Non-destructive Detection of Food Adulteration to Guarantee Human Health and Safety

The primary objective of this review is to critique the basic concepts of non-destructive detection of food adulteration and fraud which collectively represent a tremendous annual financial loss worldwide and a major cause of human disease. The review covers the principles of the analytical instrumentation used for the non-destructive detection of food adulteration. Examples of practical applications of these methods for the control of food adulteration are provided and a comparative analysis of the advantages and disadvantages of instrumental methods in food technology are critiqued.Целью данного обзора является критическое рассмотрение основных понятий неразрушающего выявления фальсификации и подделки продуктов питания, которые в целом вызывают огромные ежегодные финансовые убытки во всем мире и являются одной из основных причин заболеваний человечества. Материалы и методы. Литература, указанная в данном обзоре, была получена в результате поиска библиографической информации в CAB abstracts, AGRICOLA, SciFinder Scholar, Modern Language Association (MLA), American Psychological Association (APA), OECD / EEA database по инструментам, которые используются для экологической политики и управления природными ресурсами, и Web of Science.Результаты и обсуждение. Фальсификация пищевых продуктов означает преднамеренное, обманное добавление посторонних, нестандартных или дешевых ингредиентов в продукты, или разбавление или удаление некоторых ценных ингредиентов с целью увеличения прибыли. В современных условиях производители стремятся увеличить выпуск своей продукции зачастую путем изготовления и продажи некачественных и фальсифицированных продуктов.“Неразрушающее выявление фальсификации пищевых продуктов” означает анализ образца и его существенных признаков без изменения физических и химических свойств образца. Повышение качества и безопасности пищевых продуктов путем разработки научных методов обнаружения фальсификации является главным условием для поддержания здоровья потребителей. Точная объективная оценка качества и выявление фальсификации пищевых продуктов представляется важнейшей целью пищевой промышленности. В связи с совершенствованием технологии фальсификации продуктов важно быть в курсе современных, самых точных методов контроля их фальсификации. С этой целью данный обзор рассматривает основные понятия выявления фальсификации продуктов питания, принципы устройств и возможные практические применения современных методов неразрушающего выявления фальсификации продуктов питания; сравнительный анализ преимуществ и недостатков инструментальных методов, используемых в пищевых технологиях. Каждый из рассмотренных методов обсуждается с точки зрения возможных различных консистенций продуктов – газов (свободного пространства вокруг продукта), свободно текущих жидкостей (соков), мутных и вязких жидкостей (меда как продукта растительного происхождения, растительных масел) и интактных продуктов (фруктов и овощей).Выводы. Результаты, освещенные в обзоре, рекомендуется использовать при контроле качества и безопасности пищевых продуктов.Метою даного огляду є критичний розгляд основних понять неруйнівного виявлення фальсифікації і підробки продуктів харчування, які в цілому викликають величезні щорічні фінансові збитки у всьому світі і є однією з основних причин захворювань людства. Матеріали і методи. Література, зазначена в даному огляді, була отримана в результаті пошуку бібліографічної інформації в in CAB abstracts, AGRICOLA, SciFinder Scholar, Modern Language Association (MLA), American Psychological Association (APA), OECD/EEA database щодо інструментів, які використовуються для екологічної політики та управління природними ресурсами, та Web of Science. Результати та обговорення. Фальсифікація харчових продуктів означає умисне, облудне додавання сторонніх, нестандартних або дешевих інгредієнтів в продукти, або розбавлення чи видалення деяких цінних інгредієнтів з метою збільшення прибутків. У сучасних умовах виробники прагнуть збільшити випуск своєї продукції найчастіше шляхом виготовлення та продажу неякісних та фальсифікованих продуктів. “Неруйнівне виявлення фальсифікації харчових продуктів” означає аналіз зразка і його істотних ознак без зміни фізичних і хімічних властивостей зразка. Підвищення якості та безпеки харчових продуктів шляхом розробки наукових методів виявлення фальсифікації є головною умовою для підтримки здоров’я споживачів. Точна об’єктивна оцінка якості і виявлення фальсифікації харчових продуктів представляється найважливішою метою харчової промисловості. У зв’язку з удосконаленням технології фальсифікації продуктів важливо бути в курсі сучасних, найбільш точних методів контролю їх фальсифікації. З цією метою даний огляд розглядає основні поняття виявлення фальсифікації продуктів харчування, принципи пристроїв і можливі практичні застосування сучасних методів неруйнівного виявлення фальсифікації продуктів харчування; порівняльний аналіз переваг і недоліків інструментальних методів, що застосовуються в харчових технологіях. Кожен з розглянутих методів обговорюється з точки зору можливих різних консистенцій продуктів - газів (вільного простору навколо продукту), вільно текучих рідин (соків), каламутних та в'язких рідин (меду як продукту рослинного походження, рослинних масел) і інтактних продуктів (фруктів і овочів). Висновки. Результати, висвітлені в огляді, рекомендується використовувати під час контролю якості та безпеки харчових продуктів

