Laser-Induced Graphene Electrodes Modified with a Molecularly Imprinted Polymer for Detection of Tetracycline in Milk and Meat

Abstract

Tetracycline (TC) is a widely known antibiotic used worldwide to ‘’treat animals. Its residues in animal-origin foods cause adverse health effects to consumers. Low-cost and real-time measuring systems of TC in food samples are, therefore, extremely needed. In this work, a three-electrode sensitive and label-free sensor was developed to detect TC residues from milk and meat extract samples, using CO2 laser-induced graphene (LIG) electrodes modified with gold nanoparticles (AuNPs) and a molecularly imprinted polymer (MIP) used as a synthetic biorecognition element. LIG was patterned on a polyimide (PI) substrate, reaching a minimum sheet resistance (Rsh) of 17.27 ± 1.04 Ω/sq. The o-phenylenediamine (oPD) monomer and TC template were electropolymerized on the surface of the LIG working electrode to form the MIP. Surface morphology and electrochemical techniques were used to characterize the formation of LIG and to confirm each modification step. The sensitivity of the sensor was evaluated by differential pulse voltammetry (DPV), leading to a limit of detection (LOD) of 0.32 nM, 0.85 nM, and 0.80 nM in buffer, milk, and meat extract samples, respectively, with a working range of 5 nM to 500 nM and a linear response range between 10 nM to 300 nM. The sensor showed good LOD (0.32 nM), reproducibility, and stability, and it can be used as an alternative system to detect TC from animal-origin food products.

Recent trends in nanostructured carbon-based electrochemical sensors for the detection and remediation of persistent toxic substances in real-time analysis

“…The remarkable qualities of the 0D CDs include minimal toxicity, excellent cytocompatibility, outstanding electrical conductance, and affordability. A 2D GR that has been transformed into a GR sheet having a transverse width of under 100 nm is known as GD [113][114][115][116][117][118]. The properties of graphene and quantum dots are represented by GD.…”

Recent Trends in the Development of Carbon-Based Electrodes Modified with Molecularly Imprinted Polymers for Antibiotic Electroanalysis

“…MIPs are a class of polymers synthesized from at least a template molecule (target molecule) and a functional monomer, but, depending on the polymerization method, a cross-linking reagent, a porogenic solvent, and an initiator may also be required. Functional monomers can be linked to the templates through non-covalent (hydrogen bond, ionic or hydrophobic) or covalent interactions to form complexes before the cross-linking reaction in the solvent [3]. A general procedure for MIP synthesis involves three simple steps (Figure 2): (1) pre-polymerization complex (pre-complex) formation in solution by a combination of the template molecules with the functional monomer via covalent or non-covalent bonds;…”

“…However, in this procedure a supporting electrolyte is necessary. For water-soluble monomers and templates, the most used supporting electrolytes were acids (HCl [113]) or mixtures of acids (e.g., H 2 SO 4 and H 3 PO 4 when aniline was the monomer [8,38,91]), salts (KCl [31], K 2 HPO 4 [22,99], NaClO 4 [99], PBS [24,39,92,95,96,109,112] and BRB [3,107]) with different pH values. If the polymeriza-tion was performed in organic solvents, then the preferred supporting electrolytes were LiClO 4 [7,26], TBAP [93,105] and 4BA6FPh [17].…”

“…Despite the fact that the first antibiotic, penicillin, was accidentally discovered in 1928 by Sir Alexander Flemming [1], the term "antibiotic" was introduced only in 1941 to describe small molecules produced by a microbe, which have the capacity to inhibit the development of other microbes or even to be lethal to these [2]. Antibiotics are either secondary metabolites of certain bacterial and fungal species [3][4][5] or semi-synthetic [6][7][8] or synthetic compounds [2]. Thus, antibiotics are used in modern healthcare to treat bacterial infections.…”

“…However, this delimitation is not very strict because there are also bacteriostatic antibiotics with bactericidal activity (e.g., linezolid) or vice versa, and some bactericidal antibiotics can act as bacteriostatic antimicrobials in certain conditions [10]. Regardless of this classification, these drugs help the living organisms to fight against various bacterial infections (gastrointestinal, urinary [6], genital tract [11], skin [2], abdominal [12], central nervous system [13] and ear infections, strep throat, pneumonia, typhoid, bronchitis, sinusitis [8], arthritis, mastitis [3], tuberculosis, leprosy, malaria [14], etc. ), contributing thus to the improvement of human and animal health and reducing their mortality rate.…”