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Bisphenol A (BPA) is an endocrine disruptor which is widely present in fish under the influence of environmental pollution. It is essential to establish a rapid detection method for BPA. Zeolitic imidazolate framework (ZIF-8) is a typical metal-organic framework material (MOFs) with a strong adsorption capacity, which can effectively adsorb harmful substances in food. Combining MOFs and surface-enhanced Raman spectroscopy (SERS) can achieve rapid and accurate screening of toxic substances. In this study, a rapid detection method for BPA was established by preparing a new reinforced substrate Au@ZIF-8. The SERS detection method was optimized by combining SERS technology with ZIF-8. The Raman peak at 1172 cm−1 was used as the characteristic quantitative peak, and the lowest detection concentration of BPA was as low as 0.1 mg/L. In the concentration range of 0.1~10 mg/L, the linear relationship between SERS peak intensity and the concentration of BPA was good, and R2 was 0.9954. This novel SERS substrate was proven to have great potential in rapidly detecting BPA in food. [ABSTRACT FROM AUTHOR]

Lotus leaf is a super-hydrophobic material found in nature. Drawing inspiration from the micro-nano structure of lotus leaf surface, a hybrid surface-enhanced Raman spectroscopy (SERS) substrate owning both hydrophobic and hydrophilic properties was developed. The biomimetic part, which was fabricated by replicating the surface structure of lotus leaf using polydimethylsiloxane, exhibited a hydrophobic surface with a contact angle of 150.3°. Meanwhile, silver nanoparticles-coated filter paper was assembled on the top of the biomimetic part to render hydrophilic regions for SERS detection. Silver nanoparticles on the surface of filter paper owned a size of approximately 70–80 nm with an interval of about 5–10 nm. The hydrophobic/hydrophobic hybrid regions on the substrate significantly enhanced Raman signals of rhodamine 6g with mitigated coffee ring effects, showing a limit of detection low to 10−10 M. Notably, the limit of detection of this technique for thiram on apple surface reached 0.5 ng/cm2, which was lower than the reported methods. The prepared substrate displayed exceptional uniformity and stability, with an RSD value of 7.21% calculated based upon 30 randomly selected Raman signals, and experienced a decrease in signal by only 29.7% after 30-d storage. This biomimetic substrate can be utilized for batch detection of pesticide residues on fresh produce with high sensitivity, thereby owning great potential for application as a rapid detection tool for food safety. [ABSTRACT FROM AUTHOR]

With the globalization of food and its complicated networking system, a wide range of food contaminants is introduced into the food system which may happen accidentally, intentionally, or naturally. This situation has made food safety a critical global concern nowadays and urged the need for effective technologies capable of dealing with the detection of food contaminants as efficiently as possible. Hence, Surface-enhanced Raman spectroscopy (SERS) has been taken as one of the primary choices for this case, due to its extremely high sensitivity, rapidity, and fingerprinting interpretation capabilities which account for its competency to detect a molecule up to a single level. Here in this paper, we present a comprehensive review of various SERS-based novel approaches applied for direct and indirect detection of single and multiple chemical and microbial contaminants in food, food products as well as water. The aim of this paper is to arouse the interest of researchers by addressing recent SERS-based, novel achievements and developments related to the investigation of hazardous chemical and microbial contaminants in edible foods and water. The target chemical and microbial contaminants are antibiotics, pesticides, food adulterants, Toxins, bacteria, and viruses. In this paper, different aspects of SERS-based reports have been addressed including synthesis and use of various forms of SERS nanostructures for the detection of a specific analyte, the coupling of SERS with other analytical tools such as chromatographic methods, combining analyte capture and recognition strategies such as molecularly imprinted polymers and aptasensor as well as using multivariate statistical analyses such as principal component analysis (PCA)to distinguish between results. In addition, we also report some strengths and limitations of SERS as well as future viewpoints concerning its application in food safety. [ABSTRACT FROM AUTHOR]

Highlights • Core-shell nanomaterials are synthesized in this study. • It owned sensitive, fast, convenient, nondestructive and with good SERS effect. • It was excellent in rapid detection of pigments in food. Abstract With the widespread application of synthetic pigments in the food industry, food safety incidents caused by illegal addition of pigments have become more frequent. In this study, we synthesized core–shell nanomaterials for use in sensitive, fast, convenient, nondestructive detection and having good surface-enhanced Raman scattering (SERS) effect. The optimal synthetic conditions were selected to study semi-quantitative detection. Calculations for acid orange II and brilliant blue were done using density functional theory, and the characteristic peaks and vibration conditions for each pigment were identified. Acid orange II and brilliant blue in the food samples yellow croaker, braised pork, red pepper, green dumpling, and red wine were detected by SERS screening. Results were compared with those obtained by standard high-performance liquid chromatography method in order to verify the SERS method. The core–shell nanoparticles showed good performance in the rapid detection of pigments in food. [ABSTRACT FROM AUTHOR]

