Surface-enhanced Raman spectroscopy for polychlorinated biphenyl detection: Recent developments and future prospects

Ultrasensitive monitoring of PCB77 in environmental samples using a visible-driven photoelectrochemical sensing platform coupling with exonuclease I assisted in target recycling

Due to the urgent need for detecting trace amounts of 3,3',4,4'-tetrachlorobiphenyl (PCB77) in the environment, we have developed an efficient and visible-driven photoelectrochemical (PEC) sensing platform based on carbon quantum dots (CQDs) modified titanium dioxide nanorods (TiO2 NRs), coupling with exonuclease I (Exo I) assisted in target recycling for significant signal amplification. CQDs/TiO2 NRs with high visible-light absorption ability and electron-hole separation efficiency is used as photoactive substrate for anchoring anti-PCB77 aptamer and its complementary DNA (cDNA). With the addition of PCB77, the specific interaction between PCB77 and its aptamer forces aptamer to separate from the electrode surface, resulting in an increase in photocurrent density. Adding Exo I in the test system, a self-catalytic target cycle was motivated, which significantly increased the PEC signal by more than twice, achieving signal amplification. The relationship between the photocurrent density changes and the concentrations of PCB77 are utilized to achieve quantitative detection of PCB77. The designed PEC sensing platform has good analytical performance with a detection limit as low as 0.33 pg L-1, high selectivity and stability. Moreover, the PEC sensor is successfully used to evaluate the content of PBC77 in the environment samples. The established sensing platform provides a simple and efficient method for detecting trace amounts of PCB77 in the environment.

Methyltrimethoxysilane modified tin dioxide microspheres with hydrophobic networks and abundant adsorbed oxygen for efficient solid-phase microextraction of polychlorinated biphenyls

Methyltrimethoxysilane (MTMS) modified tin dioxide microspheres (MTMS/SnO2) were prepared by a facile hydrothermal method and heated reflux reaction strategy. The characterization results indicate that the modification of MTMS induced the formation of a hydrophobic network within the composites, while maintaining abundant adsorbed oxygen species. Subsequently, the MTMS/SnO2 microspheres were used as a solid-phase microextraction (SPME) coating for the efficient extraction and sensitive determination of trace polychlorinated biphenyls (PCBs) in aqueous solutions coupled to gas chromatography-mass spectrometry. MTMS/SnO2 coating exhibited superior extraction performances for PCBs compared with commercial SPME and pure SnO2 microspheres coatings, owing to the hydrophobic crosslinking and adsorbed oxygen-enhanced hydrogen bonding. The proposed analytical method presented respectable linearity in the concentration range 0.25-1000 ng L-1, with low limits of detection varying from 0.036 to 0.14 ng L-1 for seven PCBs and excellent precision, with relative standard deviations of 5.7-9.8% for a single fiber and 8.2-13.1% for five fibers. Finally, the proposed method was successfully used for determination of PCBs in real water with recoveries ranging from 75.8 to 115.6%. This study proposed a new type SPME coating of MTMS/SnO2 microspheres, which extended the potential of SnO2 in capturing and determining organic pollutants.

Porous rod-shaped Fe2O3/Ag/BP: a novel substrate for highly sensitive SERS detection of persistent organic pollutants

A surface enhanced Raman scattering (SERS) substrate of porous rod-shaped ferric oxide (Fe2O3) combined with silver nanoparticles (Ag NPs) and black phosphorus (Fe2O3/Ag/BP) was fabricated to detect the persistent organic pollutants (POPs) at low concentration. The organic pollutant Rhodamine 6G (R6G) was used as the probe molecule to study the performances of Fe2O3/Ag/BP, and 4-chlorobiphenyl (PCB-3) was the target of detection. The limit of detection (LOD) of R6G based on this novel SERS substrate Fe2O3/Ag/BP was as low as 1.0 × 10-15M, which was five orders of magnitude lower than that of Fe2O3/Ag (10-10M). The enhancement factor (EF) of Fe2O3/Ag/BP was 6.44 × 108, which was 3.1 times higher than that of porous rod-shaped Fe2O3/Ag (2.08 × 108). The Raman signal of R6G based on Fe2O3/Ag/BP had a good homogeneity, and the relative standard deviation (RSD) of Raman signal intensities of R6G at 1643 cm-1was only 5.97%. Furthermore, the Fe2O3/Ag/BP substrate exhibited a recyclability through the photocatalytic degradation of R6G. The LOD of PCB-3 based on Fe2O3/Ag/BP was 10-9M. Besides, Fe2O3/Ag/BP had a high SERS activity even it was kept in a centrifuge tube without requiring complicated treatment. These results highlight the potential application of Fe2O3/Ag/BP for ultra-trace detection of POPs in the environment.