INKJET PRINTED PAPER SURFACE ENHANCED RAMAN SPECTROSCOPY DEVICES FOR TRACE CHEMICAL ANALYSIS

The needs of an ever growing human population are fueling demands for better and cheaper sensors for the early detection of harmful chemicals, pathogens and diseases markers from a variety of sources such as food, water, bodily fluids and contaminated surfaces. To address this, recent innovations utilize Microelectromechanical Systems (MEMS) technology to integrate multiple laboratory functions onto millimeter-sized chips to form Micro Total Analysis Systems (µTAS) or Lab-on-chip (LOC) devices. While sophisticated and powerful, the use of these devices for chemical and biological sensing is limited by complicated fabrication processes, high cost and robustness of the sensors. In this work we have developed a simple and inexpensive but exceptionally sensitive portable chemical and biological sensing platform through the innovative use of paper combined with Surface Enhanced Raman spectroscopy (SERS). Paper is functionalized with plasmonic nanostructures to transform it into a SERS substrate, while the natural properties of paper are leveraged for sample collection, cleanup, and analyte concentration in user-friendly formats such as wipes, dipsticks, and filters. The use of simple deposition methods such as inkjet printing for sensor fabrication combined with paper as the construction material means that sensors can be made at a very low cost. Additionally, the ability to be printed on demand eliminates issues with sensor shelf-life, while the absence of mechanical components makes these paper sensors much more robust than conventional sensors. In this work, practical applications of paper SERS sensors for the detection of food contaminants, narcotics, pesticides and other chemicals at trace levels are presented. Paper SERS sensors, by virtue of their low cost, simplicity of fabrication, high sensitivity and ease of use, promises to make chemical and biological sensing more accessible to the common user

Multiamperometric-SERS detection of melamine on gold screen-printed electrodes

A new, simple and fast protocol to generate gold-based SERS substrates is presented in this work. Melamine is a compound widely used in the industry that can be toxic for humans if consumed even in low concentrations. EC-SERS is an excellent alternative to classical methods to detect and quantify this compound because Raman spectroscopy provides a fingerprint of the molecules, providing very good sensitivity. In this work, timeresolved Raman spectroelectrochemistry is employed to generate a SERS substrate and to detect melamine, all in a single experiment. The dynamic character of this technique provides valuable information about the interaction of the molecule with the generated substrate. An optimization of the spectroelectrochemical method based on a multi-pulse amperometric detection has been performed. The new protocol presented in this work shows significant figures of merit in a very short experiment time, just 25 s.Authors acknowledge the financial support from Agencia Estatal de Investigación/Ministerio de Ciencia e Innovacion /10.13039/ 501100011033 (Grant PID2020-113154RB-C21) and Ministerio de Ciencia, Innovación y Universidades (Grant RED2018-102412-T). W. Ch. thanks JCyL for his postdoctoral fellowship (Grant BU297P18). S.H. and M.P-E. thank JCyL and European Social Fund for their predoctoral fellowships

