Flexible SERS platform based on PET/ITO/Ag for detection of pesticides

https://kent-islandora.s3.us-east-2.amazonaws.com/node/14392/83903-thumbnail.jpgSurface-Enhanced Raman Spectroscopy (SERS) is a sensitive, non-destructive, rapid and powerful detection technique used for wide range of biological systems and chemicals analytes in low concentration and also as a diagnostic tool for environmental and biomedical analysis [1].To enhance the Raman signal the special SERS platform, usually made of silicon, glass or another brittle material, or metallic nanoparticles are required [2]. Due to extensive use of those chemical substances for plant fungicide and insecticide protection the detection and identification of pesticides on the surface of fruits and vegetables is a crucial issue. We show a new type of elastic SERS platform made of poly(ethylene terephthalate) (PET) covered with a layer of indium tin oxide (ITO). This composite is subjected to dielectric barrier discharge (DBD) that develops the active surface of the PET/ITO foil. To enhance the Raman signal, a modified composite was covered with a thin layer of silver using the physical vapor deposition (PVD) technique. The SERS platform was used for measurements popular pesticides, i.e., Thiram and Carbaryl and to quantitative analysis of those pesticides from fruits. The presented SERS platform exhibits excellent enhancement and reproducibility of the Raman signal, which enables the trace analysis of these pesticides in the range up to their maximum residues limit. [3]. REFERENCES [1] Pilot R, Signorini R, Durante C, Bhamidipati DM, Fabris L., Biosensors (2019); 9, 57 [2] Mosier-Boss PA., Nanomaterials (2017);7,142 [3] Nowicka AB, Czaplicka M, Kowlaska AA, Szymborski T, Kamińska A., Biosensors (2019); 9,</p

Flexible PET/ITO/Ag SERS Platform for Label-Free Detection of Pesticides

We show a new type of elastic surface-enhanced Raman spectroscopy (SERS) platform made of poly(ethylene terephthalate) (PET) covered with a layer of indium tin oxide (ITO). This composite is subjected to dielectric barrier discharge (DBD) that develops the active surface of the PET/ITO foil. To enhance the Raman signal, a modified composite was covered with a thin layer of silver using the physical vapor deposition (PVD) technique. The SERS platform was used for measurements of para-mercaptobenzoic acid (p-MBA) and popular pesticides, i.e., Thiram and Carbaryl. The detection and identification of pesticides on the surface of fruits and vegetables is a crucial issue due to extensive use of those chemical substances for plant fungicide and insecticide protection. Therefore, the developed PET/ITO/Ag SERS platform was dedicated to quantitative analysis of selected pesticides, i.e., Thiram and Carbaryl from fruits. The presented SERS platform exhibits excellent enhancement and reproducibility of the Raman signal, which enables the trace analysis of these pesticides in the range up to their maximum residues limit. Based on the constructed calibration curves, the pesticide concentrations from the skin of apples was estimated as 2.5 &micro;g/mL and 0.012 &micro;g/mL for Thiram and Carbaryl, respectively. Additionally, the PET/ITO/Ag SERS platform satisfies other spectroscopic properties required for trace pesticide analysis e.g., ease, cost-effective method of preparation, and specially designed physical properties, especially flexibility and transparency, that broaden the sampling versatility to irregular surfaces

Efficiency of Mn Removal of Different Filtration Materials for Groundwater Treatment Linking Chemical and Physical Properties

This paper presents research on Fe and Mn removal from groundwater. In treatment systems of aeration followed by rapid filtration (no chemical dosage), manganese removal is possible due to the manganese dioxide catalyst present on the grains of filtration material. The goal of the presented research was to find a correlation between the catalyst layer’s composition as well as its internal porosity and the effectiveness and stability of manganese removal in the filtration process. In order to establish the influence of catalyst characteristics on manganese removal effectiveness, the filtration experiment was conducted using filtration materials with catalytic contact layers of different origin. Oxide coated auto-activated silica sand and Gabon manganese ore were tested. Inactive silica sand was used as reference. The results of filtration experiments were combined with analyses of chemical composition, internal porosity, and crystalline parameters of catalyst contact layers of grains. For the determination catalyst contact layer parameters, the following methods were used: Raman spectroscopy, X-ray powder diffractometry (XRD), Scanning Electron Microscope – Energy dispersive spectroscopy (SEM-EDAX), nitrogen adsorption. Pilot scale research on the filtration process demonstrated that auto-activated filtration material was characterized by the highest efficiency of manganese removal and stability of effects during the whole research. The effectiveness of Gabon manganese ore dropped from 90% and stabilized on the level of ca. 60% within 15 days of the experiment

