Simulated Physiological Conditions Research Articles

Precise design, preparation, and biomechanical evaluation of customized additively manufactured Ti6Al4V porous fusion cage

The stress shielding phenomenon and subsidence risk caused by the excessive stiffness of dense Ti6Al4V (Ti64) cages affects their application in lumbar fusion surgeries. Advances in additive manufacturing techniques have facilitated the production of porous Ti64 cages with decreased stiffness for the better biomechanical performance. Precise design and preparation of porous cage were crucial for achieving the optimal performance in the fusion surgery. This study introduced a workflow for precise design, preparation, and biomechanical assessment of porous Ti64 cage with designated mechanical properties. Hierarchical optimization was used to obtain the porous cage with designated mechanical properties, including microscale optimization based on the compression load condition to obtain the basic cellular structure and macroscale optimization to determine the framework layout within the cage to achieve the desired stiffness under simulated physiological loading conditions. Numerical simulations of fusion surgery confirmed that the optimized porous cage reduced the stress shielding phenomenon and the subsidence risk of the cage. Further, the cage was prepared via laser powder bed fusion and post-treated via flowing acid etching method to achieve the designed mechanical properties and topological morphology. The compression experiments confirmed that the porous cage contributed to enhancing subsidence resistance. The proposed workflow can be expanded to the precise design, preparation, and biomechanical assessment of various porous implants.

In vitro comparison of human and murine trabecular meshwork cells: implications for glaucoma research

The trabecular meshwork (TM) is crucial for regulating intraocular pressure (IOP), and its dysfunction significantly contributes to glaucoma, a leading cause of vision loss and blindness worldwide. Although rodents are commonly used as animal models in glaucoma research, the applicability of these findings to humans is limited due to the insufficient understanding of murine TM. This study aimed to compare primary human TM (hTM) and murine TM (mTM) cells in vitro to enhance the robustness and translatability of murine glaucoma models. In this in vitro study, we compared primary hTM and mTM cells under simulated physiological and pathological conditions by exposing both cell types to the glucocorticoid dexamethasone (DEX) and Transforming Growth Factor β (TGFB2), both of which are critical in the pathogenesis of several ophthalmological diseases, including glaucoma. Phagocytic properties were assessed using microbeads. Cells were analyzed through immunocytochemistry (ICC) and Western blot (WB) to evaluate the expression of extracellular matrix (ECM) components, such as Fibronectin 1 (FN1) and Collagen IV (COL IV). Filamentous-Actin (F-Act) staining was used to analyze cross-linked actin network (CLAN) formation. Additionally, we evaluated cytoskeletal components, including Vimentin (VIM), Myocilin (MYOC), and Actin-alpha-2 (ACTA2). Our results demonstrated significant similarities between human and murine TM cells in basic morphology, phagocytic properties, and ECM and cytoskeletal component expression under both homeostatic and pathological conditions in vitro. Both human and murine TM cells exhibited epithelial-to-mesenchymal transition (EMT) after exposure to DEX or TGFB2, with comparable CLAN formation observed in both species. However, there were significant differences in FN1 and MYOC induction between human and murine TM cells. Additionally, MYOC expression in hTM cells depended on fibronectin coating. Our study suggests that murine glaucoma models are potentially translatable to human TM. The observed similarities in ECM and cytoskeletal component expression and the comparable EMT response and CLAN formation support the utility of murine models in glaucoma research. The differences in FN1 and MYOC expression between hTM and mTM warrant further investigation due to their potential impact on TM properties. Overall, this study provides valuable insights into the species-specific characteristics of TM and highlights opportunities to refine murine models for better relevance to human glaucoma.

Novel Type of Non‐Toxic, Degradable, Luminescent Ratiometric Thermometers Based on Dyes Embedded in Disulfide‐Bridged Periodic Mesoporous Organosilica Particles

