Nonspecific Protein Adsorption Research Articles

Bifunctional MoO3-x/CuS Heterojunction Nanozyme-Driven "Turn-On" SERS Signal for the Sensitive Detection of Cerebral Infarction Biomarker S100B.

The use of nanozymes has become a promising auxiliary approach to "turn on" surface-enhanced Raman scattering (SERS) signals for the label-free detection of disease markers. Nevertheless, there are still major challenges to develop bifunctional nanomaterials with both excellent enzyme-like activity and high SERS performance. To this end, a novel Z-scheme MoO3-x/CuS heterojunction was first constructed as a powerful "two-in-one" substrate, which can not only catalyze leucomalachite green (LMG) to SERS-active malachite green (MG) but also serve as an efficient substrate to amplify the SERS signal of catalysate. Due to the strong interfacial coupling effect between the MoO3-x and CuS nanomaterial, which promoted the separation and transport of carriers in the heterojunction, the MoO3-x/CuS heterojunction showed higher peroxidase-like activity compared to individual components and the previously reported heterojunction nanozymes. Inspired by these results, a sandwich-type SERS immunoassay for the detection of the cerebral infarction biomarker S100 calcium-binding protein (S100B) was proposed based on the output signal of MG at 1620 cm-1. Furthermore, introducing the antifouling material chitosan on the surface of the MoO3-x/CuS heterojunction can effectively resist nonspecific protein adsorption and significantly improve the detection accuracy of the immunoassay. Therefore, the SERS immunoassay based on the MoO3-x/CuS heterojunction realized highly sensitive and selective detection of S100B in the concentration range of 0.001 to 100 ng/mL, with a low limit of detection of 0.47 pg/mL. The developed method has been successfully used for the accurate detection of S100B in clinical serum. The results showed that the level of S100B in the serum of cerebral infarction patients can be distinguished from those of healthy individuals and intracranial tumor patient controls. In addition, the acquired values of S100B in the serum of cerebral infarction patients based this strategy were well consistent with the results of electrochemiluminescence (ECL) detection with a relative error of less than ±7.3. It is expected that this work may open up a paradigm for improving detection sensitivity and accuracy for the early diagnosis and treatment monitoring of cerebral infarction in the clinic.

Zwitterionic Polymers for Biomedical Applications: Antimicrobial and Antifouling Strategies toward Implantable Medical Devices and Drug Delivery.

Poly(ethylene glycol) (PEG) is extensively utilized in biomedical applications due to its biocompatibility; however, its thermal instability and susceptibility to oxidative degradation significantly constrain its long-term effectiveness. Zwitterionic polymers, characterized by their distinctive structure, enhanced stability, and superior biocompatibility, offer a more advantageous alternative. These polymers exhibit super hydrophilicity, resist nonspecific protein adsorption, and maintain stability in biological environments due to their charge-neutral ionic nature. Zwitterionic polymers enhance anticancer drug delivery by precisely targeting tumor cells and facilitating an efficient drug release. Their inherent antifouling properties and prolonged circulation within the bloodstream render them highly suitable for redox-sensitive drug carriers, thereby augmenting the antitumor efficacy. Moreover, zwitterionic polymers markedly mitigate biofouling in implants, biosensors, and wound dressings, thereby improving both their functionality and their therapeutic outcomes. These advantages arise from the formation of robust hydration layers, which significantly enhance the hemocompatibility and inhibit the adhesion of proteins, platelets, and bacteria. Zwitterionic polymers, including sulfobetaine (SB), phosphorylcholine (PC), and carboxybetaine (CB), are increasingly employed in blood-contacting devices and as effective coating materials for implantable devices. This mini-review paper aims to explore the recent diverse biomedical applications of zwitterionic polymers and highlight their advantageous properties compared with unmodified polymers. We will cover their use in drug delivery systems, tumor targeting nanocarriers, antibiofouling and antibacterial activities in implantable devices, tissue engineering, and diagnostic devices, demonstrating how their unique properties can translate into different applications. Through this exploration, this Perspective will display the potential of zwitterionic polymers as innovative polymer materials in the field of biomedical engineering and beyond.

