Glycan Nanobiosensors

Development of an impedance-based biosensor for determination of IgG galactosylation levels

The glycan profile of immunoglobulin G (IgG) molecule and its changes are associated with a number of different diseases. Galactosylation of IgG was recently suggested as a potential biomarker for rheumatoid arthritis, inflammatory bowel disease and many cancers. In this paper, we propose a portable impedance-based biosensor that utilizes lectin array technology to detect glycans in IgG. Biotinylated Griffonia simplicifolia (GSL II) and Ricinus communis agglutinin I (RCA I) lectins were used in our biosensor design for determination of the ratio of N-acetyl glucosamine (GlcNAc) to galactose (Gal) respectively, which is termed agalactosylation factor (AF). Streptavidin gold nanoparticles (GNP) were conjugated to biotinylated lectin bonded to the carbohydrate in the glycoprotein to magnify the change in impedance signal and enhance detection sensitivity. The method was successfully applied to differentiation of the galactosylation levels in human and rat IgG. In addition, we present proof of concept use of our biosensor for differentiation of COVID-19 positive patient samples from negative patients. Consequently, the sensor can be useful in future applications to distinguish between glycan profiles of IgG from healthy and patient samples in disease studies. Our biosensor permits analysis of human serum without conventional time-consuming IgG purification steps or pretreatment using enzyme digestion to cut the sugars from the glycoprotein molecule. The results suggest that the proposed point of care (POC) biosensor can be used for evaluating disease progression and treatment efficacy via monitoring changes in the galactosylation profiles of IgG in patients.

How to choose proper magnetic particles for bioaffinity interactions? The case for immobilised glyconanoconjugate

In this study, an assay for detection of the cancer biomarker Thomsen-nouvelle (Tn) antigen on the ELISA plates format was designed and developed. The effects of size and the interfacial density of the negative charge of magnetic beads (MBs) on the specific sensitivity of the bioaffinity interaction were studied. In particular, glyconanoconjugate, i.e. glycan Tn antigen conjugated to bovine serum albumin (BSA) was covalently immobilised on MBs for the bioaffinity detection of anti-Tn antibodies as cancer biomarkers. Six different MBs were used in the study, i.e. carboxy-modified MBs of 250 nm, 500 nm, 1000 nm and 2800 nm and epoxy-modified MBs of 2800 nm and 4500 nm. In order to evaluate which MBs are the best suited for detection of the analyte anti-Tn antibodies, sensitivities of detection (slopes from calibration curves) were calculated. Next, specific sensitivities were calculated for each type of MBs as a ratio of sensitivity of detection to the mass of MBs. From zeta potential ζ for each type of MBs, the interfacial charge density on MBs was calculated, expressed as the density of zeta potential ζ_d (ratio of zeta potential to surface area of MBs, i.e. ζ_d = ζ/A). Then, we evaluated the effect of size and ζ_d on the specific sensitivity of detection of anti-Tn antibodies in order to understand the immobilisation process on nanoscale. We also identified an optimal value of ζ_d on MBs; this was essential to achieve highly sensitive detection of the analyte, which made it possible to attain limit of detection (LOD) of (0.31 ± 0.01) ng mL^-1 or (2.10 ± 0.04) pM for analyte detection. In addition, the optimal assay configuration was highly selective and enabled reliable detection of the analyte in human serum with a recovery index in the range of 102-104%.

Sulfation of Heparan and Chondroitin Sulfate Ligands Enables Cell-Specific Homing of Nanoprobes

Demystifying the sulfation code of glycosaminoglycans (GAGs) to induce precise homing of nanoparticles in tumor cells or neurons influences the development of a potential drug- or gene-delivery system. However, GAGs, particularly heparan sulfate (HS) and chondroitin sulfate (CS), are structurally highly heterogeneous, and synthesizing well-defined HS/CS composed nanoparticles is challenging. Here, we decipher how specific sulfation patterns on HS and CS regulate receptor-mediated homing of nanoprobes in primary and secondary cells. We discovered that aggressive cancer cells such as MDA-MB-231 displayed a strong uptake of GAG-nanoprobes compared to mild or moderately aggressive cancer cells. However, there was no selectivity towards the GAG sequences, thus indicating the presence of more than one form of receptor-mediated uptake. However, U87 cells, olfactory bulb, and hippocampal primary neurons showed selective or preferential uptake of CS-E-coated nanoprobes compared to other GAG-nanoprobes. Furthermore, mechanistic studies revealed that the 4,6-O-disulfated-CS nanoprobe used the CD44 and caveolin-dependent endocytosis pathway for uptake. These results could lead to new opportunities to use GAG nanoprobes in nanomedicine.