AbstractDespite the excellent thermometric performance of many developed luminescent nanomaterials, their use has not gone beyond proof‐of‐concept in vivo experiments to date. An important issue that needs to be resolved before moving toward true biomedical applications of engineered nanothermometers is their potential toxicity and bioaccumulation in the human body considering the ultimate objective of clinical applications. Since most reported nanothermometers currently are not degradable materials and are mainly based on the incorporation of heavy metal ions, these aspects remain of genuine concern in the fields of nanomedicine, nanobiotechnology, nanotoxicology, and nanopharmacology. This work explores the possibility of designing visible, as well as near‐infrared, emitting luminescent ratiometric nanothermometers based on appropriate organic dye mixtures embedded in hollow disulfide‐bridged periodic mesoporous organosilica (PMO) particles. Such hybrid particles show excellent thermometric performance in the physiological temperature range (20–50 °C), favorable degradability in simulated physiological conditions, as well as no toxicity to healthy normal human dermal fibroblast (NHDF) cells in a wide concentration range. Considering the simplicity of the approach from the synthetic point of view, and the large available library of known fluorescent dyes emitting in various regions of the electromagnetic range, this motif renders a very promising approach to designing novel non‐toxic, decomposable, luminescent ratiometric thermometers.

Application of 3D printing to create an in vitro aneurysm rupture model.

Currently available benchtop (in vitro) aneurysm models are inadequate for testing the efficacy of endovascular device treatments. Specifically, current models do not represent the mechanical instability of giant aneurysms (defined as aneurysms with 25 mm in height or width) and do not predictably rupture under simulated physiological conditions. Hence, in vitro aneurysm models with biomechanically relevant material properties and a predictable rupture timeframe are needed to accurately assess the efficacy of new medical device treatment options. Understanding the material properties of an aneurysm (e.g., shear and compression modulus) as it approaches rupture is a crucial step toward creating a pathologically relevant and sophisticated in vitro aneurysm rupture model. We investigated the change in material properties of a blood vessel, via enzymatic treatment, to simulate the degradation of an aneurysm wall and used this information to create a sophisticated aneurysm rupture model using the latest in additive manufacturing technologies (3D printing) with tissue-like materials. Mechanical properties (shear and compression modulus) of swine carotid vessels were evaluated before and after incubation with collagenase D enzyme (30 min at 37°C) to simulate the effect of biochemical activity on aneurysm wall approaching rupture compared to control vessels (untreated). Mechanical strength of a soft and flexible 3D-printed material (VCA-A30: 30 shore A hardness) was tested for comparison to these arterial vessels. This material was then used to create spherical shaped, giant-sized (25-mm diameter) aneurysm phantoms and were run under neurovascular pressures (120/80 ± 5 mmHg), beats per minute (BPM = 70) and flows representing the middle cerebral artery [MCA: 142.67 (±20.13) mL/min] using a blood analog [3.6 (±0.4) cP viscosity] with non-Newtonian shear-thinning properties. The shear modulus of swine carotid vessel before treatment was 12.2 (±2.7) KPa and compression modulus was 663.5 (±111.6) KPa. After enzymatic treatment by collagenase D, shear modulus of animal tissues reduced by 33% (p-value = .039) while compression modulus remained statistically unchanged (p-value = .615). Control group (untreated vessels) showed minimal reduction (13%, p-value = .226) in shear modulus and 78% increase (p-value = .034) in compression modulus. The shear modulus of the 3D-printed material was 228.59 (±24.82) KPa while its compression modulus was 668.90 (±13.16) KPa. This material was used to prototype a sophisticated in vitro giant aneurysm rupture model. When subjected to physiological pressures and flow rates, the untreated models consistently ruptured at ~12 min. These results indicate that aneurysm rupture can be recreated consistently in a benchtop in vitro model, utilizing the latest 3D-printed materials, connected to a physiologically relevant programmable pump. Further studies will investigate the optimization of various aneurysm dome thickness regions within the aneurysm, with tunable rupture times for comparison of aneurysm device deployment and benchtop controls based on the measurable effects of pressure and flow changes within the aneurysm models. These optimized in vitro rupture models could ultimately be used to test the efficacy of device treatment options and rupture risk by quantifying specific device rupture times and aneurysm rupture position.