Hydrogen-Bonded Organic Framework Enhanced Antifouling Property for Efficient In Situ Electrochemical Assay of Cerebral Ascorbic Acid.

Accurate determination of cerebral ascorbic acid (AA) is crucial for understanding ischemic stroke (IS) related pathological events. Carbon fiber microelectrodes (CFEs) have proven to be robust tools with high sensitivity toward AA, however, they face ongoing challenges for in situ measurement due to the non-specific adsorption of proteins in brain tissue. In this study, the hydrogen-bonded organic framework PFC-71 is synthesized and modified on CFEs through π-π stacking interactions with carboxylated carbon nanotubes (CNT-COOH). It is found that the gating effect and hydrophilicity of PFC-71 provided the CFE with excellent antibiofouling properties. As a result, AA exhibited a low oxidation potential of -30mV on the CFE/CNT-COOH/PFC-71, even in the presence of 20mgmL-1 bovine serum albumin. Given the structural advantages of CFE/CNT-COOH/PFC-71, a ratiometric electrochemical strategy for AA is established, enabling the in situ assay of cerebral AA in a middle cerebral artery occlusion (MCAO) model with high accuracy and stability.

Dual responsive drug-loaded nanomotor based on zwitterionic materials for the treatment of peritoneal metastatic cancer

Innovative treatments for peritoneal metastatic cancer have attracted widespread attention from researchers. Here, we propose a drug-loaded nanomotor (PSBMA/l-Arg/DOX, PLD) based on zwitterionic materials for the treatment of peritoneal metastatic cancer through intraperitoneal injection. Zwitterionic polymer nanocarriers (PSBMA NPs) are obtained by radical polymerization with zwitterionic SBMA as the polymerization monomer and N,N’-Bis(acryloyl)cystamine (BAC) as the cross-linking agent. The zwitterionic substrate of this nanomotor has the ability to resist non-specific protein adsorption in ascites. The loaded l-arginine enables the nanomotor to have the ability to chemotaxis towards high concentrations of ROS/iNOS in tumors and be catalyzed to produce NO, achieving deep penetration into tumor tissue. Furthermore, the disulfide bond (SS) carried by the crosslinking agent used in the preparation of the nanomotor can respond to the high expression of reducing glutathione in the tumor microenvironment and undergo degradation, releasing a large amount of loaded drug DOX. Cell and animal disease model experiments confirme the good therapeutic effect of this drug-loaded nanomotor, providing new therapeutic concepts and strategies for the treatment of peritoneal metastatic cancer.

Biocompatibility and corrosion resistance of drug coatings with different polymers for magnesium alloy cardiovascular stents

Recently, advances in enhancing corrosion properties through various techniques, and the clinical application of biodegradable cardiovascular stents made from magnesium (Mg) alloys face challenges to corrosion resistance, blood compatibility, and biocompatibility. Drug-eluting stents (DES) offer a solution to enhance the corrosion resistance of Mg alloys while simultaneously reducing the occurrence of restenosis. In this study, WE43 Mg alloy was pretreated using electropolishing technology, and different polymers (PEG and PLLA) were used as drug-polymer coatings for the Mg alloy. At the same time, PTX, an anticoagulant, was incorporated to achieve drug coating of different polymers on WE43 Mg alloy. The corrosion resistance of different polymer-drug coatings was assessed using a plasma solution. Furthermore, in vitro and in vivo tests were used to evaluate the blood biocompatibility of these coatings. The results indicated the PTX-PEG-coated WE43 Mg alloy exhibited the highest corrosion resistance and the most stable drug release profile among the tested coatings. Its hemolysis rate of 0.6 % was within the clinical requirements (<5 %). The incorporation of PEG prevents non-specific protein adsorption and nanoparticle aggregation, enhancing the surface hemocompatibility of WE43 Mg alloy. Therefore, the PTX-PEG coating shows promising potential for application in the development of drug-coated Mg alloy.