One-step fabrication of flexible polyamide@Ag-dodecanethiol membranes for highly sensitive SERS detection of thiram

The surface-enhanced Raman scattering (SERS) is an effective spectral technology based on Raman scattering, but in practice, the commonly used SERS substrates suffer from low sensitivity and poor stability. In order to overcome these limitations, the SERS substrates were prepared from hydrophobic modification of dodecanethiol (C12) coupled with a flexible substrate, which was then used for pesticides detection in water. A flexible PA@Ag-C12 substrate with surface functionalization has been obtained. This work aims to investigate the self-assembly of Ag NPs modified with C12 onto polyamide (PA) membranes. Initially, transmission electron microscopy and scanning electron microscopy were used to analyze the substrate's morphology. Then with the help of an energy-dispersive spectrometer, sulfur content of C12-modified Ag NPs was analyzed. In order to determine the hydrophobicity of the modified Ag NPs, the contact angle was used. The results indicate that the gap between Ag NPs on PA membrane can be effectively controlled in order to prevent Ag NPs from aggregating. Furthermore, the finite-difference time-domain analysis indicated that the PA@Ag-C12 substrate exhibited a stronger electromagnetic enhancement effect than the PA@Ag substrate. By reducing NPs gaps on the PA membrane, the number of 'hot spots' increased, and the SERS performance of the substrate was improved as a result. According to the results of this study, this method can greatly reduce the manufacturing costs and time costs of the SERS substrate while maintaining the original uniformity. The SERS performance of PA@Ag-C12 was found to be three orders of magnitude better than that of PA@Ag direct self-assembled substrate, and the detection limit for Rhodamine 6G (R6G) was approximately 8.47 × 10-14M. On the basis of the PA@Ag-C12 substrate, thiram is detectable at a detection limit of 5.88 × 10-11M with a high degree of sensitivity and repeatability.

Thin layer chromatography coupled with surface enhanced Raman scattering for rapid separation and on-site detection of multi-components

The separation and detection of multi-component mixtures has always been a challenging task. Traditional detection methods often suffer from complex operation, high cost, and low sensitivity. Surface enhanced Raman scattering (SERS) technique is a high sensitivity, powerful and rapid detection tool, which can realize the specific detection of single substance components, but it must solve the problem that multi-component mixtures cannot be accurately determined. Thin layer chromatography (TLC) technology, as a high-throughput separation technology, uses chromatographic plate as the stationary phase, and could select different developing phases for separation experiments. The advantages of TLC technology in short distance and rapid separation are widely used in protein, dye and biomedical fields. However, TLC technology has limitations in detection ability and difficulty in obtaining ideal signal intensity. The combination of TLC technology and SERS technology made the operation procedure simple and the sample size small, which can achieve rapid on-site separation and quantitative detection of mixtures. Due to the rapid development of TLC-SERS technology, it has been widely used in the investigation of various complex systems. This paper reviews the application of TLC-SERS technology in food science, environmental pollution and biomedicine.

Rapid Detection of Malathion, Phoxim and Thiram on Orange Surfaces Using Ag Nanoparticle Modified PDMS as Surface-Enhanced Raman Spectroscopy Substrate

Malathion, phoxim, and thiram are organophosphates and organosulfur pesticides widely used in agricultural products. The residues of these pesticides present a direct threat to human health. Rapid and on-site detection is critical for minimizing such risks. In this work, a simple approach was introduced using a flexible surface-enhanced Raman spectroscopy (SERS) substrate. The prepared Ag nanoparticles-polydimethylsiloxane (AgNPs-PDMS) substrate showed high SERS activity, good precision (relative standard deviation = 5.33%), and stability (30 days) after optimization. For target pesticides, the linear relationship between characteristic SERS bands and concentrations were achieved in the range of 10~1000, 100~5000, and 50~5000 μg L-1 with LODs down to 3.62, 41.46, and 15.69 μg L-1 for thiram, malathion, and phoxim, respectively. Moreover, SERS spectra of mixed samples indicated that three pesticides can be identified simultaneously, with recovery rates between 96.5 ± 3.3% and 118.9 ± 2.4%, thus providing an ideal platform for detecting more than one target. Pesticide residues on orange surfaces can be simply determined through swabbing with the flexible substrate before acquiring the SERS signal. This study demonstrated that the prepared substrate can be used for the rapid detection of pesticides on real samples. Overall, this method greatly simplified the pre-treatment procedure, thus serving as a promising analytical tool for rapid and nondestructive screening of malathion, phoxim, and thiram on various agricultural products.

