of the electronic density. Although mass-weighting schemes in ADMP exist, a systematic procedure to define an optimal value of the fictitious masses is not available yet. In this work, in order to rationally evaluate the electronic mass, fictitious electronic normal modes are defined through the diagonalization of the Hessian of the electronic density matrix. If the same frequency is imposed on all such modes (compatible with the chosen integration time step), then the corresponding μ matrix can be calculated and then employed for the following propagation. Analysis of several ADMP test simulations reveals that such Hessian-based mass-weighting approach is able to ensure, together with a 0.1/0.2 fs time steps, a high separation between the (real) nuclear and the (fictitious) electronic frequencies, which determines a high adiabaticity. This high, unprecedented, accuracy in the propagation leads, in turn, to low errors in the estimated nuclear vibrational frequencies, making the ADMP method totally comparable to a fully converged BO molecular dynamics simulation but more computationally efficient. This work, therefore, contributes to a further development of the ADMP ab initio molecular dynamics method, aimed at improving its accuracy through a more rational evaluation of the fictitious electronic mass parameter.

Diabetes and Cognitive Decline: An Innovative Approach to Analyzing the Biophysical and Vibrational Properties of the Hippocampus

Diabetes Mellitus (DM) is a disease characterized by high blood glucose levels, known as hyperglycemia. Diabetes represents a risk factor for the development of neurodegenerative diseases, such as Alzheimer's Disease (AD), one of the most prevalent neurodegenerative diseases worldwide, which leads to progressive mental, behavioral, and functional decline, affecting many brain structures, especially the hippocampus. Here, we aim to characterize the ultrastructural, nanomechanical, and vibrational changes in hyperglycemic hippocampal tissue using atomic force microscopy (AFM) and Raman spectroscopy. DM was induced in rats by streptozotocin injection (type 1) or dietary intervention (type 2). Cryosections of the hippocampus were prepared and analyzed on an MM8 AFM (Bruker) in Peak Force Quantitative Nanomechanics mode, performing 25 μm2 scans in 9 regions of 3 samples from each group. Ultrastructural and nanomechanical data such as surface roughness, area, volume, Young's modulus, and adhesion were evaluated. The hippocampal samples were also analyzed on a T64000 Spectrometer (Horiba), using a laser λ = 632.8 nm, and for each sample, four spectra were obtained in different regions. AFM analyses show changes on the ultrastructural scale since diabetic animals had hippocampal tissue with greater roughness and volume. Meanwhile, diabetic tissues had decreased adhesion and Young's modulus compared to control tissues. These were corroboratedby Raman data that shows changes in the molecular composition of diabetic tissues. The individual spectra show that the most significant changes are in the amide, cholesterol, and lipid bands. Overall, the data presented here show that hyperglycemia induces biophysical alterations in the hippocampal tissue of diabetic rats, providing novel biophysical and vibrational cues on the relationship between hyperglycemia and dementia.

Microcapsule Preparation and Properties of Flavonoid Extract from Immature Citrus reticulata 'Chachiensis' Peel

Citrus reticulata 'Chachiensis' is a citrus cultivar in the Rutaceae family, and its peel is commonly utilized as a raw material for Guangchenpi. This study used flavonoid extract from the peel of immature Citrus reticulata 'Chachiensis' (CCE) as the raw material to investigate the encapsulation ability of different wall materials (plant-based proteins, including soybean protein isolation (SPI), pea protein (PP), and zein; carbohydrates, including maltodextrin (MD), Momordica charantia polysaccharide (MCP), and gum acacia (GA); and composite wall materials of both types) on CCE. The wall material with the highest encapsulation rate was selected for the preparation of CCE microcapsules. Furthermore, the physicochemical characteristics, antioxidant capacity, bioavailability, and storage stability of the CCE microcapsules were explored. The results indicated that among all wall materials, the composite wall material PPMD had the highest encapsulation rate, which was 84.44 ± 0.34%. After encapsulation, the microcapsules tended to have a yellow color and exhibited characteristics such as system stability, low moisture content, and low hygroscopicity. In vitro antioxidant assays revealed that the encapsulation of CCE significantly increased the scavenging rates of DPPH and ABTS free radicals. In vitro gastrointestinal digestion experiments indicated that the release rate of PPMD-CCE in intestinal fluid was significantly greater than that of free CCE, ultimately reaching 85.89 ± 1.53%. Storage experiments demonstrated that after 45 days under various temperature and light conditions, the retention rate of CCE in the microcapsules was significantly greater than that of free CCE. The above findings provide new possibilities for the application of PP and plant proteins and lay a foundation for the future industrial application of CCE.

Development of SERS Active Nanoprobe for Selective Adsorption and Detection of Alzheimer's Disease Biomarkers Based on Molecular Docking

Purpose

Development of SERS-based Raman nanoprobes can detect the misfolding of Amyloid beta (Aβ) 42 peptides, making them a viable diagnostic technique for Alzheimer's disease (AD). The detection and imaging of amyloid peptides and fibrils are expected to help in the early identification of AD.

Methods

Here, we propose a fast, easy-to-use, and simple scheme based on the selective adsorption of Aβ42 molecules on SERS active gold nanoprobe (RB-AuNPs) of diameter 29 ± 3 nm for Detection of Alzheimer's Disease Biomarkers. Binding with the peptides results in a spectrum shift, which correlates with the target peptide. We also demonstrated the possibility of using silver nanoparticles (AgNPs) as precursors for the preparation of a SERS active nanoprobe with carbocyanine (CC) dye and AgNPs known as silver nanoprobe (CC-AgNPs) of diameter 25 ± 4 nm.

Results

RB-AuNPs probe binding with the peptides results in a spectrum shift, which correlates with the target peptide. Arginine peak appears after the conjugation confirms the binding of Aβ 42 with the nanoprobe. Tyrosine peaks appear after conjugated Aβ42 with CC-AgNPs providing binding of the peptide with the probe. The nanoprobe produced a strong, stable SERS signal. Further molecular docking was utilized to analyse the interaction and propose a structural hypothesis for the process of binding the nanoprobe to Aβ42 and Tau protein.

Conclusion

This peptide-probe interaction provides a general enhancement factor and the molecular structure of the misfolded peptides. Secondary structural information may be obtained at the molecular level for specific residues owing to isotope shifts in the Raman spectra. Conjugation of the nanoprobe with Aβ42 selectively detected AD in bodily fluids. The proposed nanoprobes can be easily applied to the detection of Aβ plaques in blood, saliva, and sweat samples.