Current Methods for Extraction and Concentration of Foodborne Bacteria with Glycan-Coated Magnetic Nanoparticles: A Review

Rapid and accurate food pathogen detection is an essential step to preventing foodborne illnesses. Before detection, removal of bacteria from the food matrix and concentration to detectable levels are often essential steps. Although many reviews discuss rapid concentration methods for foodborne pathogens, the use of glycan-coated magnetic nanoparticles (MNPs) is often omitted. This review seeks to analyze the potential of this technique as a rapid and cost-effective solution for concentration of bacteria directly from foods. The primary focus is the mechanism of glycan-coated MNP binding, as well as its current applications in concentration of foodborne pathogens. First, a background on the synthesis, properties, and applications of MNPs is provided. Second, synthesis of glycan-coated particles and their theorized mechanism for bacterial adhesion is described. Existing research into extraction of bacteria directly from food matrices is also analyzed. Finally, glycan-coated MNPs are compared to the magnetic separation technique of immunomagnetic separation (IMS) in terms of cost, time, and other factors. At its current state, glycan-coated MNPs require more research to fully identify the mechanism, potential for optimization, and extraction capabilities directly in food matrices. However, current research indicates glycan-coated MNPs are an incredibly cost-effective method for rapid food pathogen extraction and concentration.

Recent advances of chitosan-based nanoparticles for biomedical and biotechnological applications

Chitosan is a natural alkaline polysaccharide, which widely exists in marine crustaceans such as shrimp and crab, has been shown to have various biological activities. It has attracted considerable attention in biomedicine and nanomaterials fields because of its excellent properties, such as biocompatibility, biodegradability, non-toxicity and easy access. In addition, because of active hydroxyl and amino groups in chitosan molecules, different functional groups can be introduced into chitosan molecules by molecular modification or chemical modification, which extends their applications. Nanoparticles with small size and large surface area can be used as diagnostic and therapeutic tools in the biomedical field, which make it easier to understand, detect and treat human diseases. The nanomaterials based on chitosan have important applications in biomedicine, industry, pharmacy, agriculture, and other fields. This review highlights the recent advances on chitosan-based nanoparticles for antibacterial property, drug and gene delivery, cancer and hyperthermia therapy, cell imaging, restorative dentistry, wound healing, tissue engineering and other biomedical fields. The nanotechnology fields involving biosensors, water treatment, food industry and agriculture are also briefly reviewed.

Dual electrochemical sensing of spiked virus and SARS-CoV-2 using natural bed-receptor (MV-gal1)

It has been necessary to use methods that can detect the specificity of a virus during virus screening. In this study, we use a dual platform to identify any spiked virus and specific SARS-CoV-2 antigen, sequentially. We introduce a natural bed-receptor surface as Microparticle Vesicle-Galactins1 (MV-gal1) with the ability of glycan binding to screen every spiked virus. MV are the native vesicles which may have the gal-1 receptor. Gal-1 is the one of lectin receptor which can bind to glycan. After dropping the MV-gal1 on the SCPE/GNP, the sensor is turned on due to the increased electrochemical exchange with [Fe(CN)6]-3/-4 probe. Dropping the viral particles of SARS-CoV-2 cause to turn off the sensor with covering the sugar bond (early screening). Then, with the addition of Au/Antibody-SARS-CoV-2 on the MV-gal1@SARS-CoV-2 Antigen, the sensor is turned on again due to the electrochemical amplifier of AuNP (specific detection).For the first time, our sensor has the capacity of screening of any spike virus, and the specific detection of COVID-19 (LOD: 4.57 × 102 copies/mL) by using the natural bed-receptor and a specific antibody in the point of care test.

Surface plasmon resonance study for a reliable determination of the affinity constant of multivalent grafted beads

In this study, galactose-grafted beads were prepared using the main design principle of the cluster effect. Galactose was chosen as the sugar for investigation because it acts as the main building block of long glycan chains and because a simple and fast protocol is still required for its immobilization. For the analysis, the lectin, ligand of the galactose, was immobilized on a gold plasmonic substrate. After preliminary characterization of the galactose-grafted beads, the investigation of the surface plasmon surface behavior of the system was carried out, for studying the affinity constant of the multivalent beads. The results of steady-state and of the kinetics analysis evidenced a higher affinity of the galactose-grafted beads over the beadless galactose solution. For the association kinetics analysis, a Langmuir isotherm was applied to the data. The analysis of the rate of dissociation evidenced the most important differences between the two samples, based on the more difficult release of the galactose-grafted beads during washing. To confirm the influence of the glycoside cluster effect, a low-density lectin substrate was tested, and the results evidenced that the characteristic size of the molecules determines a threshold for the cluster density. The calculated detection limit and dissociation constants were 3.5 μM and 40.2 μM, respectively. Considering those results, the evaluation of the affinities toward the receptors depends on the cluster density and then, it should be designed for mimicking the biological samples.

