Biochemical Environment Research Articles

Sodium bicarbonate alters protein stability and blood coagulability in a simulated Impella purge gap model.

The Impella® microaxial blood pumps utilize purge fluid containing heparin to prevent biofouling of internal surfaces. Purge fluid interfaces with blood or blood components at two notable internal locations: (1) 5-8μm radial gap ("Radial Gap" or "Gap 1") between the motor shaft and bearing, a site accessible by blood proteins or small molecules; and (2) 100 μm axial gap ("Axial Gap" or "Gap 2") between the impeller rotor and bearing, the site of mixing with larger circulating blood components. Despite its efficacy, heparin in the purge fluid complicates overall patient anticoagulation management. Here, we investigate sodium bicarbonate as an alternative to heparin in the purge fluid in a simulated purge gap micro-environment. To assess protein stability simulated at Gap 1, human serum albumin (HSA; 40 mg/ml) species were quantified utilizing size exclusion liquid chromatography (SEC-HPLC) after stirring with purge fluid (5% dextrose in water (D5W) with heparin (25 U/ml) or sodium bicarbonate (25 or 50 mEq/L)) over a 24-h period. pH measurements were taken immediately prior to stirring. Mixing between blood and purge fluid at Gap 2 was mimicked in vitro utilizing a 60:40 blood: purge fluid ratio. Purge fluid consisted of D5W with or without sodium bicarbonate (25 or 50 mEq/L). Human citrated blood samples were freshly collected with or without the addition of heparin (5U/ml). Coagulability was determined via thromboelastography (TEG). pH measurements of blood mixtures were taken immediately before and after TEG analysis. Sodium bicarbonate alone or synergistically with heparin was effective in increasing protein stability, increasing pH, and reducing coagulability. In the Gap 1 model, sodium bicarbonate led to preservation of HSA monomer after 24h mixing, with monomer composing 88.3 ± 2.3% and 88.6 ± 0.9% of total HSA species for 25 or 50 mEq/L sodium bicarbonate, respectively. Only 60.4 ± 4.3% monomer was observed with D5W alone (p < 0.005). HSA aggregates and fragments were evident in heparin and D5W purge mixtures, but absent in sodium bicarbonate (25 and 50 mEq/L). pH of HSA mixtures significantly increased in the presence of sodium bicarbonate. In the Gap 2 model, combined heparin (5U/ml) and sodium bicarbonate prolonged clotting time (TEG-ACT), leading to an average increase of 795 ± 275 s (p=0.04) and 846 243 s (p=0.03). This trend of reduced coagulability was similarly observed in clot initiation time (R time), clot formation time (K time), and clotting rate (α angle). Blood mixture pH measurements increased with addition of sodium bicarbonate in both heparinized and non-heparinized blood samples. Sodium bicarbonate in the purge fluid has the potential to significantly increase protein stability and reduce protein denaturation at the Impella® radial gap (Gap 1), while reducing blood coagulation at the Impella® axial gap (Gap 2). The influence of sodium bicarbonate on the biochemical environment of the purge fluid may ensure stable purge flow resistance and play a synergistic or supportive role in the purge gap micro-environment when used with systemic anticoagulation.

Structure of Geobacter cytochrome OmcZ identifies mechanism of nanowire assembly and conductivity.

OmcZ nanowires produced by Geobacter species have high electron conductivity (>30 S cm-1). Of 111 cytochromes present in G. sulfurreducens, OmcZ is the only known nanowire-forming cytochrome essential for the formation of high-current-density biofilms that require long-distance (>10 µm) extracellular electron transport. However, the mechanisms underlying OmcZ nanowire assembly and high conductivity are unknown. Here we report a 3.5-Å-resolution cryogenic electron microscopy structure for OmcZ nanowires. Our structure reveals linear and closely stacked haems that may account for conductivity. Surface-exposed haems and charge interactions explain how OmcZ nanowires bind to diverse extracellular electron acceptors and how organization of nanowire network re-arranges in different biochemical environments. In vitro studies explain how G. sulfurreducens employ a serine protease to control the assembly of OmcZ monomers into nanowires. We find that both OmcZ and serine protease are widespread in environmentally important bacteria and archaea, thus establishing a prevalence of nanowire biogenesis across diverse species and environments.