In silico investigation of lipid-based compounds implicated in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal, currently incurable neurodegenerative disease that progressively affects the upper motor neurons in the brain and lower motor neurons in the spinal cord. A significant portion of patients exhibit abnormalities in lipid metabolism, which appear to contribute to denervation and subsequent motor neuron degeneration. This study aimed to computationally identify lipid-based compounds associated with ALS and elucidate their pathological and therapeutic roles to facilitate effective ALS diagnosis and treatment. The methodologies employed encompassed rational database searches, pharmacokinetic and target predictions, as well as docking and molecular dynamics simulations (MDS). The findings from the disease-to-lipids analysis identified 20 lipid compounds correlated with ALS, primarily categorized as potential inhibitors within the functional classes of vitamins, antibiotics, organic acids, and phytochemicals. Pharmacokinetic predictions revealed that only four compounds exhibited permeability across the blood–brain barrier, namely 4-hydroxynonenal, resveratrol, rotenone, and valproic acid. Docking simulations indicated the highest binding affinity for 4-hydroxynonenal with alkaline ceramidase 2 (−4.516 kcal/mol), resveratrol with carbonic anhydrase 6 (−7.070 kcal/mol), rotenone with cytochrome P450 2C19 (−7.378 kcal/mol), and valproic acid with glutamate carboxypeptidase 2 (−5.629 kcal/mol). Furthermore, MDS and molecular mechanics/generalized born surface area calculations demonstrated the stability and binding energies of the complexes under simulated physiological conditions. In summary, further investigation is warranted to explore the synergistic effects of resveratrol and valproic acid in ALS, the mechanisms underlying 4-hydroxynonenal adduct-assisted aggregate formation of certain enzymes in ALS, and the impact of prolonged human exposure to rotenone from marine food sources (such as fish) on the development of ALS.

Biophysical studies of human serum albumin with cocaine and cocaethylene: Understanding the drug-protein interaction in simulated physiological conditions

In this study, HSA was used as a transport protein model to simulate the transport dynamics and availability of cocaine (COC) and its pharmacologically active metabolite, cocaethylene (CE). In the interaction studies between the alkaloids and HSA, the binding constant (Kb) values were higher for CE (2.92 to 8.33 × 104 M−1) than COC (1.15 to 3.77 × 104 M−1) at different temperatures. Thermodynamic parameter calculations indicate that COC preferentially interacts through van der Waals forces and hydrogen bonds, while CE interacts hydrophobically. Competition studies using the ANS probe confirmed the more hydrophobic characteristics of CE. Synchronized fluorescence indicated that both compounds preferentially interact in the microregion of the Trp214 residue. Based on 3D fluorescence, UV–vis, and circular dichroic results, changes in the secondary structure of the protein were confirmed. Studies to assess the HSA binding site were carried out using warfarin (site I), diazepam (site II), and digitoxin (subdomain IIIB) as markers, and it was verified that both compounds interact preferentially at the site I. Finally, based on the 1H NMR and theoretical studies, it was possible to propose the alkaloid epitope in the interaction with HSA. In conclusion, when compared to COC, CE presented greater HSA protein affinity, justifying its longer plasma lifetime and increasing the drug’s effects on the body.

Protective Encapsulation of a Bioactive Compound in Starch-Polyethylene Glycol-Modified Microparticles: Degradation Analysis with Enzymes.

Starch is a promising polymer for creating novel microparticulate systems with superior biocompatibility and controlled drug delivery capabilities. In this study, we synthesized polyethylene glycol (PEG)-modified starch microparticles and encapsulated folic acid using a solvent-mediated acid-base precipitation method with magnetic stirring, which is a simple and effective method. To evaluate particle degradation, we simulated physiological conditions by employing an enzymatic degradation approach. Our results with FTIR and SEM confirmed the successful synthesis of starch-PEG microparticles encapsulating folic acid. The average size of starch microparticles encapsulating folic acid was 4.97 μm and increased to 6.01 μm upon modification with PEG. The microparticles were first exposed to amylase at pH 6.7 and pepsin at pH 1.5 at different incubation times at physiological temperature with shaking. Post-degradation analysis revealed changes in particle size and morphology, indicating effective enzymatic degradation. FTIR spectroscopy was used to assess the chemical composition before and after degradation. The initial FTIR spectra displayed characteristic peaks of starch, PEG, and folic acid, which showed decreased intensities after enzymatic degradation, suggesting alterations in chemical composition. These findings demonstrate the ongoing development of starch-PEG microparticles for controlled drug delivery and other biomedical applications and provide the basis for further exploration of PEG-starch as a versatile biomaterial for encapsulating bioactive compounds.

