Quantitative and qualitative evaluation of adsorption/desorption of bovine serum albumin on hydrophilic and hydrophobic surfaces

Self-powered portable photoelectrochemical sensor based on dual-photoelectrode for microplastics detection

Plastic pollution has emerged as a significant global concern due to its potential threat to human health. The advancement of self-powered photoelectrochemical (PEC) sensors based on dual-photoelectrode presents ongoing challenges. The photoanode PEC analysis method is normally employed due to its remarkable photocurrent and low detection limit; however, it exhibits limited anti-interference capability in real sample detection. Conversely, the photocathode analysis method demonstrates excellent anti-interference detection capabilities, effectively mitigating the inherent disadvantages associated with the photoanode. Consequently, we have developed a self-powered PEC portable sensor that integrates both a photocathode and a photoanode, enabling accurate, sensitive, and convenient detection of polystyrene microplastics (PS MPs). Under optimal conditions, the sensor has a detection limit of 0.09 μg/mL, with a linear range from 0.5 to 1000 μg/mL. The method has good anti-interference ability to heavy metal ions and organics. In the presence of interfering substances, the accuracy can be maintained at over 97%. In addition, the sensor has demonstrated excellent performance in complex aquatic environments, providing an innovative design strategy for constructing PEC sensors aimed at detecting PS MPs.

A novel core-shell microsphere with hydrophobic and gel chromatography functions enhances protein purification

The spatial configuration and bonding conditions of polysaccharide microspheres make it difficult to distinguish molecules with similar hydrophobic properties in practical applications. Fortunately, medium modification offers more flexible chromatography conditions and higher selectivity, providing new solutions for complex purification environments. We synthesized hydrophobic composite core-shell agarose microspheres equipped with hydrophobic ligands and investigated the effects of hydrophobic ligand coupling on the morphology, particle size, pressure resistance, functional group change and protein adsorption capacity of microspheres. On this basis, the protein adsorption kinetics indicated that the best coupling temperature and time of phenyl and butyl were 40 °C, 8 h and 20 °C, 16 h, respectively. When the concentration of (NH4)2SO4 salt in the mobile phase is 2 M, and the pH is 7.0, the dynamic adsorption capacity of the medium for BSA reaches 12.6 mg/mL. The separation, purification efficiency, and resolution of these microspheres in a crude enzyme solution containing flavin monooxygenase improved significantly, demonstrating the practical implications and potential applications of this research. Overall, our findings reveal that this natural polysaccharide core-shell medium increases the modifiable sites of ligands, and can modify ligands in both the inner and outer layers, exhibiting its potential application in biomolecular separation.

Frequency-Selective Microbubble Targeting In Vitro: A Step Toward Multicolor Ultrasound Molecular Imaging

Ultrasound molecular imaging (USMI) utilizing targeted microbubbles (tMBs) and primary acoustic radiation force (Frad) pulses has demonstrated enhanced sensitivity in recent studies. However, current USMI techniques are limited to a single ligand-receptor pair per imaging scan. With the advent of the buried-ligand architecture (BLA), "cloaked" ligand-receptor binding and tMB adhesion can be activated by Frad pulses, enabling multicolor USMI. This approach permits the selective activation of two or more tMB species, each binding to its cognate receptors based on distinct resonance frequencies (f0) tuned by Frad pulses. The goal of this study was to demonstrate frequency-selective tMB adhesion to receptor-bearing microvessel tubes in vitro. Size-isolated BLA tMBs of 1 and 5 μm diameter were synthesized with f0 equal to 7 and 4 MHz, respectively (within the frequency limits of our ultrasound probe). The 1 μm tMBs were conjugated with IELLQAR peptide for P-selectin targeting, while the 5 μm tMBs were conjugated with cyclo-RGD peptide for αvβ3 integrin targeting. The MB gas volume fraction (φMB) was used to unify size and concentration into a single parameter. Frequency-selective tMB binding was quantified using fluorescence microscopy. Specific targeting was evaluated by comparing RGD- or IELLQAR-MB attachment to control RAD- or nonligand-bearing MBs, respectively. The results confirmed specific frequency-selective targeting of the two tMB species to their cognate receptors when activated by Frad pulses at their respective f0, both individually and in a cocktail. In the cocktail population, φMB of RGD-MB targeting increased 18-fold at 4 MHz compared to 7 MHz, while IELLQAR-MB targeting φMB increased 5-fold at 7 MHz compared to 4 MHz. In conclusion, this study presents the first demonstration of frequency-selective targeting of two different receptor species by two different tMB species, representing a significant step toward multicolor USMI and the potential for simultaneous imaging of multiple biomarkers in vivo within a single scan.

Interaction of solid lipid nanoparticles with bovine serum albumin: physicochemical mechanistic insights

This study investigates the interaction of solid lipid nanoparticles (SLNs) with the transport protein bovine serum albumin (BSA) in terms of thermodynamic signatures, employing both spectroscopic and calorimetric techniques. When nanoparticles are exposed to biological media, proteins are adsorbed on their surfaces, leading to protein corona formation. Therefore, controlling the formation of the protein corona is essential for in vivo therapeutic efficacy. Although SLNs have previously been explored solely as potential nano-carriers for drug delivery, no prior efforts have been made to study their interactions with biomolecules from a biophysical and mechanistic perspective. SLNs are colloidal dispersions of the solid lipid in an aqueous solution stabilized by surfactants. Herein, a hot emulsification methodology was employed to formulate SLNs, and their interactions with BSA were analyzed. The SLNs were characterized using transmission electron microscopy (TEM) and dynamic light scattering (DLS) techniques to obtain information on their size, zeta potential, and shape. Fluorescence data suggested the presence of weak interactions between the SLNs and BSA. Static quenching is confirmed using time-correlated single-photon counting (TCSPC) experiments. Differential scanning calorimetric (DSC) and fluorescence spectroscopic experiments suggest the thermal stabilization of BSA by the SLNs. This stabilization results from the enhancement of the secondary structure of the protein without significantly altering the tertiary structure. Isothermal calorimetry (ITC) results suggest weak interactions between the SLNs and BSA, although not in a site-specific manner. Overall, mechanistic insights into lipid nanoparticle-protein interactions obtained from such studies efficiently overcome the hurdles associated with targeted drug delivery.

Polyzwitterions: controlled synthesis, soft materials and applications

Polyzwitterions refer to polymers containing both positive and negative charged groups in one side chain, which have shown unique physicochemical properties and significant potential in diverse applications due to their amphiphilic and net-neutral charged properties. This review aims to highlight the recent advances in the design and synthesis of polyzwitterions including direct polymerization of zwitterionic monomers and deionization of polymers. Furthermore, the formation of polyzwitterion based soft materials such as nanoparticles by self-assembly, hydrogels, coatings and polyzwitterion brushes, as well as the influence of the microstructure on their properties and applications are discussed. The potential applications of polyzwitterions in drug delivery, antifouling, lubrication, energy storage and antibacterial are also summarized. Finally, the prospects of polyzwitterions are proposed.