Watching a Single Enzyme at Work Using Single-Molecule Surface-Enhanced Raman Scattering and DNA Origami-Based Plasmonic Antennas

The detection of a single-enzyme catalytic reaction by surfaced-enhanced Raman scattering (SERS) is presented by utilizing DNA origami-based plasmonic antennas. A single horseradish peroxidase (HRP) was accommodated on a DNA origami nanofork plasmonic antenna (DONA) containing gold nanoparticles, enabling the tracing of single-molecule SERS signals during the peroxide reduction reaction. This allows monitoring of the structure of a single enzymatic catalytic center and products under suitable liquid conditions. Herein, we demonstrate the chemical changes of HRP and the appearance of tetramethylbenzidine (TMB), which works as a hydrogen donor before and after the catalytic reaction. The results show that the iron in HRP adopts Fe4+ and low spin states with the introduction of H2O2, indicating compound-I formation. Density functional theory (DFT) calculations were performed for later catalytic steps to rationalize the experimental Raman/SERS spectra. The presented data provide several possibilities for tracking single biomolecules in situ during a chemical reaction and further developing plasmon-enhanced biocatalysis.

Raman spectroscopy in the study of amyloid formation and phase separation

Neurodegenerative diseases, such as Alzheimer's and Parkinson's, share a common pathological feature of amyloid structure accumulation. However, the structure-function relationship between these well-ordered, β-sheet-rich, filamentous protein deposits and disease etiology remains to be defined. Recently, an emerging hypothesis has linked phase separation, a process involved in the formation of protein condensates, to amyloid formation, suggesting that liquid protein droplets serve as loci for amyloid initiation. To elucidate how these processes contribute to disease progression, tools that can directly report on protein secondary structural changes are needed. Here, we review recent studies that have demonstrated Raman spectroscopy as a powerful vibrational technique for interrogating amyloid structures; one that offers sensitivity from the global secondary structural level to specific residues. This probe-free technique is further enhanced via coupling to a microscope, which affords structural data with spatial resolution, known as Raman spectral imaging (RSI). In vitro and in cellulo applications of RSI are discussed, highlighting studies of protein droplet aging, cellular internalization of fibrils, and Raman imaging of intracellular water. Collectively, utilization of the myriad Raman spectroscopic methods will contribute to a deeper understanding of protein conformational dynamics in the complex cellular milieu and offer potential clinical diagnostic capabilities for protein misfolding and aggregation processes in disease states.

Bio-synthesis and characterization of silver nanoparticles from Trichoderma species against cassava root rot disease

Cassava root rot disease caused by the fungal pathogens Fusarium solani and Lasiodiplodia theobromae produces severe damages on cassava production. This research was conducted to produce and assess silver nanoparticles (AgNPs) synthesized by Trichoderma harzianum for reducing root rot disease. The results revealed that using the supernatants of T. harzianum on a silver nitrate solution changed it to reddish color at 48 h, indicating the formation of AgNPs. Further characterization was identified using dynamic light scattering (DLS) and scanning electron microscope (SEM). DLS supported that the Z-average size is at 39.79 nm and the mean zeta potential is at - 36.5 mV. SEM revealed the formation of monodispersed spherical shape with a diameter between 60-75 nm. The antibacterial action of AgNPs as an antifungal agent was demonstrated by an observed decrease in the size of the fungal colonies using an increasing concentration of AgNPs until the complete inhibition growth of L. theobromae and F. solani at > 58 µg mL-1 and at ≥ 50 µg mL-1, respectively. At in vitro conditions, the applied AgNPs caused a decrease in the percentage of healthy aerial hyphae of L. theobromae (32.5%) and of F. solani (70.0%) compared to control (100%). The SR-FTIR spectra showed the highest peaks in the first region (3000-2800 cm-1) associated with lipids and fatty acids located at 2962, 2927, and 2854 cm-1 in the AgNPs treated samples. The second region (1700-1450 cm-1) consisting of proteins and peptides revealed the highest peaks at 1658, 1641, and 1548 cm-1 in the AgNPs treated samples. The third region (1300-900 cm-1), which involves nucleic acid, phospholipids, polysaccharides, and carbohydrates, revealed the highest peaks at 1155, 1079, and 1027 cm-1 in the readings from the untreated samples. Finally, the observed root rot severity on cassava roots treated with AgNPs (1.75 ± 0.50) was significantly lower than the control samples (5.00 ± 0.00).

High pressure Raman study of isobutyramide

Isobutyramide (IBA) has attracted considerable attention due to its expansive prospects for practical applications in the synthesis of drugs, dyes and other organic compounds. Herein we perform the high-pressure studies of IBA crystal by Raman spectral measurements at room temperature from ambient pressure to 30 GPa by using diamond anvil cells (DACs) to gain comprehensive insights into its structure and stability. Raman vibrational modes of IBA crystal at ambient pressure are resolved based on the experimental results and the first-principles theoretical calculations. High-pressure Raman scattering results show the Raman bands splitting, emergence/disappearance of the Raman bands and discontinuous wavenumber shifts at 1, 2 and 10 GPa, which indicate that IBA crystal undergoes three structural phase transitions at corresponding pressure. In addition, softening of the C = O and N-H stretching vibrational modes of IBA with increasing pressure can be interpreted by the reorganization of the hydrogen bond network of IBA molecules due to phase transition.

Characterization of the Oxazolone and Macrocyclic Motifs in the bn (n = 2-5) Product Ions from Collision-Induced Dissociation of Protonated Oligoglycine Peptides with Isomer-Selective, Cryogenic Vibrational Spectroscopy

Collision-induced dissociation (CID) of small, protonated peptides leads to the formation of b-type fragment ions that can occur with several structural motifs driven by different covalent intramolecular bonding arrangements. Here, we characterize the so-called "oxazolone" and "macrocycle" bn ion structures that occur upon CID of oligoglycine peptides (Gn) ions (n = 2-6). This is determined by acquiring the vibrational band patterns of the cryogenically cooled, D2-tagged bn ions obtained using isomer-selective, two-color IR-IR photobleaching and analyzing them with predicted (DFT) harmonic spectra for the candidate structures. Both oxazolone and macrocyclic isomers are formed by b4, whereas only oxazolone species are created for b2 and b3 and the macrocycle is created for b5. As such, n = 4 corresponds to the minimum size where both Oxa and MC forms are present.

