A novel portable Raman scattering platform for antibiotic screening in pig urine.

Background and Aim: Public health and food safety are gaining attention globally. Consumer health can be protected from chemical residues in meat by early detection or screening for antibiotic residues before selling the meat commercially. However, conventional practices are normally applied after slaughtering, which leads to massive business losses. This study aimed to use portable surface-enhanced Raman spectroscopy (SERS) equipped with multivariate curve resolution-alternation least squares (MCR-ALS) to determine the concentrations of enrofloxacin, oxytetracycline, and neomycin concentrations. This approach can overcome the problems of business loss, costs, and time-consumption, and limit of detection (LOD). Materials and Methods: Aqueous solutions of three standard antibiotics (enrofloxacin, oxytetracycline, and neomycin) with different concentrations were prepared, and the LOD for each antibiotic solution was determined using SERS. Extracted pig urine was spiked with enrofloxacin at concentrations of 10, 20, 50, 100, and 10,000 ppm. These solutions were investigated using SERS and MCR-ALS analysis. Urine samples from pigs at 1 and 7 days after enrofloxacin administration were collected and investigated using SERS and MCR-ALS to differentiate the urinary enrofloxacin concentrations. Results: The LOD of enrofloxacin, oxytetracycline, and neomycin in aqueous solutions were 0.5, 2.0, and 100 ppm, respectively. Analysis of enrofloxacin spiking in pig urine samples demonstrated the different concentrations of enrofloxacin at 10, 20, 50, 100, and 10,000 ppm. The LOD of spiking enrofloxacin was 10 ppm, which was 10 times lower than the regulated value. This technique was validated for the first time using urine collected on days 1 and 7 after enrofloxacin administration. The results revealed a higher concentration of enrofloxacin on day 7 than on day 1 due to consecutive administrations. The observed concentration of enrofloxacin was closely correlated with its circulation time and metabolism in pigs. Conclusion: A combination of SERS sensing platform and MCR-ALS is a promising technique for on-farming screening. This platform can increase the efficiency of antibiotic detection in pig urine at lower costs and time. Expansion and fine adjustments of the Raman dataset may be required for individual farms to achieve higher sensitivity.

Label free detection of multiple trace antibiotics with SERS substrates and independent components analysis.

Surface enhanced Raman spectroscopy (SERS) has been widely studied and recognized as a powerful label-free technique for trace chemical analysis. However, its drawback in simultaneously identifying several molecular species has greatly limited its real-world applications. In this work, we reported a combination between SERS and independent component analysis (ICA) to detect several trace antibiotics which are commonly used in aquacultures, including malachite green, furazolidone, furaltadone hydrochloride, nitrofurantoin, and nitrofurazone. The analysis results indicate that the ICA method is highly effective in decomposing the measured SERS spectra. The target antibiotics could be precisely identified when the number of components and the sign of each independent component loading were properly optimized. With SERS substrates, the optimized ICA can identify trace molecules in a mixture at a concentration of 10-6 M achieving the correlation values to the reference molecular spectra of 71-98%. Furthermore, measurement results obtained from a real-world sample demonstration could also be recognized as an important basis to suggest this method is promising for monitoring antibiotics in a real aquatic environment.

Preparation of stable ultrahydrophobic and superoleophobic silica-based coating.

Silica-Based coatings having excellent water- and oil-repellent properties and good weathering stability have been deposited onto glass surface by a simple one-step dip coating technique. To achieve ultra water repellency and super oil repellency, the chemical composition of SiO2 nanoparticle employed as surface roughness enhancer and trichloro(1H,1H,2H,2H-perfluorooctyl)silane employed as surface-energy reducing substance was varied. At the optimum synthesis condition, the coating exhibited very high contact angles of 173.2, 146.7 and 147.6 degrees for water, ethylene glycol and seed oil, respectively. The achievement of excellent water- and oil-repellency is also described based on the presence of air trapped in micropore of the coating in addition to its high surface roughness and low surface free energy. The coatings have good weathering stability based on natural and accelerated weathering tests indicating feasibility for practical use.