"Grafting-from" and "Grafting-to" Poly(N-isopropyl acrylamide) Functionalization of Glass for DNA Biosensors with Improved Properties

Surface-based biosensors have proven to be of particular interest in the monitoring of human pathogens by means of their distinct nucleic acid sequences. Genosensors rely on targeted gene/DNA probe hybridization at the surface of a physical transducer and have been exploited for their high specificity and physicochemical stability. Unfortunately, these sensing materials still face limitations impeding their use in current diagnostic techniques. Most of their shortcomings arise from their suboptimal surface properties, including low hybridization density, inadequate probe orientation, and biofouling. Herein, we describe and compare two functionalization methodologies to immobilize DNA probes on a glass substrate via a thermoresponsive polymer in order to produce genosensors with improved properties. The first methodology relies on the use of a silanization step, followed by PET-RAFT of NIPAM monomers on the coated surface, while the second relies on vinyl sulfone modifications of the substrate, to which the pre-synthetized PNIPAM was grafted to. The functionalized substrates were fully characterized by means of X-ray photoelectron spectroscopy for their surface atomic content, fluorescence assay for their DNA hybridization density, and water contact angle measurements for their thermoresponsive behavior. The antifouling properties were evaluated by fluorescence microscopy. Both immobilization methodologies hold the potential to be applied to the engineering of DNA biosensors with a variety of polymers and other metal oxide surfaces.

Sensitivity-improved blocking agent-free fluorescence polarization assay through surface modification using polyethylene glycol

Fluorescence polarization (FP) assays are widely used to quantify biomolecules, and their combination with microfluidic devices has the potential for application in onsite analysis. However, the hydrophobic surface of polydimethylsiloxane (PDMS)-based microfluidic devices and the amphiphilicity of the blocking agents can cause the nonspecific adsorption of biomolecules, which in turn reduces the sensitivity of the FP assay. To address this, we demonstrated an FP assay with improved sensitivity in microfluidic devices using a polyethylene glycol-based surface modification to avoid the use of blocking agents. We evaluated the effectiveness of the modification in inhibiting nonspecific protein adsorption and demonstrated the improved sensitivity of the FP immunoassay (FPIA). Our study addressed the lack of sensitivity of FP assays in microfluidic devices, particularly for the quantification of low-abundance analytes.

Pharmaceutical proteins at the interfaces and the role of albumin

A critical measure of the quality of pharmaceutical proteins is the preservation of native conformations of the active pharmaceutical ingredients. Denaturation of the active proteins in any step before administration into patients could lead to loss of potency and/or aggregation, which is associated with an increased risk of immunogenicity of the products. Interfacial stress enhances protein instability as their adsorption to the air-liquid and liquid-solid interfaces are implicated in the formation of denatured proteins and aggregates. While excipients in protein formulations have been employed to reduce the risk of aggregation, the roles of albumin as a stabilizer have not been reviewed from practical and theoretical standpoints. The amphiphilic nature of albumin makes it accumulate at the interfaces. In this review, we aim to bridge the knowledge gap between interfacial instability and the influence of albumin as a surface-active excipient in the context of reducing the immunogenicity risk of protein formulations.

Surface functionalization of hydroxyapatite nanoparticles for biomedical applications

This review completely covers the various aspects of hydroxyapatite (HAp) nanoparticles and their role in different biological situations, and provides the surface and interface contents on (i) hydroxyapatite nanoparticles and their hybridization with organic molecules, (ii) surface designing of hydroxyapatite nanoparticles to provide their biocompatibility and photofunction, and (iii) coating technology of hydroxyapatite nanoparticles. In particular, we summarized how the HAp nanoparticles interact with the different ions and molecules and highlighted the potential for hybridization between HAp nanoparticles and organic molecules, which is driven by the interactions of the HAp nanoparticle surface ions with several functional groups of biological molecules. In addition, we highlighted the studies focusing on the interfacial interactions between the HAp nanoparticles and proteins for exploring the enhanced biocompatibility. Such studies focus on how these interactions affect the hydration layers and protein adsorption. However, the hydration layer state involves diverse molecular interactions that can alter the shape of the adsorbed proteins, thereby affecting cell adhesion and spreading on the surfaces. We also summarized the relationship between the surface properties of the HAp nanoparticles and the hydration layer. Furthermore, we spotlighted the cytocompatible photoluminescent probes that can be developed by designing HAp/organic nanohybrid structures. We then emphasized the importance of photofunctionalization in theranostics, which involves the integration of diagnostics and therapy based on the surface design of the HAp nanoparticles. Furthermore, the coating techniques using HAp nanoparticles and HAp nanoparticle/polymer composites were outlined for fusing base biomaterials with biological tissues. The advantages of HAp/biocompatible polymer composite coatings include the ability to effectively cover porous or irregularly shaped surfaces while controlling the thickness of the coating layer, and the addition of HAp nanoparticles to the polymer matrix improves the mechanical properties, increases the roughness, and forms the morphologies that mimic bone nanostructures. Therefore, the fundamental design of hydroxyapatite nanoparticles and their surfaces was suggested from various aspects for biomedical applications.

Silver(I) Complexes with Mefenamic Acid and Nitrogen Heterocyclic Ligands: Synthesis, Characterization, and Biological Evaluation

Four Ag(I) complexes with mefenamato and nitrogen heterocyclic ligands, [Ag(2-apy)(mef)]2 (1), [Ag(3-apy)(mef)] (2), [Ag2(tmpyz)(mef)2] (3), and {[Ag(4,4'-bipy)(mef)]2(CH3CN)1.5(H2O)2}n (4), (mef = mefenamato, 2-apy = 2-aminopyridine, 3-apy = 3-aminopyridine, tmpyz = 2,3,5,6-tetramethylpyrazine, 4,4'-bipy = 4,4'-bipyridine), were synthesized and characterized. The interactions of these complexes with BSA were investigated by fluorescence spectroscopy, which indicated that these complexes quench the fluorescence of BSA by a static mechanism. The fluorescence data also indicated that the complexes showed good affinity for BSA, and one binding site on BSA was suitable for the complexes. The in vitro cytotoxicity of the four complexes against human cancer cell lines (MCF-7, HepG-2, A549, and MDA-MB-468) and one normal cell line (HTR-8) was evaluated by the MTT assay. Complex 1 displayed high cytotoxic activity against A549 cells. Further studies revealed that complex 1 could enhance the intracellular levels of ROS (reactive oxygen species) in A549 cells, cause cell cycle arrest in the G0/G1 phase, and induce apoptosis in A549 cells in a dose-dependent manner.

Innovative Acrylic Resin-Hydrogel Double-Layer Coating: Achieving Dual-Anchoring, Enhanced Adhesion, and Superior Anti-Biofouling Properties for Marine Applications

Traditional anti-corrosion and anti-fouling coatings struggle against the harsh marine environment. Our study tackled this by introducing a novel dual-layer hydrogel (A-H DL) coating system. This system combined a Cu2O-SiO2-acrylic resin primer for anchoring and controlled copper ion release with a dissipative double-network double-anchored hydrogel (DNDAH) boasting superior mechanical strength and anti-biofouling performance. An acrylamide monomer was copolymerized and cross-linked with a coupling agent to form the first irreversible network and first anchoring, providing the DNDAH coating with mechanical strength and structural stability. Alginate gel microspheres (AGMs) grafted with the same coupling agent formed the second reversible network and second anchoring, while coordinating with Cu2+ released from the primer to form a system buffering Cu2+ release, enabling long-term antibacterial protection and self-healing capabilities. FTIR, SEM, TEM, and elemental analyses confirmed the composition, morphology, and copper distribution within the A-H DL coating. A marine simulation experiment demonstrated exceptional stability and anti-fouling efficacy. This unique combination of features makes A-H DL a promising solution for diverse marine applications, from ship hulls to aquaculture equipment.

