Preparation of a novel polyethyleneimine functionalized sepharose-boronate affinity material and its application in selective enrichment of food borne pathogenic bacteria

pH-responsive magnetic graphene oxide composite as an adsorbent with high affinity for rapid capture of nucleosides

A novel pH-responsive magnetic graphene oxide composite (MGO@PEI-BA) is proposed for the first time as an adsorbent for the rapid capture and detection of nucleosides (cytidine, uridine, guanosine, and adenosine). The morphology, structure, and magnetic properties of the composite were evaluated using various characterization techniques. The results indicated that the composite was successfully fabricated. A series of parameters that affect extraction and elution were optimized through one-factor-at-a-time and Box-Behnken design of response surface methodology (BBD-RSM). The unique layered structures and easily accessible active sites of the composite facilitated molecular transport, resulting in instantaneous equilibrium of nucleosides adsorption within 5 min. Based on this study, a magnetic dispersive micro-solid-phase extraction (MD-μ-SPE) method assisted by the MGO@PEI-BA was developed in combination with UHPLC-UV analysis for the determination of nucleosides in rat urine. Under the optimum conditions, a wide linear range (10-2000 ng mL-1), good linearity (r > 0.99), low detection limits (1-3 ng mL-1), low relative standard deviations (RSDs ≤ 3.9%), and satisfactory recoveries (82.7-96.3%) were achieved. These results demonstrate that the MGO@PEI-BA is an excellent adsorbent for extracting nucleosides from biological samples.

Hierarchical Macroporous Agarose Materials with Polyethyleneimine-Assisted Multiple Boronate Affinity Binding Sites for the Separation of Neomycin

Quantification of neomycin residues in food samples demands an efficient purification platform. Herein, hierarchical macroporous agarose monoliths with multiple boronate affinity sites were established for selective separation of neomycin. The silica core was synthesized by "one-step" Stöber procedures followed by modification with amino group and incorporation of polyethyleneimine. A versatile macroporous agarose monolith was prepared by emulsification strategies and functionalized with epoxy groups. After introducing polyethyleneimine-integrated silica nanoparticles onto the agarose monolith, fluorophenylboronic acids were immobilized. The physical and chemical characteristics of the composite monolith were analyzed systematically. After optimization, neomycin showed high binding ability of 23.69 mg/g, and the binding capacity can be manipulated by changing the pH and adding monosaccharides. The composite monolith was subsequently utilized to purify neomycin from the spiked model aquatic products followed by high-performance liquid chromatography analysis, which revealed a remarkable neomycin purification effect, indicating the great potential in the separation of neomycin from complicated aquatic products.

Composite Hydrogel for the Targeted Capture and Photothermal Killing of Bacteria toward Facilitating Wound Healing

Pathogenic infections pose a significant risk to public health and are regarded as one of the most difficult clinical treatment obstacles. A reliable and safe photothermal antibacterial platform is a promising technique for the treatment of bacterial infections. Given the damage that high temperatures cause in normal tissues and cells, a multifunctional hydrogel driven by photothermal energy is created by trapping bacteria to reduce heat transfer loss and conduct low-temperature photothermal sterilization efficiently. The 3-aminobenzene boronic acid (ABA)-modified graphene oxide is combined with carboxymethyl chitosan (CMCS) and cellulose nanocrystalline (CNC) networks to create the ABA-GO/CNC/CMCS composite hydrogel (composite gel). The obtained composite gel displays a uniform three-dimensional network structure, which can be rapidly heated to 48 °C under infrared light irradiation and is beneficial for killing wound infection bacteria and promoting wound healing. The results of animal experiments show that the composite gel significantly reduces inflammation by killing >99.99% of bacteria under near-infrared light irradiation. The result also demonstrates that it increases the granulation tissue thickness and collagen distribution and promotes wound healing. After treatment for 14 days, compared with the remaining 27.73% of the remaining wound area in the control group, the wound area in the composite gel with NIR group is only 0.91%. It significantly accelerates the wound healing process of Staphylococcus aureus infection and shows great potential for clinical application.

Rapid and Sensitive Fluorescence Detection of Staphylococcus aureus Based on Polyethyleneimine-Enhanced Boronate Affinity Isolation

There are increasing demands for fast and simple detection of pathogens in foodstuffs. Fluorescence analysis has demonstrated significant advantages for easy operation and high sensitivity, although it is usually hindered by a complex matrix, low bacterial abundance, and long-term bacterial enrichment. Effective enrichment procedures are required to meet the requirements for food detection. Here, boronate-functionalized cellulose filter paper and specific fluorescent probes were combined. An integrated approach for the enrichment of detection of Staphylococcus aureus was proposed. The modification of polyethyleneimine demonstrated a significant effect in enhancing the bacterial enrichment, and the boronate affinity efficiency of the paper was increased by about 51~132%. With optimized conditions, the adsorption efficiency for S. aureus was evaluated as 1.87 × 10⁸ CFU/cm², the linear range of the fluorescent analysis was 10⁴ CFU/mL~10⁸ CFU/mL (R² = 0.9835), and the lowest limit of detection (LOD) was calculated as 2.24 × 10² CFU/mL. Such efficiency was validated with milk and yogurt samples. These results indicated that the material had a high enrichment capacity, simple operation, and high substrate tolerance, which had the promising potential to be the established method for the fast detection of food pathogens.