Increasing active surface area to fabricate ultra-hydrophobic surface by using "Black silicon" with bosch etching process.

Needle-shaped pillars so-called "Black silicon" (B-Si) were fabricated by etching cleaned silicon wafer with fluorine-based deep reactive ion etching plasma. The B-Si pillar with the pillar size (a) and spacing (b) of 250 nm, and height (h) of 6.47 microm, coated with SiOxFy film had water contact angle (WCA) and ethylene glycol contact angle (ECA) of 159.8 degrees and 135.5 degrees, respectively. After coating the pillar with trichloro(1H,1H, 2H,2H-perfluorooctyl)silane (TPFS), the WCA and ECA increased to 166.2 degrees and 161.8 degrees, respectively. At the optimum etching condition, the B-Si pillar with the size a = 376 nm, b = 576 nm, h = 6.47microm, and the aspect ratio of 14.80 showed the WCA and ECA of 4.25 degrees and 14.77 degrees, respectively. After coating with the TPFS, liquid droplets ran across the sample's surface rapidly and the WCA and ECA could not be measured. Moreover, when the pillar height was increased twice, the WCA and ECA of the B-Si with and without the TPFS coating were greater than 170 degrees, indicating excellent water-and-oil repellency and can be applied for Micro-Electro-Mechanical Systems (MEMS).

Fabrication of silica-based multilayer films with self-cleaning and antireflective properties.

The silica-based multilayer films exhibiting both self-cleaning property and antireflection in the visible and near infrared regions have been deposited onto glass substrate by layer-by-layer deposition of PAH/PAA polyelectrolyte bilayers, followed by sequential deposition of PAH/SiO2 nanocomposite layers to create the nanoporous structure in the film, and finally treating with fluorosilane. To obtain the appropriate porosity and surface roughness so as to satisfy both antireflection and self-cleaning properties, the deposition of PAH/SiO2 nanocomposite layers was varied from 2 to 8 layers. Scanning electron microscopy and atomic force microscopy analysis revealed that a highly nanoporous structure was obtained from the more deposition of loosely agglomerated SiO2 nanoparticles which increased with the increased cycle of PAH/SiO2 deposition. The film consisting of 6 and 8 PAH/SiO2 layers exhibited a very low reflection of only 1-2% in the visible region and approximately 2-4% in the near infrared region, a maximum transmittance of approximately 93% in the visible region and approximately 94% in the near infrared region, and a high advancing contact angle of approximaetly 150 degrees. It is anticipated that the film which exhibited both self-cleaning and antireflection properties enables the application of the antireflection coatings under humid environments.

An effect of silicon micro-nano-patterning arrays on superhydrophobic surface.

Superhydrophobic surface can be fabricated by creating a rough surface at very fine scale and modify it with low-surface energy material. To obtain the optimum superhydrophobicity, the surface roughness must be maximized. To avoid the limitation of scaling down the pattern size by using an expensive lithography tools, the surface roughness factor (r) was increased by means of changing an asperity shape so as to increase its overall surface area. In this paper, the patterns of the asperities under studied were wave stripes, line stripes, cylindrical pillars, square pillars, pentagonal pillars, hexagonal pillars, and octagonal pillars. All pillar shapes were arranged in square arrays, hexagonal arrays, and continuous stripes. The asperities sizes and the pitches were varied from 1 to 5 microm with 10 microm of asperity height. Then the patterned surfaces were coated with polydimethylsiloxane mixed with 10 wt% dicumylperoxide. It was found that the stripe asperities can generate only hydrophobic surface with water contact angle (WCA) of 135 degrees to 145 degrees. The pillars with square and hexagonal arrays had the WCA of 149 degrees to 158 degrees. The pentagonal pillars with square and hexagonal arrays achieved the highest WCA with an average WCA of 156 degrees. It was evident that the pillar shape had significant effect on the superhydrophobicity.