Investigation of biosensing properties in magnetron sputtered metallized UV-curable polymer microneedle electrodes

Direct management and assessment of metal film properties applied to polymer microneedle (MN) biosensors remains difficult due to constraints inherent to their morphology. By simplifying the three-dimensional structure of MNs and adjusting the deposition time, different thicknesses of Au films were deposited on the UV-cured polymer planar and MN substrates. Several properties relevant to the biosensing of the Au films grown on the polymer surfaces were investigated. The results demonstrate the successful deposition of pure and stable Au nanoparticles onto the surface of UV-curable polymer materials. Initially, Au islands formed within the first minute of deposition; however, as the sputtering time extended, these islands transformed into Au nanoparticle films and disappeared. The hydrophilicity of the surface remains unchanged, while the surface resistance of the thin film decreases with increasing thickness, and the adhesion to the substrate decreases as the thickness increases. In short, a sputtering time of 5-6 min results in Au films with a thickness of 100-200 nm, which exhibit exceptional comprehensive biosensing performance. Additionally, MNs made of Au/UV-curable polymers and produced using magnetron sputtering maintain their original shape, enhance their mechanical characteristics, and gain new functionalities. The Au/UV-curable polymer MNs exhibited remarkable electrode performance despite being soaked in a 37 °C PBS solution for 14 days. These discoveries have important implications in terms of decreasing the dependence on valuable metals in MN biosensors, lowering production expenses, and providing guidance for the choice and design of materials for UV-curable polymer MN metallization films.

Near-Field Terahertz Morphological Reconstruction Nanoscopy for Subsurface Imaging of Protein Layers

Protein layers formed on solid surfaces have important applications in various fields. High-resolution characterization of the morphological structures of protein forms in the process of developing protein layers has significant implications for the control of the layer's quality as well as for the evaluation of the layer's performance. However, it remains challenging to precisely characterize all possible morphological structures of protein in various forms, including individuals, networks, and layers involved in the formation of protein layers with currently available methods. Here, we report a terahertz (THz) morphological reconstruction nanoscopy (THz-MRN), which can reveal the nanoscale three-dimensional structural information on a protein sample from its THz near-field image by exploiting an extended finite dipole model for a thin sample. THz-MRN allows for both surface imaging and subsurface imaging with a vertical resolution of ∼0.5 nm, enabling the characterization of various forms of proteins at the single-molecule level. We demonstrate the imaging and morphological reconstruction of single immunoglobulin G (IgG) molecules, their networks, a monolayer, and a heterogeneous double layer comprising an IgG monolayer and a horseradish peroxidase-conjugated anti-IgG layer. The established THz-MRN presents a useful approach for the label-free and nondestructive study of the formation of protein layers.

Electrochemical Immunosensor for the Quantification of Galectin-3 in Saliva

Heart failure (HF) is an emerging epidemic and remains a major clinical and public health problem. Advances in the healthcare management of HF may lead to lower morbidity and mortality rates but require diagnostics to guide the process. Current diagnostics/prognostics approaches rely on expensive equipment, centralized facilities and trained personnel, marginalizing healthcare access in developing countries and rural communities. These issues have led researchers to focus on developing portable and affordable diagnostics that can be deployed at the point-of-care (POC). Typically, HF biomarkers are measured in blood not saliva. Recently, our team correlated concentrations of salivary Galectin-3 (Gal-3) to outcomes in patients with HF. We have developed an analytical device which consists of an immunoassay based on a screen-printed carbon electrode (SPCE) to quantify Gal-3 levels in saliva samples. Using 10 μL of saliva, the proposed electrochemical immunoassay achieved a concentration dependent signal response in the clinically relevant range with a limit of detection of 9.66 ng/mL. In addition, the storage stability of the modified electrode was investigated, and only a 10.9% loss in current response over a 35-day period. The results of the immunoassay on the modified SPCEs suggest validity as a POC biosensor system for the management of HF.

Transparent antibiofouling coating to improve the efficiency of Nannochloropsis gaditana and Chlorella sorokiniana culture photobioreactors at the pilot-plant scale

The implementation of industrial-scale facilities for microalgae cultivation is limited due to the high operation costs. One of the main problems in obtaining an efficient and long-lasting microalgae culture system is biofouling. The particular issue when developing antibiofouling surfaces for microalgae cultures is that the material must be transparent. The main purpose of this work was to evaluate the antibiofouling efficiency of a non-toxic polydimethylsiloxane-based coating prepared with polyethylene glycol-based copolymer on different photobioreactors at the pilot-plant scale. The antifouling properties result from the development of a fouling-release coating utilizing hydrogel technology. Nannochloropsis gaditana and Chlorella sorokiniana were cultured outdoors for 3 months over the summer, when biofouling formation is at its highest due to environmental conditions, to test the coating's antibiofouling efficiency. Although biofouling was not completely prevented in either photobioreactor, the coating significantly reduced cell adhesion compared to the polydimethylsiloxane control (70% less adhesion). Therefore, this coating was shown to be a good alternative for constructing efficient closed-photobioreactors at the pilot-plant scale, at least for cultures lasting 3 months.

Electrospun methacrylated natural/synthetic composite membranes for gingival tissue engineering

New functional materials for engineering gingival tissue are still in the early stages of development. Materials for such applications must maintain volume and have advantageous mechanical and biological characteristics for tissue regeneration, to be an alternative to autografts, which are the current benchmark of care. In this work, methacrylated gelatin (GelMa) was photocrosslinked with synthetic immunomodulatory methacrylated divinyl urethanes and defined monomers to generate composite scaffolds. Using a factorial design, with the synthetic monomers of a degradable polar/hydrophobic/ionic polyurethane (D-PHI) and GelMa, composite materials were electrospun with polycarbonate urethane (PCNU) and light-cured in-flight. The materials had significantly different relative hydrophilicities, with unique biodegradation profiles associated with specific formulations, thereby providing good guidance to achieving desired mechanical characteristics and scaffold resorption for gingival tissue regeneration. In accelerated esterase/collagenase degradation models, the new materials exhibited an initial rapid weight loss followed by a more gradual rate of degradation. The degradation profile allowed for the early infiltration of human adipose-derived stromal/stem cells, while still enabling the graft's structural integrity to be maintained. In conclusion, the materials provide a promising candidate platform for the regeneration of oral soft tissues, addressing the requirement of viable tissue infiltration while maintaining volume and mechanical integrity. STATEMENT OF SIGNIFICANCE: There is a need for the development of more functional and efficacious materials for the treatment of gingival recession. To address significant limitations in current material formulations, we sought to investigate the development of methacrylated gelatin (GelMa) and oligo-urethane/methacrylate monomer composite materials. A factorial design was used to electrospin four new formulations containing four to five monomers. Synthetic immunomodulatory monomers were crosslinked with GelMa and electrospun with a polycarbonate urethane resulting in unique mechanical properties, and resorption rates which align with the original design criteria for gingival tissue engineering. The materials may have applications in tissue engineering and can be readily manufactured. The findings of this work may help better direct the efforts of tissue engineering and material manufacturing.

Electro-conductive chitosan/graphene bio-nanocomposite scaffold for tissue engineering of the central nervous system

Degenerative central nervous system (CNS) disorders and traumatic brain injuries are common nowadays. These may induce the loss of neuronal cells and delicate connections essential for optimal CNS function. The CNS tissue has restricted regeneration ability, hindering the development of effective therapies. Developing cell and tissue instructive materials may bring up new treatment possibilities. In this study, chitosan-graphene nano platelets (GNPs) composite films were developed to regenerate brain cells. This study evaluates the effects of GNP concentration (0.5, 1 and 2 wt%) and their alignment on mechanical, electrical, surface, protein adsorption and biological properties of the regenerative scaffolds. Incorporating and aligning GNPs into chitosan matrix improved all the physical and biological properties. On reinforced scaffolds, HT22 cell morphology mimics pyramidal brain cells, which are responsible for the brain's highly branched neural network. Additionally, the reinforced scaffolds supported Mesenchymal Stem like Cells growth and were biocompatible in vivo. The alignment of GNPs in the chitosan matrix offered the appropriate physicochemical and biological properties to promote adhesion, proliferation and shape morphogenesis of hippocampal HT22 neuronal cells. Overall, this study delineates the enormous potential offered by the GNP-reinforced scaffolds for regeneration of central nervous system, especially the brain.