Investigating the role of fine grain structure on mineral deposition and resistance to corrosion initiated mechanical failure of the fine grained AZ31 magnesium alloy

ABSTRACT In the present work, fine grained AZ31 magnesium (Mg) alloy was produced by equal channel angular pressing (ECAP) and exposed to simulated physiological conditions to investigate the role of refined microstructure on biomineralisation, degradation and corrosion initiated mechanical failure. ECAP was carried out at 200°C in Bc route for up to four passes (one complete cycle) and a grain refinement up to 1.9 ± 1.1 μm was achieved in AZ31 Mg alloy from a starting size of 36 ± 4.1 μm. X-ray diffraction (XRD) analysis confirms the development of non-basal texture in the ECAPed AZ31 alloy. The phases deposited on the surface of the samples after immersion carried out in simulated physiological environment were analysed by XRD and scanning electron microscopy which confirms the higher level of mineral phase deposition on ECAPed AZ31 alloy due to increased surface energy (39.11 ± 2.1 mJ/cm2) compared with base alloy (20.5 ± 5.3 mJ/cm2). Higher tensile strength (169.9 ± 5.5 MPa) was observed for the fine grained AZ31 Mg alloy compared with the base alloy (120.5 ± 3.7 MPa) to resist the corrosion initiated mechanical failure after exposing the samples to corroding simulated physiological environment for 1 day.

Antimicrobial Hydrogels Based on Cationic Curdlan Derivatives for Biomedical Applications.

Hydrogels based on biocompatible polysaccharides with biological activity that can slowly release an active principle at the wound site represent promising alternatives to traditional wound dressing materials. In this respect, new hydrogels based on curdlan derivative with 2-hydroxypropyl dimethyl octyl ammonium groups (QCurd) and native curdlan (Curd) were obtained at room temperature by covalent cross-linking using a diepoxy cross-linking agent. The chemical structure of the QCurd/Curd hydrogels was investigated by Fourier transform infrared spectroscopy (FTIR) spectroscopy. Scanning electron microscopy (SEM) revealed well-defined regulated pores with an average diameter between 50 and 75 μm, and hydrophobic micro-domains of about 5 μm on the pore walls. The high swelling rate (21-24 gwater/ghydrogel) and low elastic modulus values (7-14 kPa) make them ideal for medical applications as wound dressings. To evaluate the possible use of the curdlan-based hydrogels as active dressings, the loading capacity and release kinetics of diclofenac, taken as a model drug, were studied under simulated physiological skin conditions. Several mathematical models have been applied to evaluate drug transport processes and to calculate the diffusion coefficients. The prepared QCurd/Curd hydrogels were found to have good antibacterial properties, showing a bacteriostatic effect after 48 h against S. aureus, MRSA, E. coli, and P. aeruginosa. The retarded drug delivery and antimicrobial properties of the new hydrogels support our hypothesis that they are candidates for the manufacture of wound dressings.

Assessing mechanical properties and stability of silver-doped carbon-coated urethral stent application

Carbon coatings doped with Ag nanoparticles (a-C/Ag) are promising materials to enhance ureteral stents' biological, mechanical, and tribological properties. This paper aims to assess the degradation profile and mechanical behaviour of silicone stents coated with a-C and a-C/Ag films under simulated physiological conditions. a-C coating containing about 5 at. % Ag was deposited on silicone stent substrates by magnetron sputtering. The chemical composition, roughness, and wettability of the coatings were analysed. The morphology and mechanical properties of the coatings were characterised before and after 30 days of immersion in synthetic urine. Remarkably, the a-C/Ag coating demonstrated exceptional resistance to degradation, exhibiting no signs of film delamination even after 30 days of incubation under accelerated degradation conditions. Moreover, the stability of the a-C/Ag coating was evaluated by monitoring its release in synthetic urine, revealing an initial rapid release within the first two days, followed by a controlled and gradual release of silver ions from the coating. Additionally, the a-C/Ag coating practically kept the breaking force of the silicone stent (∼5 % loss) with a significant diminution in elongation at break due to the substate embrittlement during the sputtering process. Overall, this study provides valuable insights into the performance of a-C/Ag coating on silicone stents, highlighting their ability to maintain structural integrity, resist degradation, and withstand substantial forces. These findings support the promising potential of a-C/Ag coating in enhancing the reliability and durability of urological stents.