Progress in the Development of Antifouling Electrochemical Biosensors

Electrochemical biosensors a subclass of biosensors, consisting of a biosensing element and an electrochemical transducer, have been widely used in various fields due to their excellent performance and portable device. However, in complex actual samples, non-specific adsorption of proteins and solid particles, and adhesion of cells and bacteria will lead to problems such as reduced sensor sensitivity, prolonged response time, and expanded detection errors. Therefore, constructing antifouling sensing platforms to effectively resist the bioadhesion of non-targets is crucial for the performance of biosensors. This study first introduces the commonly used classifications of electrochemical biosensors and their main contaminants. It also provides a comprehensive overview of the construction methods and application research of electrochemical antifouling sensors using different strategies, including the construction of physical, chemical and biological modification interfaces. In addition, the research progress on antifouling and antibacterial dual-action coatings for electrochemical detection is also reviewed. Finally, the challenges and future development trends of various methods are summarized, providing clues for better practical applications of electrochemical biosensors.

BMP2 Binds Non-Specifically to PEG-Passivated Biomaterials and Induces pSMAD 1/5/9 Signalling.

Biomaterials are widely employed across diverse biomedical applications and represent an attractive strategy to explore how extracellular matrix components influence cellular response. In this study, the previously developed streptavidin platforms is aimed to use to investigate the role of glycosaminoglycans (GAGs) in bone morphogenetic protein 2 (BMP2) signaling. However, it is observed that the interpretation of findings is skewed due to the GAG-unrelated, non-specific binding of BMP2 on components of biomaterials. Non-specific adsorption of proteins is a recurrent and challenging issue for biomaterial studies. Despite the initial incorporation of anti-fouling polyethylene glycol (PEG) chains within biomaterials, the residual non-specific BMP2 adsorption still triggered BMP2 signaling within the same range as conditions of interest. The various options are explored to prevent BMP2 non-specific adsorption and a successful blocking condition involving a combination of bovine serum albumin and trehalose are identified. Furthermore, the effect of this blocking step improved when using gold platforms instead of glass, particularly with Chinese hamster ovary (CHO) cells. With this specific example, it is suggested that non-specific adsorption of BMPs on biomaterials may be a general concern - often undetected by classical surface-sensitive techniques - that needs to be addressed to better interpret cellular responses.

Impact of protein fouling on electrochemistry of hyaluronic acid/curcumin/carbon nanotubes modified electrode: Toward electrochemical measurement of dopamine

Dopamine detection and concentration identification using electrochemical sensing technique is critically important for a wide range of disease diagnosis and monitoring. However, the sensitivity of electrochemical sensing can be significantly affected from the non-specific protein adsorption in biological fluid samples. In this study, we aim to creating a modified electrode with excellent resistance to protein fouling. Herein, we have developed an antifouling electrochemical dopamine sensing interface integrated hydrophilicity hyaluronic acid (HA) with curcumin/multi-walled carbon nanotubes (CM/MWCNTs) via a facile method. The HA integrated with CM/MWCNTs composites-based electrochemical sensor exhibited synergistic effects: (i) the abundant hydrophilic groups in the HA structure (water contact angle, 30.88°) facilitated the formation of a hydrated layer on the electrode surface to prevent fouling; (ii) CM/MWCNTs catalyzed the electrooxidation of dopamine; (iii) electrostatic interactions between the negatively charged HA/CM/MWCNTs and positively charged dopamine in neutral condition. The morphology and structure of the nanocomposite were characterized. The HA/CM/MWCNTs-modified electrode exhibited the improved hydrophilicity with a water contact angle of 30.92° and enhanced electrochemical response of the modified electrode for dopamine sensing in a variety of conditions with protein in the electrolyte. Moreover, the HA/CM/MWCNTs-modified sensor also exhibited superior dopamine analytical performance in human serum samples, with the dopamine detection accuracy approaching 97 % and be interference-free from proteins. The constructed electrochemical sensor presented great potential in dopamine detection in clinic setups.