Cell response to substrate energy dissipation outweighs rigidity sensing.

The mechanical properties of the extracellular matrix (ECM) are essential for tissue homeostasis, as they determine cell spreading, differentiation, proliferation and migration through the concerted action of mechanoresponsive proteins such as YAP. However, interpretation of the mechanical crosstalk between cells and the ECM using hydrogel mimetics has been limited by the intricacies to engineer viscoelasticity typical of the ECM, the difficulty in discerning viscoelastic from viscoplastic behaviors, and the convolution of their mechanical and non-mechanical properties. As a result, whether cells sense ECM energy dissipation (i.e. viscoelasticity) independently of stiffness remains unknown. Here, we exploit fundamental polypeptide conformational changes under force to produce titin-based protein hydrogels with tailored viscoelasticity and preserved chemical composition, ultrastructure, crosslinking density, and biochemical environment. Using our system, we demonstrate that cells respond to changes in viscoelastic cues only, as nuclear YAP decreases with substrate energy dissipation. Furthermore, the rate of YAP translocation to the nucleus is more sensitive to changes in energy dissipation than in stiffness; indicating that the response to the viscous component engineered into our ECM mimetics supersedes rigidity effects. This observation implies that cells perceive ECM rigidity and energy dissipation by non-overlapping mechanisms, illustrating the relevance of ECM viscoelasticity in the biology of the cell.

Analysis of the mechanical characteristics of collective skeletal muscle cell migration upon the biochemical environment of injured muscle.

Skeletal muscle tissues inherently contain undifferentiated myoblasts and satellite cells, providing sources for self-regeneration following the injury. Muscle regeneration requires collective migration of constituent cells toward the injured sites, while muscle differentiation also requires collective migration for proper alignment. Despite the importance of the collective behavior of muscle cells, most studies on muscle cell motility during skeletal muscle regeneration involve single-cell behavior, and little is known about the collective behavior. In this study, we constructed an in vitro cell-based platform to model skeletal muscles with specific biomolecules released from the skeletal muscle cells using conditioned media from the normal versus injured culture conditions. We measured the migration behavior and the mechanical characteristics of the cell clusters represented by the traction force and intercellular stress under different media conditions. We then identified that the heterogeneous population of skeletal muscle cell clusters exhibited distinct collective migration patterns in the injury-mimicking state compared to the normal-mimicking condition. Furthermore, the traction and stress maps of the migrating cells also showed uniquely different patterns in each media condition and were closely related to the migrating behaviors. These results suggest that the selective activation of specific cells in the migrating clusters by the biochemical cues from the normal and injured skeletal muscles can induce these distinct migrating patterns and mechanical characteristics.

Enhancing electrochemical sensing through the use of functionalized graphene composites as nanozymes.

Graphene-based nanozymes possess inherent nanomaterial properties that offer not only a simple substitute for enzymes but also a versatile platform capable of bonding with complex biochemical environments. The current review discusses the replacement of enzymes in developing biosensors with nanozymes. Functionalization of graphene-based materials with various nanoparticles can enhance their nanozymatic properties. Graphene oxide functionalization has been shown to yield graphene-based nanozymes that closely mimic several natural enzymes. This review provides an overview of the classification, current state-of-the-art development, synthesis routes, and types of functionalized graphene-based nanozymes for the design of electrochemical sensors. Furthermore, it includes a summary of the application of functionalized graphene-based nanozymes for constructing electrochemical sensors for pollutants, drugs, and various water and food samples. Challenges related to nanozymes as electrocatalytic materials are discussed, along with potential solutions and approaches for addressing these shortcomings.