Determining the nanostructure and main axis of gly-his-gly fibrils using the amide I' bands in FTIR, VCD, and Raman spectra

The zwitterionic tripeptide glycyl-histidine-glycine (GHG) has been shown to self-assemble into visible crystalline fibrils that form a gel-supporting network with a very high storage modulus. Here we elaborate on the theory and experimental setup behind our novel approach employed to determining the main fibril axis for these gel-forming fibrils by simulating the amide I band profile for infrared absorption (IR), vibrational circular dichroism (VCD), and visible Raman scattering. We also highlight that combining these three vibrational spectroscopies can help in validating structures that are solved using powder x-ray diffraction analysis (PXRD). The PXRD analysis yielded a GHG fibril unit cell with P21 symmetry containing two peptide monomers and two water molecules. The monomers adopt a conformation reminiscent of the distorted polyproline II conformation obtained for tri-lysine in aqueous solution. Stabilization occurs primarily through peptide-peptide intermolecular hydrogen bond interactions, while the role of water in peptide hydration is minimal. The comparison of simulated and experimental amide I' band profiles suggests that the xz plane of the crystal unit cell is being predominantly probed in the experimental IR and VCD spectra, with the x axis of the unit cell pointing in the direction of the main fibril axis. The monomer peptide in the unit cell interacts with six adjacent peptides forming hydrophobic channels by edge-to-face and parallel-displaced ππstacking in the y direction. These cores are further stabilized by a plethora of intermolecular interactions in the x and z directions. Our result suggests that the hydrophobic xz-surfaces would be a good target for the adsorption of hydrophobic drugs.

Spectroscopic Analysis of the Effect of Ibuprofen Degradation Products on the Interaction between Ibuprofen and Human Serum Albumin

BACKGROUND

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are one of the most commonly used groups of medicinal compounds in the world. The wide access to NSAIDs and the various ways of storing them due to their easy accessibility often entail the problem with the stability and durability resulting from the exposure of drugs to external factors. The aim of the research was to evaluate in vitro the mechanism of competition between ibuprofen (IBU) and its degradation products, i.e., 4'-isobutylacetophenone (IBAP) and (2RS)-2-(4- formylphenyl)propionic acid (FPPA) during transport in a complex with fatted (HSA) and defatted (dHSA) human serum albumin.

METHODS

The research was carried out using spectroscopic techniques, such as spectrophotometry, infrared spectroscopy and nuclear magnetic resonance spectroscopy.

RESULTS

The comprehensive application of spectroscopic techniques allowed, among others, for the determination of the binding constant, the number of classes of binding sites and the cooperativeness constant of the analyzed systems IBU-(d)HSA, IBU-(d)HSA-FPPA, IBU-(d)HSA-IBAP; the determination of the effect of ibuprofen and its degradation products on the secondary structure of albumin; identification and assessment of interactions between ligand and albumin; assessment of the impact of the presence of fatty acids in the structure of albumin and the measurement temperature on the binding of IBU, IBAP and FPPA to (d)HSA.

CONCLUSION

The conducted research allowed us to conclude that the presence of ibuprofen degradation products and the increase in their concentration significantly affect the formation of the IBU-albumin complex and thus, the value of the association constant of the drug, changing the concentration of its free fraction in the blood plasma. It was also found that the presence of an ibuprofen degradation product in a complex with albumin affects its secondary structure.

Immobilization of Cyclodextrin glycosyltransferase onto three dimensional- hydrophobic and two dimensional- hydrophilic supports: A comparative study

Cyclodextrin glycosyltransferase (CGTase) degrades starch into cyclodextrin via enzymatic activity. In this study, we immobilize CGTase from Thermoanaerobacter sp. on two supports, namely graphene nanoplatelets (GNP) consisting of short stacks of graphene nanoparticles and a calcium-based two-dimensional metal organic framework (Ca-TMA). The uptakes of CGTase on GNP and Ca-TMA reached 40 and 21 mg g-1 respectively, but immobilized CGTase on Ca-TMA showed a higher specific activity (38 U mg-1 ) than that on GNP (28 U mg-1 ). Analysis of secondary structures of CGTase, shows that immobilization reduces the proportion of β-sheets in CGTase from 56% in the free to 49% and 51.3% for GNP and Ca-TMA respectively, α-helix from 38.5% to 18.1 and 37.5%, but led to increased β-turns from 5.5 to 40% and 11.2% for GNP and Ca-TMA, respectively. Lower levels of conformational changes were observed over the more hydrophilic Ca-TMA compared to hydrophobic GNP, resulting in its better activity. Increased β-turns were found to correlate with lower β-CD production, while more β-sheets and α-helix favored more β-CD. Reusability studies revealed that GNP retains up to 74% of initial CGTase activity, while Ca-TMA dropped to 33% after eight consecutive uses. The results obtained in this work provide insight on the effect of support's surface properties on CGTase performance and can assist in developing robust CGTase-based biocatalysts for industrial application.

Enhancing Bone Infection Diagnosis with Raman Handheld Spectroscopy: Pathogen Discrimination and Diagnostic Potential

Osteomyelitis is a bone disease caused by bacteria that can damage bone. Raman handheld spectroscopy has emerged as a promising diagnostic tool for detecting bone infection and can be used intraoperatively during surgical procedures. This study involved 120 bone samples from 40 patients, with 80 samples infected with either Staphylococcus aureus or Staphylococcus epidermidis. Raman handheld spectroscopy demonstrated successful differentiation between healthy and infected bone samples and between the two types of bacterial pathogens. Raman handheld spectroscopy appears to be a promising diagnostic tool in bone infection and holds the potential to overcome many of the shortcomings of traditional diagnostic procedures. Further research, however, is required to confirm its diagnostic capabilities and consider other factors, such as the limit of pathogen detection and optimal calibration standards.

Protocol for determining protein dynamics using FT-IR spectroscopy

In biological systems, protein function depends on spatial and temporal changes known as protein dynamics, which can be probed by amide hydrogen/deuterium (H/D) exchange. Here, we present a protocol for determining protein dynamics by Fourier-transform infrared (FT-IR) spectroscopy. We describe steps for protein sample preparation and FT-IR spectra collection. We then detail procedures for spectra analysis. Applications include the effects of protein mutation or protein and metal ion or ligand interactions on the protein H/D exchange rate. For complete details on the use and execution of this protocol, please refer to Yu et al. (2013).1.

