Aptasensors for pesticide detection

Background Food safety has attracted considerable attention in recent years. As a rapid, fingerprint-type recognition and nondestructive detection technique, surface-enhanced Raman scattering (SERS) has been among the promising techniques to meet the increasing needs for food safety analysis. Currently, emerging flexible SERS substrates as an alternative for colloidal and rigid SERS substrates have received great interest. Flexible SERS substrates possess the advantages of easy sampling by wrapping or swabbing on nonplanar surfaces, which facilitate the detection of contaminants from food surfaces and shed new lights on the nondestructive and sensitive detection of food analytes. Scope and approach In this review, the characteristics of different flexible materials such as cellulose, polymer film, cotton fabric, adhesive tape and bio-materials for constructing flexible SERS substrates are introduced, detection strategies including infiltration scheme, swab-sampling and in-situ detection are discussed, and recent applications of flexible SERS substrates in detecting trace pesticides in fruits and vegetables, chemical residues in animal farming including fungicides and antibiotics, illegal food additives and food-borne pathogens are highlighted. Key findings and conclusions Flexible SERS substrates have been increasingly studied for detecting food contaminants. In preparing SERS substrates, different properties of the materials should be considered. For the detection strategies, compared with conventional infiltration scheme, swab-sampling is unique for flexible substrates and can collect target molecules directly from the surface, while in-situ detection is the most convenient, facile and nondestructive. Encouraging application results available show that flexible SERS substrates possess enormous potentials for food safety analysis and surveillance.

Advances in flexible surface-enhanced Raman scattering (SERS) substrates for nondestructive food detection: Fundamentals and recent applications

Background Food quality and safety are very important from health as well as fiscal point of view. Surface-enhanced Raman spectroscopy (SERS) techniques have unique advantages in the field of food detection , with characteristics of fast analysis speed, high detection sensitivity, and without interference from the water phase. Scope and approach In this review, recent and potential advances in the application of SERS in food safety and quality from the perspective of SERS substrate and SERS composite systems are addressed. SERS systems such as molecular labeling, immunochromatographic assay, microfluidics, molecularly imprinted polymers, colorimetry and imaging are discussed, and their main advantages and limitations are highlighted. The applications of SERS in food safety are reviewed critically, with focus on the detection of microorganisms, pesticides, metal ions and antibiotics. Furthermore, applications of SERS in food quality regarding food freshness and ingredients are discussed. Key findings and conclusions SERS technology has been widely used in food testing, but it still has shortcomings. In order to establish SERS as a routine tool for the monitoring of food safety and quality, future research should focus on minimizing technical costs, standardizing experimental protocols, developing new SERS substrates, and integrating SERS with other methods to overcome its shortcomings.

Evolving trends in SERS-based techniques for food quality and safety: A review

Label-free optical biosensors are an intriguing option for the analyses of many analytes, as they offer several advantages such as high sensitivity, direct and real-time measurement in addition to multiplexing capabilities. However, development of label-free optical biosensors for small molecules can be challenging as most of them are not naturally chromogenic or fluorescent, and in some cases, the sensor response is related to the size of the analyte. To overcome some of the limitations associated with the analysis of biologically, pharmacologically, or environmentally relevant compounds of low molecular weight, recent advances in the field have improved the detection of these analytes using outstanding methodology, instrumentation, recognition elements, or immobilization strategies. In this review, we aim to introduce some of the latest developments in the field of label-free optical biosensors with the focus on applications with novel innovations to overcome the challenges related to small molecule detection. Optical label-free methods with different transduction schemes, including evanescent wave and optical fiber sensors, surface plasmon resonance, surface-enhanced Raman spectroscopy, and interferometry, using various biorecognition elements, such as antibodies, aptamers, enzymes, and bioinspired molecularly imprinted polymers, are reviewed.