Interaction between Nanoparticles, Membranes and Proteins: A Surface Plasmon Resonance Study

Regardless of the promising use of nanoparticles (NPs) in biomedical applications, several toxic effects have increased the concerns about the safety of these nanomaterials. Although the pathways for NPs toxicity are diverse and dependent upon many parameters such as the nature of the nanoparticle and the biochemical environment, numerous studies have provided evidence that direct contact between NPs and biomolecules or cell membranes leads to cell inactivation or damage and may be a primary mechanism for cytotoxicity. In such a context, this work focused on developing a fast and accurate method to characterize the interaction between NPs, proteins and lipidic membranes by surface plasmon resonance imaging (SPRi) technique. The interaction of gold NPs with mimetic membranes was evaluated by monitoring the variation of reflectivity after several consecutive gold NPs injections on the lipidic membranes prepared on the SPRi biochip. The interaction on the membranes with varied lipidic composition was compared regarding the total surface concentration density of gold NPs adsorbed on them. Then, the interaction of gold and silver NPs with blood proteins was analyzed regarding their kinetic profile of the association/dissociation and dissociation constants (koff). The surface concentration density on the membrane composed of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine and cholesterol (POPC/cholesterol) was 2.5 times higher than the value found after the injections of gold NPs on POPC only or with dimethyldioctadecylammonium (POPC/DDAB). Regarding the proteins, gold NPs showed preferential binding to fibrinogen resulting in a value of the variation of reflectivity that was 8 times higher than the value found for the other proteins. Differently, silver NPs showed similar interaction on all the tested proteins but with a variation of reflectivity on immunoglobulin G (IgG) 2 times higher than the value found for the other tested proteins.

Frequency Changes in Terminal Alkynes Provide Strong, Sensitive, and Solvatochromic Raman Probes of Biochemical Environments.

The C≡C stretching frequencies of terminal alkynes appear in the "clear" window of vibrational spectra, so they are attractive and increasingly popular as site-specific probes in complicated biological systems like proteins, cells, and tissues. In this work, we collected infrared (IR) absorption and Raman scattering spectra of model compounds, artificial amino acids, and model proteins that contain terminal alkyne groups, and we used our results to draw conclusions about the signal strength and sensitivity to the local environment of both aliphatic and aromatic terminal alkyne C≡C stretching bands. While the IR bands of alkynyl model compounds displayed surprisingly broad solvatochromism, their absorptions were weak enough that alkynes can be ruled out as effective IR probes. The same solvatochromism was observed in model compounds' Raman spectra, and comparisons to published empirical solvent scales (including a linear regression against four meta-aggregated solvent parameters) suggested that the alkyne C≡C stretching frequency mainly reports on local electronic interactions (i.e., short-range electron donor-acceptor interactions) with solvent molecules and neighboring functional groups. The strong solvatochromism observed here for alkyne stretching bands introduces an important consideration for Raman imaging studies based on these signals. Raman signals for alkynes (especially those that are π-conjugated) can be exceptionally strong and should permit alkynyl Raman signals to function as probes at very low concentrations, as compared to other widely used vibrational probe groups like azides and nitriles. We incorporated homopropargyl glycine into a transmembrane helical peptide via peptide synthesis, and we installed p-ethynylphenylalanine into the interior of the Escherichia coli fatty acid acyl carrier protein using a genetic code expansion technique. The Raman spectra from each of these test systems indicate that alkynyl C≡C bands can act as effective and unique probes of their local biomolecular environments. We provide guidance for the best possible future uses of alkynes as solvatochromic Raman probes, and while empirical explanations of the alkyne solvatochromism are offered, open questions about its physical basis are enunciated.

A 3D‐Bioprinted Functional Module Based on Decellularized Extracellular Matrix Bioink for Periodontal Regeneration

Poor fiber orientation and mismatched bone-ligament interface fusion have plagued the regeneration of periodontal defects by cell-based scaffolds. A 3D bioprinted biomimetic periodontal module is designed with high architectural integrity using a methacrylate gelatin/decellularized extracellular matrix (GelMA/dECM) cell-laden bioink. The module presents favorable mechanical properties and orientation guidance by high-precision topographical cues and provides a biochemical environment conducive to regulating encapsulated cell behavior. The dECM features robust immunomodulatory activity, reducing the release of proinflammatory factors by M1 macrophages and decreasing local inflammation in Sprague Dawley rats. In a clinically relevant critical-size periodontal defect model, the bioprinted module significantly enhances the regeneration of hybrid periodontal tissues in beagles, especially the anchoring structures of the bone-ligament interface, well-aligned periodontal fibers, and highly mineralized alveolar bone. This demonstrates the effectiveness and feasibility of 3D bioprinting combined with a dental follicle-specific dECM bioink for periodontium regeneration, providing new avenues for future clinical practice.

