Enhanced Interfacial H-Bond Networks Promote Glycan-Glycan Recognition and Interaction.

H-bond networks at heterogeneous interfaces play crucial roles in bioseparation, biocatalysis, biochip array profiling, and functional nanosystem self-assembly, but their precise modulation and enhancement remain challenging. In this study, we have discovered that interfacial hydrophobic hydration significantly enhances H-bond networks at the interface between a glycan-modified adsorbent and a methanol-water-acetonitrile ternary solution. The enhanced H-bond networks greatly promote the adsorbent-solution heterogeneous glycan-glycan recognition and interaction. This novel hydrophobic hydration-enhanced hydrophilic interaction (HEHI) strategy improves the affinity and efficiency of intact glycopeptide enrichment. Compared with the commonly used hydrophilic-interaction enrichment strategy, 23.5 and 48.5% more intact N- and O-glycopeptides are identified, and the enrichment recoveries of half of the glycopeptides are increased >100%. Further, in-depth profiling of both N- and O-glycosylation occurring on SARS-CoV-2 S1 and hACE2 proteins has been achieved with more glycan types and novel O-glycosylation information involved. Interfacial hydrophobic hydration provides a powerful tool for the modulation of hydrophilic interactions in biological systems.

Combining Topography and Chemistry to Produce Antibiofouling Surfaces: A Review.

Despite decades of research on the reduction of surface fouling from biomolecules or micro-organisms, the ultimate antibiofouling surface remains undiscovered. The recent covid-19 pandemic strengthened the crucial need for such treatments. Among the numerous approaches that are able to provide surfaces with antibiofouling properties, chemical, biological, and topographical strategies have been implemented for instance in the marine, medical, or food industries. However, many of these methods have a biocidal effect and, with antibioresistance and biocide resistance a growing threat on humanity, strategies based on reducing adsorption of biomolecules and micro-organism are necessary for long-term solutions. Bioinspired strategies, combining both surface chemistry and topography, are currently at the heart of the best innovative and sustainable solutions. The synergistic effect of micro/nanostructuration, together with engineered chemical or biological functionalization is believed to contribute to the development of antibiofouling surfaces. This review aims to present approaches combining hydrophobic or hydrophilic chemistries with a specific topography to avoid biofouling in various industrial environments and healthcare facilities.

Synthesis, Pharmacokinetic Characterization and Antioxidant Capacity of Carotenoid Succinates and Their Melatonin Conjugates.

Carotenoid succinates were synthesized from hydroxy carotenoids and were coupled to a commercially available derivative of melatonin via amide bond for producing more powerful anti-oxidants and yet new hybrid lipophilic bifunctional molecules with additional therapeutic effects. The coupling reactions produced conjugates in acceptable to good yields. Succinylation increased the water solubility of the carotenoids, while the conjugation with melatonin resulted in more lipophilic derivatives. The conjugates showed self-assembly in aqueous medium and yielded relatively stable colloidal solutions in phosphate-buffered saline. Antioxidant behavior was measured with ABTS and the FRAP methods for the carotenoids, the carotenoid succinates, and the conjugates with melatonin. A strong dependence on the quality of the solvent was observed. TEAC values of the new derivatives in phosphate-buffered saline were found to be comparable to or higher than those of parent carotenoids, however, synergism was observed only in FRAP assays.

Hybrid polymer/ionic liquid electrospun membranes with tunable surface charge for virus capture in aqueous environments

Although electrospun-based membranes may be engineered as efficient platforms for the capture of biomolecules in aqueous environments, the capability of such membranes to selectively capture viruses and proteins is often limited due to poor and constrained surface affinity for molecular bonding. In order to generate more efficient electrospun-based membranes, fine-tuning Van der Waals and ionic interactions is required to control chemical affinities with such contaminants and support advanced remediation solutions. Here, diallydimethylammonium chloride and poly(acrylonitrile) electrospun nanofibres were developed to enhance the adsorption of specific contaminant molecules compared to equivalently shaped pristine poly(acrylonitrile) nanofibre membranes. The results showed that the incorporation of the ionic liquid improved contact with water by forming super-hydrophilic nanofibres with narrow diameters and smaller pore size distributions, while also significantly changing the surface charge of the material and shifting the isoelectric point of the surface from 3 to 4.4. The specific surface area of the membranes was also increased by up to 4 times upon ionic liquid loading, which was found to support efficient coronavirus capture and filtration efficiency. This new strategy represents a promising way to control surface properties of virus filtration membranes towards efficient and targeted remediation solutions.

