Construction of a stable zwitterionic layer on negatively-charged membrane via surface adsorption and cross-linking

Parallel Monitoring of Glucose, Free Amino Acids, and Vitamin C in Fruits Using a High-Throughput Paper-Based Sensor Modified with Poly(carboxybetaine acrylamide)

Herein, a cost-effective and portable microfluidic paper-based sensor is proposed for the simultaneous and rapid detection of glucose, free amino acids, and vitamin C in fruit. The device was constructed by embedding a poly(carboxybetaine acrylamide) (pCBAA)-modified cellulose paper chip within a hydrophobic acrylic plate. We successfully showcased the capabilities of a filter paper-based microfluidic sensor for the detection of fruit nutrients using three distinct colorimetric analyses. Within a single paper chip, we simultaneously detected glucose, free amino acids, and vitamin C in the vivid hues of cyan blue, purple, and Turnbull's blue, respectively, in three distinctive detection zones. Notably, we employed more stable silver nanoparticles for glucose detection, replacing the traditional peroxidase approach. The detection limits for glucose reached a low level of 0.049 mmol/L. Meanwhile, the detection limits for free amino acids and vitamin C were found to be 0.236 mmol/L and 0.125 mmol/L, respectively. The feasibility of the proposed sensor was validated in 13 different practical fruit samples using spectrophotometry. Cellulose paper utilizes capillary action to process trace fluids in tiny channels, and combined with pCBAA, which has superior hydrophilicity and anti-pollution properties, it greatly improves the sensitivity and practicality of paper-based sensors. Therefore, the paper-based colorimetric device is expected to provide technical support for the nutritional value assessment of fruits in the field of rapid detection.

Influence of UV-irradiation intensity and exposure duration on the hemobiocompatibility enhancement of a novel synthesized phosphobetaine zwitterions polyethersulfone clinical hemodialysis membranes

To improve the biocompatibility of polyethersulfone (PES) membranes utilized for biomedical hemodialysis (HD) applications, surface grafting with hydrophilic polymers has become a reliable modification strategy. Like most photochemical catalyzed reactions, UV-assisted grafting is distinctly advantageous for inducing permanent surface chemistry, enhancing hydrophilicity, improving morphology, and surface charge of membranes. PES membranes may be hydrophilic and chemically stable; however, they also have low protein-binding capacity and very susceptible to fouling and target analyte binding. In this study, novel zwitterionic polymers (PVP-ZW) have been synthesized by UV-assisted grafting PVP to a phosphobetaine monomer in a reaction involving dimethylamino and dioxaphospholane-2-oxide terminal groups in an NVP monomer solution at varying UV exposure conditions. The highlight of the present study is the investigation of the hemocompatibility of coated PES HD membranes at varying UV exposure conditions with respect to membrane chemistry and morphology and its influence on human serum protein adsorption. A clinical investigation of inflammatory biomarker release from incubated coated membranes within uremic blood samples of HD patients reveals they are weak complement and coagulation activators compared to bare PES membrane. The trend of fibrinogen adsorption on coated PES membranes was observed to increase with reducing UV intensity and exposure duration. Fibrinogen adhesion only increased with roughened membrane surfaces, and this also led to the formation of biological activation pathways hindering biocompatibility. Resistance against fibrinogen absorption on zwitterionic modified PES membrane could be linked with the creation of electrostatically induced neutral zwitterionic PVP-phosphobetaine hydration layer with hydrophilic character. Experimental results are accompanied by spectroscopic and morphological imaging evidence. Zwitterion coated PES membranes (PES-PVP-ZW) fabricated from higher UV intensities through longer exposure durations showed significant presence of surface deformations in the forms of inherent exfoliations due to harsh UV reaction conditions. The zeta potential and surface roughness of coated membranes also played significant role in the fibrinogen adsorption on PES membranes during ultrafiltration.

Biomimetic surface coatings for marine antifouling: Natural antifoulants, synthetic polymers and surface microtopography

Marine biofouling is a ubiquitous problem that accompanies human marine activities and marine industries. It exerts detrimental impacts on the economy, environment, ecology, and safety. Traditionally, mainstream approaches utilize metal ions to prevent biological contamination, but this also leads to environmental pollution and damage to the ecosystem. Efficient and environmentally friendly coatings are urgently needed to prevent marine devices from biofouling. Since nature is always the best teacher for humans, it offers us delightful thoughts on the research and development of high-efficiency, broad-spectrum and eco-friendly antifouling coatings. In this work, we focus on the research frontier of marine antifouling coatings from a bionic perspective. Enlightened by three distinctive dimensions of bionics: chemical molecule bionic, physiological mechanism bionic, and physical structure bionic, the research status of three main bioinspired strategies, which are natural antifoulants, bioinspired polymeric antifouling coatings, and biomimetic surface microtopographies, respectively, are demonstrated. The antifouling mechanisms are further interpreted based on biomimetic comprehension. The main fabrication methods and antifouling performances of these coatings are presented along with their advantages and drawbacks. Finally, the challenges are summarized, and future research prospects are proposed. It is believed that biomimetic antifouling strategies will contribute to the development of nontoxic antifouling techniques with exceptional repellency and stability.