Presence Of Bovine Serum Albumin Research Articles

Benchtop Fabricated Nano-Roughened Microstructured Electrodes for Electrochemical and Surface-Enhanced Raman Scattering Sensing.

Tailoring a material's surface with hierarchical structures from the micro- to the nanoscale is key for fabricating highly sensitive detection platforms. To achieve this, the fabrication method should be simple, inexpensive, and yield materials with a high density of surface features. Here, using benchtop fabrication techniques, gold surfaces with hierarchically structured roughness are generated for sensing applications. Hierarchical gold electrodes are prepared on pre-stressed polystyrene substrates via electroless deposition and amperometric pulsing. Electrodes fabricated using 1mm H[AuCl₄] and roughened with 80 pulses revealed the highest electroactive surface area. These electrodes are used for enzyme-free detection of glucose in the presence of bovine serum albumin and achieved a limit of detection of 0.36mm, below glucose concentrations in human blood. The surfaces nanoroughened with 100 pulses also showed excellent surface-enhanced Raman scattering (SERS) response for the detection of rhodamine 6G, with an enhancement factor of ≈2×106 compared to detection in solution, and for the detection of a self-assembled monolayer of thiophenol, with an enhancement factor of ≈30 compared to the response from microstructured gold surfaces. It is envisioned that the simplicity and low fabrication cost of these gold-roughened structures will expedite the development of electrochemical and SERS sensing devices.

Impact of Lipid Composition on Vesicle Protein Adsorption: A BSA Case Study.

Investigating the interaction between liposomes and proteins is of paramount importance in the development of liposomal formulations with real potential for bench-to-bedside transfer. Upon entering the body, proteins are immediately adsorbed on the liposomal surface, changing the nanovehicles' biological identity, which has a significant impact on their biodistribution and pharmacokinetics and ultimately on their therapeutic effect. Albumin is the most abundant plasma protein and thus usually adsorbs immediately on the liposomal surface. We herein report a comprehensive investigation on the adsorption of model protein bovine serum albumin (BSA) onto liposomal vesicles containing the zwitterionic lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), in combination with either cholesterol (CHOL) or the cationic lipid 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP). While many studies regarding protein adsorption on the surface of liposomes with different compositions have been performed, to the best of our knowledge, the differential responses of CHOL and DOTAP upon albumin adsorption on vesicles have not yet been investigated. UV-vis spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed a strong influence of the phospholipid membrane composition on protein adsorption. Hence, it was found that DOTAP-containing vesicles adsorb proteins more robustly but also aggregate in the presence of BSA, as confirmed by DLS and TEM. Separation of liposome-protein complexes from unadsorbed proteins performed by means of centrifugation and size exclusion chromatography (SEC) was also investigated. Our results show that neither method can be regarded as a golden experimental setup to study the protein corona of liposomes. Yet, SEC proved to be more successful in the separation of unbound proteins, although the amount of lipid loss upon liposome elution was higher than expected. In addition, coarse-grained molecular dynamics simulations were employed to ascertain key membrane parameters, such as the membrane thickness and area per lipid. Overall, this study highlights the importance of surface charge and membrane fluidity in influencing the extent of protein adsorption. We hope that our investigation will be a valuable contribution to better understanding protein-vesicle interactions for improved nanocarrier design.

Lymph Node Targeting Mediated by Albumin Hitchhiking of Synthetic Tn Glycolipid Leads to Robust In Vivo Antibody Production.