Recent Developments in the Use of Glyconanoparticles and Related Quantum Dots for the Detection of Lectins, Viruses, Bacteria and Cancer Cells

Carbohydrate-coated nanoparticles-glyconanoparticles-are finding increased interest as tools in biomedicine. This compilation, mainly covering the past five years, comprises the use of gold, silver and ferrite (magnetic) nanoparticles, silicon-based and cadmium-based quantum dots. Applications in the detection of lectins/protein toxins, viruses and bacteria are covered, as well as advances in detection of cancer cells. The role of the carbohydrate moieties in stabilising nanoparticles and providing selectivity in bioassays is discussed, the issue of cytotoxicity encountered in some systems, especially semiconductor quantum dots, is also considered. Efforts to overcome the latter problem by using other types of nanoparticles, based on gold or silicon, are also presented.

Revisiting inorganic nanoparticles as promising therapeutic agents: A paradigm shift in oncological theranostics

Cancer remains a global health problem largely due to a lack of effective therapies. Major cancer management strategies include chemotherapy, surgical resection, and radiation. Unfortunately, these strategies have a number of limitations, such as non-specific side effects, uneven delivery of the drugs, and lack of proper monitoring technology. Inorganic nanoparticles (NPs) are considered promising agents in treating and tracing cancer due to their unique physicochemical properties such as the controlled release of drugs, bioavailability, biocompatibility, stability, and large surface area. Also, they enhance the solubility of hydrophobic drugs, prolong their circulation time, prevent undesired off-targeting and subsequent side effects, making them efficient particles in cancer theranostics. Promising inorganic-NPs include gold, selenium, silica, and oxide NPs. Further, several techniques are used to modify the surface of inorganic-NPs, making them more efficient for the effective transport of therapeutic cargos to overcome cellular barriers. Thus, inorganic-NPs function effectively, surmounting the intrinsic drawbacks of traditional organic NPs. This mini-review summarizes the significant inorganic-NPs, their properties, surface modifications, cellular uptake, and bio-distributions, along with their potential use in cancer theranostics. We also discuss the promises and challenges faced during the inorganic-NPs mediated therapeutic approach for cancer and these particles' status in the clinical setting.

TEMPO-Cellulose Nanocrystal-Capped Gold Nanoparticles for Colorimetric Detection of Pathogenic DNA

Nanocellulose-assisted gold nanoparticles are considered promising materials for developing eco-friendly diagnostic tools for biosensing applications. In this study, we synthesized 2,2,6,6-tetramethylpiperidin-1-piperidinyloxy (TEMPO)-oxidized cellulose nanocrystal (TEMPO-CNC)-capped gold nanoparticles (AuNPs) for the colorimetric detection of unamplified pathogenic DNA oligomers of methicillin-resistant Staphylococcus aureus. The fabricated TEMPO-CNC-AuNPs (TC-AuNPs) were characterized using UV-visible spectroscopy, transmission electron microscopy, atomic force microscopy, and dynamic light scattering. The average diameter of the synthesized AuNPs was approximately 30 nm. The aqueous solution of TC-AuNPs was stable and exhibited an absorption peak at 520 nm. The chemical interaction between TC-AuNPs and the surface charge of the target and non-target DNA determined the colorimetric differences under ionic conditions. A dramatic color change (red → blue) was observed in the TC-AuNP solution with the target DNA under ionic conditions due to the aggregation of AuNPs. However, no observable color change occurred in the TC-AuNP solution with the non-target DNA under similar conditions owing to the better shielding effects of the charged moieties. The colorimetric detection limit of the TC-AuNPs was demonstrated to be as low as 20 fM pathogenic DNA. Therefore, the use of TEMPO-oxidized CNC-capped AuNPs is efficient and straightforward as a biosensor for the colorimetric detection of pathogenic DNA.

Temperature-Controlled Adhesion to Carbohydrate Functionalized Microgel Films: An E. coli and Lectin Binding Study

The preparation of thermoresponsive mannose functionalized monolayers of poly(N-isopropylacrylamide) microgels and the analysis of the specific binding of concanavalin A (ConA) and E. coli above and below the lower critical solution temperature (LCST) are shown. Via inhibition and direct binding assays it is found that ConA binding is time-dependent, where at short incubation times binding is stronger above the LCST. Given larger incubation times, the interaction of ConA to the microgel network is increased below the LCST when compared to temperatures above the LCST, possibly due to increased ConA diffusion and multivalent binding in the more open microgel network below the LCST. For E. coli, which presents only monovalent lectins and is too large to diffuse into the network, binding is always enhanced above the LCST. This is due to the larger mannose density of the microgel layer above the LCST increasing the interaction to E. coli. Once bound to the microgel layer above the LCST, E. coli cannot be released by cooling down below the LCST. Overall, this suggests that the carbohydrate presenting microgel layers enable specific binding where the temperature-induced transition between swollen and collapsed microgels may increase or decrease binding depending on the receptor size.