Spectroscopic Investigation of Phosphorus Mineralization as Affected by the Calcite-Water Interfacial Chemistry

The mineralization and bioavailability of phytic acid, the predominant organic phosphorus (OP) species in many soils, have generally been rendered limited due to its interaction with soil minerals. In particularly calcareous and neutral to slightly alkaline soils, phytic acid is known to actively react with calcite, although how this interaction affects phytic acid mineralization is still unknown. This study, therefore, investigated the mechanisms regarding how the calcite-water interface influences phytic acid mineralization by phytase, at pHs 6 and 8 using in situ spectroscopic techniques including solution nuclear magnetic resonance and attenuated total reflection Fourier transform infrared spectroscopy. The findings indicated a pH-specific effect of the calcite-water interface. Inhibited phytase activity and thus impaired phytic acid mineralization were induced by calcite at pH 6, while the opposite effect was observed at pH 8. How the interaction between phytic acid and calcite and between phytase and calcite differed between the two pH values contributed to the pH-specific effect. The results demonstrate the importance of soil pH, enzyme-, and OP-clay mineral interactions in controlling the mineralization and transformation of OP and, consequently, the release of phosphate in soils. The findings can also provide implications for the management of calcite-rich and limed soils.

Combined In Silico and In Vitro Study to Reveal the Structural Insights and Nucleotide-Binding Ability of the Transcriptional Regulator PehR from the Phytopathogen Ralstonia solanacearum

The transcriptional regulator PehR regulates the synthesis of the extracellular plant cell wall-degrading enzyme polygalacturonase, which is essential in the bacterial wilt of plants caused by one of the most devastating plant phytopathogens, Ralstonia solanacearum. The bacterium has a wide global distribution infecting many different plant species, resulting in massive agricultural and economic losses. Because the PehR molecular structure has not yet been determined and the structural consequences of PehR on ligand binding have not been thoroughly investigated, we have used an in silico approach combined with in vitro experiments for the first time to characterize the PehR regulator from a local isolate (Tezpur, Assam, India) of the phytopathogenic bacterium R. solanacearum F1C1. In this study, an in silico approach was employed to model the 3D structure of the PehR regulator, followed by the binding analysis of different ligands against this regulatory protein. Molecular docking studies suggest that ATP has the highest binding affinity for the PehR regulator. By using molecular dynamics (MD) simulation analysis, involving root-mean-square deviation, root-mean-square fluctuations, hydrogen bonding, radius of gyration, solvent-accessible surface area, and principal component analysis, it was possible to confirm the sudden conformational changes of the PehR regulator caused by the presence of ATP. We used an in vitro approach to further validate the formation of the PehR-ATP complex. In this approach, recombinant DNA technology was used to clone, express, and purify the gene encoding the PehR regulator from R. solanacearum F1C1. Purified PehR was used in ATP-binding experiments using fluorescence spectroscopy and Fourier transform infrared spectroscopy, the outcomes of which showed a potent binding to ATP. The putative PehR-ATP-binding analysis revealed the importance of the amino acids Lys190, Glu191, Arg192, Arg375, and Asp378 for the ATP-binding process, but further study is required to confirm this. It will be simpler to comprehend the catalytic mechanisms of a crucial PehR regulator process in R. solanacearum with the aid of the ATP-binding process hints provided by these structural biology applications.

Evaluation of IR and Raman spectroscopic markers of human collagens: Insides for indicating colorectal carcinogenesis

Vibrational spectroscopic methods are widely used in the molecular diagnostics of carcinogenesis. Collagen, a component of connective tissue, plays a special role as a biochemical marker of pathological changes in tissues. The vibrational bands of collagens are very promising to distinguish between normal colon tissue, benign and malignant colon polyps. Differences in these bands indicate changes in the amount, structure, conformation and the ratio between the individual structural forms (subtypes) of this protein. The screening of specific collagen markers of colorectal carcinogenesis was carried out based on the FTIR and Raman (λ_ex 785 nm) spectra of colon tissue samples and purified human collagens. It was found that individual types of human collagens showed significant differences in their vibrational spectra, and specific spectral markers were found for them. These collagen bands were assigned to specific vibrations in the polypeptide backbone, amino acid side chains and carbohydrate moieties. The corresponding spectral regions for colon tissues and colon polyps were investigated for the contribution of collagen vibrations. Mentioned spectral differences in collagen spectroscopic markers could be of interest for early ex vivo diagnosis of colorectal carcinoma if combine vibrational spectroscopy and colonoscopy.

Zinc-based subcuticular absorbable staples: An in vivo and in vitro study

A zinc-nutrient element alloy (Zn-1.0Cu-0.5Ca) was developed into subcuticular absorbable staples (SAS) as a robust alternative to the commercially available poly(l-lactide-co-glycolide) (PLGA) SAS for the first time. The fixation properties of the Zn SAS were measured via pull-out tests and in-situ lap-shear pull-out test comparatively against the PLGA SAS. The Zn SAS exhibited fixation force of 18.9±0.2 N, which was over three times higher than that of PLGA SAS (5.5±0.1 N). The Zn SAS was used to close incision wounds in a SD rat model for biodegradability and biocompatibility characterisation at 1, 4 and 12 weeks. The Zn SAS showed uniform degradation behaviour after in vivo implantation at the average rate of 198±54, 112±28, and 70±24 μm/y after 1, 4, and 12 weeks, which reduced the fixation force to 16.8±1.1 N, 15.4±0.9 N, 12.7±0.7 N, respectively. These findings showed the potential of the Zn SAS for the closure of heavy loading and slowing healing tissues. The Zn SAS enabled successful closure and healing of the incision wound, similar to the PLGA staples. However, the slow long-term degradation rate of the Zn SAS may lead to unnecessary implant retention. In addition, the alloy SAS resulted in higher local foreign body responses due to their stiffness. Reducing the implant cross-section profile and applying low stiffness and a corrosion-accelerating coating are suggested as possible approaches to reduce post-service implant retention and improve the biocompatibility of the Zn SAS. STATEMENT OF SIGNIFICANCE: This work reports the fabrication of the first metallic subcuticular absorbable staples (SAS) made from Zn-Cu-Ca alloy for skin wound closure applications. The Zn-based SAS were characterised in vitro and in vivo (SD rat model) for biodegradability, fixation properties, biocompatibility and inflammatory responses, which were compared against the commercially available PLGA-based SAS. The Zn-based SAS provided a secure attachment of the full-thickness wounds on SD rats and allowed successful healing during the 12-week service period. In addition, the in vitro results showed that the Zn-based SAS provided more than three times higher fixation strength than the commercial PLGA, indicating the potential of the Zn-based SAS for load-bearing wound closure application.