Esterified-sawdust decorated with AgNPs as solid-phase extraction membranes for enrichment and high-sensitivity detection of polychlorinated biphenyls

Polychlorinated biphenyls (PCBs) are a class of persistent organic pollutants, which cause serious harm to human health and ecological environment. Thus, a low-cost membrane was developed for highly effective removal and rapid surface-enhanced Raman scattering (SERS) detection of PCBs by filling esterified-sawdust (CA-SD) modified with silver nanoparticles (AgNPs) into solid phase extraction (SPE) column. SD was first modified by an esterification cross-linking strategy and then AgNPs were anchored on the CA-SD to prepare highly sensitive and reproducible SERS substrates (AgNPs/CA-SD). Due to the contraction of the surface area of the CA-SD caused by drying, the gap between the AgNPs could be reduced, thereby generating a large number of hot spots and driving more target molecules into them to obtain the enhanced SERS signals. The AgNPs/CA-SD-based SPE membrane showed excellent SERS activity with an enhancement factor of 5.98 × 10⁸ for the R6G analysis. The proposed SERS-active SPE membrane with functionalization of mercapto-β-cyclodextrin was further developed for the determination of PCB-77 and PCB-1 with the LODs of 1.43 × 10^-9 M and 2.12 × 10^-8 M, respectively. In addition, each PCB in the mixed sample could be quickly distinguished based on the characteristic peaks. The current research exhibits great potential for the simultaneous detection of multiple environmental contaminants and can meet the needs of on-site emergency detection.

Flexible Hydrophobic CFP@PDA@AuNPs Stripes for Highly Sensitive SERS Detection of Methylene Blue Residue

Considering the inherent hydrophilic and porous nature of paper, the rapid absorption and diffusion of aqueous analyte solutions on paper-based SERS substrates may severely affect the Raman detection sensitivity and accuracy in the detection of target molecules. In this work, a series of hydrophobic CFP@PDA@AuNPs stripes were obtained through in situ synthesizing of gold nanoparticles (AuNPs) on a polydopamine (PDA)-decorated cellulose filter paper (CFP) and functionalized with perfluorodecanethiol (PFDT). When the SERS performance of the substrates was examined using 4-ATP, the hydrophobic CFP@PDA@AuNPs substrate showed superior sensitivity, reproducibility and stability due to the hydrophobic enrichment effect, with the detection limit decreasing to 10−9 M and the enhancement factor as high as 2.55 × 107. More importantly, it was feasible to apply the hydrophobic paper substrate as an excellent SERS sensor to detect methylene blue (MB) residues in lake water in a highly sensitive manner. The lowest detectable limit of MB was 100 nM, and it showed a low relatively standard deviation (RSD) value of 5.28%. Hydrophobic CFP@PDA@AuNPs stripes may serve as excellent sensors for target molecule detection and have tremendous potential in food security, and environmental and chemical detection.

Graphene-embedded oblique V-shaped silver nanoarrays for hydrophobic pollutants pre-concentration and high-sensitivity SERS detection

A surface enhanced Raman scattering (SERS) substrate of silver nanorod modified with graphene and silver nanorod (AgNR@Graphene@AgNR) has been fabricated to improve the sensitivity of SERS detection of hydrophobic pollutants, in which, graphene is an interlayer and AgNR is arranged on both sides of the graphene. The embedded graphene could help the oblique V-shaped AgNR structure to improve the sensitivity of SERS detection with a significant electric field enhancement effect. The annealing treatment of the substrate, shortening the nanometer gap between the graphene and AgNR, is benefit for producing a large number of "hot spots" at the fold, which has been verified by the finite difference time domain (FDTD) simulation. The enhancement factor (EF) of AgNR@Graphene@AgNR could reach up to 1.6 × 10⁸ with a good reproducibility. The substrate could achieve high-sensitivity detection of 4-chlorobiphenyl (PCB-3) and 3, 3', 4, 4'-tetrachlorobiphenyl (PCB-77) with the limit of detections (LODs) of 1.72 × 10^-10 M and 2.11 × 10^-8 M, and the effective identification of PCBs mixture has been realized through principal component analysis (PCA), which means that the AgNR@Graphene@AgNR substrate has a potential significance for the detection and analysis of hydrophobic pollutant mixtures in the environment.