Chemotaxis of capacitated ram spermatozoa to ewe follicular fluid

Sperm orientation mechanisms, as chemotaxis, are essential for the sperm to reach the oocyte and then fertilize it. The follicular fluid is the biochemical environment where the oocyte develops until its ovulation, and its composition changes throughout the estrous cycle. The follicular fluid is released together with the oocyte at the moment of ovulation, and it has been proposed as a chemoattractant for spermatozoa. This chemotactic ability has been demonstrated in some mammals, but to date, no studies have been done in the ovine species. Also, it has been reported that only capacitated and hyperactivated spermatozoa can respond to chemotactic stimuli. Therefore, the aim of this work was to study the chemotactic response of ovine spermatozoa to ewe follicular fluid, obtained at various stages of the estrous cycle, and to evaluate the influence of the capacitation status in the chemotaxis mechanism. In order to perform the experiments, ovine follicular fluids were obtained in the early and late follicular and luteal phases, and two concentrations, 2 and 10%, were tested. Semen samples were collected from nine Rasa Aragonesa rams, and spermatozoa were selected by the swim-up/dextran method. In vitro capacitation was induced by incubation without (cap-TALP) or with cAMP-elevating agents (cap-Cocktail). After sperm quality evaluation (motility, viability, and capacitation state), the chemotactic assays were carried out with the aim of the commercial device (IBIDI® µ-Slide Chemotaxis chamber, Ibidi GmbH). Swim- up, cap-TALP or cap-Cocktail samples were loaded in the chambers in the presence of follicular fluid. Individual trajectories were analyzed by the OpenCASA software (Alquezar-Baeta et al., PLoS Comput Biol, 15(1), 2019), which calculates a chemotaxis index. Differences were analysed by χ² test, except for the chemotaxis index (ANOVA) using GraphPad PRISM® (Version 8.0.1). Follicular fluid at 2 and 10% concentrations, obtained in luteal and early follicular phases, induced sperm chemoattraction. This chemotactic response was only observed in capacitated spermatozoa, which supports previous evidence in other species. These results reveal, for the first time, the chemotactic effect of ewe follicular fluid in ram spermatozoa. Grants: AGL-2017- 83799-R and DGA A07-17R. S.M.-J. has a predoctoral contract from the Diputación General de Aragón (DGA).

Discovering dominant ammonia assimilation: Implication for high-strength nitrogen removal in full scale biological treatment of landfill leachate

Landfill leachate containing high-strength nitrogen is generated in domestic waste landfilling. The integration of anoxic and aerobic process (AO) based on nitrification and denitrification, has been a mainstream process of biological nitrogen removal (BNR). But the high-strength organics as well as aerobic effluent reflux might change the biochemical environment designed and operated as AO. In view of the nitrogen balance in a full scale landfill leachate treatment plant with two-stage AO, we found that approximately 90% removal of total nitrogen (TN) and ammonia (NH4+-N) focused on primary anoxic and aerobic stage. Meanwhile, the less nitrate and nitrite in the aerobic effluent were incapable of sustaining denitrification or anaerobic ammonia oxidation (anammox). The high reflux flow from aerobic to anoxic process enabled the similar microbial community and functional genes in anoxic and aerobic process units. However, the functional genes involving ammonia assimilation in all process units showcased the highest abundance compared to those correlated with other BNR pathways, including nitrification and denitrification, assimilatory and dissimilatory nitrate reduction, nitrogen fixation and anammox. The ammonia assimilation dominated the removals of TN and NH4+-N, rather than other BNR mechanism. The insight of dominant ammonia assimilation is favorable for illustrating the authentic BNR mechanism of landfill leachate in AO, thereby guiding the optimization of engineering design and operation.