Multi‐responsive co‐assembled polyurethane nanomicelles as anticancer drug delivery carriers

AbstractIn order to obtain a kind of anticancer drug delivery carriers with good stability in blood circulation, high cellular uptake, and controlled drug release ability, folate‐modified polyurethane with disulfide bonds and amino groups (FPUSN) and polyurethane with carboxyl groups (PUC) were respectively synthesized. FPUSN and PUC could co‐assemble in water to form nanomicelles (FPUSN/PUC) via electrostatic interaction. When the mass ratio of FPUSN to PUC was 12, FPUSN/PUC‐12 micelles had obvious negative‐to‐positive charge‐reversal property with decreasing pH from 7.4 to 5.0. Doxorubicin‐loaded micelles (FPUSN/PUC‐12@DOX) with negative charges showed excellent stability under simulated normal physiological condition. However, the charge‐reversal happened at pH 6.5 and positive charges increased with the pH decrease. When the glutathione concentration was 10 mM, the structure of FPUSN/PUC‐12@DOX micelles was broken. So FPUSN/PUC‐12@DOX micelles exhibited significant acid/reduction‐sensitive drug release properties and then DOX could be rapidly released in simulated tumor intracellular environment. Cellular experimental results demonstrated that FPUSN/PUC‐12 micelles could enhance cellular uptake under acid condition and FPUSN/PUC‐12@DOX micelles had better anti‐proliferation effect against HGC‐27 cells at pH 6.5 than that at pH 7.4 owing to multi‐responsive synergistic effects. Therefore, FPUSN/PUC micelles will have great application potential as drug delivery carriers for enhancing anticancer efficacy.

Rational virtual screening, ADME, and molecular simulation studies of potential inhibitors of human superoxide dismutase 1 in a dysfunctional antioxidant system

Superoxide dismutase 1 (SOD1), a copper-dependent enzyme, facilitates the conversion of superoxide anions into hydrogen peroxide and oxygen, thereby regulating superoxide levels. Dysfunctions in SOD1 have been linked to neurodegenerative disorders such as amyotrophic lateral sclerosis, as well as liver and lung cancers. This study aimed to identify SOD1 modulators using in silico rational virtual enrichment screening, pharmacokinetics, docking, and molecular dynamic simulation (MDS). The findings yielded 38 compounds, predominantly exhibiting high gastrointestinal absorption but mostly non-permeable across the blood–brain barrier, with few exhibiting inhibitory effects on selected cytochrome P450s. Molecular docking revealed that compound 1 (PubChem CID: 36791369) exhibited the highest binding affinity (−6.771 kcal·mol-1), followed by compound 19 (PubChem CID: 30935) with −6.468 kcal·mol-1, and compound 20 (PubChem CID: 135744521) with −5.978 kcal·mol-1. MDS and molecular mechanics/generalized Born surface area analysis indicated that the compound CID 36791369 – SOD1 complex and compound CID 30935 – SOD1 complex remained stable and energetically favorable under simulated physiological conditions at 0 ns and 100 ns. In conclusion, this study identified 38 compounds, among which compounds SN5, SN6, SN7, SN12, and SN25 emerged as potential inhibitors of SOD1 based on overall analyses. Further, research will be necessary to investigate the therapeutic effectiveness of these top five compounds in vitro and in vivo against SOD1.

Theanine Capture of Reactive Carbonyl Species in Humans after Consuming Theanine Capsules or Green Tea.

Acrolein (ACR), methylglyoxal (MGO), and glyoxal (GO) are a class of reactive carbonyl species (RCS), which play a crucial role in the pathogenesis of chronic and age-related diseases. Here, we explored a new RCS inhibitor (theanine, THE) and investigated its capture capacity on RCS in vivo by human experiments. After proving that theanine could efficiently capture ACR instead of MGO/GO by forming adducts under simulated physiological conditions, we further detected the ACR/MGO/GO adducts of theanine in the human urine samples after consumption of theanine capsules (200 and 400 mg) or green tea (4 cups, containing 200 mg of theanine) by using ultraperformance liquid chromatography-time-of-flight-high-resolution mass spectrometry. Quantitative assays revealed that THE-ACR, THE-2ACR-1, THE-MGO, and THE-GO were formed in a dose-dependent manner in the theanine capsule groups; the maximum value of the adducts of theanine was also tested. Furthermore, besides the RCS adducts of theanine, the RCS adducts of catechins could also be detected in the drinking tea group. Whereas, metabolite profile analysis showed that theanine could better capture RCS produced in the renal metabolic pathway than catechins. Our findings indicated that theanine could reduce RCS in the body in two ways: as a pure component or contained in tea leaves.

