Carbohydrate recognition: a nascent technology for the detection of bioanalytes

Rapid Evaluation of Antibacterial Carbohydrates on a Microfluidic Chip Integrated with the Impedimetric Neoglycoprotein Biosensor

The colonization of some bacteria to their host cell is mediated by selective adhesion between adhesin and glycan. The evaluation of antiadhesive carbohydrates in vitro has great significance in discovering new antibacterial drugs. In this paper, a microfluidic chip integrated with impedimetric neoglycoprotein biosensors was developed to evaluate the antibacterial effect of carbohydrates. Mannosylated bovine serum albumin (Man-BSA) was taken as the neoglycoprotein and immobilized on the microelectrode-modified gold nanoparticles (Au NPs) to form a bionic glycoprotein nanosensing surface (Man-BSA/Au NPs). Salmonella typhimurium (S. typhimurium) was selected as a bacteria model owing to its selective adhesion to the mannose. Electrochemical impedance spectroscopy (EIS) was used to characterize the adhesion capacity of S. typhimurium to the Man-BSA/Au NPs and evaluate the antiadhesive efficacy of nine different carbohydrates. It was illustrated that the 4-methoxyphenyl-α-D-pyran mannoside (Phenyl-Man) and mannan peptide (Mannatide) showed excellent antiadhesive efficacy, with IC50 values of 0.086 mM and 0.094 mM, respectively. The microfluidic device developed in this study can be tested in multiple channels. Compared with traditional methods for evaluating the antibacterial drug in vitro, it has the advantages of being fast, convenient, and cost-effective.

Bacterial identification and adhesive strength evaluation based on a mannose biosensor with dual-mode detection

A biosensor integrated with mannose nano-surface was developed for the identification and adhesive strength evaluation of bacteria. Different bacteria were studied on the designed surface by both electrochemical impedance spectroscopy (EIS) and surface enhanced Raman spectroscopy (SERS). S. typhimurium and E. coli JM109 (type 1 pili) were found to be captured by the mannose nano-surface. SERS spectra were used to identify the species of captured bacteria by combing with partial least squares discriminant analysis (PLS-DA). Meanwhile, binding affinities of the two captured bacteria to mannose nano-surface were obtained by EIS measurements and Frumkin isotherm model analysis, which were 6.859 × 10²³ M^-1 and 2.054 × 10¹⁷ M^-1 respectively. A higher binding affinity indicates a stronger adhesive strength. Hence the results show the S. typhimurium has a stronger adhesive strength to mannose. Normalized impedance change (NIC) was proved to have a positive relevant relationship with binding affinities, which could be used as an indicator for the adhesive strength of bacteria. It was demonstrated that 100% accuracy of bacteria species discrimination and good consistency of NIC and adhesive strength for blind samples. The developed biosensor can provide both qualitative and quantitative information of selective recognition between bacteria and mannose.

Emerging nano-biosensing with suspended MNP microbial extraction and EANP labeling

Emerging nano-biosensing with suspended MNP microbial extraction and EANP labeling may ensure a secure microbe-free food supply, as rapid response detection of microbial contamination is of utmost importance. Many biosensor designs have been proposed over the past two decades, covering a broad range of binding ligands, signal amplification, and detection mechanisms. These designs may consist of self-contained test strips developed from the base up with complicated nanoparticle chemistry and intricate ligand immobilization. Other methods use multiple step-wise additions, many based upon ELISA 96-well plate technology with fluorescent detection. In addition, many biosensors use expensive antibody receptors or DNA ligands. But many of these proposed designs are impracticable for most applications or users, since they don't FIRST address the broad goals of any biosensor: Field operability, Inexpensive, with Real-time detection that is both Sensitive and Specific to target, while being as Trouble-free as possible. Described in this review are applications that utilize versatile magnetic nanoparticles (MNP) extraction, electrically active nanoparticles (EANP) labeling, and carbohydrate-based ligand chemistry. MNP provide rapid pathogen extraction from liquid samples. EANP labeling improves signal amplification and expands signaling options to include optical and electrical detection. Carbohydrate ligands are inexpensive, robust structures that are increasingly synthesized for higher selectivity. Used in conjunction with optical or electrical detection of gold nanoparticles (AuNP), carbohydrate-functionalized MNP-cell-AuNP nano-biosensing advances the goal of being the FIRST biosensor of choice in detecting microbial pathogens throughout our food supply chain.

Environmental application of nanotechnology: air, soil, and water

Global deterioration of water, soil, and atmosphere by the release of toxic chemicals from the ongoing anthropogenic activities is becoming a serious problem throughout the world. This poses numerous issues relevant to ecosystem and human health that intensify the application challenges of conventional treatment technologies. Therefore, this review sheds the light on the recent progresses in nanotechnology and its vital role to encompass the imperative demand to monitor and treat the emerging hazardous wastes with lower cost, less energy, as well as higher efficiency. Essentially, the key aspects of this account are to briefly outline the advantages of nanotechnology over conventional treatment technologies and to relevantly highlight the treatment applications of some nanomaterials (e.g., carbon-based nanoparticles, antibacterial nanoparticles, and metal oxide nanoparticles) in the following environments: (1) air (treatment of greenhouse gases, volatile organic compounds, and bioaerosols via adsorption, photocatalytic degradation, thermal decomposition, and air filtration processes), (2) soil (application of nanomaterials as amendment agents for phytoremediation processes and utilization of stabilizers to enhance their performance), and (3) water (removal of organic pollutants, heavy metals, pathogens through adsorption, membrane processes, photocatalysis, and disinfection processes).