Tn antigen is a tumor-associated carbohydrate antigen, which is present prominently on the tumor cell surfaces and attracts an interest in vaccine development. This work demonstrates that a synthetic Tn antigen carrying glycoconjugate forms a complex with circulating albumin, delivers the antigen to lymph nodes (LNs), and leads to the efficient production of antibodies against the antigen. Synthetic Tn antigen glycoconjugate, possessing DSPE-PEG2000 linker and lipophilic moieties, undergoes micellization in PBS buffer. In the presence of bovine serum albumin (BSA), demicellization of the glycolipid occurs, with a rate constant of 0.18 min-1. In vitro studies show that the glycoconjugate binds preferentially to BSA in the presence of cells. Immunological assessments in mice models reveal the albumin-enabled delivery of the Tn glycoconjugate to antigen-presenting cells in the LNs, specifically leading to a robust humoral immune response. ELISA titers show superior binding, with a saturation dilution of 1:51 200 for Tn glycoconjugate, in comparison to that mediated by the Tn-BSA covalent conjugate with a saturation dilution of 1:6400. Immunohistochemical staining shows delivery of Tn glycoconjugate at the LNs, specifically at the subcapsular sinus and interfollicular areas. The work highlights the potential of albumin-mediated target delivery strategy for cancer immunotherapies.

Clarifying the role of carboxyl functionality in squaraines towards aggregation and self-assembly through photophysical characterization and BSA interactions

The demand for near-infrared (NIR) probes with robust and stable fluorescence signals has surged, driven by their applications in optical sensing and bioimaging. Squraine dyes as NIR fluorescent probes have gained significant traction. However, understanding their behavior in aqueous media is important for their successful application. Herein we report the synthesis and photophysical characterization of carboxy-functionalized unsymmetrical squaraine dyes capable of light absorption and emission in the near-infrared (NIR) wavelength region. Structural variations in alkyl chain length, and spacer chain length between the primary chromophore and –COOH group were systematically introduced to investigate their impact on self-assembly in aqueous media leading to dye aggregation and their differential interactions with Bovine Serum Albumin (BSA) as a model protein. In phosphate buffer (PB) the absorption intensity decreased drastically along with pronounced shoulders due to dye aggregation leading to complete fluorescence quenching. However, in the presence of BSA, the intensity of shoulder bands reduced coupled with a sharp increase in the absorption associated with monomeric dye with the increasing concentration of BSA, indicating the prevention of dye aggregation owing to dye-BSA interactions. The prevention of dye aggregation due to dye-BSA interaction also led to a tremendous increase in the fluorescence intensities as a function of the increasing BSA concentrations. Site-selective study off BSA showed that these dyes bind preferably at Site-II using hydrophilic interactions. Thus, these dyes show great potential as FRET or fluorescent on/off probes for biosensing, non-covalent labeling of proteins, and fluorescent probes for bioimaging.

Polyethylene glycol-polyvinylidene fluoride/TiO2 nanocomposite polymer coatings with efficient antifouling strategies: Hydrophilized defensive surface and stable capacitive deionization

Capacitive deionization (CDI) is flourishing as an energy-efficient and cost-effective water desalination method. However, challenges such as electrode degradation and fouling have hindered the practical deployment of CDI technology. To address these challenges, the key point of our strategy is applying a hydrophilic coating composed of polyethylene glycol (PEG)-functionalized nano-TiO2/polyvinylidene fluoride (PVDF) to the electrode interface (labeled as APPT electrode). The PEG/PVDF/TiO2 layer not only mitigates the co-ion depletion, but also imparts the activated carbon (AC) electrode hydrophilicity. As anticipated, the APPT electrode possessed an enhanced desalination capacity of 83.54 μmol g−1 and a low energy consumption of 17.99 Wh m−3 in 10 mM sodium chloride solution compared with the bare AC electrode. Notably, the APPT maintained about 93.19 % of its desalination capacity after 50 consecutive adsorption–desorption cycles in the presence of bovine serum albumin (BSA). During the trial, moreover, no obvious overall performance decline was noted in concentration reduction (Δc), water recovery (WR) and productivity (P) over 50 cycles. This strategy realizes energy-efficient, antifouling and stable brackish water desalination and has great promise for practical applications.