Lake pigment characteristics and their applicability in reconstructing phytoplankton communities under irregular hydrological regulation in a floodplain lake system

The strong hydrological characteristics and complex biochemical environment of floodplain lake systems make it difficult to obtain accurate, convincing results from sediment pigments used as paleoenvironmental indicators. Understanding pigment migration and preservation mechanisms under hydrological regulation will help explain past ecological changes in these lake systems. This study investigates phytoplankton community structure, chlorophyll distribution, and associated environmental factors throughout a hydrological cycle in Poyang Lake, China. In conjunction with pigment sediment characteristics, this study also compared pigment deposition and preservation mechanisms among three hydrological lake zones (i.e., sub-lakes, main lake, and water channel). Results show a critical loss in sediment pigment information in the main lake and the water channel resulting from the lake’s strong hydrodynamic conditions. Moreover, oxygen and sunlight had a general inhibitory effect on pigment in the overlying water, while unfavourable pH environments could affect pigments in the sediment that devoid of protective cell mechanisms. Results also show that as a biological proxy index, sub-lakes sediment pigments accurately reflect phytoplankton community structure in overlying water. Additionally, due to the relative stability of the sub-lakes environment, it can be considered the preferential lake zone from which to obtain proxy indexes in floodplain environments.

Amyloid Fibrillation of Insulin: Amelioration Strategies and Implications for Translation.

Insulin is a therapeutically relevant molecule with use in treating diabetes patients. Unfortunately, it undergoes a range of untoward and often unpredictable physical transformations due to alterations in its biochemical environment, including pH, ionic strength, temperature, agitation, and exposure to hydrophobic surfaces. The transformations are prevalent in its physiologically active monomeric form, while the zinc cation-coordinated hexamer, although physiologically inactive, is stable and less susceptible to fibrillation. The resultant molecular reconfiguration, including unfolding, misfolding, and hydrophobic interactions, often results in agglomeration, amyloid fibrillogenesis, and precipitation. As a result, a part of the dose is lost, causing a compromised therapeutic efficacy. Besides, the amyloid fibrils form insoluble deposits, trigger immunologic reactions, and harbor cytotoxic potential. The physical transformations also hold back a successful translation of non-parenteral insulin formulations, in addition to challenges related to encapsulation, chemical modification, purification, storage, and dosing. This review revisits the mechanisms and challenges that drive such physical transformations in insulin, with an emphasis on the observed amyloid fibrillation, and presents a critique of the current amelioration strategies before prioritizing some future research objectives.

Brushite nanoparticles based electrochemical sensor for detection of uric acid, xanthine, hypoxanthine and caffeine

The research in the field of biosensors has recently been focused on the design and development of functional electrode materials that can respond to changes in their biochemical environment. Here, we report the synthesis of dicalcium phosphate dihydrate (DCPD), also known as brushite (CaHPO4·2H2O) by soft chemical method and its application for electrochemical sensing of four different analytes. Phase purity, structure, chemical composition and surface morphology of the synthesized nanoparticles have been investigated using powder XRD, FTIR, SEM, XPS and HRTEM methods. Electrochemical sensor was prepared by modifying GCE with brushite and the modified electrodes were successfully used for either independent or simultaneous determination of uric acid, xanthine, hypoxanthine and caffeine in their mixture. The brushite/GCE exhibited four strong well-defined separate peaks corresponding to the oxidation of UA, XN, HXN and CF in phosphate buffer saline (PBS) at pH 7.4. The fabricated electrode showed low detection limits (S/N = 3) of 0.576, 1.0, 0.076 and 1.26 μM for UA, XN, HXN and CF respectively. Practical application of the fabricated electrode has been demonstrated by determining UA, XN, HXN and CF in human urine and coffee samples by direct method. The brushite offers scope for fabrication of sensor systems for implantable medical applications.