A simple and efficient approach for preparing cationic coating with tunable electroosmotic flow for capillary zone electrophoresis-mass spectrometry-based top-down proteomics

BackgroundCapillary zone electrophoresis-tandem mass spectrometry (CZE-MS/MS) has become a valuable analytical technique in top-down proteomics (TDP). CZE-MS/MS-based TDP typically employs separation capillaries with neutral coatings (i.e., linear polyacrylamide, LPA). However, issues related to separation resolution and reproducibility remain with the LPA-coated capillaries due to the unavoidable non-specific protein adsorption onto the capillary wall. Cationic coatings can be critical alternatives to LPA coating for CZE-MS/MS-based TDP due to the electrostatic repulsion between the positively charged capillary inner wall and proteoform molecules in the acidic separation buffer. Unfortunately, there are only very few studies using cationic coating-based CZE-MS/MS for TDP studies. ResultsIn this work, we aimed to develop a simple and efficient approach for preparing separation capillaries with a cationic coating, i.e., poly (acrylamide-co-(3-acrylamidopropyl) trimethylammonium chloride [PAMAPTAC]) for CZE-MS/MS-based TDP. The PAMAPTAC coating-based CZE-MS produced significantly better separation resolution of proteoforms compared to the traditionally used LPA-coated approach. It achieved reproducible separation and measurement of a simple proteoform mixture and a complex proteome sample (i.e., a yeast cell lysate) regarding migration time, proteoform intensity, and the number of proteoform identifications. The PAMAPTAC coating-based CZE-MS enabled the detection of large proteoforms (≥30 kDa) from the yeast cell lysate reproducibly without any size-based prefractionation. Interestingly, the mobility of proteoforms using the PAMAPTAC coating can be predicted accurately using a simple semi-empirical model. SignificanceThe results render the PAMAPTAC coating as a valuable alternative to the LPA coating to advance CZE-MS-based TDP towards high-resolution separation and highly reproducible measurement of proteoforms in complex samples.

Endothelium-Inspired Hemocompatible Silicone Surfaces: An Elegant Balance between Antifouling Properties and Endothelial Cell Selectivity.

To address the adverse reactions caused by the implantation of blood-contacting materials, researchers have developed different strategies, of which mimicking multiple key features of endothelial cells is the most effective. However, simultaneously immobilizing multiple chemical components on a single material surface and maintaining the effects of individual components are challenging. In this work, endothelium-mimicking silicone surfaces were developed by incorporating the antifouling polymer poly(oligo(ethylene glycol) methacrylate), the glycosaminoglycan analog poly(sodium 4-vinyl-benzenesulfonate) and a nitric oxide catalyst (selenocystamine dihydrochloride). Through the rational regulation of multiple chemical components, the surfaces harmoniously resisted nonspecific protein adsorption, platelet adhesion and activation and smooth muscle cell hyperproliferation while promoting endothelial cell proliferation and migration. The coculture experiment with HUVECs and HUVSMCs showed that the optimum selectivity of HUVECs/HUVSMCs was ∼1.7. This work contributes insight into the control of antifouling properties and endothelial selectivity, providing a new avenue for the development of blood-contacting materials.

A Photothermal Polymeric Platform for Efficient and Safe Gene Transfection: When Polyethylenimine Collaborates with Indocyanine Green.

Gene transfection, defined by the delivery of nucleic acids into cellular compartments, stands as a crucial procedure in gene therapy. While branched polyethylenimine (PEI) is widely regarded as the "gold standard" for nonviral vectors, its cationic nature presents several issues, including nonspecific protein adsorption and notable cytotoxicity. Additionally, it often fails to achieve high transfection efficiency, particularly with hard-to-transfect cell types. To overcome these challenges associated with PEI as a vector for plasmid DNA (pDNA), the photothermal agent indocyanine green (ICG) is integrated with PEI and pDNA to form the PEI/ICG/pDNA (PI/pDNA) complex for more efficient and safer gene transfection. The negatively charged ICG serves a dual purpose: neutralizing PEI's excessive positive charges to reduce cytotoxicity and, under near-infrared irradiation, inducing local heating that enhances cell membrane permeability, thus facilitating the uptake of PI/pDNA complexes to boost transfection efficiency. Using pDNA encoding vascular endothelial growth factor as a model, our system shows enhanced transfection efficiency in vitro for hard-to-transfect endothelial cells, leading to improved cell proliferation and migration. Furthermore, in vivo studies reveal the therapeutic potential of this system in accelerating the healing of infected wounds by promoting angiogenesis and reducing inflammation. This approach offers a straightforward and effective method for gene transfection, showing potentials for tissue engineering and cell-based therapies.