Synthesis and evaluation of modified lens using plasma treatment containing timolol-maleate loaded lauric acid-decorated chitosan-alginate nanoparticles for glaucoma

Reducing intraocular pressure (IOP) with eye drops is one of the most common ways to control glaucoma. Low bioavailability and high frequency of administration in eye drops are major challenges in ocular pharmacotherapy. Contact lenses have attracted the attention of scientists in recent decades as an alternative method. In this study, with the aim of long-term drug delivery and better patient compatibility, contact lenses with surface modification and nanoparticles were used. In this study, timolol-maleate was loaded into polymeric nanoparticles made of chitosan conjugate with lauric acid and sodium alginate. Then silicon matrix was mixed with a curing agent (10:1), and the suspension of nanoparticles was added to the precursor and cured. Finally, for surface modification, the lenses were irradiated with oxygen plasma at different exposure times (30, 60, and 150 s) and soaked in different BSA concentrations (1, 3, and 5% w/v). The results showed nanoparticles with a size of 50 nm and a spherical shape were synthesized. The best surface modification of the lenses was for 5 (% w/v) albumin concentration and 150 s exposure time, which had the highest increase in hydrophilicity. Drug release from nanoparticles continued for 3 days and this amount increased to 6 days after dispersion in the modified lens matrix. The drug model and kinetic study show the Higuchi model completely supported the release profile. This study represents the novel drug delivery system to control intra-ocular pressure as a candidate platform for glaucoma treatment. Improved compatibility and drug release from the designed contact lenses would prepare new insight into the mentioned disease treatment.

Globular Proteins and Where to Find Them within a Polymer Brush-A Case Study

Protein adsorption by polymerized surfaces is an interdisciplinary topic that has been approached in many ways, leading to a plethora of theoretical, numerical and experimental insight. There is a wide variety of models trying to accurately capture the essence of adsorption and its effect on the conformations of proteins and polymers. However, atomistic simulations are case-specific and computationally demanding. Here, we explore universal aspects of the dynamics of protein adsorption through a coarse-grained (CG) model, that allows us to explore the effects of various design parameters. To this end, we adopt the hydrophobic-polar (HP) model for proteins, place them uniformly at the upper bound of a CG polymer brush whose multibead-spring chains are tethered to a solid implicit wall. We find that the most crucial factor affecting the adsorption efficiency appears to be the polymer grafting density, while the size of the protein and its hydrophobicity ratio come also into play. We discuss the roles of ligands and attractive tethering surfaces to the primary adsorption as well as secondary and ternary adsorption in the presence of attractive (towards the hydrophilic part of the protein) beads along varying spots of the backbone of the polymer chains. The percentage and rate of adsorption, density profiles and the shapes of the proteins, alongside with the respective potential of mean force are recorded to compare the various scenarios during protein adsorption.

Transdermal on-demand drug delivery based on an iontophoretic hollow microneedle array system

Transdermal drug delivery has emerged as an alternative administration route for therapeutic drugs, overcoming current issues in oral and parenteral administration. However, this technology is hindered by the low permeability of the stratum corneum of the skin. In this work, we develop a synergic combination of two enhancing technologies to contribute to an improved and on-demand drug delivery through an iontophoretic system coupled with hollow microneedles (HMNs). For the first time, a polymeric HMN array coupled with integrated iontophoresis for the delivery of charged molecules and macromolecules (e.g. proteins) is devised. To prove the concept, methylene blue, fluorescein sodium, lidocaine hydrochloride, and bovine serum albumin-fluorescein isothiocyanate conjugate (BSA-FITC) were first tested in an in vitro setup using 1.5% agarose gel model. Subsequently, the ex vivo drug permeation study using a Franz diffusion cell was conducted, exhibiting a 61-fold, 43-fold, 54-fold, and 17-fold increment of the permeation of methylene blue, fluorescein sodium, lidocaine hydrochloride, and BSA-FITC, respectively, during the application of 1 mA cm^-2 current for 6 h. Moreover, the total amount of drug delivered (i.e. in the skin and receptor compartment) was analysed to untangle the different delivery profiles according to the types of molecule. Finally, the integration of the anode and cathode into an iontophoretic hollow microneedle array system (IHMAS) offers the full miniaturisation of the concept. Overall, the IHMAS device provides a versatile wearable technology for transdermal on-demand drug delivery that can improve the administration of personalised doses, and potentially enhance precision medicine.

pH-Dependent Changes in Structural Stabilities of Bt Cry1Ac Toxin and Contrasting Model Proteins following Adsorption on Montmorillonite

The environmental fate of insecticidal Cry proteins, including time-dependent conservation of biological properties, results from their structural stability in soils. The complex cascade of reactions involved in biological action requires Cry proteins to be in solution. However, the pH-dependent changes in conformational stability and the adsorption-desorption mechanisms of Cry protein on soil minerals remain unclear. We used Derjaguin-Landau-Verwey-Overbeek (DLVO) calculation and differential scanning calorimetry to interpret the driving forces and structural stabilities of Cry1Ac and two contrasting model proteins adsorbed by montmorillonite. The structural stability of Cry1Ac is closer to that of the "hard" protein, α-chymotrypsin, than that of the "soft" bovine serum albumin (BSA). The pH-dependent adsorption of Cry1Ac and α-chymotrypsin could be explained by DLVO theory, whereas the BSA adsorption deviated from it. Patch-controlled electrostatic attraction, hydrophobic effects, and entropy changes following protein unfolding on a mineral surface could contribute to Cry1Ac adsorption. Cry1Ac, like chymotrypsin, was partly denatured on montmorillonite, and its structural stability decreased with an increase in pH. Moreover, small changes in the conformational heterogeneity of both Cry1Ac and chymotrypsin were observed following adsorption. Conversely, adsorbed BSA was completely denatured regardless of the solution pH. The moderate conformational rearrangement of adsorbed Cry1Ac may partially explain why the insecticidal activity of Bt toxin appears to be conserved in soils, albeit for a relatively short time period.

Development of a Microfluidic Chip Powered by EWOD for In Vitro Manipulation of Bovine Embryos

Digital microfluidics (DMF) holds great potential for the alleviation of laboratory procedures in assisted reproductive technologies (ARTs). The electrowetting on dielectric (EWOD) technology provides dynamic culture conditions in vitro that may better mimic the natural embryo microenvironment. Thus far, EWOD microdevices have been proposed for in vitro gamete and embryo handling in mice and for analyzing the human embryo secretome. This article presents the development of the first microfluidic chip utilizing EWOD technology designed for the manipulation of bovine embryos in vitro. The prototype sustains the cell cycles of embryos manipulated individually on the chips during in vitro culture (IVC). Challenges related to the chip fabrication as well as to its application during bovine embryo IVC in accordance with the adapted on-chip protocol are thoroughly discussed, and future directions for DMF in ARTs are indicated.

