Development of boronic acid-functionalized mesoporous silica-coated core/shell magnetic microspheres with large pores for endotoxin removal

In Situ Preparation of Star-Shaped Protein-"Smart" Polymer Conjugates with pH and Thermo-Dual Responsibility for Bacterial Separation

To achieve effective separation and enrichment of bacteria, a novel synthetic scheme was developed to synthesize star-style boronate-functionalized copolymers with excellent hydrophilicity and temperature and pH responsiveness. A hydrophilic copolymer brush was synthesized by combining surface-initiated atom-transfer radical polymerization with amide reaction using bovine serum albumin as the core. The copolymer brush was further modified by introducing and immobilizing fluorophenylboronic acids through an amide reaction, resulting in the formation of boronate affinity material BSA@poly(NIPAm-co-AGE)@DFFPBA. The morphology and organic content of BSA@poly(NIPAm-co-AGE)@DFFPBA were systematically characterized. The BSA-derived composites demonstrated a strong binding capacity to both Gram-positive and Gram-negative bacteria. The binding capabilities of the affinity composite to Staphylococcus aureus and Salmonella spp. were 195.8 × 1010 CFU/g and 79.2 × 1010 CFU/g, respectively, which indicates that the novel composite exhibits a high binding capability to bacteria and shows a particularly more significant binding capacity toward Gram-positive bacteria. The bacterial binding of BSA@poly(NIPAm-co-AGE)@DFFPBA can be effectively altered by adjusting the pH and temperature. This study demonstrated that the star-shaped affinity composite had the potential to serve as an affinity material for the rapid separation and enrichment of bacteria in complex samples.

Enrichment of sialic acid-containing casein glycomacropeptide in protein hydrolysates using phenylboronic acid-functionalized mesoporous silica nanoparticles

Glycomacropeptide (GMP) is a bioactive peptide of high value, rich in glycosylation sites and with physiological and dietary therapeutic value. The enrichment and detection of GMP facilitates the accurate quantification and the identification of adulteration of GMP in food products. In GMP, sialic acid is an abundant glycosyl group and is mainly located at the end of the sugar chain. Here, we propose a novel GMP enrichment strategy based on the affinity of sialic acid for phenylboronic acid groups that shift with environmental pH. As an enrichment material, mesoporous silica nanoparticles were progressively modified with aminopropyl and phenylboronic acid groups. The developed material showed excellent selectivity for sialic acid in the presence of galactose and fucose as interferents. The adsorption behavior of sialic acid-containing GMP fits the Langmuir adsorption model, offering a recovery of 71.72% (in terms of sialic acid content) and a GMP relative purity of 0.957. Results from sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography confirm that the enriched GMP contains almost no other unexpected proteins and peptides, indicating that the developed strategy holds promise for purifying GMP in various dairy systems.

Preparation and application of UPLC silica microsphere stationary phase:A review

In this review, microspheres for ultra-performance liquid chromatography (UPLC) were reviewed in accordance with the literature in recent years. As people's demands for chromatography are becoming more and more sophisticated, the preparation and application of UPLC stationary phases have become the focus of researchers in this field. This new analytical separation science not only maintains the practicality and principle of high-performance liquid chromatography (HPLC), but also improves the step function of chromatographic performance. The review presents the morphology of four types of sub-2 μm silica microspheres that have been used in UPLC, including non-porous silica microspheres (NPSMs), mesoporous silica microspheres (MPSMs), hollow silica microspheres (HSMs) and core-shell silica microspheres (CSSMs). The preparation, pore control and modification methods of different microspheres are introduced in the review, and then the applications of UPLC in drug analysis and separation, environmental monitoring, and separation of macromolecular proteins was presented. Finally, a brief overview of the existing challenges in the preparation of sub-2 μm microspheres, which required further research and development, was given.

Design of AgNPs doped chitosan/sodium lignin sulfonate/polypyrrole films with antibacterial and endotoxin adsorption functions

There is an urgent need to develop materials to prevent bacterial infection and the deleterious effects of endotoxins. In this study, we introduce a one-step electrodeposition method to prepare films composed of chitosan/Ag/polypyrrole and layer-by-layer self-assembly to introduce lignin sulphonate (LS) to obtain chitosan/Ag/polypyrrole/LS films. Antibacterial effects against both E. coli and S. aureus are shown by bacterial growth profiles and observation of bacteriostatic zones. Meanwhile, the addition of self-assembled LS improved the antibacterial effect of the film. For E. coli, the inhibition zone diameter was 0.93 cm, while for S. aureus, the inhibition zone diameter was 0.72 cm. Rapid and efficient endotoxin adsorption effects were shown whereby the electrostatic interactions between chitosan and endotoxin molecules played a major role. After adsorption for 1 h, in initial concentration of 1 EU/mL endotoxin solution, the adsorption efficiency could reach up to 85 %, while in initial concentration of 5 EU/mL endotoxin solution, the adsorption efficiency could reach up to 87.6 %. The results suggest chitosan/Ag/polypyrrole/LS films for their capability as a new type of antibacterial film with intrinsic endotoxin adsorption activity.

Advances in the Development of Biomaterials for Endotoxin Adsorption in Sepsis

Sepsis, a life-threatening and intractable disease without any specific treatment, is activated by endotoxin. Some attempts at removing endotoxin to treat sepsis from the blood circulation using different hemoperfusion cartridges have been proposed recently, but they have failed to reduce the mortality of severe septic patients. This review summarizes the latest advances in the development of endotoxin adsorbents. In particular, we highlight two critical parameters for endotoxin adsorbents when they are applied in blood purification: the dissociation constant and the maximum adsorption capacity. We also discuss potential challenges and research directions for the future development of endotoxin adsorbents.

Boronic Acid Functionalized Nanosilica for Binding Guest Molecules

Dendritic fibrous nanosilica (DFNS) has very high surface area and well-defined nanochannels; therefore, it is very useful as supporting material for numerous applications including catalysis, sensing, and bioseparation. Due to the highly restricted space, addition of molecular ligands to DFNS is very challenging. This work studies how ligand conjugation in nanoscale pores in DFNS can be achieved through copper-catalyzed click reaction, using an optional, in situ synthesized, temperature-responsive polymer intermediate. A clickable boronic acid is used as a model to investigate the ligand immobilization and the molecular binding characteristics of the functionalized DFNS. The morphology, composition, nanoscale pores, and specific surface area of the boronic acid functionalized nanosilica were characterized by electron microscopy, thermogravimetric and elemental analysis, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption measurements. The numbers of boronic acid molecules on the modified DFNS with and without the polymer were determined to be 0.08 and 0.68 mmol of ligand/g of DFNS, respectively. We also studied the binding of small cis-diol molecules in the nanoscale pores of DFNS. The boronic acid modified DFNS with the polymer intermediate exhibits higher binding capacity for Alizarin Red S and nicotinamide adenine dinucleotide than the polymer-free DFNS. The two types of boronic acid modified DFNS can bind small cis-diol molecules in the presence of large glycoproteins, due in large part to the effect of size exclusion provided by the nanochannels in the DFNS.