Preparation of nickel-chelated iminodiacetate-functionalized macroporous agarose monolith using modular and clickable building blocks for affinity separation of histidine-tagged recombinant proteins

Selective separation and purification of protein from complex medium is required to completely investigate the structure and function of the target protein. In this study, a composite macroporous agarose monolith containing iminodiacetate-chelated Ni²⁺ ligands was synthesized for selective separation and purification of histidine-tagged recombinant proteins. The large and interconnected pores in the monolith enabled fast binding of proteins with high matrix tolerance in treating complex mediums. To realize the selective protein binding, the iminodiacetate was directly conjugated to epoxy-functionalized agarose monolith via simple chemical reactions between epoxy and imino groups. After chelated Ni²⁺, the composite monolith could bind histidine-tagged recombinant proteins through the coordination interaction between transition metal ions and the imidazole ring of histidine. To further increase the binding capacities of the monolith, a hydrophilic intermediate polymer chain containing multiple iminodiacetate immobilization sites was conjugated to the azide-functionalized agarose monolith via Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The morphology and chemical composition of the composite agarose monolith were characterized systematically. The protein binding capacities of the obtained composite agarose monolith were subsequently investigated. The binding capacities of the composite agarose monolith towards the model proteins Gp10 and Lys84 were 0.93 and 0.51 mg/mL, respectively. The protein binding of the composite agarose monolith could be manipulated by adjusting the temperature and concentrations of imidazole. These results demonstrate that the composite agarose monolith could be used as an affinity medium for rapid separation and purification of histidine-tagged recombinant proteins from biological samples.

Fabrication of copolymer brushes grafted superporous agarose gels: Towards the ultimate ideal particles for efficient affinity chromatography

A composite immobilized-metal affinity agarose particle was designed for the selective separation and purification of histidine-tagged proteins from complicated biological samples. The composite particle was constructed using superporous agarose particles as supporting matrix, flexible copolymer brushes as scaffolds to render higher ligand densities, and Ni²⁺-chelated iminodiacetic acids as recognition elements. Superporous agarose composite particles endow high permeability and interfering substance tolerance. The copolymer brush was prepared by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide and glycidyl methacrylate, followed by iminodiacetic acids and Ni²⁺ ions. The physical and chemical properities of the composite particle were thoroughly investigated. The composite particles were shown to be able to selectively separate histidine-tagged recombinant proteins in the presence of high quantities of interfering chemicals in a model protein-binding experiment. By altering the temperature, the protein binding of the composite particles can be modulated. The superporous agarose particles supported polymer brush enables fast and efficient separation and purification of target proteins with high permeability, low backpressure, and high interfering matrix tolerance, which pave the path for bioseparation through designing and fabrication of novel agarose particles-based functional materials.

Boronate-modified polyethyleneimine dendrimer as a solid-phase extraction adsorbent for the analysis of luteolin via HPLC

Luteolin (LTL) is a flavonoid containing a cis-diol, which has significant anti-inflammatory, anti-allergic, anti-diabetic, anti-cancer and neuroprotective activities. In this work, a silver modified boric acid affinity polyvinyl imine (PEI) dendritic adsorbent (PPEI-Ag@CPBA) was prepared on polystyrene (PS) for the rapid recognition and selective separation of LTL. A thin layer of polydopamine (PDA) was formed on the surface of the substrate by self-polymerization, and a PDA-coated PS material (PS@PDA) was obtained. PEI with sufficient active amino groups was grafted onto PS@PDA to obtain a PEI-modified material (PS@PDA@PEI), then AgNO3 was reduced with NaBH4, and PS@PDA@PEI was embedded on Ag. Finally, PPEI-Ag@CPBA was obtained through the condensation reaction of PEI with 4-carboxyphenyl boric acid (CPBA). The adsorption conditions were optimized, the optimal pH and the optimum amount of adsorbent were determined, and the maximum adsorption capacity was found to be 2.49 mg g-1. This method has been successfully applied to the selective identification of LTL in peanut shell samples, and provides a practical platform for the detection of LTL in complex substrates.

Tailor-made magnetic nanocomposite with pH and thermo-dual responsive copolymer brush for bacterial separation

Rapid detection of pathogenic bacteria particularly in food samples demands efficient separation and enrichment strategies. Here, hydrophilic temperature-responsive boronate affinity magnetic nanocomposites were established for selective enrichment of bacteria. The thermo-responsive polymer brushes were developed by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide (NIPAm) and allyl glycidyl ether (AGE), followed by a reaction of epoxy groups, and incorporation of fluorophenylboronic acid. The physical and chemical characteristics of the magnetic nanocomposites were analyzed systematically. After optimization, S. aureus and Salmonella spp. showed high binding capacities of 32.14 × 10⁶ CFU/mg and 50.98 × 10⁶ CFU/mg in 0.01 M PBS (pH 7.4) without bacteria death. Bacterial bindings can be controlled by altering temperature and the application of competing monosaccharides. The nanocomposite was then utilized to enrich S. aureus and Salmonella spp. from the spiked tap water, 25% milk, and turbot extraction samples followed by multiplex polymerase chain reaction (mPCR), which resulted in high bacteria enrichment, and demonstrated great potential in separation of bacteria from food samples.