Photoacoustic/ultrasound dual-modal imaging of human nails: A pilot study

Traditional diagnostic techniques including visual examination, ultrasound (US), and magnetic resonance imaging (MRI) have limitations of in-depth information for the detection of nail disorders, resolution, and practicality. This pilot study, for the first time, evaluates a dual-modality imaging system that combines photoacoustic tomography (PAT) with the US for the multiparametric quantitative assessment of human nail. The study involved a small cohort of five healthy volunteers who underwent PAT/US imaging for acquiring the nail unit data. The PAT/US dual-modality imaging successfully revealed the fine anatomical structures and microvascular distribution within the nail and nail bed. Moreover, this system utilized multispectral PAT to analyze functional tissue parameters, including oxygenated hemoglobin, deoxyhemoglobin, oxygen saturation, and collagen under tourniquet and cold stimulus tests to evaluate changes in the microcirculation of the nail bed. The quantitative analysis of multispectral PAT reconstructed images demonstrated heightened sensitivity in detecting alterations in blood oxygenation levels and collagen content within the nail bed, under simulated different physiological conditions. This pilot study highlights the potential of PAT/US dual-modality imaging as a real-time, noninvasive diagnostic modality for evaluating human nail health and for early detection of nail bed pathologies.

HSA and DNA binding analysis of antiviral drug cidofovir: Spectroscopic and molecular docking techniques

This article discusses the interaction of antiviral drug cidofovir (CDV) with biomolecules (HSA and DNA) under simulated physiological conditions (pH 7.4). The binding propensity of CDV with DNA was assessed through UV–visible absorption spectroscopy, fluorescence spectroscopy, and molecular docking. The results of fluorescence spectroscopy indicated that the binding of CDV to DNA induced fluorescence quenching through a static quenching mechanism, with a binding constant of 1.03 × 103 M−1 at 293 K. The groove mode of CDV binding to calf thymus DNA (ct-DNA) was validated using dye displacement assays. The results from molecular docking confirmed the binding mode and supported the findings obtained through spectroscopic techniques. Furthermore, the binding propensity of CDV with HSA was assessed through fluorescence spectroscopy, UV–visible absorption spectroscopy, and docking simulation. The fluorescence data indicated that CDV quenches the intrinsic fluorescence of the protein through a static quenching process, with a binding constant of 5.60 × 103 M−1 at 293 K. Meanwhile, the results of docking simulation confirmed our spectroscopic findings.

Osteoblast responsive biosilica-enriched gelatin microfibrillar microenvironments

Engineering of scaffolds for bone regeneration is often inspired by the native extracellular matrix mimicking its composite fibrous structure. In the present study, we used low loadings of diatomite earth (DE) biosilica to improve the bone regeneration potential of gelatin electrospun fibrillar microenvironments. We explored the effect of increasing the DE content from 1 % to 3 % and 5 %, respectively, on the physico-chemical properties of the fibrous scaffolds denoted FG_DE1, FG_DE3, FG_DE5, regarding the aqueous media affinity, stability under simulated physiological conditions, morphology characteristics, and local mechanical properties at the surface. The presence of biosilica generated composite structures with lower swelling degrees and higher stiffness when compared to gelatin fibers. Increasing DE content led to higher Young modulus, while the stability of the protein matrix in PBS, at 37 °C, over 21 was significantly decreased by the presence of diatomite loadings. The best preosteoblast response was obtained for FG_DE3, with enhanced mineralization during the osteogenic differentiation when compared to the control sample without diatomite. 5 % DE in FG_DE5 proved to negatively influence cells' metabolic activity and morphology. Hence, the obtained composite microfibrillar scaffolds might find application as osteoblast-responsive materials for bone tissue engineering.

Cell-Penetrating Drug Carrier by Molecular Recognition of Sphingomyelin on Plasma Membranes.

Plasma membranes not only maintain the intracellular microenvironment through their phospholipid bilayer but also eliminate exogenous compounds outside the cell membranes. Most drugs especially with high polarity are prevented from entering into cells to exert their effects. Therefore, it is of great significance to design effective drug carriers with a penetrating ability toward plasma membranes. In this study, a dual-templated MIP (dt-MIPs) carrier with controllable microstructure and high drug loading capacity was prepared using highly expressed sphingomyelin on the plasma membrane and tenofovir (TFV), a first-line drug for HIV and chronic hepatitis B, as template molecules. The drug release experiments performed in vitro under simulated physiological conditions demonstrated that sustained and stable adsorption of TFV on dt-MIPs was more than 80% over 50 h. By a combination of flow cytometry and confocal microscopy, dt-MIPs were found to have efficient cell permeability. Furthermore, mass-spectrometry-based intracellular pharmacokinetic studies demonstrated that TFV was delivered completely into cells within 30 min with the delivery of dt-MIPs. The study presented above suggested that dt-MIPs are expected to be alternative nanoscale drug carriers for enhanced drug permeability and controlled release.