Structural Identification and Antioxidant Activity of Loach Protein Enzymatic Hydrolysates

Loach, rich in nutrients, such as proteins, amino acids, and mineral elements, is being gradually favored by consumers. Therefore, in this study, the antioxidant activity and structural characteristics of loach peptides were comprehensively analyzed. The loach protein (LAP) with a molecular weight between 150 and 3000 Da was graded by ultrafiltration and nanofiltration processes, which exhibited excellent scavenging activity against DPPH radical (IC50 2.91 ± 0.02 mg/mL), hydroxyl radical (IC50 9.95 ± 0.03 mg/mL), and superoxide anion radical (IC50 13.67 ± 0.33 mg/mL). Additionally, LAP was purified by gel filtration chromatography, and two principal components (named as LAP-I and LAP-II) were isolated. A total of 582 and 672 peptides were identified in LAP-I and LAP-II, respectively, through structural analysis. The XRD results revealed that LAP-I and LAP-II had an irregular amorphous structure. The 2D-NMR spectroscopy results suggested that LAP-I had a compact stretch conformation in the D₂O solution, while LAP-II had a folded conformation. Overall, the study results suggested that loach peptide could be a potential antioxidant agent and might provide valuable information for chain conformation and antioxidant mechanism research further.

Recent development of surface-enhanced Raman scattering for biosensing

Surface-Enhanced Raman Scattering (SERS) technology, as a powerful tool to identify molecular species by collecting molecular spectral signals at the single-molecule level, has achieved substantial progresses in the fields of environmental science, medical diagnosis, food safety, and biological analysis. As deepening research is delved into SERS sensing, more and more high-performance or multifunctional SERS substrate materials emerge, which are expected to push Raman sensing into more application fields. Especially in the field of biological analysis, intrinsic and extrinsic SERS sensing schemes have been widely used and explored due to their fast, sensitive and reliable advantages. Herein, recent developments of SERS substrates and their applications in biomolecular detection (SARS-CoV-2 virus, tumor etc.), biological imaging and pesticide detection are summarized. The SERS concepts (including its basic theory and sensing mechanism) and the important strategies (extending from nanomaterials with tunable shapes and nanostructures to surface bio-functionalization by modifying affinity groups or specific biomolecules) for improving SERS biosensing performance are comprehensively discussed. For data analysis and identification, the applications of machine learning methods and software acquisition sources in SERS biosensing and diagnosing are discussed in detail. In conclusion, the challenges and perspectives of SERS biosensing in the future are presented.

Development and evaluation of bioinspired pH-responsive sericin-chitosan-based hydrogel for controlled colonic delivery of PETase: Harnessing PETase-triggered degradation of microplastics

The gravity of threats posed by microplastic pollution to the environment cannot be overestimated. Being ubiquitous in the living environment, microplastics reach humans through the food chain causing various hazardous effects. Microplastics can be effectively degraded by PETase enzymes. The current study reports, for the first time, a hydrogel-encapsulated, bioinspired colonic delivery of PETase. A free radical polymerization-assisted hydrogel system was synthesized from sericin, chitosan, and acrylic acid using N,N'-methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The hydrogel was characterized with FTIR, PXRD, SEM, and thermal analysis to confirm the development of a stabilized hydrogel system. The hydrogel showed 61 % encapsulation efficiency, maximum swelling, and cumulative PETase release (96 %) at pH 7.4. The mechanism of PETase release exhibited the Higuchi pattern of release with an anomalous transport mechanism. SDS-PAGE analysis confirmed the preservation of the post-release structural integrity of PETase. The released PETase exhibited concentration- and time-dependent degradation of polyethylene terephthalate in vitro. The developed hydrogel system exhibited the intended features of a stimulus-sensitive carrier system that can be efficiently used for the colonic delivery of PETase.

The relevance of short peptides for an understanding of unfolded and intrinsically disordered proteins

Over the last thirty years the unfolded state of proteins has attracted considerable interest owing to the discovery of intrinsically disordered proteins which perform a plethora of functions despite resembling unfolded proteins to a significant extent. Research on both, unfolded and disordered proteins has revealed that their conformational properties can deviate locally from random coil behavior. In this context results from work on short oligopeptides suggest that individual amino acid residues sample the sterically allowed fraction of the Ramachandran plot to a different extent. Alanine has been found to exhibit a peculiarity in that it has a very high propensity for adopting polyproline II like conformations. This Perspectives article reviews work on short peptides aimed at exploring the Ramachandran distributions of amino acid residues in different contexts with experimental and computational means. Based on the thus provided overview the article discussed to what extent short peptides can serve as tools for exploring unfolded and disordered proteins and as benchmarks for the development of a molecular dynamics force field.

Encapsulated laccase in bimetallic Cu/Zn ZIFs as stable and reusable biocatalyst for decolorization of dye wastewater

Laccase have received extensive attention in pollutant degradation, but its practical viability is largely affected by the poor stability, easy inactivation and difficulty in recycling for the present. Enzyme immobilization offers enhanced enzyme stability and constructs a synergistic system for the efficient adsorption and degradation of pollutants. In this study, bimetallic Cu/Zn ZIFs were synthesized by co-precipitation method as the protective carrier for laccase. Lac@Cu-ZIF-90 exhibited a good protective effect on laccase and showed a high operational stability in various interfering environments. Free laccase was completely inactivated at pH 7.0 but Lac@Cu-ZIF-90 could maintain 50.0 % activity. Benefiting from the encapsulation of laccase and porous structure of Cu-ZIF-90, the Lac@Cu-ZIF-90 exhibited decolorization efficiency for dye wastewater. More importantly, the Lac@Cu-ZIF-90 could be recovered from the dye solution and re-used to adsorb and degrade the synthetic dye for multiple times, its removal rate for reactive deep green was only decreased about 10.8 % after five cycles. This work reveals that the Cu-ZIF-90 provides a favorable environment for laccase and as a protective layer to relieve the conformation change, which provides an efficient strategy to decolorize dye wastewater. Therefore, Cu-ZIF-90 promises applications as enzymes encapsulation has great potential in water remediation.

