Paper-Based SERS Platform for One-Step Screening of Tetracycline in Milk

Abstract

Throughout the last decade, the expansion of food testing has been gradually moving towards ordinary high throughput screening methods performed on-site. The demand for point-of-care testing, able to distinguish molecular signatures with high accuracy, sensitivity and specificity has been significantly increasing. This new requirement relies on the on-site detection and monitorization of molecular signatures suitable for the surveillance of food production and processing. The widespread use of antibiotics has contributed to disease control of livestock but has also created problems for the dairy industry and consumers. Its therapeutic and subtherapeutic use has increased the risk of contamination in milk in enough concentrations to cause economic losses to the dairy industry and have a health impact in highly sensitive individuals. This study focuses on the development of a simple Surface-Enhanced Raman Spectroscopy (SERS) method for fast high throughput screening of tetracycline (TET) in milk. For this, we integrate a paper-based low-cost, fully recyclable and highly stable SERS platform, with a minimal sample preparation protocol. A two-microliter sample of milk solutions spiked with TET (from 0.01 to 1000 ppm) is dried on a silver nanoparticle coated cardboard substrate and measured via a Raman spectrophotometer. The SERS substrate showed to be extremely stable with a shelf life of several months. A global spectrum principal component analysis approach was used to test all the detected vibrational modes and their correlation with TET concentration. Peak intensity ratios (455 cm−1/1280 cm−1 and 874 cm−1/1397 cm−1) were found to be correlated with TET concentrations in milk, achieving a sensitivity as low as 0.1 ppm. Results indicate that this SERS method combined with portable Raman spectrometer is a potential tool that can be used on-site for the monitoring of TET residues and other antibiotics.

Surface‐enhanced Raman spectroscopy for on‐site analysis: A review of recent developments

“…used as supports for SERS substrate preparation. [88,89] A flexible SERS substrate made from a common filter paper loaded with gold F I G U R E 6 Schematic representation of a dual-wavelength diode laser with separated heater elements H 1 and H 2 , two distributed Bragg reflector (DBR) gratings, and electrical contacts C 1 , C 2 , C Y , and C out . DBR: distributed Bragg reflector.…”

Substrates for Surface-Enhanced Raman Scattering Formed on Nanostructured Non-Metallic Materials: Preparation and Characterization

“…SERS substrates may be, however, also produced on other nanostructured inorganic films, for example on ZrO 2 [ 10 ]. Moreover, in addition to SERS materials formed on inorganic substrates, there are also widely used so called paper-based SERS substrates that are formed on cellulose [ 11 , 12 , 13 ]. This type of SERS substrate is also not described in this work.…”

Application of Plasma-Printed Paper-Based SERS Substrate for Cocaine Detection

“…The choice of substrate and materials deposition technique are two other important considerations for SERS-based applications. Paper-based substrates are highly attractive as they are low-cost, disposable and can be readily modified by inkjet printing, drop-casting, direct writing and soaking with different nanomaterials [ 19 , 20 , 21 , 22 , 23 ]. Moreover, paper-based substrates are flexible, which could allow for swabbing applications [ 24 , 25 ] within the forensics field for detection of illicit drugs and explosives.…”