Analysis of Binding Modes between Three Perfluorosulfonates and GPER Based on Computational Simulation and Multiple Spectral Methods.

Perfluorinated compounds (PFCs) belong to a significant category of global environmental pollutants. Investigating the toxicological effects of PFCs within biological systems is of critical significance in various disciplines such as life sciences, environmental science, chemistry, and ecotoxicology. In this study, under simulated human physiological conditions (pH = 7.4), a combination of multiple spectroscopic techniques and computational simulations was employed to investigate the impact of perfluorinated compounds (PFCs) on the G protein-coupled estrogen receptor (GPER). Additionally, the research focused on exploring the binding modes and toxicological mechanisms between PFCs and GPER at the molecular level. All three perfluorinated sulfonic acids (PFSAs) can induce quenching of GPER fluorescence through static quenching and non-radiative energy transfer. Steady-state fluorescence calculations at different temperatures revealed apparent binding constants in the order of 106, confirming a strong binding affinity between the three PFSAs and GPER. Molecular docking studies indicated that the binding sites of PFSAs are located within the largest hydrophobic cavity in the head region of GPER, where they can engage in hydrogen bonding and hydrophobic interactions with amino acid residues within the cavity. Fourier transform infrared spectroscopy, three-dimensional fluorescence, and molecular dynamics simulations collectively indicate that proteins become more stable upon binding with small molecules. There is an overall increase in hydrophobicity, and alterations in the secondary structure of the protein are observed. This study deepens the comprehension of the effects of PFCs on the endocrine system, aiding in evaluating their potential impact on human health. It provides a basis for policy-making and environmental management while also offering insights for developing new pollution monitoring methods and drug therapies.

Ensemble-Based Virtual Screening Led to the Discovery of Novel Lead Molecules as Potential NMBAs.

Neuromuscular blocking agents (NMBAs) are routinely used during anesthesia to relax skeletal muscle. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels; NMBAs can induce muscle paralysis by preventing the neurotransmitter acetylcholine (ACh) from binding to nAChRs situated on the postsynaptic membranes. Despite widespread efforts, it is still a great challenge to find new NMBAs since the introduction of cisatracurium in 1995. In this work, an effective ensemble-based virtual screening method, including molecular property filters, 3D pharmacophore model, and molecular docking, was applied to discover potential NMBAs from the ZINC15 database. The results showed that screened hit compounds had better docking scores than the reference compound d-tubocurarine. In order to further investigate the binding modes between the hit compounds and nAChRs at simulated physiological conditions, the molecular dynamics simulation was performed. Deep analysis of the simulation results revealed that ZINC257459695 can stably bind to nAChRs' active sites and interact with the key residue Asp165. The binding free energies were also calculated for the obtained hits using the MM/GBSA method. In silico ADMET calculations were performed to assess the pharmacokinetic properties of hit compounds in the human body. Overall, the identified ZINC257459695 may be a promising lead compound for developing new NMBAs as an adjunct to general anesthesia, necessitating further investigations.

The role of multi-walled carbon nanotubes in enhancing the hydrolysis and thermal stability of PLA.

Polylactic acid (PLA) is a bioresorbable and biodegradable polymer extensively used in various biomedical and engineering applications. In this study, we investigated the mass loss and thermal properties of PLA-multi-walled carbon nanotube (MWCNT) composites under simulated physiological conditions. The composites were prepared by melting PLA with 0.1, 0.5, 1.0, and 5.0 wt% MWCNTs using an ultrasonic agitator, and FTIR analysis confirmed composite formation. Subsequently, the composites were subjected to hydrolysis under simulated physiological conditions (pH 7.4 and 37°C) for up to 60days. The results revealed that the mass loss of the composites decreased with increasing MWCNT content, suggesting that the presence of MWCNTs decelerated the hydrolysis process. On day 58, the mass loss of pure PLA was 12.5%, decreasing to 8.34% with 0.1% MWCNT, 5.94% with 0.5% MWCNT, 4.59% with 1% MWCNT, and 3.54% with 5.0% MWCNT. This study offers valuable insights into the behavior of PLA-MWCNT composites under physiologically simulated conditions, facilitating the development of new polymer composites with enhanced thermal stability and degradation resistance for biomedical applications.