Recent trends in sorbents for bioaffinity chromatography

Isolation or enrichment of biological molecules from complex biological samples is mostly a prerequisite in proteomics, genomics, and glycomics. Different techniques have been used to advance the efficiency of the purification of biological molecules. Bioaffinity chromatography is one of the most powerful technique that plays an important role in the isolation of target biological molecules by the specific interactions with ligands that are immobilized on different support materials. This review examines the recent developments in bioaffinity chromatography particularly over the past 5 years in the literature. Also properties of supports, immobilization techniques, types of binding agents, and methods used in bioaffinity chromatography applications are summarized.

Preparation of Boronic Acid-Functionalized Cryogels Using Modular and Clickable Building Blocks for Bacterial Separation

Composite cryogels containing boronic acid ligands are synthesized for effective separation and isolation of bacteria. The large and interconnected pores in cryogels enable fast binding and release of microbial cells. To control bacterial binding, an alkyne-tagged boronic acid ligand is conjugated to azide-functionalized cryogel via the Cu(I)-catalyzed azide-alkyne cycloaddition reaction. The boronic acid-functionalized cryogel binds Gram-positive and Gram-negative bacteria through reversible boronate ester bonds, which can be controlled by pH and simple monosaccharides. To increase the capacity of affinity separation, a new approach is used to couple the alkyne-tagged phenylboronic acid to cryogel via an intermediate polymer layer that provides multiple immobilization sites. The morphology and chemical composition of the composite cryogel are characterized systematically. The capability of the composite cryogel for the separation of Gram-positive and Gram-negative bacteria is investigated. The binding capacities of the composite cryogel for Escherichia coli and Staphylococcus epidermidis are 2.15 × 10⁹ and 3.36 × 10⁹ cfu/g, respectively. The bacterial binding of the composite cryogel can be controlled by adjusting pH. The results suggest that the composite cryogel may be used as affinity medium for rapid separation and isolation of bacteria from complex samples.

Photoconjugation of temperature- and pH-responsive polymer with silica nanoparticles for separation and enrichment of bacteria

A new photoconjugation approach was developed to prepare nanoparticle-supported boronic acid polymer for effective separation and enrichment of bacteria. The photo-activated polymer immobilization was demonstrated by coupling an azide-modified copolymer of N-isopropylacrylamide and glycidyl methacrylate to a perfluorophenyl azide-modified silica surface. The thermoresponsive polymer was synthesized using reversible addition fragmentation chain transfer polymerization followed by conversion of the pendant epoxides into azide groups. The perfluorophenyl azide-modified silica nanoparticles were synthesized by an amidation reaction between amino-functionalized silica and pentafluorobenzoyl chloride, and a subsequent treatment with sodium azide. Bacteria-capturing boronic acid was conjugated to the silica-supported polymer chains via Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction. The particle size, morphology and organic content of the composite nanoparticles were characterized systematically. The capability of the nanocomposite to bind Gram-positive and Gram-negative bacteria was investigated. The nanocomposite exhibited high binding capacities for E. coli (13.4 × 10⁷ CFU/mg) and S. epidermidis (7.66 × 10⁷ CFU/mg) in phosphate buffered saline. The new photoconjugation strategy enables fast and straightforward grafting of functional polymers on surface, which opens many new opportunities for designing functional materials for bioseparation and biosensing.

A novel colorimetric sensing platform for the detection ofS. aureuswith high sensitivity and specificity

In this study, a novel colorimetric sensing platform was developed for the detection of S. aureus using dog immunoglobulin G (IgG) as the capture antibody and chicken anti-protein A immunoglobulin Y labeled with horseradish peroxidase (HRP-IgY) as the detection antibody. Dog IgG labeled with magnetic beads was used to capture S. aureus through the interaction between the Fc region of dog IgG and Staphylococcal protein A (SPA). HRP-IgY was introduced to recognize the residual SPA on the surface of S. aureus and to create a sandwich format, after which a soluble 3,3′,5,5′-tetramethylbenzidine (TMB) substrate was added. A stop solution was utilized to cease the enzymatic chromogenic reaction, and then optical density was read at 450 nm. Under optimal conditions, the proposed method displayed a low detection limit of 1.0 × 10³ CFU mL⁻¹ and a wide linear range of 3.1 × 10³ to 2.0 × 10⁵ CFU mL⁻¹. This detection method exhibited high specificity against other foodborne bacteria. The recovery rates ranged from 95.2% to 129.2%. To our knowledge, this is the first report to employ dog IgG and chicken IgY as an antibody pair to detect S. aureus. This technique exhibits high application potential for S. aureus monitoring in various kinds of samples.

Utilization of dog IgG and chicken anti-protein A IgY as an antibody pair for sensitive and selective detection of S. aureus.