Bacterial isolation by lectin-modified microengines

New template-based self-propelled gold/nickel/polyaniline/platinum (Au/Ni/PANI/Pt) microtubular engines, functionalized with the Concanavalin A (ConA) lectin bioreceptor, are shown to be extremely useful for the rapid, real-time isolation of Escherichia coli (E. coli) bacteria from fuel-enhanced environmental, food, and clinical samples. These multifunctional microtube engines combine the selective capture of E. coli with the uptake of polymeric drug-carrier particles to provide an attractive motion-based theranostics strategy. Triggered release of the captured bacteria is demonstrated by movement through a low-pH glycine-based dissociation solution. The smaller size of the new polymer-metal microengines offers convenient, direct, and label-free optical visualization of the captured bacteria and discrimination against nontarget cells.

Protein adsorption on a glycosylated polyacrylonitrile surface: monitoring with QCM and SPR

A simple and efficient method to fabricate a glycosylated surface on a polyacrylonitrile-based film is described. Construction and protein adsorption processes were monitored in situ using a QCM. A PANCHEMA film was deposited on the gold surface of the quartz crystal, and the glycosylated surface was then constructed through surface modification. Con A and BSA were used as probes to study the specificity of this surface to proteins. It can recognize Con A, while showing no specific interaction with BSA. The binding affinity indicates the presence of strong multivalent interactions between Con A and the glucose residues (cluster glycoside effect). Reproducibility and repeatability of the glycosylated polymer surface are sufficient to allow specific adsorption of Con A.

Trityl-derivatized carbohydrates immobilized on a polystyrene microplate

Carbohydrate biosensors, including carbohydrate arrays, are attracting increased attention for the comprehensive and high-throughput investigation of protein-carbohydrate interactions. Here, we describe an effective approach to fabricating a robust microplate-based carbohydrate array capable of probing protein binding and screening for inhibitors in a high-throughout manner. This approach involves the derivatization of carbohydrates with a trityl group through an alkyl linker and the immobilization of the trityl-derivatized carbohydrates (mannose and maltose) onto microplates noncovalently to construct carbohydrate arrays. The trityl carbohydrate derivative has very good immobilization efficiency for polystyrene microplates and strong resistance to aqueous washing. The carbohydrate arrays can probe the interactions with the lectin Concanavalin A and screen this protein for the well-known inhibitors methyl alpha-D-mannopyranoside and methyl alpha-D-glucopyranoside in a high-throughput manner. The method described in this paper represents a convenient way of fabricating robust noncovalent carbohydrate arrays on microplates and offers a convenient platform for high-throughput drug screening.

Molecular recognition of sugars by lanthanide (III) complexes of a conjugate of N, N-bis[2-[bis[2-(1, 1-dimethylethoxy)-2-oxoethyl]amino]ethyl]glycine and phenylboronic acid

A novel conjugate of phenylboronic acid and an Ln(DTPA) derivative, in which the central acetate pendant arm was replaced by the methylamide of L-lysine, was synthesized and characterized. The results of a fit of variable (17)O NMR data and a (1)H NMRD profile show that the water residence lifetime of the Gd(III) complex (150 ns) is shorter than that of the parent compound Gd(DTPA)(2-) (303 ns). Furthermore, the data suggest that several water molecules in the second coordination sphere of Gd(III) contribute to the relaxivity of the conjugate. The Ln(III) complexes of this conjugate are highly suitable for molecular recognition of sugars. The interaction with various sugars was investigated by (11)B NMR spectroscopy. Thanks to the thiourea function that links the phenylboronic acid targeting vector with the DTPA derivative, the interactions are stronger than that of phenylboronic acid itself. In particular, the interaction with N-propylfructosamine, a model for the glucose residue in glycated human serum albumin (HSA), is very strong. Unfortunately, the complex also shows a rather strong interaction with hexose-free HSA (K(A) = 705 +/- 300).

Future aspects of bioprocess monitoring

Nature has the impressive ability to efficiently and precisely control biological processes by applying highly evolved principles and using minimal space and relatively simple building blocks. The challenge is to transfer these principles into technically applicable and precise analytical systems that can be used for many applications. This article summarizes some of the new approaches in sensor technology and control strategies for different bioprocesses such as fermentations, biotransformations, and downstream processes. It focuses on bio- and chemosensors, optical sensors, DNA and protein chip technology, software sensors, and modern aspects of data evaluation for improved process monitoring and control.