Dielectrophoresis-Based SERS Sensors for the Detection of Cancer Cells in Microfluidic Chips

The detection of freely circulating cancer cells (CTCs) is one of the greatest challenges of modern medical diagnostics. For several years, there has been increased attention on the use of surface-enhanced Raman spectroscopy (SERS) for the detection of CTCs. SERS is a non-destructive, accurate and precise technique, and the use of special SERS platforms even enables the amplification of weak signals from biological objects. In the current study, we demonstrate the unique arrangement of the SERS technique combined with the deposition of CTCs cells on the surface of the SERS platform via a dielectrophoretic effect. The appropriate frequencies of an alternating electric field and a selected shape of the electric field can result in the efficient deposition of CTCs on the SERS platform. The geometry of the microfluidic chip, the type of the cancer cells and the positive dielectrophoretic phenomenon resulted in the trapping of CTCs on the surface of the SERS platform. We presented results for two type of breast cancer cells, MCF-7 and MDA-MB-231, deposited from the 0.1 PBS solution. The limit of detection (LOD) is 20 cells/mL, which reflects the clinical potential and usefulness of the developed approach. We also provide a proof-of-concept for these CTCs deposited on the SERS platform from blood plasma

Lung Cancer: Spectral and Numerical Differentiation among Benign and Malignant Pleural Effusions Based on the Surface-Enhanced Raman Spectroscopy

We present here that the surface-enhanced Raman spectroscopy (SERS) technique in conjunction with the partial least squares analysis is as a potential tool for the differentiation of pleural effusion in the course of the cancerous disease and a tool for faster diagnosis of lung cancer. Pleural effusion occurs mainly in cancer patients due to the spread of the tumor, usually caused by lung cancer. Furthermore, it can also be initiated by non-neoplastic diseases, such as chronic inflammatory infection (the most common reason for histopathological examination of the exudate). The correlation between pleural effusion induced by tumor and non-cancerous diseases were found using surface-enhanced Raman spectroscopy combined with principal component regression (PCR) and partial least squares (PLS) multivariate analysis method. The PCR predicts 96% variance for the division of neoplastic and non-neoplastic samples in 13 principal components while PLS 95% in only 10 factors. Similarly, when analyzing the SERS data to differentiate the type of tumor (squamous cell vs. adenocarcinoma), PLS gives more satisfactory results. This is evidenced by the calculated values of the root mean square errors of calibration and prediction but also the coefficients of calibration determination and prediction (R2C = 0.9570 and R2C = 0.7968), which are more robust and rugged compared to those calculated for PCR. In addition, the relationship between cancerous and non-cancerous samples in the dependence on the gender of the studied patients is presented

Detection of circulating tumor cells (CTCs) by SERS-based immunomagnetic optofluidic device

https://kent-islandora.s3.us-east-2.amazonaws.com/node/14388/83895-thumbnail.jpgThe isolation and characterization of circulating tumor cells (CTCs) has great potential for non-invasive biopsy. In this study, a surface-enhanced Raman spectroscopy (SERS) method was developed using magnetic nanoparticles and a solid SERS-active substrate integrated with an external field-assisted microfluidic device to efficiently isolate CTCs from blood samples. A new SERS substrate was used, developed by physically modifying the surface with a femtosecond laser, sputtering the active SERS layer and chemically modifying the surface with anti-EpCAM antibodies. Magnetic nanoparticles (Fe2O3) were coated with SERS active metal and then modified with para-mercaptobenzoic acid (p-MBA), which acts simultaneously as a Raman reporter and a linker with anti-EpCAM antibodies. The sensitive immune recognition of tumor cells is aided by the introduction of a controlled external magnetic field into the microfluidic chip. The integration of the SERS-active platform and p-MBA labeled immuno-Ag@Fe2O3 nanostructures with the microfluidic device ensures lower demand for samples and analytes, precise operation, increases the reproducibility of spectral responses and enables miniaturization and portability of the presented approach. We used four target tumor cell lines with relatively large (human prostate metastatic adenocarcinoma cells (LNCaP)), medium (adenocarcinomic human alveolar basal epithelial cells (A549)), weak (human prostate tumor line (PC3)) and no expression of EpCAM (tumor cells) cervical cancer (HeLa)) to estimate the detection limits on the basis of constructed calibration curves blood samples from lung cancer patients were used to validate the developed method.[1] M. Czaplicka, K. Niciński, A. Nowicka, T. Szymborski i A. Kamińska, Cancers, 2020, 12 (3315), 1-21. </ol