Simultaneous and rapid detection of polychlorinated phenols in water samples by surface-enhanced Raman spectroscopy combined with principal component analysis

In this work, a simple, high-throughput, and sensitive analytical method based on surface-enhanced Raman spectroscopy (SERS) and principal component analysis (PCA) was fabricated for simultaneous and rapid determination of three polychlorinated phenols (PCPs) including 2,4-dichlorophenol (2,4-DCP), 2,4,5-trichlorophenol (2,4,5-TCP), and 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP). The aggregated Ag nanoparticles (AgNPs) induced by inorganic salt ions were used as sensitive SERS substrate, and the electromagnetic field distribution of AgNPs with different distances was simulated by finite difference time domain (FDTD) to verify the theory feasibility. The high throughput and rapid detection can be achieved by commercial 96-pore plate. Under the optimum conditions, the linear relationship between the Raman intensity and the concentrations of PCPs was established with satisfied correlation coefficient. The limits of detection (LOD) for 2,4-DCP, 2,4,5-TCP, and 2,3,4,6-TeCP are 0.27 mg L-1, 0.09 mg L-1, and 0.10 mg L-1 by rules of 3σ, respectively. The simultaneous quantitative analysis can be achieved thanks to the independent Raman characteristic peaks of three PCPs. Afterwards, the PCA method was used to eliminate the limitations of overlapping of characteristic Raman peaks in structural analogues of 2,4-DCP, 2,4,5-TCP, and 2,3,4,6-TeCP. The recovery experiments including single PCPs and mixed PCP samples show satisfied recoveries ranging from 85.0 to 113.9% and 80.4 to 114.0% with RSDs in range of 0.4-9.5% and 1.1-10.7%, respectively. The proposed method shows great potentials in rapid, high-throughput, and sensitive monitoring of the contaminants in water and pesticide samples with similar structure. Here, we introduced aggregated Ag nanoparticles (AgNPs) induced by inorganic salt ion for simultaneous, rapid, and sensitive determination of polychlorinated phenols (PCPs) including 2,4-dichlorophenol (2,4-DCP), 2,4,5-trichlorophenol (2,4,5-TCP), and 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP) by surface-enhanced Raman spectroscopy (SERS) combined with principal component analysis (PCA). The AgNPs induced by inorganic salt ions were used as sensitive SERS substrate, and the electromagnetic field distribution of AgNPs with different distances was simulated by finite difference time domain (FDTD) to verify the theory feasibility. The PCA method was used to eliminate the limitations of overlapping of characteristic Raman peaks in structural analogues of 2,4-DCP, 2,4,5-TCP, and 2,3,4,6-TeCP. The proposed method shows great potentials in rapid, high-throughput, and sensitive monitoring of the contaminants in water and pesticide samples with similar structure.

Molecular–substrate interaction on dynamic SERS detection of butylated hydroxyanisole on a silver nano-tripod substrate

A SERS enhancement model with a surface adsorption effect is proposed by dynamical SERS analysis of butylated hydroxyanisole on a silver nano-tripod substrate.

Development of Au NPs-decorated filter paper as a SERS platform for the detection of benzidine

In this paper, a simple and cost-efficient strategy was used to construct a uniform Au NPs distribution on the surface of flexible filter paper for the detection of benzidine. Taking full advantage of the adsorption properties of filter paper, small gold nanoparticles were adsorbed onto its surface as gold seeds, and subsequently grown by electroless plating to form a highly uniform distribution of Au NPs substrates. By changing the electroless plating time, an optimal substrate was obtained. The as-prepared substrate exhibited satisfactory sensitivity with a low detection limit of 10-13 M for 4-ATP, and good reproducibility and homogeneity. Furthermore, the as-prepared substrates were successfully used for the detection of benzidine in environmental water, with a minimum detection concentration as low as 0.1 ppm and recoveries in the range of 92.4 to ∼108.5%. This study indicated that filter paper-based SERS substrates have great potential value in the detection of environmental organic pollutants.