The role of mathematical models in designing mechanopharmacological therapies for asthma

Healthy lung function depends on a complex system of interactions which regulate the mechanical and biochemical environment of individual cells to the whole organ. Perturbations from these regulated processes give rise to significant lung dysfunction such as chronic inflammation, airway hyperresponsiveness and airway remodelling characteristic of asthma. Importantly, there is ongoing mechanobiological feedback where mechanical factors including airway stiffness and oscillatory loading have considerable influence over cell behavior. The recently proposed area of mechanopharmacology recognises these interactions and aims to highlight the need to consider mechanobiology when identifying and assessing pharmacological targets. However, these multiscale interactions can be difficult to study experimentally due to the need for measurements across a wide range of spatial and temporal scales. On the other hand, integrative multiscale mathematical models have begun to show success in simulating the interactions between different mechanobiological mechanisms or cell/tissue-types across multiple scales. When appropriately informed by experimental data, these models have the potential to serve as extremely useful predictive tools, where physical mechanisms and emergent behaviours can be probed or hypothesised and, more importantly, exploited to propose new mechanopharmacological therapies for asthma and other respiratory diseases. In this review, we first demonstrate via an exemplar, how a multiscale mathematical model of acute bronchoconstriction in an airway could be exploited to propose new mechanopharmacological therapies. We then review current mathematical modelling approaches in respiratory disease and highlight hypotheses generated by such models that could have significant implications for therapies in asthma, but that have not yet been the subject of experimental attention or investigation. Finally we highlight modelling approaches that have shown promise in other biological systems that could be brought to bear in developing mathematical models for optimisation of mechanopharmacological therapies in asthma, with discussion of how they could complement and accelerate current experimental approaches.

PDE5 inhibitors and male reproduction: Is there a place for PDE5 inhibitors in infertility clinics or andrology laboratories?

The objective of this review study is to evaluate the therapeutic role of PDE5 inhibitors (PDE5is) in the amelioration of oligoasthenospermia in infertile males. PDE5is have a beneficial influence on the secretory function of the Leydig and Sertoli cells, the biochemical environment within the seminiferous tubule, the contractility of the testicular tunica albuginea, and the prostatic secretory function. In several studies, the overall effect of sildenafil and vardenafil increased quantitative and qualitative sperm motility. Furthermore, some studies indicate that PDE5is influence positively the sperm capacity to undergo capacitation under biochemical conditions that are known to induce the sperm capacitation process. Additional research efforts are necessary in order to recommend unequivocally the usage of sildenafil, vardenafil, or avanafil for the alleviation of male infertility.

In Vitro Mimicking of Obesity-Induced Biochemical Environment to Study Obesity Impacts on Cells and Tissues.

Obesity represents a heavy burden for modern healthcare. The main challenge facing obesity research progress is the unknown underlying pathways, which limits our understanding of the pathogenesis and developing therapies. Obesity induces specific biochemical environments that impact the different cells and tissues. In this piece of writing, we suggest mimicking obesity-induced in vivo biochemical environments including pH, lipids, hormones, cytokines, and glucose within an in vitro environment. The concept is to reproduce such biochemical environments and use them to treat the tissue cultures, explant cultures, and cell cultures of different biological organs. This will allow us to clarify how the obesity-induced biochemistry impacts such biological entities. It would also be important to try different environments, in terms of the compositions and concentrations of the constitutive elements, in order to establish links between the effects (impaired regeneration, cellular inflammation, etc.) and the factors constituting the environment (hormones, cytokines, etc.) as well as to reveal dose-dependent effects. We believe that such approaches will allow us to elucidate obesity mechanisms, optimize animal models, and develop therapies as well as novel tissue engineering applications.

Walking speed does not affect net vastus lateralis fascicle length change on average during weight acceptance

Faster walking speeds increase the demand on quadriceps muscles to produce adequate force to decelerate body mass and control knee flexion. Quadriceps fascicle behavior (i.e., fascicle length changes) influences force generation, which in turn affects mechanical loading of the articular cartilage during walking and the biochemical environment of the knee joint. The fascicle behavior underlying different walking speeds remains unclear but should be characterized to better understand how the quadriceps muscles accommodate faster walking speeds, speeds that often associate with better cartilage health outcomes. Our purpose was to quantify quadriceps muscle net fascicle length change during weight acceptance across a range of walking speeds in the context of more well-documented changes in muscle activity and knee joint moments. We hypothesized that vastus lateralis (VL) fascicles in healthy young adults would produce force with more overall lengthening in early stance at faster walking speeds with concomitant increases in muscle–tendon unit (MTU) lengthening, internal peak knee extensor moment (pKEM), vertical ground reaction force (GRF), and muscle activity. Participants walked for two-minute trials at their preferred speed and at 0.75 m/s and 1.75 m/s. We found that on average, the VL accommodates the greater mechanical demands of walking at faster speeds with greater muscle activity and while resisting muscle lengthening behavior. We infer then that tendon stretch accommodates MTU lengthening in healthy young adults across a range of speeds and suggest these results motivate additional studies aimed at evaluating VL fascicle behavior individuals with known quadriceps strength deficits, inhibition, or heightened risk for developing osteoarthritis.

