SERS Detection of Penicillin G Using Magnetite Decorated with Gold Nanoparticles

Abstract

Sensitive and reliable procedures for detecting vestigial antibiotics are of great relevance for water quality monitoring due to the occurrence of such emergent pollutants in the aquatic environment. As such, we describe here research concerning the use of multifunctional nanomaterials combining magnetic and plasmonic components. These nanomaterials have been prepared by decorating magnetite nanoparticles (MNP) with colloidal gold nanoparticles (Au NPs) of distinct particle size distributions. Several analytical conditions were investigated in order to optimize the surface enhanced Raman scattering (SERS) detection of penicillin G (PG) dissolved in water. In particular, the dependence of the SERS signal by using distinct sized Au NPs adsorbed at the MNP was investigated. Additionally, microscopic methods, including Raman confocal microscopy, were employed to characterize the SERS substrates and then to qualitatively detect penicillin G using such substrates. For example, magnetic-plasmonic nanocomposites can be employed for magnetically concentrate analyte molecules and their removal from solution. As a proof of concept, we applied magneto-plasmonic nanosorbents in the removal of aqueous penicillin G and demonstrate the possibility of SERS sensing this antibiotic.

Magnetite-Supported Gold Nanostars for the Uptake and SERS Detection of Tetracycline

“…Figure 2a shows the TEM images of the MNPs, confirming that the Fe 3 O 4 particles have a well-defined cubic shape and an average dimension of 80 nm (diagonal). Our previous work reports that the method employed results in cubic-shaped ferrimagnetic NPs with a saturation magnetization of 86 emu/g composed of magnetite as the main crystalline phase [33,48,49]. The surface of the as-prepared MNP was decorated with AuNS using an adaptation of the seed-mediated growth method described by Wang and co-workers [50].…”

“…An interesting possibility to circumvent this problem involves the capture of molecules of the pollutant by a sorbent material that besides allowing for pre-concentration procedures also acts as an SERS substrate for optical detection [32]. In this context, we have been interested in developing magneto-plasmonic hybrid nanomaterials that combine magnetic properties and SERS activity, thus exploring the magnetic separation ability offered by a magnetic oxide (e.g., Fe 3 O 4 ) and the plasmonic behaviour of a nanometal (e.g., Au) [32,33]. Several approaches have been reported in the literature to produce magneto-plasmonic nanomaterials for SERS-sensitive detection, aiming at environmental applications [32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47], but only a few reports have described the SERS detection of antibiotics [33,41,44].…”

Functionalized Inorganic Nanoparticles for Magnetic Separation and SERS Detection of Water Pollutants

“…Sensors based on Au or bimetallic nanostructures have also been used as SERS‐active substrate for trace detection of antibiotics, such as oxytetracycline, tetracycline, ciprofloxacin, nitrofuran and penicillin G . Li and co‐workers have reported Au–Ag cubes as highly active SERS substrate for direct detection of trace ciprofloxacin in water (8 × 10 –8 m ) and also in chicken wings (2 × 10 –7 m ) …”

“…Thus, an excess of ferrous ions results in the formation of spherical micrometric particles, whereas an excess of hydroxide ion result into cubic and smaller NPs. Our research group has used this process for the synthesis of well‐defined cubic shaped Fe 3 O 4 NPs as ferrimagnetic adsorbents for decontamination of water via magnetic separation , , . These systems show high magnetization values which facilitate fast and efficient separation from the medium but on the other hand lack colloidal stability, requiring mechanical stirring for prolonged contact times.…”

“…Noteworthy, this method achieved a detection limit as low as 1 mg L –1 , which is in line with the minimum threshold established for PCP. We have reported magneto‐plasmonic nanosorbents for the removal of aqueous penicillin G and demonstrate the potential for SERS sensing of this antibiotic . The nanocomposites employed have been prepared by surface‐modification of colloidal magnetite NPs with siliceous shells enriched in dithiocarbamate groups, followed by adsorption of Au NPs, aiming at the SERS detection of penicillin G.…”