Spectroscopic and Theoretical Analysis of the Interaction between Plasma Proteins and Phthalimide Analogs with Potential Medical Application

One of the groups of organic compounds with potential use in medicine and pharmacy is phthalimide derivatives. They are characterized by a wide range of properties such as antibacterial, antifungal, and anti-inflammatory. In this study, we focused on research on four phthalimide derivatives with proven non-toxicity, which are cyclooxygenase inhibitors. With the use of molecular docking study and spectroscopic methods, such as fluorescence, circular dichroism, and FT-IR spectroscopies, we analyzed the way the tested compounds interact with plasma proteins. Among the many proteins present in the plasma, we selected three: albumin, α1-acid glycoprotein, and gamma globulin, which play significant roles in the human body. The obtained results showed that all tested compounds bind to the analyzed proteins. They interact most strongly with albumin, which is a transport protein. However, interactions with serum albumin and orosomucoid do not cause significant changes in their structures. Only in the case of gamma globulins significant changes were observed in protein secondary structure.

ELISA Based Immunoreactivity Reduction of Soy Allergens through Thermal Processing

Allergens are proteins and are, therefore, likely to be denatured when subjected to thermal treatment. Traditional cooking has so far been able to reduce allergen sensitivity by around 70–90%. This study was aimed at evaluating the effect of a broad range of thermal treatments on the reduction of soy immunoreactivity (IR) in a 5% slurry using a sandwich ELISA technique. Cooking at 100 °C (10–60 min) and different thermal processing conditions, such as in commercial sterilization (with a process lethality (Fo) between 3 and 5 min) and selected severe thermal processing conditions (Fo > 5 and up to 23 min) were used in the study to evaluate their influence on allergen IR. Based on an IR comparison with an internal soy allergen standard, the allergen concentration in the untreated soy sample was calculated to be equivalent to 333 mg/kg (ppm). Cooking conditions only reduced the IR sensitivity to about 10 mg/kg (~1.5 log reductions), while the thermal processing treatments lowered the allergen IR up to 23 × 10−3 mg/kg (or 23 ppb) (>4 log reductions). FTIR analysis indicated significant changes in protein structure resulting from the thermal processing treatments, with a higher degree of allergen reduction corresponding with a higher value of random coil percentages. The influence of process severity on color and rheological properties was, however, minimal.

The Convergence of FTIR and EVs: Emergence Strategy for Non-Invasive Cancer Markers Discovery

In conjunction with imaging analysis, pathology-based assessments of biopsied tissue are the gold standard for diagnosing solid tumors. However, the disadvantages of tissue biopsies, such as being invasive, time-consuming, and labor-intensive, have urged the development of an alternate method, liquid biopsy, that involves sampling and clinical assessment of various bodily fluids for cancer diagnosis. Meanwhile, extracellular vesicles (EVs) are circulating biomarkers that carry molecular profiles of their cell or tissue origins and have emerged as one of the most promising biomarkers for cancer. Owing to the biological information that can be obtained through EVs' membrane surface markers and their cargo loaded with biomolecules such as nucleic acids, proteins, and lipids, EVs have become useful in cancer diagnosis and therapeutic applications. Fourier-transform infrared spectroscopy (FTIR) allows rapid, non-destructive, label-free molecular profiling of EVs with minimal sample preparation. Since the heterogeneity of EV subpopulations may result in complicated FTIR spectra that are highly diverse, computational-assisted FTIR spectroscopy is employed in many studies to provide fingerprint spectra of malignant and non-malignant samples, allowing classification with high accuracy, specificity, and sensitivity. In view of this, FTIR-EV approach carries a great potential in cancer detection. The progression of FTIR-based biomarker identification in EV research, the rationale of the integration of a computationally assisted approach, along with the challenges of clinical translation are the focus of this review.

Synergy of Hofmeister effect and ligand crosslinking enabled the facile fabrication of super-strong, pre-stretching-enhanced gelatin-based hydrogels

Hydrogels are becoming increasingly popular in biomedical and soft machine manufacturing, but their practical application is limited by poor mechanical properties. In recent years, Hofmeister effect-enhanced gelatin hydrogels have become popular. However, the synergy of the Hofmeister effect using other toughening methods is still less investigated. We have fabricated an ultra-high strength gelatin-based hydrogel by introducing ligand cross-linking and hydrogen bonds. Unlike conventional double-network hydrogels, the dense physical cross-linking involving sacrificial bonds gives the hydrogel excellent fatigue resistance and self-recovery properties. The enhancement of mechanical properties by the Hofmeister effect is attributed to the disruption of the hydration shell of the gelatin molecular chains, which leads to stronger interactions between the molecular chains. The mechanical properties of the hydrogels are adjustable over a wide range by varying the concentration of the soaked (NH₄)₂SO₄ solution. The fixation of the gelatin molecular chain orientation by the Hofmeister effect and the reorganization of the coordination bonds allow the hydrogels to be self-reinforced by pre-stretching. At the same time, the modulus contraction of hydrogels in high-concentration salt solutions, and relaxation and swelling in dilute solutions exhibit ionic stimulation responses and shape recovery capability, and hybrid hydrogels have great potential as bio-actuators.

Non-destructive insights into photosynthetic and photoprotective mechanisms in Arabidopsis thaliana grown under two light regimes

Probing insights into understanding photosynthetic processes via non-invasive means has an added advantage when used in phenotyping or precision agriculture. We employed Raman spectroscopy and fluorescence-based methods to investigate both the changes in the photosynthetic processes and the underlying protective mechanisms on Arabidopsis thaliana wild-type (WT), and ros1, which is a mutant of a repressor of transcriptional gene silencing, both grown under low light (LL: 100 μmol m^-2s^-1) and high light (HL: 400 μmol m^-2s^-1) regimes. Raman imaging detected a lower carotenoid intensity after two weeks in those plants grown under HL, compared to those grown under the LL regime; we interpret this as the result of oxidative damage of β-carotene molecules. Further, the data revealed a significant depletion in carotenoids with enhanced phenolics around the midrib and tip of the WT leaves, but not in the ros1. On the contrary, small necrotic zones appeared after two weeks of HL in the ros1 mutant, pointing to the starting oxidative damage. The lower maximum quantum yield of the photochemistry (F_v/F_m) in the WT as well as in the ros1 mutant grown in HL (compared to those in the LL two weeks post-exposure), indicates the HL partially inactivated photosystems. Chlorophyll a fluorescence imaging further showed high non-photochemical quenching (NPQ) in the plants grown under the HL regime for both the WT and the ros1 mutant, but the spatial heterogeneity of NPQ images was much higher in the HL-grown ros1 mutant. Fluorescence screening methods revealed significantly high values of chlorophyll proxies in the WT as well as in the ros1 mutant two weeks after in the HL compared to those under LL. The data generally revealed an increased accumulation of phenolics under HL in both the WT and ros1 mutant plants, but the proxies of anthocyanin and flavonols were significantly lower in the ros1 mutant than in the WT. The comparatively low accumulation of anthocyanin in the ros1 mutant compared to the WT supports the Raman data. We conclude that integrated use of these techniques can be efficiently applied for a better understanding of insights into photosynthetic mechanisms.