Effect of bovine serum albumin on gallic acid and tannic acid radical scavenging properties and binding kinetics with 2,2-diphenyl-1-picrylhydrazyl

A detailed study on gallic acid (GA), tannic acid (TA) antioxidant properties, and binding kinetics with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH˙) in the presence of bovine serum albumin (BSA) was performed using electronic absorption (UV/Vis), fluorescence, and Fourier transform infrared (FTIR), spectroscopy methods. The effective concentration (EC50), antioxidant reducing power (ARP), stoichiometry (EC100), and the number of reduced DPPH˙(n) were determined using the DPPH˙ assay. It was shown that the antioxidant efficacy of GA/TA reduces slightly in the presence of BSA. However, the duration of the antioxidant activity of GA/TA increases as a result of the complex formation with BSA. The concentration of free and BSA-bound GA/TA was determined using fluorescence spectra. The rate constant (kobs), which describes the main reaction between antioxidant and DPPH˙, and the second-order rate constant (k2) were determined. FTIR studies showed that the binding of GA/TA with BSA causes conformational changes in the secondary structure of the protein (decrease of α-helixes, an increase of β-sheet structures). Moreover, TA induces more pronounced effects compared to GA.

Effects of polystyrene nanoplastics on the binding of ciprofloxacin to bovine serum albumin

Nanoplastics (NPs) and antibiotics have attracted more attention due to the potential toxicity to humans. Studies on their interactions as well as their subsequent combinations can provide useful information for understanding their health risks. In this study, bovine serum albumin (BSA) was used as the model protein to study the effects of polystyrene nanoplastics (PSNPs) on the binding of ciprofloxacin (CPFX) to BSA. The results showed that both the esterase-like activity of BSA in the presence and absence of PSNPs presented an increasing trend when increasing CPFX, and the enhancement when adding PSNPs could be attributed to the alteration of BSA conformation caused by PSNPs. The spectral analysis results indicated that the intrinsic fluorescence quenching of BSA in presence of CPFX is less affected by PSNPs, and PSNPs cannot directly affect the interactions between BSA and CPFX. Additionally, the binding experiments indicated that the presence of PSNPs is likely to promote the binding of CPFX to BSA molecules. This work will provide useful information on the influences of NPs to the health risks of antibiotics, and new insights into the toxic effects in the scene of co-existence.

The dynamics of PEG‐coated nanoparticles in concentrated protein solutions up to the molecular crowding range

AbstractPolymer‐coated nanoparticles are widely studied in the context of nanomedicine and it is therefore of utmost importance to understand not only how their structure but also how their colloidal dynamics are affected by physiologically relevant conditions. A characteristic feature of the cytosol of cells is the very high concentration of proteins among other matrix components, often termed macromolecular crowding. Here, the structure and colloidal dynamics of poly(ethylene glycol) (PEG)‐coated gold nanoparticles in the presence of bovine serum albumin (BSA) concentrations ranging from 0 to 265 mg/mL are studied with X‐ray photon correlation spectroscopy. For protein–nanoparticle mixtures with high BSA concentrations, comparable to intracellular levels, a significant deviation of the apparent viscosity from expectations for pure BSA solutions is found. The findings strongly indicate that the nanoscopic viscous properties of the dense protein solutions are significantly affected by the nanoparticles. At these high concentrations, the colloidal stability of the samples depends on the molecular weight of the coating PEG–ligand, whereas at lower concentrations no differences are observed.

Enhanced selectivity towards melanoma cells with zinc(II)-Schiff bases containing imidazole derivatives.

