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The aim of the work is the development of the procedure for ceftriaxone (antibiotic drug of cephalosporin class) detection in urine using surface-enhanced Raman spectroscopy (SERS). Hydroxylamine stabilized silver nanoparticles were used as SERS-active material. Additional urine pretreatment steps were developed in order to eliminate the influence of creatinine on the ceftriaxone SERS signal. These steps include adjusting of the sample pH to alkaline value (pH 13) and purification of the sample using silica gel column chromatography. Alkali pH increases SERS signal of ceftriaxone, while silica gel separates the analyte from creatinine-the main admixture in urine which provides inappropriate SERS signal background. Additionally, it was found that total protein content up to 0.2 mg/mL (upper level for urine of healthy person) and pH deviation of initial urine do not influence on SERS signal of ceftriaxone. The proposed detection procedure enables fast (~ 10 min) determination of ceftriaxone in artificially spiked urine samples within 5 to 500 μg/mL range of concentrations which matches the range of the drug concentrations in urine after injection of therapeutically required dosages. Limits of detection (3σ) and quantification (10σ) were found to be 0.4 and 2.0 μg/mL, correspondingly. Graphical abstract Application of urine pretreatment enables the purification of target analyte from intrinsic urine components and improves SERS-based detection of ceftriaxone (antibiotic drug).

We suggest the use of a simple and cheap synthesis of micro- and nanosized copper­(I) oxide particles with variable color as a demonstration of size-dependent optical properties of semiconductors for high school students. The synthesis of Cu2O particles is performed by reducing alkaline copper­(II)–citrate complex (Benedict’s reagent) with glucose. Significant color and size changes of Cu2O particles at various reaction conditions are observed and discussed. Proposed demonstration is very useful for introducing students (including undergraduate students) to size-dependent optical properties of semiconductors and principles of synthesis of nanosized objects.

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The authors describe a series of simple experiments related to the synthesis, oxidation, and aggregation of plasmonic copper nanoparticles (CuNPs) stabilized by iodide ions. These experiments can help with (i) substituting noble-metal-based plasmonic nanoparticles for nanotechnology-oriented lessons, (ii) demonstrating high reactivity of nanosized objects, and (iii) attracting students’ attention by colorful experiments. The main compounds required for the experiments are CuSO4, KI, NaBH4, and diluted H2SO4. These compounds are relatively safe, available, cost-effective, and do not require special recycling. The color of the reaction mixture rapidly changes from colorless (diluted CuSO4) to wine red (fresh CuNPs) and then to yellow (oxidized CuNPs) or dark green and blue (agglomerated CuNPs), making the reactions more visible to the students. The fast oxidation of CuNPs by the oxygen in air was proposed to demonstrate the high reactivity of nanosized copper and to enrich the nanotechnology lessons with chemical reactions. The authors also highlight and discuss the importance of accounting for potential side reactions (e.g., hydrolysis) for the synthesis and oxidation of CuNPs. The important role of iodide ions in providing colloidal stability of CuNPs is discussed, and several comparative experiments with other stabilizers are proposed. In addition, the authors compare the optical properties of CuNPs with those of gold- and silver-based nanoparticles. The experiments are designed to be completed in less than 45 min and have been regularly used at chemistry club lessons for secondary school students in 2017 and 2018. The efficiency of the experiments has also been tested several times with undergraduate students at Saratov State University.