Electrostatic Repulsive Features of Free-Standing Titanium Dioxide Nanotube-Based Membranes in Biofiltration Applications

This study presents the electrostatic repulsive features of electrochemically fabricated titanium dioxide nanotube (NT)-based membranes with different surface nanomorphologies in cross-flow biofiltration applications while maintaining a creatinine clearance above 90%. Although membranes exhibit antifouling behavior, their blood protein rejection can still be improved. Due to the electrostatically negative charge of the hexafluorotitanate moiety, the fabricated biocompatible, superhydrophilic, free-standing, and amorphous ceramic nanomembranes showed that about 20% of negatively charged 66 kDa blood albumin was rejected by the membrane with ∼100 nm pores. As the nanomorphology of the membrane was shifted from NTs to nanowires by varying fabrication parameters, pure water flux and bovine serum albumin (BSA) rejection performance were reduced, and the membrane did not lose its antifouling behavior. Herein, nanomembranes with different surface nanomorphologies were fabricated by a multi-step anodic oxidation process and characterized by scanning electron microscopy, atomic force microscopy, water contact angle analysis, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The membrane performance of samples was measured in 3D printed polyethylene terephthalate glycol flow cells replicating implantable artificial kidney models to determine their blood toxin removal and protein loss features. In collected urine mimicking samples, creatinine clearances and BSA rejections were measured by the spectrophotometric Jaffe method and high-performance liquid chromatography.

Patterned Biolayers of Protein Antigens for Label-Free Biosensing in Cow Milk Allergy

This paper focuses on creating one-dimensional diffractive grooved structures of antigen proteins on glass substrates for the label-free detection of antibodies to dairy allergens. In particular, the fabrication of protein structures is carried out by combining microcontact printing with physisorption, imines coupling, and thiol-ene click chemistry. The work first sets up these patterning methods and discusses and compares the main aspects involved in them (structure, biolayer thickness, functionality, stability). Homogeneous periodic submicron structures of proteins are created and characterized by diffractive measurements, AFM, FESEM, and fluorescence scanning. Then, this patterning method is applied to proteins involved in cow milk allergy, and the resulting structures are implemented as optical transducers to sense specific immunoglobulins G. In particular, gratings of bovine serum albumin, casein, and β-lactoglobulin are created and assessed, reaching limits of detection in the range of 30-45 ng·mL^-1 of unlabeled antibodies by diffractive biosensing.

Biomimetic calcium phosphate coating on medical grade stainless steel improves surface properties and serves as a drug carrier for orthodontic applications

OBJECTIVE

Recently, stainless steel (SSL) miniscrew implants have been used in orthodontic clinics as temporary anchorage devices. Although they have excellent physical properties, their biocompatibility is relatively poor. Previously, our group developed a two-phase biomimetic calcium phosphate (BioCaP) coating that can significantly improve the biocompatibility of medical devices. This study aimed to improve the biocompatibility of SSL by coating SSL surface with the BioCaP coating.

METHODS

Titanium (Ti) discs and SSL discs (diameter: 5 mm, thickness: 1 mm) were used in this study. To form an amorphous layer, the Ti discs were immersed in a biomimetic modified Tyrode solution (BMT) for 24 h. The SSL discs were immersed in the same solution for 0 h, 12 h, 24 h, 36 h and 48 h. To form a crystalline layer, the discs were then immersed in a supersaturated calcium phosphate solution (CPS) for 48 h. The surface properties of the BioCaP coatings were analysed. In addition, bovine serum albumin (BSA) was incorporated into the crystalline layer during biomimetic mineralisation as a model protein.

RESULTS

The morphology, chemical composition and drug loading capacity of the BioCaP coating on smooth SSL were confirmed. This coating improved roughness and wettability of SSL surface. In vitro, with the extension of BMT coating period, the cell seeding efficiency, cell spreading area and cell proliferation on the BioCaP coating were increased.

SIGNIFICANCE

These in vitro results show that the BioCaP coating can improve surface properties of smooth medical grade SSL and serve as a carrier system for bioactive agents.

Zwitterionic Biomaterials

The term "zwitterionic polymers" refers to polymers that bear a pair of oppositely charged groups in their repeating units. When these oppositely charged groups are equally distributed at the molecular level, the molecules exhibit an overall neutral charge with a strong hydration effect via ionic solvation. The strong hydration effect constitutes the foundation of a series of exceptional properties of zwitterionic materials, including resistance to protein adsorption, lubrication at interfaces, promotion of protein stabilities, antifreezing in solutions, etc. As a result, zwitterionic materials have drawn great attention in biomedical and engineering applications in recent years. In this review, we give a comprehensive and panoramic overview of zwitterionic materials, covering the fundamentals of hydration and nonfouling behaviors, different types of zwitterionic surfaces and polymers, and their biomedical applications.

Alternative Excipients for Protein Stabilization in Protein Therapeutics: Overcoming the Limitations of Polysorbates

Given their safety and efficiency in protecting protein integrity, polysorbates (PSs) have been the most widely used excipients for the stabilization of protein therapeutics for years. In recent decades, however, there have been numerous reports about visible or sub-visible particles in PS-containing biotherapeutic products, which is a major quality concern for parenteral drugs. Alternative excipients that are safe for parenteral administration, efficient in protecting different protein drugs against various stress conditions, effective in protein stabilization in high-concentrated liquid formulations, stable under the storage conditions for the duration of the product's shelf-life, and compatible with other formulation components and the primary packaging are highly sought after. The aim of this paper is to review potential alternative excipients from different families, including surfactants, carbohydrate- and amino acid-based excipients, synthetic amphiphilic polymers, and ionic liquids that enable protein stabilization. For each category, important characteristics such as the ability to stabilize proteins against thermal and mechanical stresses, current knowledge related to the safety profile for parenteral administration, potential interactions with other formulation components, and primary packaging are debated. Based on the provided information and the detailed discussion thereof, this paper may pave the way for the identification or development of efficient excipients for biotherapeutic protein stabilization.

Instability Challenges and Stabilization Strategies of Pharmaceutical Proteins

Maintaining the structure of protein and peptide drugs has become one of the most important goals of scientists in recent decades. Cold and thermal denaturation conditions, lyophilization and freeze drying, different pH conditions, concentrations, ionic strength, environmental agitation, the interaction between the surface of liquid and air as well as liquid and solid, and even the architectural structure of storage containers are among the factors that affect the stability of these therapeutic biomacromolecules. The use of genetic engineering, side-directed mutagenesis, fusion strategies, solvent engineering, the addition of various preservatives, surfactants, and additives are some of the solutions to overcome these problems. This article will discuss the types of stress that lead to instabilities of different proteins used in pharmaceutics including regulatory proteins, antibodies, and antibody-drug conjugates, and then all the methods for fighting these stresses will be reviewed. New and existing analytical methods that are used to detect the instabilities, mainly changes in their primary and higher order structures, are briefly summarized.

Adsorption Analysis of Exopolymeric Substances as a Tool for the Materials Selection of Photobioreactors Manufacture

An improved method that allows the robust characterization of surfaces is necessary to accurately predict the biofouling formation on construction materials of photobioreactors (PBR). Exopolymeric substances (EPS), such as proteins and polysaccharides, have been demonstrated to present a similar behavior to cells in terms of surface adhesion. In this work, these EPS were used to optimize parameters, such as EPS concentration or adsorption time, to evaluate accurately the adsorption capacity of surfaces and, with it, predict the biofouling formation in contact with microalgae cultures. Once the method was optimized, the characterization of seven commercial polymeric surfaces was submitted to different abrasive particles sizes, which modified the roughness of the samples, as well as protein and polysaccharide lawns, which were prepared and carried out in order to evaluate the characteristics of these substances. The characterization consisted of the determination of surface free energy, water adhesion tension, and critical tension determined from the measurement of the contact angle, roughness, surface zeta potential, and the EPS adhesion capacity of each material. This will be useful to understand the behavior of the surface in the function of its characteristics and the interaction with the solutions of EPS, concluding that the hydrophobic and smooth surfaces present good anti-biofouling characteristics.

