One-step synthesis of silver/dopamine nanoparticles and visual detection of melamine in raw milk

Abstract

In this work, we propose a simple, sensitive and reliable assay for melamine in raw milk with dopaminestabilized silver nanoparticles (AgNPs) as a colorimetric reader. Dopamine can reduce Ag + and functionalize the produced AgNPs to form monodispersed AgNPs. The coexisting melamine in reaction solution could bind dopamine through Michael addition and Schiff base reactions, which leads to the aggregation of AgNPs and induces a colorimetric response. The one-step assay is simple, rapid and highly sensitive. The color-change is quantitatively correlated with the concentration of melamine in the range of 10 ppb to 1.26 ppm, which is below the safety limit in China (1.0 ppm) and EU (2.0 ppm). The coexisting substances including phenylalanine, DL-leucine, L-glutamate, sulfanilic acid, Mg 2+ , galactose, lysine, urea and glucose do not affect the determination of melamine. The colorimetric sensor can be used for rapid monitoring of raw milk quality.

Amperometric magnetobiosensors using poly(dopamine)-modified Fe3O4 magnetic nanoparticles for the detection of phenolic compounds

“…In addition, the high-resolution spectrum (Figure 2B) displayed the characteristic doublet, due to Fe 2p 3/2 and Fe 2p 1/2 core-level region, assigned to the aromatic O-H asymmetry stretching vibration of CH 2 groups. Other relevant peaks appeared at 1,602 cm -1 due to overlap of C=C resonance vibrations in aromatic ring and 1,519 cm -1 (N-H scissoring vibrations) 52,53 . Moreover, the spectrum for pDA displayed a large relative absorbance in the 1,500-1,100 cm -1 region, due to the polymer formation, attributable to C-O and C-N functional groups 16,17 .…”

Dopamine-Induced Growth of Au and Ag Nanoparticles on ITO Substrate and Their Application in PCPDTBT-Based Polymer Solar Cell

“…Because dopamine is sensitive to oxidation, dopamine hydrochloride, a dopamine precursor, is widely used as a commercial chemical, which includes chloride ions that is responsible for the production of AgCl. The generation of AgCl can be minimized by controlling the pH value of the solution [16,17].…”

Colorimetric Detection of Mercury(Ⅱ) Based on Silver Nanoparticles

“…实验结果表明, Dp 浓度 在 40 μmol/L 之前, 空白和样品溶液的响应信号均是逐 渐增强, 这是因为 AgNPs 的生成量随 Dp 浓度的增大而 增加, Dp 浓度达到 40 μmol/L 之后空白和样品吸收强度 不再变化, 说明 AgNPs 的生成量不再增加. Dp 浓度过高 或过低都会对体系产生影响 [27] . 浓度过高, 会增大背景 噪音, 浓度过低, 则又降低银纳米粒子的单分散性.…”