Optical Biosensors for Label-Free Detection of Small Molecules

The need and desire to understand the environment, especially the quality of one’s local water and air, has continued to expand with the emergence of the digital age. The bottleneck in understanding the environment has switched from being able to store all of the data collected to collecting enough data on a broad range of contaminants of environmental concern. Nanomaterial enabled sensors represent a suite of technologies developed over the last 15 years for the highly specific and sensitive detection of environmental contaminants. With the promise of facile, low cost, field-deployable technology, the ability to quantitatively understand nature in a systematic way will soon be a reality. In this review, we first introduce nanosensor design before exploring the application of nanosensors for the detection of three classes of environmental contaminants: pesticides, heavy metals, and pathogens.

https://link.springer.com/content/pdf/10.1186/s12951-018-0419-1.pdf

Nanomaterial enabled sensors for environmental contaminants

Label-free aptamer-based sensor for specific detection of malathion residues by surface-enhanced Raman scattering.

Rapid detection of organophosphorus pesticide residue on Prussian blue modified dual-channel screen-printed electrodes combing with portable potentiostat

Herein, a novel in situ surface-enhanced Raman scattering (SERS) method was proposed based on the prepared SERS substrate with good flexibility, excellent optical transparency, and high SERS activity. The SERS substrate was fabricated through the Au colloids injected with an ethanol and hexane mixture to form Au monolayer film (Au MLF) on the water/oil interface and followed by transferred to the sticky side of transparent tape after hexane volatilization. Transmission electron microscopy and scanning electron microscopy revealed that Au NPs with particle sizes of 25 nm were densely assembled and evenly distributed on the flexible and transparent tape. This Au MLF/tape was directly covered on the irregular shape samples and the detection signal was collected by the laser transmitting into the tape and interacting with the analytes. The optimal SERS signal intensity was obtained by tuning the concentration of Au colloid and addition volume of the mixture of ethanol and hexane to regulate the numbers of Au NPs on water/oil interface. The SERS intensity of six sample points selected randomly show a good repeatability with RSD = 4.92% (n = 6 × 8) and satisfying uniformity with RSD of 8.6% within an area of 4.0 × 4.0 μm. Also, the obtained Au MLF/tape SERS substrate showed good detection accuracy and recovery when used to detect residual malachite green (MG) residue on the surfaces of real fish samples with detection limit of 0.04 μmol/L (S/N = 3). Therefore, the developed Au MLF/tape SERS substrate has potential applications in the in situ SERS detection.

Water/Oil Interfacial Self-Assembled Gold Nanoarrays Modified on Transparent Tape for In Situ Surface-Enhanced Raman Scattering

The invention discloses a preparation method and an application of a flexible transparent SERS substrate. The method comprises the following steps of heating an HAuCl4 water solution to be boiling under vigorous stirring, rapidly adding a citrate aqueous solution, and condensing and refluxing for 13-17 minutes after the color change of the solution is stable, stopping heating, and cooling to roomtemperature under stirring to obtain Au nano-sol; and adding the Au nano-sol into a beaker, and slowly injecting a mixed solution of n-hexane and ethanol into the Au nano-sol by using a needle cylinder syringe at room temperature, slowly forming two phases of water oil, wherein a layer of nanometer Au film is gradually formed at the water-oil interface, and after the oil phase naturally volatilizes, directly covering by using an adhesive tape for uncovering the single-layer nano Au on the water phase surface, removing residual gold sol on the surface of the adhesive tape by using deionized water to prepare the flexible transparent SERS substrate. By adoption of the technology, the Au nano-particles can have better distribution uniformity on an adhesive tape, the flexibility and the viscosity of the adhesive tape can be well maintained, direct measurement can be carried out by a laser backlight mode, and in-situ detection is realized.

Preparation method and application of flexible transparent SERS substrate

One‐step Electrodeposition of Tris(hydroxymethyl) Aminomethane – Prussian Blue on Screen‐printed Electrode for Highly Efficient Detection of Glycosylated Hemoglobin

Qianwei Shi

Papers

Label-free aptamer-based sensor for specific detection of malathion residues by surface-enhanced Raman scattering.

Rapid detection of organophosphorus pesticide residue on Prussian blue modified dual-channel screen-printed electrodes combing with portable potentiostat

Water/Oil Interfacial Self-Assembled Gold Nanoarrays Modified on Transparent Tape for In Situ Surface-Enhanced Raman Scattering

Preparation method and application of flexible transparent SERS substrate

One‐step Electrodeposition of Tris(hydroxymethyl) Aminomethane – Prussian Blue on Screen‐printed Electrode for Highly Efficient Detection of Glycosylated Hemoglobin