Zinc(II)-complexes with the general formula [Zn(L)2] containing 8-hydroxyquinoline Schiff bases functionalized with 1-(3-aminopropyl)imidazole or 1-(3-aminopropyl)-2-methyl-1H-imidazole on 2-position and their respective ligands (HL1 or HL2) were synthesized and characterized by NMR, UV-Vis, FTIR and CD spectroscopies as well as ESI-MS spectrometry. Single crystals of HL2 and [Zn(L1)2]n were analysed by SC-XRD. [Zn(L1)2]n shows a 1D polymeric chain structure of alternating Zn(II) cations and bridging Schiff base ligands, in contrast to previously reported monomeric structures of analogous complexes. DFT calculations were performed to rationalize the polymeric X-ray structure of Zn(L1)2. Results showed that the ligands can bind as bi- or tridentate to Zn(II) and there is the possibility of a dynamic behavior for the complexes in solution. Both ligands and complexes present limited stability in aqueous media, however, in the presence of bovine serum albumin the complexes are stable. Molecular docking simulations and circular dichroism spectroscopic studies suggest binding to this protein in close proximity to the Trp213 residue. Biological studies on a panel of cancer cells revealed that the Zn(II)-complexes have a lower impact on cell viability than cisplatin, except for triple-negative breast cancer cells in which they were comparable. Notwithstanding, they display much higher selectivity towards cancer cells vs. normal cells, than cisplatin. They induce the generation of ROS and DNA double-strand breaks, primarily through apoptosis as the mode of cell death. Overall, the novel Zn(II)-complexes demonstrate improved induction of apoptosis and higher selectivity, particularly for melanoma cells, compared to previously reported analogues, making them promising candidates for clinical application.

Further study on particle size, stability, and complexation of silver nanoparticles under the composite effect of bovine serum protein and humic acid.

Silver nanoparticles (AgNPs) are widely used due to their unique antibacterial properties and excellent photoelectric properties. Wastewater treatment plants form a pool of AgNPs due to the social cycle of wastewater. During biological treatment processes, the particle size and stability of AgNPs change. We studied the particle size changes and stability of silver nanoparticles in the presence of bovine serum albumin (BSA) and humic acid (HA). The experimental results indicated that silver nanoparticles can complex with the functional groups in BSA. For AgNP-BSA composites, as the BSA concentration increases, the size of the silver nanoparticles first decreases and then increases. AgNPs can combine with the amide, amino, and carboxyl groups in HA. As the concentration of HA increases, the particle size and large particle size distribution of AgNPs increase. This increasing trend is more obvious when the HA concentration is lower than 20 mg L-1. When HA and BSA exist at the same time, HA will occupy the adsorption sites of BSA on the surface of AgNPs, and the AgNP-HA complex will dominate the system. This study aims to provide key operational control strategies for the process operation of wastewater treatment plants containing AgNPs and theoretical support for promoting water environment improvement and economic development such as tourism.

Rapid screening of dyes for self-aggregation, adsorption and metabolic integrity – Quantitative metrics as a prelude to biological studies

The traditional development of dyes for biological applications typically begins with synthesis, is followed by spectroscopic/photophysical characterization, and culminates in testing with cultured cells or in animals. The present work describes a set of facile, low-technology, invitro, largely quantitative absorption spectrophotometric assays in aqueous solution as a prelude to biological studies. The assays include the following: (1) Self-aggregation in phosphate-buffered saline (PBS), with or without the presence of 3 % bovine serum albumin (BSA), via reciprocal change in concentration and pathlength; (2) Adsorption to solid materials as biomolecular surrogates, including cellulose, chitosan, polyethylene (PE), styrene-divinylbenzene beads (XAD-4), polyacrylic beads (XAD-7), anion exchange beads (IRA-67), cation exchange beads (CG-50), polytetrafluoroethylene (PTFE) membranes, and Nylon membranes; (3) Hydrophilicity/hydrophobicity assessment, by measurement (not calculation) of logP values; and (4) Metabolic integrity, by exposure to a rat liver homogenate. Twenty-two dyes were examined in the assays. The dyes represent diverse classes (acridine, anthraquinone, azo, benzimidazole, coumarin, cyanine, flavonoid, naphthalene, phthalocyanine, polyene, tetrapyrrole, triarylmethine, xanthene), polarity (anionic, cationic, nonionic, hydrophobic, amphipathic), and absorption (ultraviolet, visible, near-infrared). As one example, indocyanine green (ICG), an FDA-approved dye for invivo use, (i) aggregates at the concentration of 5 μM but disaggregates in the presence of BSA; (ii) in PBS is very adsorptive (>80 % binding) to various materials (cellulose, chitosan, PE, IRA-67, CG-50, PTFE, Nylon) and quite adsorptive (50–80 % binding) to XAD-4 and XAD-7, (iii) exhibits only marginal preference for water versus 1-octanol (1.5:1), and (iv) is largely digested by rat liver homogenate. A single dye can be examined in the span of one day. The quantitative metrics should prove valuable for establishing biologically relevant features of diverse dyes by simple studies in aqueous solution.

