Recent Advances in Food Safety Detection: Split Aptamer-Based Biosensors Development and Potential Applications

Ensuring food safety is a shared responsibility across the entire food supply chain, encompassing manufacturers, processors, retailers, consumers, and regulatory bodies. However, traditional detection methods have several limitations, including slow processing times, high costs, limited sensitivity, and susceptibility to false positives or negatives. These shortcomings underscore the urgent need for faster, more accurate, and cost-effective detection technologies. Aptamers and aptasensors have emerged as promising alternatives. Aptamers offer advantages over traditional recognition probes due to their high affinity and specificity for diverse targets. The aptasensors enable rapid detection, cost reduction, shelf life extension, and minimal batch-to-batch variability, making them highly suitable for food safety applications. Detecting small molecules such as toxins, antibiotics, pesticides, contaminants, and heavy metals remains challenging due to steric hindrance, nonspecific binding, and reduced accuracy. Recent advancements in aptamer technology have focused on pre- and postmodifications to enhance detection performance. One of the most promising innovations is the development of split aptamers. These engineered aptamers, designed to operate in segments known as split aptamers, offer improved flexibility and binding specificity, effectively addressing the challenges of detecting small-sized targets. This review examines the evolution of aptamers and aptasensors, focusing on their application in detecting small molecules that are essential to food safety. It reported the strategies for modifying and optimizing selected aptamers, providing details on developing split aptamers as a promising approach to address the unique challenges of small-molecule detection. Additionally, recent advancements in split aptamer technology and its integration into aptasensor development are highlighted, showcasing how these innovations are revolutionizing the detection of food safety hazards by overcoming the limitations of traditional detection methods.

(2,9-Dimethyl-1,10-phenanthroline)bis-[2-(pyridin-2-yl)phen-yl]iridium(III) hexa-fluoro-phosphate and (2,9-dimethyl-1,10-phenanthroline)bis-[5-methyl-2-(pyridin-2-yl)phen-yl]iridium(III) hexa-fluoro-phosphate-diethyl ether-aceto-nitrile (1/0.61/0.78)

The title compounds, [Ir(C14H12N2)(C11H8N)2]PF6 (1) and [Ir(C14H12N2)(C12H10N)2]PF6·0.61C2H10O·0.78CH3CN (2), crystallize in the space groups Pbca and P1, respectively, each structure containing one monocationic Ir complex and one PF6 - anion in the asymmetric unit. The anion and solvent in compound 2 are disordered. The Ir-N(phenanthroline) bond lengths of ca. 2.21 Å indicate a greater steric effect of the 2,9-dimethyl-1,10-phenanthroline ligand compared to 1,10-phenanthroline. Both structures show offset parallel inter-molecular π-π inter-actions between the pyridine rings of the phenanthroline ligands, and that of 1 also exhibits similar inter-actions between the phenyl and pyridine rings of the phenyl-pyridine ligands.

Heavy Metal Ions Detection Using Nanomaterials-Based Aptasensors

Heavy metals ions as metallic pollutants are a growing global issue due to their adverse effects on the aquatic ecosystem, and human health. Unfortunately, conventional detection methods such as atomic absorption spectrometry exhibit a relatively low limit of detection and hold numerous disadvantages, and therefore, the development of an efficient method for in-situ and real-time detection of heavy metal residues is of great importance. The aptamer-based sensors offer distinct advantages over antibodies and emerged as a robust sensing platform against various heavy metals due to their high sensitivity, ease of production, simple operations, excellent specificity, better stability, low immunogenicity, and cost-effectiveness. The nucleic acid aptamers in conjugation with nanomaterials can bind to the metal ions with good specificity/selectivity and can be used for on-site monitoring of metal ion residues. This review aimed to provide background information about nanomaterials-based aptasensor, recent advancements in aptamer conjunction on nanomaterials surface, the role of nanomaterials in improving signal transduction, recent progress of nanomaterials-based aptasening procedures (from 2010 to 2022), and future perspectives toward the practical applications of nanomaterials-based aptasensors against hazardous metal ions for food safety and environmental monitoring.

Label free detection of auramine O by G-quadruplex-based fluorescent turn-on strategy

Auramine o (AO) is a synthetic dye used in paper and textile industries. Although it has been an unauthorized food additive in many countries due to its toxic and carcinogenic possibility, its illegal uses have been detected in certain food products such as pasta, semolina and spices and also in pharmaceuticals. The presence of AO in food products should be monitored, therefore, to minimize the negative health effects on consumers. In this study, a simple, highly sensitive and selective label free detection method was investigated for AO by G-quadruplex-based fluorescent turn-on strategy. The optimum fluorescent detection assay was achieved with a specific G-quadruplex DNA sequence, c-myc, at 400 nM in Tris-HCl buffer at pH 7.4. The linearity of fluorescence intensity depending on AO concentration ranged from 0 to 0.07 µM and LOD and LOQ were 3 nM and 10 nM, respectively. The G-quadruplex-based detection assay was highly specific for AO as compared to other two synthetic food colorings and successfully applied to determine AO in pasta, bulgur and curry powder with recoveries in the range from 70.33% to 106.49%. This G-quadruplex-based label free detection assay has a significant potential to be used in the detection of AO in food products.

Luminescent Strategies for Label-Free G-Quadruplex-Based Enzyme Activity Sensing

By catalyzing highly specific and tightly controlled chemical reactions, enzymes are essential to maintaining normal cellular physiology. However, aberrant enzymatic activity can be linked to the pathogenesis of various diseases. Therefore, the unusual activity of particular enzymes can represent testable biomarkers for the diagnosis or screening of certain diseases. In recent years, G-quadruplex-based platforms have attracted wide attention for the monitoring of enzymatic activities. In this Personal Account, we discuss our group's works on the development of G-quadruplex-based sensing system for enzyme activities by using mainly iridium(III) complexes as luminescent label-free probes. These studies showcase the versatility of the G-quadruplex for developing assays for a variety of different enzymes.

Heavy metal complexation of thiol-containing peptides from soy glycinin hydrolysates

Many thiol-containing molecules show heavy metal complexation ability and are used as antidotes. In this study, the potential function associated with thiol-containing peptides (TCPs) from soy protein hydrolysates as natural detoxicants for heavy metals is reported. TCPs enriched by Thiopropyl-Sepharose 6B covalent chromatography had different molecular weight distributions as well as different numbers of proton dissociable groups, depending on the proteases and degree of hydrolysis. The major contribution of sulfhydryl groups was confirmed by the largest pH decrease between 8.0 and 8.5 of the pH titration curves. The complexation of TCPs with heavy metalswas evaluated by stability constants (β_n) of TCP-metal complexes whose stoichiometry was found to be 1:1 (ML) and 1:2 (ML₂). TCPs from degree of hydrolysis of 25% hydrolysates gave high affinities towards Hg²⁺, Cd²⁺, and Pb²⁺ (giving similar or even bigger lgβ values than that of glutathione). A significantly positive correlation was found between the logarithm of stability constants for ML₂ (lgβ₂) and the sulfhydryl group content. Molecular weight distribution of TCPs affected the complexation with Pb²⁺ notably more than Hg²⁺ and Cd²⁺. These results suggest that soy TCPs have the potential to be used in the formulation of functional foods to counteract heavy metal accumulation in humans.

A ruthenium(II) complex supported by trithiacyclononane and aromatic diimine ligand as luminescent switch-on probe for biomolecule detection and protein staining

A new ruthenium(II) complex has been developed for detection of biomolecules. This complex is highly selective for histidine over other amino acids and has been applied to protein staining in an SDS-PAGE gel.