An inner filter effect-based fluorescent aptasensor for sensitive detection of kanamycin in complex samples using gold nanoparticles and graphene oxide quantum dots

In this work, a label-free fluorescent aptasensor based on the inner filter effect (IFE) between gold nanoparticles (AuNPs) and graphene oxide quantum dots (GOQDs) was developed for the detection of kanamycin in complex samples. AuNPs are capable of functioning as the fluorescence absorber of GOQDs because of the complementary overlap between their absorption spectra and the emission spectra of GOQDs. AuNPs can effectively quench the fluorescence of GOQDs via the IFE and modulate it with their aggregation state. In the presence of kanamycin, the aptamer is released from the surface of AuNPs, leading to their salt-induced aggregation and the fluorescence recovery of GOQDs. Under the optimum conditions, the fluorescence intensity of GOQDs was linearly proportional to the concentration of kanamycin over the range from 5 to 600 nM, with a detection limit of 3.6 nM. Moreover, the fluorescent aptasensor was successfully applied for kanamycin detection in complex samples (milk, honey and serum), which might hold great promise for kanamycin detection in food safety control and clinical research.

Novel sandwich-type electrochemiluminescence aptasensor based on luminol functionalized aptamer as signal probe for kanamycin detection

A novel sandwich electrochemiluminescence (ECL) aptasensor was developed for highly sensitive detection of kanamycin using luminol-functionalized aptamer as a signal probe. The aptasensor used polyethyleneimine (PAMAM), molybdenum disulfide, and multi-walled carbon nanotubes as the substrate, which provided enough binding sites for aptamer1 (the aptamer which modified NH₂) coupling. We found that kanamycin could be detected using the aptamer1 containing the same base sequence as aptamer2 (the aptamer which modified SH) on the electrode self-assembly. In addition, PAMAM nanocomposites can be used to effectively improve the ECL intensity by loading a high volume of luminol molecules and silver nanoparticles. In the presence of kanamycin, the sandwiched aptasensor was formed between aptamer1 and the probe of aptamer2 connecting silver nanoparticles, luminol, and PAMAM, resulting in a proportional increase of ECL intensity. Since the significantly enhanced loading of luminol by PAMAM accelerated the electron transfer, the sensitive aptasensor exhibited a wide linear range of detection from 1 × 10^-3 to 1 × 10³ ng/mL and a low detection limit of 0.21 pg/mL (S/N) for kanamycin. The fabricated aptasensor was successfully applied in quantitative analysis of kanamycin in milk samples.

A Review on Metal- and Metal Oxide-Based Nanozymes: Properties, Mechanisms, and Applications

Since the ferromagnetic (Fe3O4) nanoparticles were firstly reported to exert enzyme-like activity in 2007, extensive research progress in nanozymes has been made with deep investigation of diverse nanozymes and rapid development of related nanotechnologies. As promising alternatives for natural enzymes, nanozymes have broadened the way toward clinical medicine, food safety, environmental monitoring, and chemical production. The past decade has witnessed the rapid development of metal- and metal oxide-based nanozymes owing to their remarkable physicochemical properties in parallel with low cost, high stability, and easy storage. It is widely known that the deep study of catalytic activities and mechanism sheds significant influence on the applications of nanozymes. This review digs into the characteristics and intrinsic properties of metal- and metal oxide-based nanozymes, especially emphasizing their catalytic mechanism and recent applications in biological analysis, relieving inflammation, antibacterial, and cancer therapy. We also conclude the present challenges and provide insights into the future research of nanozymes constituted of metal and metal oxide nanomaterials.