Bio-templated Substrates for Biosensor Applications

Nanopatterning of materials is of particular interest for applications in biosensors, microfluidics, and drug delivery devices. In biosensor applications there is a need for rapid, low cost, and durable system for detection. This dissertation aims to investigate methods to pattern nanostructured surfaces using virus particles as templates. The virus species used in these experiments is a cysteine modified tobacco mosaic virus. The first project utilized the lamellar microphase separation of a block copolymer to pattern the virus particles. Although microphase separation of the poly(styrene-b-2-vinylpyridine) (PS-P2VP) into lamellae was confirmed, specificity of the viruses to the gold doped block of the polymer could not be achieved. Single virus particles lay across multiple lamellae and aggregated in side-to-side and head-to-tail arrangements. The second project studied the effect of a surfactant on virus assembly onto a gold chip. The experiments included placing a gold chip in virus solutions with varying triton concentrations (0-0.15%), then plating the virus particles with a metal. Results showed that as the triton concentration in the virus solution increases, the virus density on the surface decreases. The gold coated virus particles were applied to Surface Enhanced Raman Spectroscopy (SERS) detection in the final project. SERS is of interest for biosensor applications due to its rapid detection, low cost, portability, and label-free characteristics. In recent years, it has shown signal enhancement using gold, silver, and copper nanoparticles in solutions and on roughened surfaces. The gold plated virus surfaces were tested as SERS substrates using R6G dye as the analyte. An enhancement factor (EF) of 10^4 was seen in these samples versus the non-SERS substrate. This corresponded to the sample with 0.05% triton in the virus solution which showed the most intersection points between the virus particles and the most uniform coverage of the viruses on the surface. This value is lower than that of previous studies; however, future work may be performed to optimize conditions to achieve the highest signal possible

Commercial Gold Nanoparticles on Untreated Aluminum Foil: Versatile, Sensitive, and Cost-Effective SERS Substrate

We introduce low-cost, tunable, hybrid SERS substrate of commercial gold nanoparticles on untreated aluminum foil (AuNPs@AlF). Two or three AuNP centrifugation/resuspension cycles are proven to be critical in the assay preparation.The limits of detection (LODs) for 4-nitrobenzenethiol (NBT) and crystal violet (CV) on this substrate are about 0.12nM and 0.19 nM, respectively, while maximum analytical SERS enhancement factors (AEFs) are about 107. In comparative assays LODs for CV measured on AuNPs@Au film and AuNPs@glass are about 0.35 nM and 2 nM, respectively. The LOD for melamine detected on AuNPs@ Al foil is 27 ppb with 3 orders of magnitude for linear response range. Overall, AuNPs@AlF demonstrated competitive performance in comparison with AuNPs@Au film substrate in SERS detection of CV, NBT, andmelamine. To check the versatility of the AuNPs@AlF substrate we also detectedKNO3 with LODs of 0.7mMand SERS EF around 2 × 103, which is on the same order with SERS EF reported for this compound in the literature

TLC-SERS Plates with a Built-In SERS Layer Consisting of Cap-Shaped Noble Metal Nanoparticles Intended for Environmental Monitoring and Food Safety Assurance

Takei H, Saito J, Kato K, Vieker H, Beyer A, Gölzhäuser A. TLC-SERS Plates with a Built-In SERS Layer Consisting of Cap-Shaped Noble Metal Nanoparticles Intended for Environmental Monitoring and Food Safety Assurance. Journal of Nanomaterials. 2015;2015: 316189 .We report on a thin layer chromatograph (TLC) with a built-in surface enhanced Raman scattering (SERS) layer for in-situ identification of chemical species separated by TLC. Our goal is to monitor mixture samples or diluted target molecules suspended in a host material, as happens often in environmental monitoring or detection of food additives. We demonstrate that the TLC-SERS can separate mixture samples and provide in-situ SERS spectra. One sample investigated was a mixture consisting of equal portions of Raman-active chemical species, rhodamine 6 G (R6G), crystal violet (CV), and 1,2-di(4-pyridyl)ethylene (BPE). The three components could be separated and their SERS spectra were obtained from different locations. Another sample was skim milk with a trace amount of melamine. Without development, no characteristic peaks were observed, but after development, a peak was observed at 694 cm(-1). Unlike previous TLC-SERS whereby noble metal nanoparticles are added after development of a sample, having a built-in SERS layer greatly facilitates analysis as well as maintaining high uniformity of noble metal nanoparticles