Secondary Structures in Synthetic Poly(Amino Acids): Homo- and Copolymers of Poly(Aib), Poly(Glu), and Poly(Asp)

The secondary structure of poly(amino acids) is an excellent tool for controlling and understanding the functionality and properties of proteins. In this perspective article the secondary structures of the homopolymers of oligo- and poly-glutamic acid (Glu), aspartic acid (Asp), and α-aminoisobutyric acid (Aib) are discussed. Information on external and internal factors, such as the nature of side groups, interactions with solvents and interactions between chains is reviewed. A special focus is directed on the folding in hybrid-polymers consisting of oligo(amino acids) and synthetic polymers. Being part of the SFB TRR 102 "Polymers under multiple constraints: restricted and controlled molecular order and mobility" this overview is embedded into the cross section of protein fibrillation and supramolecular polymers. As polymer- and amino acid folding is an important step for the utilization and design of future biomolecules these principles guide to a deeper understanding of amyloid fibrillation.

Raman microscopic spectroscopy as a diagnostic tool to detect Staphylococcus epidermidis in bone grafts

INTRODUCTION

Raman microscopic spectroscopyis a new approach for further characterization and detection of molecular features in many pathological processes. This technique has been successfully applied to scrutinize the spatial distribution of small molecules and proteins within biological systems by in situ analysis. This study uses Raman microscopic spectroscopyto identify any in-depth benefits and drawbacks in diagnosing Staphylococcus epidermidis in human bone grafts.

MATERIAL AND METHODS

40 non-infected human bone samples and 10 human bone samples infected with Staphylococcus epidermidis were analyzed using Raman microscopic spectroscopy. Reflectance data were collected between 200 cm^-1 and 3600 cm^-1 with a spectral resolution of 4 cm^-1 using a Senterra II microscope (Bruker, Ettlingen, Germany). The acquired spectral information was used for spectral and unsupervised classification, such as principal component analysis.

RESULTS

Raman measurements produced distinct diagnostic spectra that were used to distinguish between non-infected human bone samples and Staphylococcus epidermidis infected human bone samples by spectral and principal component analyses. A substantial loss in bone quality and protein conformation was detected by human bone samples co-cultured with Staphylococcus epidermidis. The mineral-to-matrix ratio using the phosphate/Amide I ratio (p = 0.030) and carbonate/phosphate ratio (p = 0.001) indicates that the loss of relative mineral content in bones upon bacterial infection is higher than in non-infected human bones. Also, an increase of alterations in the collagen network (p = 0.048) and a decrease in the structural organization and relative collagen in infected human bone could be detected. Subsequent principal component analyses identified Staphylococcus epidermidis in different spectral regions, respectively, originating mainly from CH₂ deformation (wagging) of protein (at 1450 cm^-1) and bending and stretching modes of C-H groups (∼2800-3000 cm^-1).

CONCLUSION

Raman microscopic spectroscopyis presented as a promising diagnostic tool to detect Staphylococcus epidermidis in human bone grafts. Further studies in human tissues are warranted.

Spectral and theoretical study of SARS-CoV-2 ORF10 protein interaction with endogenous and exogenous macroheterocyclic compounds

The coronavirus disease 2019 (COVID-19) caused by the SARS-CoV-2 coronavirus has spread rapidly around the world in a matter of weeks. Most of the current recommendations developed for the use of antivirals in COVID-19 were developed during the initial waves of the pandemic, when resources were limited and administrative or pragmatic criteria took precedence. The choice of drugs for the treatment of COVID-19 was carried out from drugs approved for medical use. COVID-19 is a serious public health problem and the search for drugs that can relieve the disease in infected patients at various stages is still necessary. Therefore, the search for effective drugs with inhibitory and/or virucidal activity is a paramount task. Accessory proteins of the virus play a significant role in the pathogenesis of the disease, as they modulate the host's immune response. This paper studied the interaction of one of the SARS-CoV-2 accessory proteins ORF10 with macroheterocyclic compounds - protoporphyrin IX d.m.e., Fe(III)protoporphyrin d.m.e. and 5,10,15,20-tetrakis(3'-pyridyl)chlorin tetraiodide, which are potential inhibitors and virucidal agents. The SARS-CoV-2 ORF10 protein shows the highest affinity for Chlorin, which binds hydrophobically to the alpha structured region of the protein. Protoporphyrin is able to form several complexes with ORF10 close in energy, with alpha- and beta-molecular recognition features, while Fe(III)protoporphyrin forms complexes with the orientation of the porphyrin macrocycle parallel to the ORF10 alpha-helix. Taking into account the nature of the interaction with ORF10, it has been suggested that Chlorin may have virucidal activity upon photoexposure. The SARS-CoV-2 ORF10 protein was expressed in Escherichia coli cells, macroheterocyclic compounds were synthesized, and the structure was confirmed. The interaction between macrocycles with ORF10 was studied by spectral methods. The results of in silico studies were confirmed by experimental data.

Acetic Acid Enables Precise Tailoring of the Mechanical Behavior of Protein-Based Hydrogels

Engineering viscoelastic and biocompatible materials with tailored mechanical and microstructure properties capable of mimicking the biological stiffness (<17 kPa) or serving as bioimplants will bring protein-based hydrogels to the forefront in the biomaterials field. Here, we introduce a method that uses different concentrations of acetic acid (AA) to control the covalent tyrosine-tyrosine cross-linking interactions at the nanoscale level during protein-based hydrogel synthesis and manipulates their mechanical and microstructure properties without affecting protein concentration and (un)folding nanomechanics. We demonstrated this approach by adding AA as a precursor to the preparation buffer of a photoactivated protein-based hydrogel mixture. This strategy allowed us to synthesize hydrogels made from bovine serum albumin (BSA) and eight repeats protein L structure, with a fine-tailored wide range of stiffness (2-35 kPa). Together with protein engineering technologies, this method will open new routes in developing and investigating tunable protein-based hydrogels and extend their application toward new horizons.

