Facile Synthesis of Ag NP Films via Evaporation-Induced Self-Assembly and the BA-Sensing Properties

Abstract

Herein, we design and prepare large-area silver nanoparticle (Ag NP) films based on evaporation-induced self-assembly, which offers the visual and real-time detection of chilled broiler meat freshness. The color change is based on the fact that an increase in the biogenic amine (BA) concentration causes a change in the absorption wavelength of Ag NPs caused by aggregation and etch of the Ag NPs, resulting in a yellow to brown color change, thus enabling a naked-eye readout of the BA exposure. The Ag NP films exhibit a rapid, sensitive, and linear response to BAs in a wide detection range of 2 µM to 100 µM. The Ag NP films are successfully applied as a quick-response, online, high-contrasting colorimetric sensor for visual detection of the freshness of chilled broiler meat.

Keywords: Ag NP films; BAs; evaporation-induced self-assembly; meat detection.

Figure 1

(a) Digital photographs of colorless and transparent mixed solution before drying and yellow Ag NP films after drying, and the corresponding UV−visible spectra were recorded; (b) particle size and TEM image of Ag NPs; (c) HRTEM image of Ag NPs; FTIR (d) and Raman (e) spectra of colorless and transparent mixed solution before drying and yellow Ag NP films after drying; (f) TGA analysis of PVA−glucose films and Ag NP films; (g) A mechanism for nanoparticle formation of Ag NPs.

Figure 2

(a) Photographs of Ag NP films exposed to histamine at different concentrations. (b) UV−vis spectra of Ag NPs films exposed to histamine at different concentrations. (c) Relationship between ΔA₄₂₀ and histamine concentrations, the error bars represent the standard deviation for five trials (n = 5); FTIR (d) and Raman (e) spectra of Ag NP films exposed to histamine at different concentrations.

Figure 3

Absorbance of Ag NP films decreased at 420 nm in reaction with BAs or interfering compounds (Histamine, Putrescine, Cadaverine, Spermine, Spermidine: 20 mg/m³. Benzaldehyde, Cinnamaldehyde, Capric acid, Oleic acid, Suberic acid, Oxyhumulinic acid, Malic acid, Phenylalanine, Arginine, Alanine, L-Glutamate, Guanine, Uracil, Indole, Riboflavin, 1-Hexanol, 2-Methylfuran: 50 mg/m³). Each data point is the mean of six replicate samples (mean ± standard deviation).

Figure 4

(a) The schematic of the chilled broiler meat in vacuum-packaged conditions; (b) color change in Ag NPs films in chilled broiler meat in vacuum-packaged conditions at 4 °C, and the assays were repeated four times: S1–S4; (c–e) Red value, Green value, Blue value of Ag NPs films at 4 °C.

Figure 5

Changes in (a) TVCs and (b) TVB-N in chilled broiler meat in vacuum-packaged conditions stored at 4 °C. Vertical bars represent standard deviation of the mean (n = 6). Different lowercase letters indicate significant differences at different storage times (p < 0.05).