Development of Filter-Based Surface Enhanced Raman Spectroscopic Assays for Rapid Detection of Chemical and Biological Contaminants in Water

Surface enhanced Raman spectroscopy (SERS) has been widely applied for rapid and sensitive detection of various chemical and biological targets. Here, we incorporated a syringe filter system into the SERS method to detect pesticides, protein toxins and bacteria in water. For the detection of chemical and protein targets, silver nanoparticles (Ag NPs) were aggregated by sodium chloride (NaCl) to form nanoclusters that could be trapped in the pores of the filter membrane to from the SERS-active membrane. Then a coating of capture (e.g. aptamer) was integrated on the nanoparticle substrate if needed. Then samples were filtered through the membrane. After capturing the target, the membrane was taken out and air dried before measuring by a Raman instrument. The developed filter SERS method was able to detect fungicide ferbam as low as 2.5 ppb level and had a good quantitative capability, which could also be carried out on site using a portable Raman instrument. The aptamer integrated filter SERS was able to detect ricin b chain in water at 100 ppb level. The filter membrane was then applied to detect bacteria E.Coli with the integration of 4-mpba as a capture and indicator. With SERS mapping, we can detect E.Coli down to 101 CFU/ml and the viability of bacteria on the membrane could be confirmed by incubating the membrane on TS agar down to 102 CFU/ml. This study shows the filter based SERS methods improve the detection capability in water samples, with a great versatility for various types of assays

Plasmonic Au nanostructures for surface-enhanced raman spectroscopy

Raman spectroscopy is a spectroscopic technique that provides rich structural information for identifying chemical species but finds limited applications owing to its low sensitivity. Surface-enhanced Raman spectroscopy (SERS) is capable of solving the issue of sensitivity by enormously amplifying the Raman signal through localized surface plasmon resonance (LSPR) that is induced by so-called plasmonic nanostructures. Since the inception of SERS in 1970s, significant efforts have been put in developing SERS-active substrates with high quality in terms of sensitivity, reliability, reproducibility, scalability, throughput, and cost. At present, however, SERS substrates with sufficiently high quality for both research activities and real-world applications have not stood out yet. In this dissertation, four types of plasmonic Au nanostructures will be reviewed with respects to fabrication, characterization, optimization, and evaluation for SERS applications. Firstly, faceted ZnO/Au nanonecklace arrays epitaxially grown on r-plane sapphire substrates by chemical vapor deposition and sputtering will be introduced. Secondly, Au nanoisland arrays prepared by repeated sputtering and post-deposition annealing will be presented. Thirdly, nanoporous Si/Au composites resulting from metal-assisted wet etching and sputtering will be reported. Lastly, we will present a novel plasma nanocoating technique that overcoats SiO2/Au SERS-active nanostructures with an ultra thin polymer layer, followed by the demonstration of benefits brought by such plasma nanocoating. The properties and growth mechanisms of above mentioned plasmonic Au nanostructures were investigated with scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), ellipsometry and contact angle analyzer. By correlating the enhancement of Raman signal with the experimental parameters, recipes for optimized plasmonic nanostructures were established. Furthermore, the applicability of these plasmonic Au nanostructures for SERS purposes was demonstrated by successfully detecting various chemical species at trace level. At the end of the dissertation, a brief summary on these four plasmonic Au nanostructures will be reviewed against the standards of high quality SERS substrates and corresponding recommendations will be proposed to further improve the SERS performance.Includes bibliographical references