Effects of Different Concentrations of BSA on In Vitro Corrosion Behavior of Pure Zinc in Artificial Plasma

When medical metallic materials are implanted in the body and come into contact with the body fluid environment, proteins will be rapidly adsorbed on the surface and affect the corrosion process of the material. Currently, there is no uniform understanding of the effect of protein adsorption on the corrosion behavior of materials due to the limitations of the nature of metal materials, protein concentrations, and different media environments. The effect of various bovine serum albumin (BSA) concentrations in artificial plasma (AP) on the corrosion behavior of pure Zn during 14 days of immersion was investigated in this research. The corrosion rate of pure Zn was slowed down by the addition of BSA, and the decelerating effect of lower protein concentration on the corrosion rate of Zn was more significant in the initial stage of immersion. With prolonging the immersion time, the corrosion rate of pure Zn in different media slowed down and stabilized, and the corrosion rates of pure Zn showed a decreasing trend with an increase of BSA concentration. Furthermore, the Langmuir adsorption isotherm model was utilized to study the relationship between the BSA concentration and corrosion behavior of pure Zn and to analyze the role of proteins in the degradation mechanism of pure Zn. This work could be useful for further exploration of potential clinical applications of zinc alloys.

Deciphering the Emulsification Process to Create an Albumin-Perfluorocarbon-(o/w) Nanoemulsion with High Shelf Life and Bioresistivity

This work aimed at the development of a stable albumin-perfluorocarbon (o/w) emulsion as an artificial oxygen carrier suitable for clinical application. So far, albumin-perfluorocarbon-(o/w) emulsions have been successfully applied in preclinical trials. Cross-linking a variety of different physical and chemical methods for the characterization of an albumin-perfluorocarbon (PFC)-(o/w) emulsion was necessary to gain a deep understanding of its specific emulsification processes during high-pressure homogenization. High-pressure homogenization is simple but incorporates complex physical reactions, with many factors influencing the formation of PFC droplets and their coating. This work describes and interprets the impact of albumin concentration, homogenization pressure, and repeated microfluidizer passages on PFC-droplet formation; its influence on storage stability; and the overcoming of obstacles in preparing stable nanoemulsions. The applied methods comprise dynamic light scattering, static light scattering, cryo- and non-cryo-scanning and transmission electron microscopies, nuclear magnetic resonance spectroscopy, light microscopy, amperometric oxygen measurements, and biochemical methods. The use of this wide range of methods provided a sufficiently comprehensive picture of this polydisperse emulsion. Optimization of PFC-droplet formation by means of temperature and pressure gradients results in an emulsion with improved storage stability (tested up to 5 months) that possibly qualifies for clinical applications. Adaptations in the manufacturing process strikingly changed the physical properties of the emulsion but did not affect its oxygen capacity.

Graphene Oxide Loaded on TiO2-Nanotube-Modified Ti Regulates the Behavior of Human Gingival Fibroblasts

Surface topography, protein adsorption, and the loading of coating materials can affect soft tissue sealing. Graphene oxide (GO) is a promising candidate for improving material surface functionalization to facilitate soft tissue integration between cells and biomaterials. In this study, TiO₂ nanotubes (TNTs) were prepared by the anodization of Ti, and TNT-graphene oxide composites (TNT-GO) were prepared by subsequent electroplating. The aim of this study was to investigate the effect of TNTs and TNT-GO surface modifications on the behavior of human gingival fibroblasts (HGFs). Commercially pure Ti and TNTs were used as the control group, and the TNT-GO surface was used as the experimental group. Scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction were used to perform sample characterization. Cell adhesion, cell proliferation, cell immunofluorescence staining, a wound-healing assay, real-time reverse-transcriptase polymerase chain reaction (RT-PCR), and Western blotting showed that the proliferation, adhesion, migration, and adhesion-related relative gene expression of HGFs on TNT-GO were significantly enhanced compared to the control groups, which may be mediated by the activation of integrin β1 and the MAPK-Erk1/2 pathway. Our findings suggest that the biological reactivity of HGFs can be enhanced by the TNT-GO surface, thereby improving the soft tissue sealing ability.

Enhanced Optical Biosensing by Aerotaxy Ga(As)P Nanowire Platforms Suitable for Scalable Production

Sensitive detection of low-abundance biomolecules is central for diagnostic applications. Semiconductor nanowires can be designed to enhance the fluorescence signal from surface-bound molecules, prospectively improving the limit of optical detection. However, to achieve the desired control of physical dimensions and material properties, one currently uses relatively expensive substrates and slow epitaxy techniques. An alternative approach is aerotaxy, a high-throughput and substrate-free production technique for high-quality semiconductor nanowires. Here, we compare the optical sensing performance of custom-grown aerotaxy-produced Ga(As)P nanowires vertically aligned on a polymer substrate to GaP nanowires batch-produced by epitaxy on GaP substrates. We find that signal enhancement by individual aerotaxy nanowires is comparable to that from epitaxy nanowires and present evidence of single-molecule detection. Platforms based on both types of nanowires show substantially higher normalized-to-blank signal intensity than planar glass surfaces, with the epitaxy platforms performing somewhat better, owing to a higher density of nanowires. With further optimization, aerotaxy nanowires thus offer a pathway to scalable, low-cost production of highly sensitive nanowire-based platforms for optical biosensing applications.

Microwave Treatment of Calcium Phosphate/Titanium Dioxide Composite to Improve Protein Adsorption

Calcium phosphate has attracted enormous attention as a bone regenerative material in biomedical fields. In this study, we investigated the effect of microwave treatment on calcium phosphate deposited TiO₂ nanoflower to improve protein adsorption. Hierarchical rutile TiO₂ nanoflowers (TiNF) fabricated by a hydrothermal method were soaked in modified simulated body fluid for 3 days to induce calcium phosphate (CAP) formation, followed by exposure to microwave radiation (MW). Coating the dental implants with CAP/TiNF provides a means of improving the biological properties, as the structure, morphology, and thickness of the composites can be controlled. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), field emission transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR), respectively. The composites were identified to be composed of aggregated nano-sized particles with sphere-like shapes, and the calcium phosphate demonstrated low crystallinity. The ability of bovine serum albumin (BSA) to adsorb on MW-treated CAP/TiNF composites was studied as a function of BSA concentration. The Sips isotherm was used to analyze the BSA adsorption on MW-treated CAP/TiNF composites. The MW-treated samples showed high protein adsorption capacity, thereby indicating their potential in various biomedical applications.

Surface modification of hydroxyapatite nanoparticles for bone regeneration by controlling their surface hydration and protein adsorption states

Autogenous bone and metallic implant grafting has been used to repair and regenerate bone defects. However, there are still many unresolved problems. It is suggested that bioceramic nanoparticles should be developed and designed to promote effective bone regeneration. In addition, it is necessary to synthesize bioceramic nanoparticles that can support proteins related to bone repair and regeneration such as collagen and albumin. As the protein-interactive bioceramic, hydroxyapatite (HA) deserves to be mentioned and has several attractive properties that are useful in biomedical fields (e.g., biocompatibility, protein adsorption capacity and stability in the physiological environment). In order to prepare novel HA nanoparticles with high biocompatibility, it can be considered that human bones are mainly composed of HA and contain a small amount of silicate, and therefore, the design of coexistence of HA with silicate can be focused. Moreover, it is proposed that the state of the hydration layer on the nanoparticle surfaces can be controlled by introducing heteroelements and polymer chains, which have a great influence on the subsequent protein adsorption and cell adhesion. In this perspective, in order to develop novel bioceramic nanoparticles for the treatment of bone defect, the design of highly biocompatible HA nanoparticles and the control of the hydration layer and protein adsorption states on the surfaces were systematically discussed based on their surface modification techniques, which are very important for the proper understanding of the interface between cells and bioceramics, leading to the further application in biomedical fields.

