Functional gold nanoparticles for studying the interaction of lectin with glycosyl complex on living cellular surfaces

Alginate Modification and Lectin-Conjugation Approach to Synthesize the Mucoadhesive Matrix

Alginates are natural anionic polyelectrolytes investigated in various biomedical applications, such as drug delivery, tissue engineering, and 3D bioprinting. Functionalization of alginates is one possible way to provide a broad range of requirements for those applications. A range of techniques, including esterification, amidation, acetylation, phosphorylation, sulfation, graft copolymerization, and oxidation and reduction, have been implemented for this purpose. The rationale behind these investigations is often the combination of such modified alginates with different molecules. Particularly promising are lectin conjugate macromolecules for lectin-mediated drug delivery, which enhance the bioavailability of active ingredients on a specific site. Most interesting for such application are alginate derivatives, because these macromolecules are more resistant to acidic and enzymatic degradation. This review will report recent progress in alginate modification and conjugation, focusing on alginate-lectin conjugation, which is proposed as a matrix for mucoadhesive drug delivery and provides a new perspective for future studies with these conjugation methods.

Uncovering the Binding Specificities of Lectins with Cells for Precision Colorectal Cancer Diagnosis Based on Multimodal Imaging

There is a high desire for novel targets/biomarkers to diagnose and treat colorectal cancer (CRC). Here, an approach starting from a polyacrylamide hydrogel-based lectin microarray is presented to screen the high expression of glycans on the CRC cell surface and to identify new lectin biomarkers for CRC. Three common CRC cell lines (SW480, SW620, and HCT116) and one normal colon cell line (NCM460) are profiled on the microarray with 27 lectins. The experimental results reveal that CRC cells highly express the glycans with d-galactose, d-glucose, and/or sialic acid residues, and Uelx Europaeus Agglutinin-I (UEA-I) exhibits reasonable specificity with SW480 cells. After conjugation of UEA-I with silica-coated NaGdF4:Yb3+, Er3+@NaGdF4 upconversion nanoparticles, the follow-up in vitro and in vivo experiments provide further evidence on that UEA-I can serve as tumor-targeting molecule to diagnose SW480 tumor by multimodal imaging including upconversion luminescence imaging, T1-weighted magnetic resonance imaging, and X-ray computed tomography imaging.

Gold nanoparticle-based colorimetric biosensors

Gold nanoparticles (AuNPs) provide excellent platforms for the development of colorimetric biosensors as they can be easily functionalised, displaying different colours depending on their size, shape and state of aggregation. In the last decade, a variety of biosensors have been developed to exploit the extent of colour changes as nano-particles (NPs) either aggregate or disperse, in the presence of analytes. Of critical importance to the design of these methods is that the behaviour of the systems has to be reproducible and predictable. Much has been accomplished in understanding the interactions between a variety of substrates and AuNPs, and how these interactions can be harnessed as colorimetric reporters in biosensors. However, despite these developments, only a few biosensors have been used in practice for the detection of analytes in biological samples. The transition from proof of concept to market biosensors requires extensive long-term reliability and shelf life testing, and modification of protocols and design features to make them safe and easy to use by the population at large. Developments in the next decade will see the adoption of user friendly biosensors for point-of-care and medical diagnosis as innovations are brought to improve the analytical performances and usability of the current designs. This review discusses the mechanisms, strategies, recent advances and perspectives for the use of AuNPs as colorimetric biosensors.

Targeted photodynamic therapy of breast cancer cells using lactose-phthalocyanine functionalized gold nanoparticles

Gold nanoparticles (AuNPs), which have been widely used for the delivery of photosensitizers for photodynamic therapy (PDT) of cancer, can be dispersed in aqueous solutions improving the delivery of the hydrophobic photosensitizer into the body. Furthermore, the large surface of AuNPs can be functionalized with a variety of ligands, including proteins, nucleic acids and carbohydrates, that allow selective targeting to cancer tissue. In this study, gold nanoparticles were functionalized with a mixed monolayer of a zinc phthalocyanine and a lactose derivative. For the first time, a carbohydrate was used with a dual purpose, as the stabilizing agent of the gold nanoparticles in aqueous solutions and as the targeting agent for breast cancer cells. The functionalization of the phthalocyanine-AuNPs with lactose led to the production of water-dispersible nanoparticles that are able to generate singlet oxygen and effect cell death upon irradiation. The targeting ability of lactose of the lactose-phthalocyanine functionalized AuNPs was studied in vitro towards the galectin-1 receptor on the surface of breast cancer cells. The targeting studies showed the exciting potential of lactose as a specific targeting agent for galactose-binding receptors overexpressed on breast cancer cells.

Detection of carbohydrates on the surface of cancer and normal cells by topography and recognition imaging

Galactose was detected and localized on the surface of cancer and normal cells by topography and recognition imaging at the single molecular level. There are more galactoses on cancer cells than on normal cells. The stability of galactose-lectin on cancer cells is much lower than that on normal cells.

Phenylboronic acid functionalized gold nanoparticles for highly sensitive detection of Staphylococcus aureus

Herein, we report a phenylboronic acid functionalized gold nanoparticle (GNP)-based colorimetric assay for rapid detection of Staphylococcus aureus (S. aureus) with high sensitivity. In this approach, GNPs can bind to S. aureus by the reaction of phenylboronic acid with the cis-diol configuration in glycans on the bacterial surface, providing a colorimetric readout of the binding event. Using this strategy, we have been able to quantify S. aureus at a concentration of 50 cells per mL (three times the standard deviation divided by the slope of the working curve) in aqueous solution.

Gold nanoparticle-based colorimetric assay for selective detection of aluminium cation on living cellular surfaces

A colorimetric assay based on pentapeptide (CALNN) functionalized gold nanoparticles exhibits high sensitivity and selectivity for detection of aluminium cation (Al(3+)) both in aqueous solution and on living cellular surfaces under physiological condition.