Tumor targeting pH-triggered fluorescence-switchable hyaluronic acid-based micelles with aggregation-induced emission activity for tracing drug release and intelligent drug delivery

In this study, an amphiphilic polymer (Bio-HA(TPE-CN)-mPEG) was designed and synthesized, which was fabricated by introducing hydrophobic aggregation-induced emission (AIE) fluorophore, acid-labile imine bond, methoxy poly (ethylene glycol) (mPEG) and tumor targeting ligand biotin to the backbone of hyaluronic acid. The polymer could self-assemble into micelles and solubilize hydrophobic anticancer drugs. In vitro drug release study indicated that the micelles could disassemble rapidly under acidic environment. The involvement of biotin and HA could enhance the cellular uptake of micelles by tumor cells. Modification of micelles by mPEG could minimize non-specific protein adsorption. Fluorescence studies indicated that the micelles exhibited excellent AIE features and emitted intense long-wavelength fluorescence. More excitingly, the micelles were red emissive in the normal physiological environment, but switched to blue fluorescence in the acidic tumor environment, which could be further applied for real-time monitoring and quantification of the drug release. The in vivo antitumor efficacy study demonstrated the superior antitumor activity of the PTX-loaded micelles. The Bio-HA(TPE-CN)-mPEG micelles were promising drug carriers for chemotherapy and bioimaging.

Enzymatically Built Nanoenabled Antimicrobial Coating on Urinary Catheters.

Catheter-associated urinary tract infections represent a major share of nosocomial infections, and are associated with longer periods of hospitalization and a huge financial burden. Currently, there are only a handful of commercial materials that reduce biofilm formation on urinary catheters, mostly relying on silver alloys. Therefore, we combined silver-phenolated lignin nanoparticles with poly(carboxybetaine) zwitterions to build a composite antibiotic-free coating with bactericidal and antifouling properties. Importantly, the versatile lignin chemistry enabled the formation of the coating in situ, enabling both the nanoparticle grafting and the radical polymerization by using only the oxidative activity of laccase. The resulting surface efficiently prevented nonspecific protein adsorption and reduced the bacterial viability on the catheter surface by more than 2 logs under hydrodynamic flow, without exhibiting any apparent signs of cytotoxicity. Moreover, the said functionality was maintained over a week both in vitro and in vivo, whereby the animal models showed excellent biocompatibility.

In vitro biocompatibility analysis of protein-resistant amphiphilic polysulfobetaines as coatings for surgical implants in contact with complex body fluids.

The fouling resistance of zwitterionic coatings is conventionally explained by the strong hydrophilicity of such polymers. Here, the in vitro biocompatibility of a set of systematically varied amphiphilic, zwitterionic copolymers is investigated. Photocrosslinkable, amphiphilic copolymers containing hydrophilic sulfobetaine methacrylate (SPe) and butyl methacrylate (BMA) were systematically synthesized in different ratios (50:50, 70:30, and 90:10) with a fixed content of photo-crosslinker by free radical copolymerization. The copolymers were spin-coated onto substrates and subsequently photocured by UV irradiation. Pure pBMA and pSPe as well as the prepared amphiphilic copolymers showed BMA content-dependent wettability in the dry state, but overall hydrophilic properties a fortiori in aqueous conditions. All polysulfobetaine-containing copolymers showed high resistance against non-specific adsorption (NSA) of proteins, platelet adhesion, thrombocyte activation, and bacterial accumulation. In some cases, the amphiphilic coatings even outperformed the purely hydrophilic pSPe coatings.