Adopting Intrinsic Hydrophilic Thermoplastic Starch Composites to Fabricate Antifogging Sustainable Films with High Antibiosis and Transparency

Fogging on transparent surfaces such as goggles causes a series of hazards to users. To fabricate antifogging and low-haze transparent renewable polymer materials, intrinsic hydrophilicity with high water adsorption capability of thermoplastic starch (TPS) had been adopted. Strikingly, when benzoic acid (BA) was blended with thermoplastic starch (TPS-BA), the haze of TPS-BA was only 7.8% when it suffered the cold and warm method of antifogging measurement with 87% transmittance. Simultaneously, TPS-BA achieved an 18 mm inhibition zone for Staphylococcus aureus. To reveal the antifogging mechanism of TPS-BA films, the surficial and interior structure features were evaluated by three-dimensional optical scanner, scanning electron microscopy (SEM), contact angle testing, small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), temperature-dependent Fourier transform infrared (FTIR), dynamic mechanical analysis (DMA), and so on. The incorporation of BA resulted in the roughness (Rq), water contact angle (WCA), and crystallinity of the TPS-BA film decreasing from 6.5 to 0.68 μm, 65.1 to 39.9°, and 13.6 to 6.3%, respectively. The amorphous matrix and smooth surface reduced the scattered light, allowing the TPS-BA film to achieve low haze performance and high transmittance. Importantly, the diversified and weakened hydrogen bonds formed among starch, BA, and glycerol could inhibit the formation of starch crystalline regions and allowed hydroxyl groups to quickly bond with water. Thus, when TPS-BA is placed in a high-humidity surrounding, an "expressway"is constructed for water molecules diffusing into the TPS-BA matrix. This novel low-haze, antifogging, sustainable, and facilely fabricated TPS with antibacterial properties is a promising candidate in disposable medical goggles to fight against COVID-19. © 2021 American Chemical Society. All rights reserved.

Comprehensive Characterization of PVDF Nanofibers at Macro- and Nanolevel.

This study is focused on the characterization and investigation of polyvinylidene fluoride (PVDF) nanofibers from the point of view of macro- and nanometer level. The fibers were produced using electrostatic spinning process in air. Two types of fibers were produced since the collector speed (300 rpm and 2000 rpm) differed as the only one processing parameter. Differences in fiber's properties were studied by scanning electron microscopy (SEM) with cross-sections observation utilizing focused ion beam (FIB). The phase composition was determined by Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. The crystallinity was determined by differential scanning calorimetry (DSC), and chemical analysis of fiber's surfaces and bonding states were studied using X-ray photoelectron spectroscopy (XPS). Other methods, such as atomic force microscopy (AFM) and piezoelectric force microscopy (PFM), were employed to describe morphology and piezoelectric response of single fiber, respectively. Moreover, the wetting behavior (hydrophobicity or hydrophilicity) was also studied. It was found that collector speed significantly affects fibers alignment and wettability (directionally ordered fibers produced at 2000 rpm almost super-hydrophobic in comparison with disordered fibers spun at 300 rpm with hydrophilic behavior) as properties at macrolevel. However, it was confirmed that these differences at the macrolevel are closely connected and originate from nanolevel attributes. The study of single individual fibers revealed some protrusions on the fiber's surface, and fibers spun at 300 rpm had a core-shell design, while fibers spun at 2000 rpm were hollow.

In-solution buffer-free digestion allows full-sequence coverage and complete characterization of post-translational modifications of the receptor-binding domain of SARS-CoV-2 in a single ESI-MS spectrum.