Protective effects of l-cysteine and N-acetyl-l-cysteine on boar sperm quality during hypothermic liquid storage with bovine serum albumin as a protectant

Hypothermic liquid storage at 4–5 °C has emerged as a novel approach for preserving boar semen, offering innovative possibilities for semen preservation. However, this method also presents challenges, including cold shock and excessive reactive oxygen species (ROS) production. Therefore, reducing oxidative damage induced by low temperatures becomes essential while supplementing appropriate protectants. In this study, we investigated the efficacy of Bovine Serum Albumin (BSA) compared to Polyvinylpyrrolidone (PVP) and Skim Milk Powder (SMP) in maintaining boar sperm motility and progressive motility using computer-assisted sperm analysis (CASA). Among the tested concentrations, 4 g/L of BSA exhibited the best protective effect. Subsequently, we supplemented different concentrations of l-cysteine (LC) and N-acetyl-l-cysteine (NAC) as additives in the presence of BSA as a protectant. Our results demonstrated that 1 mmol/L of LC and 0.5 mmol/L of NAC exhibited superior protection of sperm quality compared to other concentrations. Furthermore, the 1 mmol/L LC and 0.5 mmol/L NAC groups showed significantly improved plasma membrane integrity and acrosome integrity compared to the control group. These groups also exhibited enhanced antioxidant capacity, evidenced by increased mitochondrial membrane potential (MMP), ATP production, total superoxide dismutase (T-SOD) activity, total antioxidant capacity (T-AOC), glutathione (GSH), glutathione peroxidase (GSH-PX), and GPX-4 levels. Additionally, they demonstrated decreased reactive oxygen species (ROS) and malondialdehyde (MDA) levels, as well as reduced oxidized glutathione (GSSG) and glutathione reductase (GR) levels. Furthermore, LC and NAC treatment enhanced AMP-activated protein kinase (AMPK) phosphorylation. However, inhibiting AMPK using compound C did not inhibit the protective effects of LC and NAC on low-temperature preserved boar sperm. These findings suggest that 4 g/L BSA can serve as an effective protectant for hypothermic liquid storage of boar semen. Additionally, LC and NAC supplementation reduces oxidative damage by enhancing antioxidant capacity rather than through AMPK-mediated ATP supplementation. These results contribute to advancing the application of LC and NAC in hypothermic liquid storage of boar semen.

Photophysical Characterization and Biointeractions of NIR Squaraine Dyes for in Vitro and in Vivo Bioimaging.

The increasing demand for reliable near-infrared (NIR) probes exhibiting enduring fluorescence in living systems and facile compatibility with biomolecules such as peptides, antibodies or proteins is driven by the increasing use of NIR imaging in clinical diagnostics. To address this demand, a series of carboxy-functionalized unsymmetrical squaraine dyes (SQ-27, SQ-212, and SQ-215) along with non-carboxy-functionalized SQ-218 absorbing and emitting in the NIR wavelength range were designed and synthesized followed by photophysical characterization. This study focused on the impact of structural variations in the alkyl chain length, carboxy functionality positioning, and spacer chain length on dye aggregation and interaction with bovine serum albumin (BSA) as a model protein. In phosphate buffer (PB), the absorption intensity of the dyes markedly decreased accompanied by pronounced shoulders indicative of dye aggregation, and complete fluorescence quenching was seen in contrast to organic solvents. However, in the presence of BSA in PB, there was a enhancement in absorption intensity while regaining the fluorescence coupled with a remarkable increase in the intensity with increasing BSA concentrations, signifying the impact of dye-BSA interactions on preventing aggregation. Further analysis of Job's plot unveiled a 2:1 interaction ratio between BSA and all dyes, while the binding studies revealed a robust binding affinity (Ka) in the order of 107/mol. SQ-212 and SQ-215 were further tested for their in vitro and in vivo imaging capabilities. Notably, SQ-212 demonstrated nonpermeability to cells, while SQ-215 exhibited easy penetration and prominent cytoplasmic localization in in vitro studies. Injection of the dyes into laboratory mice showcased their efficacy in visualization, displaying stable and intense fluorescence in tissues without toxicity, organ damage, or behavioral changes. Thus, SQ-212 and SQ-215 are promising candidates for imaging applications, holding potential for noninvasive cellular and diagnostic imaging as well as biomarker detection when coupled with specific vectors in living systems.