Assessment of protein adhesion behaviour and biocompatibility of magnesium/Co-substituted HA-based composites for orthopaedic application

Protein adsorption has a great influence on Mg-based metallic implants, which affects cell attachment and cell growth. Adsorption of the proteins (via electrostatic interaction, hydrophobic/hydrophilic, and hydrogen-bonding) on the implant surface is greatly influenced by the surface chemistry of the implant. Hydroxyapatite (HA) is a class of CaP ceramic, beneficial for protein adsorption as it possesses Ca²⁺ and PO₄^3- in it, which are believed to be the protein binding sites on the HA surface. Moreover, HA is the popular choice for reinforcement in the magnesium matrix owing to its similarity with bone mineral composition. However, negligible interaction between HA and Mg particles during sintering is the major limitation for frequent usage of Mg-HA implants. Doping of HA with Mg²⁺ and Zn²⁺ (CoHA) ions leads to its chemistry similar to natural apatite in human bone and facilitates comparatively better bonding with the MgZn matrix. This study mainly aims to delve into the protein adsorption behaviour of Magnesium/Co-substituted HA-based Composites (M3Z-CoHA) along with their biocompatibility. Qualitative and quantitative protein adsorption analysis shows that the addition of 15 wt% CoHA to Mg matrix enhanced protein adsorption by ~60% and renders cell viability >90% after day 1, supporting cellular growth and proliferation. The implants also initiated osteogenic differentiation of the cells after day 7. The leached-out products from all the composites showed no toxicity. The morphology of the cells in all the composites was found as healthy as the control cells. Overall, the composite with 15 wt% HA reinforcement (M3Z-15CoHA) has shown favourable protein adsorption behaviour and cytocompatibility.

Mechanistic insight into differential interactions of iron oxide nanoparticles with native, glycated albumin and their effect on erythrocytes parameters

Nanoparticles and protein bioconjugates have been studied for multiple biomedical applications. We sought to investigate the interaction and structural modifications of bovine serum albumin (BSA) with iron oxide nanoparticles (IONPs). The IONPs were green synthesized using E. crassipes aqueous leaf extract following characterization using transmission electron microscopy, energy dispersive X-ray analysis and X-Ray Diffraction. Two different concentrations of native/glycated albumin (0.5 and 1.5 mg/ml) with IONPs were allowed to interact for 1 h at 37 °C. Glycation markers, protein modification markers, cellular antioxidant, and hemolysis studies showed structural modifications and conformational changes in albumin due to the presence of IONPs. UV-Visible absorbance resulted in hyperchromic and bathochromic effects of IONPs-BSA conjugates. Fluorescence measurements of tyrosine, tryptophan, advanced glycated end products, and ANS binding assay were promising and quenching effects proved IONPs-BSA conjugate formation. In FTIR of BSA-IONPs, transmittance was increased in amide A and B bands while decreased in amide I and II bands. In summary, native PAGE, HPLC, and FTIR analysis displayed a differential behaviour of IONPs with native and glycated BSA. These results provided an understanding of the interaction and structural modifications of glycated and native BSA which may provide fundamental repercussions in future studies.

Electrically-driven handling of gametes and embryos: taking a step towards the future of ARTs

Electrical stimulation of gametes and embryos and on-chip manipulation of microdroplets of culture medium serve as promising tools for assisted reproductive technologies (ARTs). Thus far, dielectrophoresis (DEP), electrorotation (ER) and electrowetting on dielectric (EWOD) proved compatible with most laboratory procedures offered by ARTs. Positioning, entrapment and selection of reproductive cells can be achieved with DEP and ER, while EWOD provides the dynamic microenvironment of a developing embryo to better mimic the functions of the oviduct. Furthermore, these techniques are applicable for the assessment of the developmental competence of a mammalian embryo in vitro. Such research paves the way towards the amelioration and full automation of the assisted reproduction methods. This article aims to provide a summary on the recent developments regarding electrically stimulated lab-on-chip devices and their application for the manipulation of gametes and embryos in vitro.

Electronic properties and surface potential evaluations at the protein nano-biofilm/oxide interface: Impact on corrosion and biodegradation

The formation of a protein nano-biofilm, which exhibits a special electronic behavior, on the surface of metals or oxide biomaterials considerably influences the crucial subsequent interactions, particularly the corrosion and biodegradation processes. This study discusses the impact of electrical surface potential (ESP) of a single or nano-biofilm of albumin protein on the electrochemical interactions and electronic property evolutions (e.g., charge carriers, space charge capacitance (SCC), and band bending) occurring on the surface oxide of CoCrMo implants. Scanning Kelvin probe force microscopy (SKPFM) results indicated that ESP or surface charge distribution on a single or nano-biofilm of the albumin protein is lower than that of a CoCrMo complex oxide layer, which hinders the charge transfer at the protein/electrolyte interface. Using a complementary approach, which involved performing Mott-Schottky analysis at the electrolyte/protein/oxide interface, it was revealed that the albumin protein significantly increases the SCC magnitude and number of n-type charge carrier owing to increased band bending at the SCC/protein interface; this facilitated the acceleration of metal ion release and metal-protein complex formation. The nanoscale SKPFM and electrochemical analyses performed in this study provide a better understanding of the role of protein molecules in corrosion/biodegradation of metallic biomaterials at the protein nano-biofilm/oxide interface.

Engineering of Surface Energy of Cell-Culture Platform to Enhance the Growth and Differentiation of Dendritic Cells via Vapor-Phase Synthesized Functional Polymer Films

Although the dendritic cell (DC)-based modulation of immune responses has emerged as a promising therapeutic strategy for tumors, infections, and autoimmune diseases, basic research and therapeutic applications of DCs are hampered by expensive growth factors and sophisticated culture procedures. Furthermore, the platform to drive the differentiation of a certain DC subset without any additional biochemical manipulations has not yet been developed. Here, five types of polymer films with different hydrophobicity via an initiated chemical vapor deposition (iCVD) process to modulate the interactions related to cell-substrate adhesion are introduced. Especially, poly(cyclohexyl methacrylate) (pCHMA) substantially enhances the expansion and differentiation of conventional type 1 DCs (cDC1s), the prime DC subset for antigen cross-presentation, and CD8⁺ T cell activation, by 4.8-fold compared to the conventional protocol. The cDC1s generated from the pCHMA-coated plates retain the bona fide DC functions including the expression of co-stimulatory molecules, cytokine secretion, antigen uptake and processing, T cell activation, and induction of antitumor immune responses. To the authors' knowledge, this is the first report highlighting that the modulation of surface hydrophobicity of the culture plate can be an incisive approach to construct an advanced DC culture platform with high efficiency, which potentially facilitates basic research and the development of immunotherapy employing DCs.