A binuclear Cu(I)-phosphine complex as a specific HSA site I binder: synthesis, X-ray structure determination, and a comprehensive HSA interaction analysis

In this research, we present a method for synthesis and a detailed description of geometry characterization of a novel binuclear Cu(I) phosphine complex, along with analysis of its interaction with HSA using spectroscopic and simulation methods. The Cu atoms are coordinated in a tetrahedral geometry, which results in coordination by two nitrogen atoms from the N,N'-(ethane-1,2-diyl)bis(1-(pyridin-2-yl)methanimine ligand (L), a chloride, and a PPh3. The complex binding constant to HSA in a biochemical environment was determined to be ∼106, which is indicative of a strong interaction. The fluorescence of HSA is significantly quenched by binding to the complex via a static mechanism, whereas the microenvironment of the tryptophan residue remains unchanged. A spontaneous binding process was indicated by a negative value for ΔG. Thermodynamic signatures reflect the dominance of hydrophobic forces during the interaction. The site marker competitive experiment combined with docking simulation analysis revealed the closeness position of the complex binding site to warfarin location in specific ligand site I of HSA. The information generated in the present study would be valuable to understand the interaction mechanistic and pharmacological behavior of Cu(I) complexes. Communicated by Ramaswamy H. Sarma

Surface properties and biocompatibility studies on bone plate by magnetorheological finishing

ABSTRACT Bone plates are essential for providing mechanical support during the healing of bone fractures by adapting to the biochemical environment. The surface quality of bone plates plays a vital role in their sustainability under adverse conditions. Magnetorheological Finishing (MRF) is an advanced surface finishing process that provides high surface finishing without disturbing the polished surface topography. However, while mapping to the workspace has a hole or pocket feature, the Magnetorheological (MR) fluid is not stable and gets trapped inside. Hence, a Feature-based hybrid MRF planning system is developed to overcome the challenge during MRF. The final average surface roughness (Ra) value of 21.56 nm from its initial roughness value of 324.12 nm is achieved on the polished surface bone plate made of Ti–6Al–4V. The enhancement in the surface characteristics of the MRF polished surface leads to the biomaterial's enhanced wear and corrosion resistance.

The application of negative pressure wound therapy in orthopedics: current concepts

We conducted a literature review to better understand the correct application and indications of negative pressure wound therapy (NPWT) in orthopedics and traumatology. A literature search was conducted on PubMed and all articles in English, Spanish, and Italian were included. Relevant articles, references, data, and relevant findings were identified, reviewed, extracted, and accepted by consensus of at least 66% of the researchers. Relevant articles were discussed by the research group. NPWT has several beneficial effects on the wound that contribute to the maintenance of a favorable biochemical and cellular environment, to the formation of granulation tissue and to faster healing. NWPT can be useful in the treatment of septic wounds after initial debridement surgery and removal of the septic foci, and in necrotizing fasciitis in the presence of gas gangrene, venous or pressure ulcers. NPWT can also be used “for prophylactic purposes” (incisional NPWT) in patients with risk factors for skin dehiscence and with a high risk of wound drainage in the post-operative period and after prosthetic surgery or internal fixation to protect the surgical scar. However, the available evidence is mostly unclear. The appropriate use of NPWT seems to reduce the number of dressing changes in complex wounds, reduce hospitalization times, and offer greater comfort to the patient; when applied on surgical incisions, it may reduce the risk of delayed healing and the risk of infections.