Greener One-Pot Synthesis of Gold Nanoparticle Glycoconjugates Using Functionalized Sugars

Abstract

Carbohydrates have been used to decorate metallic nanoparticles to form nanoglycoconjugates. However, the synthetic conditions typically require the utilization of increased temperatures and other reagents that negatively impact the stability of the conjugates. For the first time, this study is reporting the synthesis of gold–nanoparticle glycoconjugates (AuNP-GCs) in aqueous media at ambient temperatures. A series of sugars and small molecules acting as reducing, capping, and stabilizing agents were reacted with gold­(III) chloride salt to produce the AuNP-GCs. Specifically, β-d-lactose, d-mannose, and d-galactose were utilized to synthesize (N-lactosyl)-5-aminosalicylic acid gold nanoparticles (L5AS-AuNPs), (N-galactosyl)-5-aminosalicylic acid gold nanoparticles (G5AS-AuNPs), and (N,N′-dilactosyl)­diaminodiphenylethylene gold nanoparticles (LAEA-AuNPs), respectively. The formation of AuNP-GCs was monitored via ultraviolet–visible spectrophotometry, and the results confirmed the presence of the characteristic surface plasmon resonance peaks. Additional characterization data using transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD) confirmed the formation of AuNP-GCs. Of the AuNP-GCs produced, the XRD data confirmed that L5AS-AuNPs (∼20 nm), G5AS-AuNPs (∼5 nm), and LAEA-AuNPs (∼50 nm) were crystalline with predominant 111 orientations. All of the AuNP-GCs exhibited unique fluorescence and Raman activities except 4,4′-diaminodiphenylsulfone (PSA). The analytical enhancement factor, an important characterization parameter for assessing the surface-enhanced Raman scattering effect, was determined. LAEA-AuNPs resulted in enhancement factors of 11 × 104 and 6 × 104. LPSA-AuNPs resulted in enhancement factors of 8 × 104 and 6 × 104. The resulting AuNP-GCs retained stability for up to a year. 1H and 13C nuclear magnetic resonance spectra of the sugar ligand and the corresponding AuNP-GCs revealed that both hydroxyl groups on sugar moieties and aromatic protons enhanced the stability of AuNP-GCs. The findings showed that the chemistry and concentration of sugar ligands played a critical role in obtaining the desired size, shape, and optical properties.

A colorimetric immunoassay for the detection of human vascular endothelial growth factor 165 (VEGF165) based on anti-VEGF-iron oxide nanoparticle conjugation

“…S2 A shows the absorbance at 370 nm due to a metallic iron oxide core that confirms the presence of LpAB-FeNP [ 46 ]. The decrease in the absorbance intensity after the conjugation process indicates the successful attachment of anti-VEGF to LpAB-FeNP [ 47 , 48 ]. In this study, the morphology of LpAB-FeNP and LpAB-FeNP/anti-VEGF was observed by scanning electron microscopy (SEM), as depicted in Fig.…”

The fabrication of bifunctional supramolecular glycolipid-based nanocomposite gel: insights into electrocatalytic performance with effective selectivity towards gold

“…20 The hydroxyl groups in sugar molecules are reported to enhance the stability of nanoparticles, and oxidation of sugar is not required for the reduction of metals. 39 Supramolecular gel network of amphiphilic glycolipid gelator portrayed a crucial role in stabilizing the GNP. Balanced designing of gelator molecule is an essential factor for efficient reduction and stabilization of GNP within the gel.…”

Nanosensor Applications in Plant Science

“…The synthesis of gold nanoparticle glycoconjugates based on functionalised sugars was recently reported [ 214 ]. The gold nanoparticle glycoconjugates were subsequently employed in the development of a sensor for the detection of the spores and hyphae of the blue-green mould Penicillium italicum in fruit [ 215 ].…”