Assessing the predictive capabilities of design heuristics and coarse-grain simulation toward understanding and optimizing site-specific covalent immobilization of β-lactamase

For industrial applications, covalent immobilization of enzymes provides minimum leakage, recoverability, reusability, and high stability. Yet, the suitability of a given site on the enzyme for immobilization remains a trial-and-error procedure. Here, we investigate the reliability of design heuristics and a coarse-grain molecular simulation in predicting the optimum sites for covalent immobilization of TEM-1 β-lactamase. We utilized E. coli-lysate-based cell-free protein synthesis (CFPS) to produce variants containing a site-specific incorporated unnatural amino acid with a unique moiety to facilitate site directed covalent immobilization. To constrain the number of potential immobilization sites, we investigated the predictive capability of several design heuristics. The suitability of immobilization sites was determined by analyzing expression yields, specific activity, immobilization efficiency, and stability of variants. These experimental findings are compared with coarse-grain simulation of TEM-1 domain stability and thermal stability and analyzed for a priori predictive capabilities. This work demonstrates that the design heuristics successfully identify a subset of locations for experimental validation. Specifically, the nucleotide following amber stop codon and domain stability correlate well with the expression yield and specific activity of the variants, respectively. Our approach highlights the advantages of combining coarse-grain simulation and high-throughput experimentation using CFPS to identify optimal enzyme immobilization sites. This article is protected by copyright. All rights reserved.

Degradable Anti-Biofouling Polyester Coatings with Controllable Lifetimes

To achieve degradable, anti-biofouling coatings with longer lifetimes and better mechanical properties, we synthesized a series of degradable co-polyesters composed of cyclic ketene acetals, di-(ethylene glycol) methyl ether methacrylate, and a photoactive curing agent, 4-benzoylphenyl methacrylate, using a radical ring-opening polymerization. The precursor co-polyesters were spin-coated on a benzophenone-functionalized silicon wafer to form ca. 60 nm films and drop-casted on glass to form ∼32 μm films. The copolymers were cross-linked via UV irradiation at 365 nm. The degradation of films was studied by immersing the specimens in aqueous buffers of different pH values. The results show that both the pH of buffer solutions and gel fractions of networks affect the degradation rate. The coatings show good bovine serum albumin resistance capability. By adjusting the fractions of monomers, the degradation rate and degree of hydration (e.g., swelling ratio) are controllable.

Interphase Protein Layers Formed on Self-Assembled Monolayers in Crowded Biological Environments: Analysis by Surface Force and Quartz Crystal Microbalance Measurements

We investigated a viscous protein layer formed on self-assembled monolayers (SAMs) in crowded biological environments. The results were obtained through force spectroscopic measurements using colloidal probes and substantiated by exhaustive analysis using a quartz crystal microbalance with an energy dissipation technique. A hydrophobic SAM of n-octanethiol (C8 SAM) in bovine serum albumin (BSA) solution is buried under an adlayer of denatured BSA molecules and an additional viscous interphase layer that is five times more viscous than the bulk solution. C8 SAMs in fetal bovine serum induced a formation of a thicker adsorbed protein layer but with no observable viscous interphase layer. These findings show that a fouling surface is essentially inaccessible to any approaching molecules and thus has a new biological and physical identity arising from its surrounding protein layers. In contrast, the SAMs composed of sulfobetaine-terminated alkanethiol proved to be sufficiently protein-resistant and bio-inert even under crowded conditions due to a protective barrier of its interfacial water, which has implications in the accurate targeting of artificial particles for drug delivery and similar applications by screening any non-specific interactions. Finally, our strategies provide a platform for the straightforward yet effectual in vitro characterization of diverse types of surfaces in the context of targeted interactions in crowded biological environments.

Enzymatic activity of individual bioelectrocatalytic viral nanoparticles: dependence of catalysis on the viral scaffold and its length

The enzymatic activity of tobacco mosaic virus (TMV) nanorod particles decorated with an integrated electro-catalytic system, comprising the quinoprotein glucose-dehydrogenase (PQQ-GDH) enzyme and ferrocenylated PEG chains as redox mediators, is probed at the individual virion scale by atomic force microscopy-scanning electrochemical atomic force microscopy (AFM-SECM). A marked dependence of the catalytic activity on the particle length is observed. This finding can be explained by electron propagation along the viral backbone, resulting from electron exchange between ferrocene moieties, coupled with enzymatic catalysis. Thus, the use of a simple 1D diffusion/reaction model allows the determination of the kinetic parameters of the virus-supported enzyme. Comparative analysis of the catalytic behavior of the Fc-PEG/PQQ-GDH system assembled on two differing viral scaffolds, TMV (this work) and bacteriophage-fd (previous work), reveals two distinct kinetic effects of scaffolding: An enhancement of catalysis that does not depend on the virus type and a modulation of substrate inhibition that depends on the virus type. AFM-SECM detection of the enzymatic activity of a few tens of PQQ-GDH molecules, decorating a 40 nm-long viral domain, is also demonstrated, a record in terms of the lowest number of enzyme molecules interrogated by an electrochemical imaging technique.

The influence of surface charge on the tumor-targeting behavior of Fe3O4 nanoparticles for MRI

Nanomedicine-based tumor-targeted therapy has emerged as a promising strategy to overcome the lack of specificity of conventional chemotherapeutic agents. "Passive" targeting caused by the tumor EPR effect and "active" targeting endowed by the tumor-targeting moieties provide promising biomedical utilities and cancer therapy strategies for nanomedicine. However, as the nanoparticles are exposed to biological fluids, a large number of protein molecules will be adsorbed on their surface, known as protein corona, which may alter the targeting ability of the nanoparticles. The impact of different protein corona on the "passive" and "active" targeting behaviors is still ambiguous. Herein, three kinds of aqueous soluble Fe₃O₄ nanoparticles with different surface modifications were synthesized and applied to explore the correlation between their protein corona and passive/active tumor-targeting abilities. In the in vitro and in vivo studies, the protein corona exhibited completely different effects on the active and passive cancer-targeting capability of the particles. The particles presented active cancer-targeting ability if there was enough interaction time between the particles and cells. This was mainly due to the dynamic evolution of the protein corona, the proteins of which may be outcompeted by the cancer cell membrane and determine the targeting abilities. Unfortunately, the protein corona also inevitably accelerated RES/MPS uptake after the particles were injected into the body, which almost completely disabled the active targeting abilities of the particles. We believe that this in-depth understanding of protein corona will provide new ideas on the tumor-targeting mechanisms of nanoparticles and present a feasible approach to designing targeted drugs in the future.

Insights from molecular dynamics simulations of albumin adsorption on hydrophilic and hydrophobic surfaces

Protein adsorption at the surface affects the material biocompatibility directly as it is the first reaction that happens when a foreign material comes in contact with blood. In this study, the mechanism of albumin adsorption on hydrophilic and hydrophobic surfaces is investigated. Although it is studied extensively and has been of keen interest for decades, the adsorptive nature of albumin is still not fully understood with contradicting reported studies. This problem results from previous works focusing on mostly qualitative and quantitative adsorption properties of albumin, rather than the specific interaction mechanisms. The variable local surface properties across albumin can significantly impact adsorption and must be explored. In this work, the effect of hydration is found to significantly increase adsorption with minor reductions. The adsorption of albumin on hydrophilic or hydrophobic surfaces is dependent on albumin orientation, which is dictated by local charge effects. Based on these findings, an optimized material surface is proposed to minimize albumin adsorption using functional groups to limit surface availability for hydrophobic interactions while inhibiting excess electrostatic effects at hydrophilic sites. The extent of albumin adsorption and shape change are characterized herein using the heat capacity. Current study identifies interaction mechanisms previously missing in literature, which are responsible for inconsistent adsorption results.

Plasma SiOx:H Nanocoatings to Enhance the Antibacterial and Anti-Inflammatory Properties of Biomaterials

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