Albumin Protein Impact on Early-Stage In Vitro Biodegradation of Magnesium Alloy (WE43).

Mg and its alloys are promising biodegradable materials for orthopedic implants and cardiovascular stents. The first interactions of protein molecules with Mg alloy surfaces have a substantial impact on their biocompatibility and biodegradation. We investigate the early-stage electrochemical, chemical, morphological, and electrical surface potential changes of alloy WE43 in either 154 mM NaCl or Hanks' simulated physiological solutions in the absence or presence of bovine serum albumin (BSA) protein. WE43 had the lowest electrochemical current noise (ECN) fluctuations, the highest noise resistance (Zn = 1774 Ω·cm2), and the highest total impedance (|Z| = 332 Ω·cm2) when immersed for 30 min in Hanks' solution. The highest ECN, lowest Zn (1430 Ω·cm2), and |Z| (49 Ω·cm2) were observed in the NaCl solution. In the solutions containing BSA, a unique dual-mode biodegradation was observed. Adding BSA to a NaCl solution increased |Z| from 49 to 97 Ω·cm2 and decreased the ECN signal of the alloy, i.e., the BSA inhibited corrosion. On the other hand, the presence of BSA in Hanks' solution increased the rate of biodegradation by decreasing both Zn and |Z| while increasing ECN. Finally, using scanning Kelvin probe force microscopy (SKPFM), we observed an adsorbed nanolayer of BSA with aggregated and fibrillar morphology only in Hanks' solution, where the electrical surface potential was 52 mV lower than that of the Mg oxide layer.

Inhibition of Xanthine Oxidase by Pyrazolone Derivatives Bearing a 4-(Furan-2-yl)benzoic Acid Moiety

The pyrazolone-based 4-(furan-2-yl)benzoic acids have been synthesized and studied as xanthine oxidase inhibitors. This enzyme is one of the therapeutic targets for the treatment of hyperuricemia and related diseases. The compounds studied have found to exhibit low micromolar IC50 values relative to the enzyme in vitro, depending on substituents in position 3 of the pyrazolone ring. However, the inhibitory effects observed are reduced in the presence of bovine serum albumin or Tween-80. Among the pyrazolone derivatives synthesized, 4-(5-((3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)methyl)furan-2-yl)benzoic acid has been found to be the most potent inhibitor of xanthine oxidase. Kinetic results have shown that this compound is a mixed-type inhibitor with higher affinity to the free enzyme than to the enzyme-substrate complex. The results of the molecular docking and molecular dynamics show that the carboxylic group of the inhibitor can form a salt bridge with Arg880 and a hydrogen bond with Thr1010. These interactions can be key factors in the enzyme-inhibitor complex stabilization.