A novel SERS sensor for the ultrasensitive detection of kanamycin based on a Zn-doped carbon quantum dot catalytic switch controlled by nucleic acid aptamer and size-controlled gold nanorods

In this study, a novel surface enhanced Raman spectroscopy (SERS) sensor was developed for the ultrasensitive determination of kanamycin in foods. The sensor used two distinct signal amplification strategies, namely the surface plasmon resonance of gold nanorods and a Zn-doped carbon quantum dots catalytic cascade oxidation-reduction reaction switch controlled by a nucleic acid aptamer. Under optimized experimental conditions, the SERS sensor demonstrated a linear range of 10^-12 to 10^-5 g mL^-1 for the detection of kanamycin, with a limit of detection of 3.03 × 10^-13 g mL^-1. Experiments with antibiotics structurally similar to kanamycin and interferrants revealed that the sensor had excellent selectivity. Milkpowder and honey samples spiked with kanamycin were assayed, with recoveries ranging from 84.1% to 107.2% and a relative standard deviation of 0.74% to 2.81% being obtained. Quantification of kanamycin in milk samples revealed no significant difference between the results obtained with the sensor and by HPLC.

Target-initiated autonomous synthesis of metal-ion dependent DNAzymes for label-free and amplified fluorescence detection of kanamycin in milk samples

Accurate and sensitive monitoring of the abused antibiotics is vital because excessive antibiotics in human body can cause toxicity to kidney or lead to potential loss of hearing. In this work, we described a label-free and highly sensitive fluorescent aptasensing platform for detecting kanamycin in milk samples based on the synchronization signal amplification of primer exchange reaction (PER) and metal-ion dependent DNAzyme. The target kanamycin binds the aptamer sequence hybridized on a hairpin template and initiates PER for autonomous synthesis of Mg²⁺-dependent DNAzyme sequences with aid of Bst-DNA polymerase at isothermal conditions. Such a synthesis process can be repeated many times to produce lots of DNAzymes to cyclically cleave the rA site in the signal hairpin substrates under the assistance of Mg²⁺ cofactor to liberate numerous free G-quadruplex fragments. The organic dye thioflavin T (ThT) further associates with these G-quadruplex fragments to yield substantially intensified fluorescence for sensitive detection of kanamycin with a low detection limit of 0.36 nM. In addition, the developed aptamer sensing method also shows a good selectivity for kanamycin against other interfering antibiotics, and can realize the monitoring of kanamycin added in milk samples, highlighting its potential for sensitive monitoring of trace amount of kanamycin for food safety applications.

DNAzyme-powered DNA walking machine for ultrasensitive fluorescence aptasensing of kanamycin

A DNAzyme-powered DNA walking machine was constructed to develop the fluorescence aptasensing for sensitive detection of kanamycin. The aptamer for kanamycin is partially hybridized with complementary DNA (cDNA) modified on magnetic beads (MBs). The specific interaction of target and aptamer triggered the cDNA to be free tentatively, which captured walker DNA. Then the autonomous motion of DNA walker on MBs surface was propelled via DNAzyme digestion of recognition sites. The signal probe was separated, and the amplified fluorescence signal was achieved by the accumulation of the signal probe. Kanamycin was used as a model analyte, and the developed assay achieves a detection limit of 0.00039 ng·mL^-1 (S/N = 3) within a linear detection range from 0.001 to 2000 ng·mL^-1. This aptasensing strategy can be extended for detection of other antibiotics by adapting corresponding target recognition aptamer sequence. Graphical abstract The fluorescence aptasensing for sensitive detection of kanamycin based on DNAzyme-powered DNA walking machine was constructed.

Colorimetric aggregation assay for kanamycin using gold nanoparticles modified with hairpin DNA probes and hybridization chain reaction-assisted amplification

The authors describe a colorimetric method for determination of kanamycin by using gold nanoparticles (AuNPs) as the element of signal-conversion and by applying hybridization chain reaction-assisted signal amplification. The assay is carried out by monitoring the absorbance change and color change adding salt to the reaction solution containing kanamycin (analyte), hairpin DNA probe, and AuNPs. Three hairpin DNA probes with sticky ends were absorbed on the AuNPs via their sticky ends. Cating with DNA prevents them from salt-induced aggregation (which leads to a color change from red to blue) in the complete absence of kanamycin. In contrast, in the presence of kanamycin, the aptamer hairpin DNA probe binds kanamycin, and the newly exposed section of DNA triggers a cascade of hybridization chain reactions with formation of numerous dsDNAs. On addition of salt, the AuNPs form blue aggregates due to the repulsion between dsDNA and AuNPs. Under optimal conditions, the ration of absorbance at 520 and 630 nm drops with the kanamycin concentration in the range from 1 to 40 μM, and the limit of detection is 0.68 μM. The assay can selectively distinguish kanamycin from other antibiotics. The method was applied to kanamycin detection in (spiked) milk samples and gave excellent recoveries. Graphical abstract Schematic presentation of colorimetric method for kanamycin detection using gold nanoparticles modified with hairpin DNA probes and hybridization chain reaction-assisted amplification.