In this study, a novel hybrid molecularly imprinted polymer (MIP) with a surface-enhanced Raman spectroscopy (SERS) sensor was proposed for the detection of chloramphenicol in milk. The MIP was prepared by precipitation polymerization, and the template molecule was extracted by ultrasonic wave. The polymer was placed in a sodium citrate reduction reaction to prepare the chloramphenicol-MIP-Au substrate. The optimal detection conditions were carried out in a mixed solution of methanol and water (1:9). The sensor can be used to detect chloramphenicol in milk samples with a detection limit of 0.1 µg/ml. The chloramphenicol-MIP-Au substrate served not only as an enrichment medium but also as an enhancement substrate base for SERS detection. Experimental results showed that the MIP hybrid as a SERS platform owned potential for simplifying the detection step and highly selective detection of chloramphenicol in milk. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nitroimidazoles are a family of veterinary drugs containing a 5-nitroimidazole ring structure, which are commonly used antibiotics. In view of their potential genotoxicity and possible coexistence in actual samples, it is necessary to establish a rapid and effective method for the simultaneous determination of multiple nitroimidazoles. In this study, a rapid thin-layer chromatography combined with surface-enhanced Raman spectroscopy (TLC-SER) detection method for 14 nitroimidazole compounds has been established. The theoretical Raman spectra of the nitroimidazoles were calculated using the B3LYP/6-311+G(d) basis set in density functional theory (DFT) and the theoretical Raman spectra of TNZ, NBZ, ONZ, SCZ, DMZ, MNI, 2-HMZ, 4-HMZ, CMNI, IPZ, MNZ-OH and HMDMZ have been obtained for the first time. SERS detection was carried out on a gold nanoparticles (AuNPs) substrate, which exhibited strong SERS signals and a limit of detection limit of 0.1 mg/L. By optimizing the conditions used for the developing agent in TLC, 12 nitroimidazoles were successfully separated, while MNZ and RNZ still could not be separated. When combined with the chemometrics analysis method, the TLC-SERS method can realize the simultaneous detection of 14 nitroimidazoles. Actual pork samples were spiked with nitroimidazoles with a recovery rate of 80%–110% and RSD of 0.74%–16.70%, which showed that SERS and TLC-SERS methods are also effective for detection in actual samples. The detection time of this method is < 10 min, which is suitable for the rapid detection of nitroimidazoles, especially for the rapid qualitative identification of nitroimidazoles in situ. [ABSTRACT FROM AUTHOR]

Highlights: [•] IR, Raman and SERS methods have been studied on azodicarbonamide, biurea, and semicarbazide hydrochloride. [•] The molecular structure and assignment of these three molecules have been studied by DFT calculations. [•] The limit of detection of this method being as low as 10μg/mL (less than the standard regulation). [ABSTRACT FROM AUTHOR]

[Display omitted] • UV irradiation was introduced to change the SERS performance of C≡N in pesticides. • The method to detect azoxystrobin was developed based on the SERS signal of C≡N. • Simultaneous detection of multiple pesticides with cyano group could be achieved. Based on the fact that not all chemical substances possess good Raman signals, this article focuses on the Raman silent region signals of pesticides with cyano group. Under the optimized conditions of methanol–water (1:1, v/v) as the solvent, irradiation at 302 nm light source for 20 min, and the use of 0.5 mol/L KI as the aggregating agent, Surface-enhanced Raman spectroscopy (SERS) method for azoxystrobin detection was developed by the Raman silent region signal of 2230 cm−1, and verified by detecting the spiked grapes with different concentrations of azoxystrobin. Other four pesticides with cyano group also could be identified at the peak of 2180 cm−1, 2205 cm−1, 2125 cm−1, and 2130 cm−1 for acetamiprid, phoxim, thiacloprid and cymoxanil, respectively. When azoxystrobin or acetamiprid was mixed respectively with chlorpyrifos without cyano group, their SERS signals in the Raman silent region of chlorpyrifos were not interfered, while mixed with cymoxanil in different ratios (1:4, 1:1 and 4:1), respectively, each two pesticides with cyano group could be distinguished by the changes in the Raman silent region. In further, four pesticides with or without cyano group were mixed together in 1:1:1:1 (acetamiprid, cymoxanil, azoxystrobin chlorpyrifos), and each pesticide still could be identified even at 0.5 mg/L. The results showed that the SERS method combined with UV irradiation may provide a new way to monitor the pesticides with C≡N performance in the Raman silent region without interference from the food matrix. [ABSTRACT FROM AUTHOR]