A low fouling and high biocompatibility electrochemical sensor based on the electrospun gelatin‐PLGA‐CNTs nanofibers for dopamine detection in blood

AbstractThe ability to fabricate resisting nonspecific protein adsorption electrochemical sensor capable of high biocompatibility in vivo will undoubtedly underpin key future developments in life sciences. Herein, a gelatin‐poly(lactide‐co‐glycolide)‐carbon nanotubes nanofibers‐membrane in three‐dimensional porous structure without any chemical crosslinking is constructed on the carbon fiber microelectrode (e‐Gelatin‐PLGA‐CNTs/CFME) using a one‐step electrospinning technology. The nanofibers‐membrane still presents good three‐dimensional porous structure and excellent hydrophily after implantation in BSA solution. In addition, the dopamine hydrochloride (DA) sensitivity at e‐Gelatin‐PLGA‐CNTs/CFME after implantation in human blood samples exhibits almost the same as preimplantation (91% ± 9%, n = 3). Importantly, the nanofibers‐membrane possesses fast cell proliferation and a low hemolysis rate (2.27% ± 0.76%), satisfying the required biocompatibility as a constructed material for the detection in vivo. The constructed micro‐electrochemical sensor realizes the detection of DA in human blood samples. Consequently, this strategy offers a new and facile platform for the development of implanted electrochemical sensor.

Zwitterionic polymers grafting of metal organic framework encapsulated boronic acid carbon dots as antibiofouling fluorescent probe for baicalin monitoring

The sensitivity and accuracy of fluorescence probes for biological samples are affected by not only interfering molecule compounds but also the nonspecific adsorption of proteins and other macromolecules. Herein, fluorescence probe based on zwitterionic sulfobetaine methacrylate polymer (PSBMA) as an antibiofouling layer and amino boric acid carbon dots encapsulated in the metal-organic framework UiO-66-NH2 (UiO-66-NH2/BN-CDs) as a target recognition site was designed for the detection of baicalin (BAI). Owing to the introduction of BN-CDs into UiO-66-NH2 with high specific surface area, the prepared UiO-66-NH2/BN-CDs@PSBMA probe exhibited a high adsorption capacity of 78.9 mg g−1, while presented fluorescence enhancing and superior fluorescence selectivity to BAI at excitation and emission wavelengths of 400 and 425 nm, respectively. Connecting PSBMA with good hydrophilicity to UiO-66-NH2, resulted in an anti-protein capacity of over 96.3 %, effectively inhibiting protein interference with the fluorescence signal. By virtue of its good antibiofouling and recognizing capacities, the fluorescence probe exhibited a satisfactory detection range of 10–80 nmol L−1, with a fairly low detection limit of 0.0064 μmol L−1. Using the method to detect BAI in Goji berry, Sophora and Yinhuang oral solution, demonstrating its potential for the accurate and quantitative detection of BAI in complex biological samples.

Zwitterionic modification: A strategy to enhance the mechanical properties, lubricity and hemo- and biocompatibility of silicone poly(carbonate urethane urea)

Incorporating zwitterions into the blood-contacting materials has been demon-strated an effective and convenient strategy to minimize protein adsorption and platelet deposition, but is frequently detrimental to the mechanical properties. Herein a feeding 29.0 mol% sulfobetaine (SB) siloxane poly(carbonate urethane urea) (SSiPCUU) was synthesized and evaluated. Although the equilibrium water uptake ratio was increased to 1.20% markedly depressing the hydrolytic degradation resistance and mechanical properties after the zwitterionic modification, its maximum tensile stress and tear strength in the wet state still kept the highest among all the tested samples because the urea groups created therefrom gave rise to the formation of bifurcating hydrogen bonds making a significant contribution to the mechanical properties alongside the unique ion clusters formed from pendant SB species. As a consequence of zwitterionic incorporation, it exhibited an extremely low friction coefficient indicating an excellent lubricity in a wet environment without any post-treatment. Accordingly, both the nonspecific protein adsorption and platelet adhesion were evidently decreased. Moreover, it also depicted a good transparency. The high lubrication performance is desirable for lessening the damage to human blood vessels and a good transparency is favorable to the visualization of the flow of liquid in the catheter. These results illustrated the great potential of the zwitterionic SSiPCUU used in the preparation of balloon catheters, artificial blood vessels, stent coverings and other blood-contacting medical implants and devices.