Determination of Kanamycin by High Performance Liquid Chromatography

Kanamycin is an aminoglycoside antibiotic widely used in treating animal diseases caused by Gram-negative and Gram-positive infections. Kanamycin has a relatively narrow therapeutic index, and can accumulate in the human body through the food chain. The abuse of kanamycin can have serious side-effects. Therefore, it was necessary to develop a sensitive and selective analysis method to detect kanamycin residue in food to ensure public health. There are many analytical methods to determine kanamycin concentration, among which high performance liquid chromatography (HPLC) is a common and practical tool. This paper presents a review of the application of HPLC analysis of kanamycin in different sample matrices. The different detectors coupled with HPLC, including Ultraviolet (UV)/Fluorescence, Evaporative Light Scattering Detector (ELSD)/Pulsed Electrochemical Detection (PED), and Mass Spectrometry, are discussed. Meanwhile, the strengths and weaknesses of each method are compared. The pre-treatment methods of food samples, including protein precipitation, liquid-liquid extraction (LLE), and solid-phase extraction (SPE) are also summarized in this paper.

Establishment of a highly efficient conjugation protocol for Streptomyces kanamyceticus ATCC12853

Kanamycin B as the secondary metabolite of wild‐type Streptomyces kanamyceticus (S. kanamyceticus) ATCC12853 is often used for the synthesis of dibekacin and arbekacin. To construct the strain has the ability for kanamycin B production; the pSET152 derivatives from Escherichia coli ET12567 were introduced to S. kanamyceticus by intergeneric conjugal transfer. In this study, we established a reliable genetic manipulation system for S. kanamyceticus. The key factors of conjugal transfer were evaluated, including donor‐to‐recipient ratio, heat‐shock, and the overlaying time of antibiotics. When spores were used as recipient, the optimal conjugation frequency was up to 6.7 × 10⁻⁶. And mycelia were used as an alternative recipient for conjugation instead of spores; the most suitable donor‐to‐recipient ratio is 1:1 (10⁷:10⁷). After incubated for only 10–12 hr and overlaid with antibiotics subsequently, the conjugation frequency can reach to 6.2 × 10⁻⁵ which is sufficient for gene knockout and other genetic operation. Based on the optimized conjugal transfer condition, kanJ was knocked out successfully. The kanamycin B yield of kanJ‐disruption strain can reach to 543.18 ± 42 mg/L while the kanamycin B yield of wild‐type strain was only 46.57 ± 12 mg/L. The current work helps improve the content of kanamycin B in the fermentation broth of S. kanamyceticus effectively to ensure the supply for the synthesis of several critical semisynthetic antibiotics.

A kanamycin sensor based on an electrosynthesized molecularly imprinted poly-o-phenylenediamine film on a single-walled carbon nanohorn modified glassy carbon electrode

A single-walled carbon nanohorn (SWCNH) has been used to construct a molecularly imprinted electrochemical sensor for the first time. Kanamycin, a widely used aminoglycoside antibiotic, is used as a representative analyte to test the detection strategy. The kanamycin sensor was constructed by the electropolymerization of a molecularly imprinted poly-o-phenylenediamine film on a SWCNH modified glassy carbon electrode. The sensor was investigated in the presence or absence of kanamycin by cyclic voltammetry to verify the changes in the redox peak currents of K₃Fe(CN)₆. The sensor exhibits a linear range of 0.1-50 μM with a detection limit of 0.1 μM. It also shows high recognition ability, indicating that the SWCNH-based molecularly imprinted sensor is promising.