Nanoplastics could modulate the fibrillation of amyloid proteins. However, many chemical functional groups are adsorbed to change the interfacial chemistry of nanoplastics in the real world. Herein, this study aimed to investigate the effects of polystyrene (PS), carboxyl modified PS (PS-COOH), and amino modified PS (PS-NH 2) on the fibrillation of hen egg-white lysozyme (HEWL). Due to the differences in the interfacial chemistry, concentration was considered an essential factor. PS-NH 2 (10 μg/mL) could promote the fibrillation of HEWL similar to PS (50 μg/mL) and PS-COOH (50 μg/mL). Moreover, promoting the primary nucleation step of amyloid fibril formation was the primary reason. The differences in spatial conformation of HEWL were characterized by Fourier transform-infrared spectroscopy and surface enhanced Raman spectroscopy (SERS). Strikingly, a particular signal of SERS of HEWL incubated with PS-NH 2 at 1610 cm−1 was found due to the interaction between amino group of PS-NH 2 and tryptophan (or tyrosine) of HEWL. Therefore, a new perspective was provided to understand the regulation of interfacial chemistry of nanoplastics on the fibrillation of amyloid proteins. Additionally, this study suggested that SERS could be a powerful method to investigate the interactions between proteins and nanoparticles. Note: Hen egg-white lysozyme structure was referred to the RCSB protein data bank (www.rcsb.org , PDB ID: 1LYZ). [Display omitted] • Concentration was considered an essential factor in the modulation of fibrillation of lysozyme by nanoplastics. • Promoting the primary nucleation step of amyloid fibril formation was the primary reason. • SERS could be a powerful method to investigate the interactions between proteins and nanoparticles. [ABSTRACT FROM AUTHOR]

• A novel, simple and low-cost SERS substrate was synthesized for the detection of illegal food additives. • Using the novel SERS substrate, we can achieve simultaneous detection of rhodamine B and basic orange II in chili products. • This method is of great application potential for food safety detection. In food safety assessment, surface-enhanced Raman spectroscopy (SERS) is a novel detection method with the advantages of being fast, easy, and of high sensitivity. However, many SERS substrate synthesis methods are complex, and there are only a few studies on the simultaneous detection of multiple substances. In this study, a new, simple, low-cost SERS substrate was synthesised for the first time to simultaneously detect illegal food additives rhodamine B and basic orange II in chilli products. A lightweight, porous, and low-cost material of melamine foam (MF) was employed as the SERS synthesis template. The substrate's SERS effect on, and sensitivity to, rhodamine B and basic orange II were demonstrated. The molecular vibration and SERS enhancement mechanisms of the two target molecules were analysed by density functional theory (DFT) calculations. The results reveal that this fabricated substrate has great application potential for the supervision and testing industry. [ABSTRACT FROM AUTHOR]

The use of antibiotics as veterinary drugs is a significant practice to maintain the well-being of farmed animals. Meanwhile, ethical violations committed during the application of the drugs by animal producers have become a major reason for contamination of animal products which in turn causes serious side effects on public health after consumption. The side effects could be severe, long-lasting, and deadly depending on their biochemical and physiologic aftermath. To prevent contaminated products from reaching the consumer, implementing rapid and effective analytical approaches beforehand is a crucial safety assurance measure. Thus, this paper firstly explores six predominant groups of antibiotics that are commonly exploited as veterinary drugs, typically penicillins, tetracyclines, amphenicols, aminoglycosides, fluoroquinolones as well triarylmethane dyes. Then, it addresses Surface enhanced Raman spectroscopy (SERS)-based detection of the aforementioned drugs in two major categories of animal products; milk, which is the major product of the dairy industry and meat products. The objective is to acquaint readers with various approaches of SERS that have been designed and developed to examine individual drugs from each group of antibiotics in milk and meat. SERS is a surface-sensitive advanced analytical technique that has largely been exploited for chemical and biological analysis due to its unique property of enhancing Raman signals for analytes absorbed on rough Raman scattering nanomaterials. It is quite an interesting tool in drug analysis because of its nature to be exploited for sensitive and rapid as well as in-field and in-laboratory detection. In the animal farming sector, violations such as excessive dosage, prolonged use, and use of illegal drugs are very common during application; so it is important to implement promising tools such as SERS in this area. Here in this paper, we present novel approaches related to drug analysis in milk and meat products including chicken, duck meats, fish, and pork. Different direct and indirect detection techniques and strategies have been discussed. In addition, this review also addresses strengths, limitations, and future trends of SERS with a conclusion at the end. [ABSTRACT FROM AUTHOR]