Detection of Enrofloxacin and Its Metabolite Ciprofloxacin Using Gold Nanoparticles and Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Abstract

This paper describes a new, simple, and sensitive method for detecting two fluoroquinolones: enrofloxacin and its metabolite ciprofloxacin, which are widely used as drugs for humans and animals. We utilized gold nanoparticles (AuNPs) and laser desorption/ionization time-of-flight (LDI-TOF) mass spectrometry (MS) with a matrix-free format. An antibody for the drug was immobilized on a chip based on self-assembled monolayers (SAMs) on gold, and AuNPs were decorated with the drug along with a large excess of small molecules, called amplification tags (Am-tags). In this strategy, target drugs in solution bound to the antibody on the chip compete with the AuNP-immobilized drugs. The presence of targets was verified by the amplified LDI-TOF MS signals of Am-tags on AuNPs.

Nanoparticle-based laser desorption/ionization mass spectrometric analysis of drugs and metabolites

“…However, the assay preparation is a little more complicated, involving the functionalization of the nanoparticles with mass tags and selective enrichment of the analyte, than that of normal SALDI-MS analysis. Thioalkanes have unique affinity with gold through the strong Au–S bond (180 kJ mol −1 ) and their ionization efficiency enable them as mass reporter tags in LDI-MS [ 7 ]. Ha et al utilized Au NPs with mass tags of thiolalkane ligands for the detection of enrofloxacin, a commonly used antibiotic, and its metabolite ciprofloxacin ( Fig.…”

“…In addition, the uneven crystallization of the matrix and the analyte molecules may cause heterogeneous sample distribution on the MALDI plate and affect the shot-to-shot and sample-to-sample reproducibilities. Another variation of the LDI-MS, the surface assisted laser desorption/ionization (SALDI), has emerged as the technique of choice for the analysis of small molecules, such as drugs and metabolites [ 7 – 11 ]. SALDI is an ionization technique that utilizes inorganic substances, nanomaterials or composites to assist in the ionization of target analyte [ 12 ].…”

“…Many nanostructured inorganic materials such as silica, metal and metal oxide nanoparticles, semiconductor nano-particles and some carbon-based nanomaterials like graphene oxide are efficient substrates in SALDI-MS analysis for drug and metabolite analysis due to their excellent photo-absorption coefficient and heat transfer efficiency [ 7 , 16 – 22 ]. In a SALDI process, the applied laser beam heats up the substrate instead of the analyte.…”

Gold and silver nanoparticles‐based laser desorption/ionization mass spectrometry method for detection and quantification of carboxylic acids

“…In this family of methods, target plates are coated with diverse nanostructures. [3][4][5][6][7][8][9] We have recently shown new method of preparation of modified MALDI target by covering it with cationic, monoisotopic silver-109 nanoparticles (silver-109 nanoparticle-enhanced target [ 109 AgNPET]). Another method for LMW compounds analysis was using gold nanoparticleenhanced target (AuNPET).…”

“…The presented problem has been partly solved by the development of surface‐assisted desorption/ionization (SALDI) techniques. In this family of methods, target plates are coated with diverse nanostructures 3–9 . We have recently shown new method of preparation of modified MALDI target by covering it with cationic, monoisotopic silver‐109 nanoparticles (silver‐109 nanoparticle‐enhanced target [ 109 AgNPET]).…”