Preparation of Fetal Bovine Serum-Copper Phosphate Hybrid Particles under Cell Culture Conditions for Cancer Cell Treatment

Fetal bovine serum (FBS) particles, which mainly consist of bovine serum albumin, have the potential for biological and medical applications as drug carriers. The coacervation of albumin is a common technique for preparing albumin-based particles. The replacement of salt with novel metal salts such as Cu is an affordable way to embed the metal ion in the albumin-based particles. Further, increased Cu distribution is prevalent in many cancers. Here, we prepared adhesive cell-like FBS-copper phosphate hybrid particles [FBS-Cu₃(PO₄)₂], which exhibited toxicity toward cancer cells, with a narrow size distribution under cell culture conditions for preventing tumor progression. FBS-Cu₃(PO₄)₂ showed peroxidase-like activity. In addition, FBS-Cu₃(PO₄)₂ was successfully loaded with rhodamine B and conjugated with fluorescein isothiocyanate as models of drugs by coincubation. Thus, we designed a simple preparation method for optimizing FBS-Cu₃(PO₄)₂ synthesis under cell culture conditions. FBS-Cu₃(PO₄)₂ has significant potential as an efficient reactive oxygen species generator and drug-delivery agent against cancer cells. Furthermore, the RhoB-loaded FBS-Cu₃(PO₄)₂ successfully interacted with 4T1 mouse mammary tumor cells and were confirmed to exhibit toxicity.

Molecular simulations of the interfacial properties in silk-hydroxyapatite composites

Biomineralization is a common strategy used in Nature to improve the mechanical strength and toughness of biological materials. This strategy, applied in materials like bone or nacre, serves as inspiration for materials scientists and engineers to design new materials for applications in healthcare, soft robotics or the environment. In this regard, composites consisting of silk and hydroxyapatite have been extensively researched for bone regeneration applications, due to their reported cytocompatibility and osteoinduction capacity that supports bone formation in vivo. Thus, it becomes relevant to understand how silk and hydroxyapatite interact at their interface, and how this affects the overall mechanical properties of these composites. This theoretical-experimental work investigates the interfacial dynamic and structural properties of silk in contact with hydroxyapatite, combining molecular dynamics simulations with analytical characterization. Our data indicate that hydroxyapatite decreases the β-sheets in silk, which are a key load-bearing element of silk. The β-sheets content can usually be increased in silk biomaterials via post-processing methods, such as water vapor annealing. However, the presence of hydroxyapatite appears to reduce also for the formation of β-sheets via water vapor annealing. This work sheds light into the interfacial properties of silk-hydroxyapatite composite and their relevance for the design of composite biomaterials for bone regeneration.

Design and Development of a Bimodal Optical Instrument for Simultaneous Vibrational Spectroscopy Measurements

Vibrational spectroscopy techniques are widely used in analytical chemistry, physics and biology. The most prominent techniques are Raman and Fourier-transform infrared spectroscopy (FTIR). Combining both techniques delivers complementary information of the test sample. We present the design, construction, and calibration of a novel bimodal spectroscopy system featuring both Raman and infrared measurements simultaneously on the same sample without mutual interference. The optomechanical design provides a modular flexible system for solid and liquid samples and different configurations for Raman. As a novel feature, the Raman module can be operated off-axis for optical sectioning. The calibrated system demonstrates high sensitivity, precision, and resolution for simultaneous operation of both techniques and shows excellent calibration curves with coefficients of determination greater than 0.96. We demonstrate the ability to simultaneously measure Raman and infrared spectra of complex biological material using bovine serum albumin. The performance competes with commercial systems; moreover, it presents the additional advantage of simultaneously operating Raman and infrared techniques. To the best of our knowledge, it is the first demonstration of a combined Raman-infrared system that can analyze the same sample volume and obtain optically sectioned Raman signals. Additionally, quantitative comparison of confocality of backscattering micro-Raman and off-axis Raman was performed for the first time.

Biodistribution and toxicity of antimicrobial ionic silver (Ag+) and silver nanoparticle (AgNP+) species after oral exposure, in Sprague-Dawley rats

Although antimicrobial nanosilver finds numerous applications in the health and food industries, the in vivo toxicity of positively charged silver nanoparticles (AgNPs⁺) and relevant controls are largely unexplored. This study investigates the relationship between the biodistribution and toxicity of the well-known cetyltrimethylammonium bromide (CTAB)-capped AgNPs⁺ in 6-weeks old female Sprague-Dawley rats, at sublethal doses. Amounts comparative to those leaked from food products or considered for animal feed were administered through daily water intake, for an 18-day period: AgNPs⁺ (40 μg mL^-1), Ag⁺ (40 μg mL^-1), antimicrobial CTAB⁺ (24 μg mL^-1) and tap water. All exposures except for the water control had adverse effects on the health and systemic functions of rats (e.g., lethargy, hepatomegaly, splenomegaly, impediment of bone development, and/or heightened immune response). Although the total Ag accumulation in tissues (1.4-1.6 μg of Ag/g of liver, spleen, jejunum, and brain) was comparable for the two Ag species, AgNPs⁺ were generally more toxic than Ag⁺, particularly in spleen (0.8 μg Ag/g). Significantly reduced euthanasia time, alopecia, inflammatory responses in spleen, fragile veins, and enhanced lymphocytosis were observed only for AgNPs⁺. Overall, this study raises health concerns about the ingestion of capped-AgNPs⁺ or Ag⁺ by first-hand consumers and industry workers.

Supramolecular Hybrids from Cyanometallate Complexes and Diblock Copolypeptide Amphiphiles in Water

The self-assembly of discrete cyanometallates has attracted significant interest due to the potential of these materials to undergo soft metallophilic interactions as well as their optical properties. Diblock copolypeptide amphiphiles have also been investigated concerning their capacity for self-assembly into morphologies such as nanostructures. The present work combined these two concepts by examining supramolecular hybrids comprising cyanometallates with diblock copolypeptide amphiphiles in aqueous solutions. Discrete cyanometallates such as [Au(CN)2]-, [Ag(CN)2]-, and [Pt(CN)4]2- dispersed at the molecular level in water cannot interact with each other at low concentrations. However, the results of this work demonstrate that the addition of diblock copolypeptide amphiphiles such as poly-(L-lysine)-block-(L-cysteine) (Lysm-b-Cysn) to solutions of these complexes induces the supramolecular assembly of the discrete cyanometallates, resulting in photoluminescence originating from multinuclear complexes with metal-metal interactions. Electron microscopy images confirmed the formation of nanostructures of several hundred nanometers in size that grew to form advanced nanoarchitectures, including those resembling the original nanostructures. This concept of combining diblock copolypeptide amphiphiles with discrete cyanometallates allows the design of flexible and functional supramolecular hybrid systems in water.