Printer‐assisted array flexible surface‐enhanced Raman spectroscopy chip preparation for rapid and label‐free detection of bacteria

Abstract

A low‐cost array flexible surface‐enhanced Raman spectroscopy (SERS) chip was proposed with the aim of rapid detection of bacteria. The substrate of the chip was Al foil, and the detection area arrays were printed using a laser toner. Colloidal silver nanoparticles (AgNPs) were dropped onto the detection area, with the AgNPs droplets confined within the detection area by the hydrophobic properties of the toner film. The colloidal AgNPs were dried naturally to form a SERS active chip. An A4 paper‐based SERS chip was prepared using the same method for control experiments. The surface morphology of the chip was characterized by field emission scanning electron microscopy. In addition, comparison experiments were performed on the two SERS chips. The results showed that both SERS chips exhibited the best SERS enhancement when the AgNPs were added four times. The calculation of Rhodamine 6G at the 612 cm−1 peak showed that the EF of the A4 paper‐based chip and the Al foil‐based chip were 6.72 × 107 and 1.03 × 108, respectively. SERS mapping results showed that the Al foil‐based chip had much higher signal homogeneity than that of A4 paper‐based chip. Lastly, the Al foil‐based chip was used for bacterial detection. For Escherichia coli and Staphylococcus aureus, the limit of detection was 1,000 and 100 cfu/ml, and the relative standard deviation of 36 randomly selected detection points were 12.5% and 11.7%, respectively. The entire detection process was completed in a few minutes. The SERS chip has the advantages of low cost, simple manufacturing process, and short detection time; is capable of high throughput and multi‐parameter detection; and is expected to provide a rapid and effective detection method for bacteria.

Advances in surface‐enhanced Raman spectroscopy technology for detection of foodborne pathogens

“…Other flexible substrates: Along with the above-listed conventional flexible substrates, new flexible substrates based on different materials are also being developed. Yang et al (2020) used aluminum foil as a flexible substrate and assembled Ag NPs in the form of repeated drop coating onto the substrate surface to make a composite three-dimensional flexible SERS chip with an enhancement factor of 10 8 . The system was applied for highthroughput, multiparameter rapid detection of E. coli and S. aureus in few minutes.…”

“…Yang et al. (2020) used aluminum foil as a flexible substrate and assembled Ag NPs in the form of repeated drop coating onto the substrate surface to make a composite three‐dimensional flexible SERS chip with an enhancement factor of 10 8 . The system was applied for high‐throughput, multiparameter rapid detection of E. coli and S. aureus in few minutes.…”

Rapid Identification of Species, Antimicrobial‐Resistance Genotypes and Phenotypes of Gram‐Positive Cocci Using Long Short‐Term Memory Raman Spectra Methods

“…The relative standard deviations (RSDs) were shown to be from 9.7% to 13.2% and considered acceptable. [32,33] We then trained the neural network of microbial species identification model, which generated a probability distribution profile across three different species (S. capitis, E. faecium, and E. faecalis), and the maximum model was taken as the predicted models. We utilized the bootstrap method that involved five resampling rounds to evaluate the classification accuracy of the LSTM taxonomic model.…”

Flexible Surface‐Enhanced Raman Scattering Substrates: A Review on Constructions, Applications, and Challenges

“…Similarly, when the detection area arrays were printed on Al foil using a laser toner, a low‐cost array flexible SERS chip was also fabricated. [ 150 ] Besides, Lee et al [ 151 ] developed an invisible ink‐inspired process to fabricate flexible plasmonic Au‐based SERS substrates. They used green tannic acid (TNA) molecules as invisible ink, combining with AuNPs to fabricate SERS absorbents by the reduction of the Au‐TNA complex.…”