Nitrogen-rich carbon nitride as solid-phase microextraction fiber coating for high-efficient pretreatment of polychlorinated biphenyls from environmental samples

A two-dimensional nitrogen-rich carbon nitrogen (C₃N₅) material was prepared via a facile high temperature thermal polymerization. For the first time, the C₃N₅ was used as fiber coating of solid-phase microextraction (SPME) to extract and preconcentrate polychlorinated biphenyls (PCBs) before gas chromatography (GC) analysis. The X-ray diffraction, N₂ adsorption-desorption, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy were performed to investigate structure, functional groups, thermal stability, bonding type, element composition, and atomic ratio of C₃N₅. The two-dimensional planar stacking structure was further verified by scanning electron microscopy and transmission electron microscopy. Five PCBs including PCB-4, PCB-12, PCB-29, PCB-52 and PCB-101 were selected as targets to evaluate performance of SPME fiber. Under the optimal conditions, the method showed a good linear range from 0.01 to 1000 ng/mL with the correlation coefficients (R²) higher than 0.9990. Enrichment factors of the method were obtained from 2045 to 3080. The limits of detection (LODs, S/N = 3) and limits of quantification (LOQs, S/N = 10) were calculated as 0.0031-0.0111 ng/mL and 0.01-0.05 ng/mL, respectively. The precisions of intra-day and inter-day were obtained with the relative standard deviations (RSDs) at 1.5-6.6% and 0.8-6.9%, respectively. The fiber-to-fiber producibility was achieved with RSDs ranged from 3.5% to 11.4%. The method was applied to detect PCBs in river water and soil samples. The contents were calculated at 0.040-0.147 ng/mL in water and 0.520-3.218 ng/g in soil. The C₃N₅ as SPME fiber coating material may be applied to extract and preconcentrate other environmental pollutants which have similar chemical structures with PCBs.

A Review of Detection of Antibiotic Residues in Food by Surface-Enhanced Raman Spectroscopy

Antibiotics, as veterinary drugs, have made extremely important contributions to disease prevention and treatment in the animal breeding industry. However, the accumulation of antibiotics in animal food due to their overuse during animal feeding is a frequent occurrence, which in turn would cause serious harm to public health when they are consumed by humans. Antibiotic residues in food have become one of the central issues in global food safety. As a safety measure, rapid and effective analytical approaches for detecting these residues must be implemented to prevent contaminated products from reaching the consumers. Traditional analytical methods, such as liquid chromatography, liquid chromatography mass spectrometry, and capillary electrophoresis, involve time-consuming sample preparation and complicated operation and require expensive instrumentation. By comparison, surface-enhanced Raman spectroscopy (SERS) has excellent sensitivity and remarkably enhanced target recognition. Thus, SERS has become a promising alternative analytical method for detecting antibiotic residues, as it can provide an ultrasensitive fingerprint spectrum for the rapid and noninvasive detection of trace analytes. In this study, we comprehensively review the recent progress and advances that have been achieved in the use of SERS in antibiotic residue detection. We introduce and discuss the basic principles of SERS. We then present the prospects and challenges in the use of SERS in the detection of antibiotics in food. Finally, we summarize and discuss the current problems and future trends in the detection of antibiotics in food.

Electrochemical Development of an Immunosensor for Detection Polychlorinated biphenyls (PCBs) for Environmental Analysis

Polychlorinated biphenyls (PCBs) are a highly toxic family of synthetic chemical compounds. PCBs are widely spread in the environment and their toxicity can cause serious ailments to living organisms such as cancer; therefore, developing a device for the detection of PCBs in the environment is significant. In this paper, polyclonal primary anti-PCB antibodies were immobilized onto a gold screen-printed electrode with the purpose of creating an electrochemical immunosensor for the detection of Aroclor 1254. It was modified with 11-mercaptoundecanoic acid (11-MUA) and the activation of the carboxylic acid terminal was performed by cross-linking 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hyrodsuccinmide (NHS) on the electrode surface. Cyclic voltammetry, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry, atomic force microscopy (AFM), scanning electron microscopy (SEM), and contact angle measurement were employed to characterize SAM development on the gold electrode. Using a competitive assay, a 0.09 ng/mL−1 limit of detection and a linear range of 0.101–220 ng/mL−1 were determined. The self-assembled monolayers (SAM) were successful in encapsulating the PCBs on the immunosensor. The electrochemical detection showed better resolution when compared to traditional methods such as the ELISA optical technique. The novel electrochemical immunosensor approach that is discussed in this paper has the potential to offer rapid sample screening in a portable, disposable format and could contribute to the effective control and prevention of PCBs in the environment.