Enhancing colloidal stability of nanodiamond via surface modification with dendritic molecules for optical sensing in physiological environments

Pre-treatment of diamond surface in low-temperature plasma for oxygenation and in acids for carboxylation was hypothesized to promote the branching density of the hyperbranched glycidol polymer. This was expected to increase the homogeneity of the branching level and suppress interactions with proteins. As a result, composite nanodiamonds with reduced hydrodynamic diameters that are maintained in physiological environments were anticipated. Surfaces of 140-nm-sized nanodiamonds were functionalized with oxygen and carboxyl groups for grafting of hyperbranched dendritic polyglycerol via anionic ring-opening polymerization of glycidol. The modification was verified with Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. Dynamic light scattering investigated colloidal stability in pH-diverse (2–12) solutions, concentrated phosphate-buffered saline, and cell culture media. Thermogravimetric analysis of nanodiamonds-protein incubations examined non-specific binding. Fluorescence emission was tested across pH conditions. Molecular dynamics simulations modeled interparticle interactions in ionic solutions. The hyperbranched polyglycerol grafting increased colloidal stability of nanodiamonds across diverse pH, high ionic media like 10 × concentrated phosphate-buffered saline, and physiological media like serum and cell culture medium. The hyperbranched polyglycerol suppressed non-specific protein adsorption while maintaining intensive fluorescence of nanodiamonds regardless of pH. Molecular modelling indicated reduced interparticle interactions in ionic solutions correlating with the improved colloidal stability.

Fabrication of dextran-grafted magnetic polymer microspheres with low nonspecific protein adsorption as carriers for chemiluminescence immunoassays

Inhibiting the nonspecific protein adsorption on the surface of magnetic microspheres has become a pressing challenge for immunoassays. In this paper, a novel dextran-modified sandwich-type magnetic polymer microsphere was developed and demonstrated to be a promising carrier for chemiluminescence immunoassay (CLIA). Dextran-modified sandwich-type magnetic polymer microspheres (PFS-PGDN) were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) and ring-opening reaction of epoxy and aminodextran on the surface of magnetic P(GMA-MMA)-NH2@Fe3O4@SiO2 (PFS) microspheres. Then, carboxylated dextran-modified sandwich-type magnetic polymer microspheres (PFS-PGDC) were prepared by the surface carboxylation of the microspheres, which allowed the prepared microspheres to better couple with nucleic acids or antibodies. It is found that after grafting dextran, magnetic PFS-PGDC microspheres could significantly reduce the nonspecific protein adsorption by over 90 %. The chemiluminescence immunoassay assay showed a reduction of the background value to a very low level, indicating that the magnetic spheres showed significant advantages in improving the sensitivity of the chemiluminescence assay. Moreover, the chemiluminescence sensitivity and signal values of the synthesized magnetic microspheres have reached high levels. Therefore, the magnetic microspheres synthesized here hold great promise for applications in the field of CLIA.

Fast-polymerized lubricant and antibacterial hydrogel coatings for medical catheters

Medical catheters are highly susceptible to friction and infection when intervening or implanting in the body, and to thrombosis when in contact with blood. Coating medical catheters with lubricant and antibacterial hydrogel is an effective strategy but struggle to achieve. Here, hydrogel coating on the catheter surface with lubrication and antibacterial properties was constructed by the rapid polymerization of acrylamide (AAM) and sulfobetaine methacrylate (SBMA) in the presence of quaternary ammonium chitosan (QCS) based on the redox-based cross-linking method. First, the medical catheter surface was decorated with a polyethyleneimine (PEI) adhesive layer. The pre-gel solution was then applied to the catheter surface, followed by immersion in an aqueous FeSO4·7H2O solution, where a large amount of SO4-• was generated by a redox reaction between ammonium persulfate (APS) and Fe2+, which rapidly triggered the monomer to cross-link to form the coating. Polyelectrolyte PEI as the adhesive layer could bind the coating to the substrate through hydrogen bonding interactions and confer antimicrobial properties to the coating with the assistance of QCS (antibacterial rate of 95.88 % against E. coli and 97.11 % against B. subtilis). The hydrogel coatings exhibited outstanding lubricity with a low coefficient of friction (COF ≈ 0.053) and excellent antifouling properties (resists non-specific protein adsorption, inhibits platelet adhesion and prevents thrombosis (The clotting time was extended from 25.6 s to 74.7 s)) based on the integration of SBMA. This work shed new light on the design of hydrogel coatings to achieve modification of the substrate surface.