Statistical 3D morphology characterization of vaterite microspheres produced by engineered Escherichia coli

Hollow vaterite microspheres are important materials for biomedical applications such as drug delivery and regenerative medicine owing to their biocompatibility, high specific surface area, and ability to encapsulate a large number of bioactive molecules and compounds. We demonstrated that hollow vaterite microspheres are produced by an Escherichia coli strain engineered with a urease gene cluster from the ureolytic bacteria Sporosarcina pasteurii in the presence of bovine serum albumin. We characterized the 3D nanoscale morphology of five biogenic hollow vaterite microspheres using 3D high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) tomography. Using automated high-throughput HAADF-STEM imaging across several sample tilt orientations, we show that the microspheres evolved from a smaller more ellipsoidal shape to a larger more spherical shape while the internal hollow core increased in size and remained relatively spherical, indicating that the microspheres produced by this engineered strain likely do not contain the bacteria. The statistical 3D morphology information demonstrates the potential for using biogenic calcium carbonate mineralization to produce hollow vaterite microspheres with controlled morphologies. Statement of significanceThe nanoscale 3D structures of biomaterials determine their physical, chemical, and biological properties, however significant efforts are required to obtain a statistical understanding of the internal 3D morphology of materials without damaging the structures. In this study, we developed a non-destructive, automated technique that allows us to understand the nanoscale 3D morphology of many unique hollow vaterite microspheres beyond the spectroscopy methods that lack local information and microscopy methods that cannot interrogate the full 3D structure. The method allowed us to quantitatively correlate the external diameters and aspect ratios of vaterite microspheres with their hollow internal structures at the nanoscale. This work demonstrates the opportunity to use automated transmission electron microscopy to characterize nanoscale 3D morphologies of many biomaterials and validate the chemical and biological functionality of these materials.

Electrochemical detection of prostate specific antigen in the presence of an aptamer and composites of cobalt phthalocyanine-exfoliated graphite

This work focuses on the development of biosensor and their use for the detection of prostate specific antigen (PSA). The three cobalt phthalocyanine (CoPc) complexes, exfoliated graphite (EG), and an aptamer are used to make a probe for PSA detection. Each CoPc complex is π-π stacked onto the EG to form EG-CoPc(π-π) hybrid which was then used to modify a glassy carbon electrode (GCE). EG and CoPc were also used to modify the GCE sequential (seq) with CoPc on top to give GCE-EG-CoPc(seq). For the detection PSA, PSA specific aptamer was either adsorbed or covalently linked to the modified electrodes. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were the techniques used for the detection of PSA. The electrodes were found to be selective in the presence of bovine serum albumin, glucose and cysteine and were stable when 50 DPV scans were run. The electrodes showed good % recovery when human serum was spiked with different PSA concentrations.

Microfiltration of concentrated albumin solutions and the role of processing conditions on membrane fouling

Membrane processing is a subject of growing scientific and industrial interest as a valuable technology to replace conventional energy-intensive operations, but is hindered by the progressive decrease of permeate flux caused by membrane fouling. Although physico-chemical factors affecting membrane fouling have been widely investigated, less is known concerning the effects of processing conditions. Here, we focus on microfiltration of aqueous bovine serum albumin (BSA) solutions by using a novel miniaturized modular unit allowing to study both dead-end (DE) and crossflow (CF) filtration. Pure water flux measurements and Computational Fluid Dynamics (CFD) simulations were firstly performed to characterize the flow field inside the module. In presence of BSA, at the same transmembrane pressure (TMP) of 20 mbar and average pore size of 0.45 μm, a remarkable decrease in the fouling progression with time was found for CF with a peristaltic pump as compared to pressure-driven DE filtration. Furthermore, BSA concentration in the permeate was the same as in the feed for peristaltic CF, while negligible for DE. By either increasing transmembrane pressure or lowering membrane pore size, a stronger decay of permeate flux with time was observed. Scanning electron microscopy images of the membrane showed the presence of a thick surface cake layer under peristaltic CF, which became thinner by increasing TMP or reducing membrane pore size. Overall, the better performance of peristaltic CF can be interpreted in terms of reduced BSA residence time in the membrane, membrane deformability and formation of a permeable cake layer at lower TMP and larger membrane pore size. The innovative design of our filtration module and the combination of permeate flux and concentration measurements with CFD results and microscopy observations constitute the most significant aspects of this research work, which provides a multiscale picture of membrane fouling. The insight emerging from results aims to provide qualitative guidelines towards an optimal setting of processing conditions in membrane operations, which is highly needed to improve the membrane innovation pipeline.