Subunit vaccines based on the receptor-binding domain (RBD) of the spike protein of SARS-CoV-2 provide one of the most promising strategies to fight the COVID-19 pandemic. The detailed characterization of the protein primary structure by mass spectrometry (MS) is mandatory, as described in ICHQ6B guidelines. In this work, several recombinant RBD proteins produced in five expression systems were characterized using a non-conventional protocol known as in-solution buffer-free digestion (BFD). In a single ESI-MS spectrum, BFD allowed very high sequence coverage (≥ 99%) and the detection of highly hydrophilic regions, including very short and hydrophilic peptides (2-8 amino acids), and the His6-tagged C-terminal peptide carrying several post-translational modifications at Cys538 such as cysteinylation, homocysteinylation, glutathionylation, truncated glutathionylation, and cyanylation, among others. The analysis using the conventional digestion protocol allowed lower sequence coverage (80-90%) and did not detect peptides carrying most of the above-mentioned PTMs. The two C-terminal peptides of a dimer [RBD(319-541)-(His)6]2 linked by an intermolecular disulfide bond (Cys538-Cys538) with twelve histidine residues were only detected by BFD. This protocol allows the detection of the four disulfide bonds present in the native RBD, low-abundance scrambling variants, free cysteine residues, O-glycoforms, and incomplete processing of the N-terminal end, if present. Artifacts generated by the in-solution BFD protocol were also characterized. BFD can be easily implemented; it has been applied to the characterization of the active pharmaceutical ingredient of two RBD-based vaccines, and we foresee that it can be also helpful to the characterization of mutated RBDs.

Determination of Antiviral Drugs and Their Metabolites Using Micro-Solid Phase Extraction and UHPLC-MS/MS in Reversed-Phase and Hydrophilic Interaction Chromatography Modes.

Two new ultra-high performance liquid chromatography (UHPLC) methods for analyzing 21 selected antivirals and their metabolites were optimized, including sample preparation step, LC separation conditions, and tandem mass spectrometry detection. Micro-solid phase extraction in pipette tips was used to extract antivirals from the biological material of Hanks balanced salt medium of pH 7.4 and 6.5. These media were used in experiments to evaluate the membrane transport of antiviral drugs. Challenging diversity of physicochemical properties was overcome using combined sorbent composed of C18 and ion exchange moiety, which finally allowed to cover the whole range of tested antivirals. For separation, reversed-phase (RP) chromatography and hydrophilic interaction liquid chromatography (HILIC), were optimized using extensive screening of stationary and mobile phase combinations. Optimized RP-UHPLC separation was carried out using BEH Shield RP18 stationary phase and gradient elution with 25 mmol/L formic acid in acetonitrile and in water. HILIC separation was accomplished with a Cortecs HILIC column and gradient elution with 25 mmol/L ammonium formate pH 3 and acetonitrile. Tandem mass spectrometry (MS/MS) conditions were optimized in both chromatographic modes, but obtained results revealed only a little difference in parameters of capillary voltage and cone voltage. While RP-UHPLC-MS/MS exhibited superior separation selectivity, HILIC-UHPLC-MS/MS has shown substantially higher sensitivity of two orders of magnitude for many compounds. Method validation results indicated that HILIC mode was more suitable for multianalyte methods. Despite better separation selectivity achieved in RP-UHPLC-MS/MS, the matrix effects were noticed while using both chromatographic modes leading to signal enhancement in RP and signal suppression in HILIC.

Synthesis of a novel anti-fog and high-transparent coating with high wear resistance inspired by dry rice fields.

During the outbreak of COVID-19, the fogging of goggles was a fatal problem for doctors. At present, there are many ways to prevent fogging by adjusting surface wettability. However, the mechanical properties of most super-hydrophilic antifogging coatings are poor, easy to lose their antifogging properties when encountering fingers or cloth friction. To address this issue, the Konjac Glucomannan was cross-linked with water-soluble silicone fluid to form a binder, then being combined with the modified Ecokimera to prepare an eco-friendly super-hydrophilic coating that possessed excellent super-hydrophilicity, and the water contact angle (WCA) was 2.51 ± 1°. In addition, the WCA is still about 5° after 180 times of antifogging tests. The friction resistance of the coating was as high as 24 m. Moreover, the light transmittance was only reduced by 3%. Besides, they also had the excellent self-cleaning property. After being stored in the laboratory environment for 90 days, it can still maintain the hydrophilic property (WCA is about 5°). In general, the method proposed in this study is low-cost and eco-friendly, and can be widely used in the preparation of antifogging coatings.