General Surface-Enhanced Raman Spectroscopy Method for Actively Capturing Target Molecules in Small Gaps

Over the past decade, many efforts have been devoted to designing and fabricating substrates for surface-enhanced Raman spectroscopy (SERS) with abundant hot spots to improve the sensitivity of detection. However, there have been many difficulties involved in causing molecules to enter hot spots actively or effectively. Here, we report a general SERS method for actively capturing target molecules in small gaps (hot spots) by constructing a nanocapillary pumping model. The ubiquity of hot spots and the inevitability of molecules entering them lights up all the hot spots and makes them effective. This general method can realize the highly sensitive detection of different types of molecules, including organic pollutants, drugs, poisons, toxins, pesticide residues, dyes, antibiotics, amino acids, antitumor drugs, explosives, and plasticizers. Additionally, in the dynamic detection process, an efficient and stable signal can be maintained for 1-2 min, which increases the practicality and operability of this method. Moreover, a dynamic detection process like this corresponds to the processes of material transformation in some organisms, so the method can be used to monitor transformation processes such as the death of a single cell caused by photothermal stimulation. Our method provides a novel pathway for generating hot spots that actively attract target molecules, and it can achieve general ultratrace detection of diverse substances and be applied to the study of cell behaviors in biological systems.

Recent progress in mycotoxins detection based on surface-enhanced Raman spectroscopy

Mycotoxins are toxic compounds naturally produced by certain types of fungi. The contamination of mycotoxins can occur on numerous foodstuffs, including cereals, nuts, fruits, and spices, and pose a major threat to humans and animals by causing acute and chronic toxic effects. In this regard, reliable techniques for accurate and sensitive detection of mycotoxins in agricultural products and food samples are urgently needed. As an advanced analytical tool, surface-enhanced Raman spectroscopy (SERS), presents several major advantages, such as ultrahigh sensitivity, rapid detection, fingerprint-type information, and miniaturized equipment. Benefiting from these merits, rapid growth has been observed under the topic of SERS-based mycotoxin detection. This review provides a comprehensive overview of the recent achievements in this area. The progress of SERS-based label-free detection, aptasensor, and immunosensor, as well as SERS combined with other techniques, has been summarized, and in-depth discussion of the remaining challenges has been provided, in order to inspire future development of translating the techniques invented in scientific laboratories into easy-to-operate analytic platforms for rapid detection of mycotoxins.

Development of affinity between target analytes and substrates in surface enhanced Raman spectroscopy for environmental pollutant detection

Environmental pollution has long been a social concern due to the variety of pollutants and their wide distribution, persistence and being detrimental to health. It is therefore necessary to develop rapid and sensitive strategies to trace and detect these compounds. Among various detection methodologies, surface enhanced Raman spectroscopy (SERS) has become an attractive option as it enables accurate analyte identification, simple sample preparation, rapid detection and ultra-high sensitivity without any interference from water. For SERS detection, an essential yet challenging step is the effective capture of target analytes onto the surface of metal nanostructures with a high intensity of enhanced electromagnetic field. This review has systematically summarized recent advances in developing affinity between targets and the surface of SERS substrates via direct adsorption, hydrophobic functional groups, boronate affinity, metal organic frameworks (MOFs), DNA aptamers and molecularly imprinted polymers (MIPs). At the end of this review, technical limitations and outlook have been provided, with suggestions on optimizing SERS techniques for real-world applications in environmental pollutant detection.

Two-dimensional MXene modified AgNRs as a surface-enhanced Raman scattering substrate for sensitive determination of polychlorinated biphenyls

A MXene/AgNR substrate was prepared through a facile modification strategy. The substrate can perform sensitive SERS detection of polychlorinated biphenyls, which may have potential in environmental monitoring at the point of need.