A Sensor for Monitoring the Antimicrobial Activity of Wound Dressings for Both Surgical Site Infections (SSIs) and Chronic Wounds.

Antimicrobial impregnated wound dressings are a critical tool for the management, prevention, and control of surgical site infections (SSIs) and infected chronic wounds. However, the sustained therapeutic antimicrobial activity of the dressing when employed for extended periods cannot be readily determined in vivo. Consequently, dressings are changed frequently to ensure that their antimicrobial activity is maintained. Whilst frequent dressing changes allow the wound to be assessed, this is time-consuming and can cause disruption to the wound bed impairing the healing process. Furthermore, this increases medical costs for the patient and hospitals. This paper introduces a novel concept to monitor the therapeutic levels of an antimicrobial component within a wound dressing ensuring the wound dressing remains "fit for purpose" and avoiding indiscriminate use of antiseptics. This could help to inform clinicians whether the antimicrobial is still being delivered at therapeutic levels and as such when to change the dressing ensuring timely positive clinical outcomes. Silver has been used historically as an antimicrobial agent and is ubiquitous in current generations of antimicrobial wound dressings. However, its activity is complex due to the poor solubility of silver ions in the presence of chloride and the effect of complexation by other components in the dressing and wound ecosystem, not least by serum proteins. In this paper, we detail an electrochemical silver sensor (5D patent protected - WO2023275553A1), constructed using a platinum (Pt) nanoband array electrode, and characterise its response to silver ions. This is determined in the presence of bovine serum albumin (BSA) and simulated wound fluid (SWF) containing chloride and rationalised using atomic analysis of the composition of the SWF. The sensor response in SWF is compared with the antimicrobial activity of silver against Pseudomonas aeruginosa in the planktonic and biofilm state, as a function of the amount of silver nitrate added. At low concentrations, silver in SWF has good solubility but reduced antimicrobial effect due to binding of silver by BSA as shown by the sensor response. At intermediate concentrations, above 10ppm, the silver was efficacious on both planktonic microorganisms and biofilm impregnated with microorganisms and readily detected with the sensor. At high concentrations, silver precipitates and both the silver in solution and the sensor response plateaus. The data demonstrates how the sensor correlates with the antimicrobial activity of the silver in vitro and how this could be used to actively monitor antimicrobials in vivo.

AIE‐Active ‘Turn‐On’ Sensors for Highly Selective Detection of Bovine Serum Albumin**

AbstractTetraphenylethylene (TPE)‐based, two molecular ‘Turn‐On’ probes i. e. 4,4′,4′′,4′′′‐(ethene‐1,1,2,2‐tetrayl)tetraphenol (tetrahydroxy‐TPE, coded as: TPE‐1) 4,4′,4′′,4′′′‐(ethene‐1,1,2,2‐tetrayl)tetraaniline and tetraamino‐TPE, coded as: TPE‐2) have been successfully reported for the selective detection of bovine serum albumin (BSA) over its other biological competitors. The BSA sensing has been investigated using UV‐Vis absorption and fluorescence emission spectroscopy, where the fluorescence of probes tetrahydroxy‐TPE and tetra‐amino‐TPE was significantly enhanced in the presence of BSA. The BSA sensing was also characterized by visual eye detection, where a significant color change of probe tetrahydroxy‐TPE and tetra‐amino‐TPE was observed with BSA. The detection limit for BSA was calculated to be 0.2 nM and 1.41 nM for using probes tetrahydroxy‐TPE and tetra‐amino‐TPE, respectively. The binding constant was observed to be1.8×103 M and 1.4×103 M for probes tetrahydroxy‐TPE and tetra‐amino‐TPE, respectively. A molecular docking study is also performed to investigate the detailed interactions between probes tetrahydroxy‐TPE and tetra‐amino‐TPE with BSA. The lowest binding energy conformation for probes tetrahydroxy‐TPE and tetra‐amino‐TPE was found at −8.1 kcal/mol and −8.2 kcal/mol, respectively.