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Alternansucrase (ASR), classified in GH70, produces unique α-glucans with alternating α-1,3 and α-1,6 glycosidic linkages in the backbone chain from renewable sucrose which is easily obtained from nature with low cost. ASR has synthesized many products with valuable functionalities that hold enormous commercial interest and promising applications. The influence of biocatalysis and fermentation parameters on the yields, and properties of products are critical for the propositions made to promote the enzyme application. Investigations on ASR have been compiled in the review to provide information on the enzyme, products and parameters. This review summarizes studies on the characteristics, conversion mechanism, products, and beneficial applications of ASR and exhibits structure-based technologies to improve enzyme activity, specificity, and thermostability for industrial applications. Finally, prospects for further development are also proposed for various ASR applications in food and other fields., Competing Interests: Declaration of competing interest There is no conflict of interests regarding the publication of this article., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Patulin (PAT) is a mycotoxin-produced secondary metabolite that can contaminate foods, causing toxic effects on animal and human health. Therefore, for the first time, we have constructed a "turn-on" dual-mode aptamer sensor for PAT using oleic acid-coated upconversion nanomaterials (OA-UCNPs) and G-Quadruplex-hemin DNAzyme (G4-DNAzyme) as fluorescent and colorimetry probes. The sensor employs aptamers binding to PAT as recognition elements for specific molecule detection. Mxene-Au can be used as a biological inducer to assist OA-UCNPs in controlling fluorescence intensity. In addition, colorimetric signal amplification was performed using the trivalent G4-DNAzyme to increase detection sensitivity and reduce false positives. Under optimal conditions, the dual-mode aptasensor has a detection limit of 5.3 pg mL -1 in fluorescence and 2.4 pg mL -1 in colorimetric methods, respectively, with the wider linear range and limit of detection (LOD) of the colorimetric assay. The combination aptasensor can detect PAT with high sensitivity and high specificity and has broad application prospects in the field of food safety detection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

In recent years, the conventional preparation of silver nanoclusters (AgNCs) has attracted much attention due to their ultra-small size, tunable fluorescence, easy-to-engineer, as well as biocompatible material. Moreover, its great affinity towards cytosine bases on single-stranded DNA has led to the construction of biosensors, especially aptamers, for a broad variety of applications in food safety and environmental protection. In past years, numerous researchers paid attention to the construction of AgNCs aptasensor. Therefore, this review will be an effort to summarize the synthetic strategy along with the influences of factors on synthesis, categorize the sensing mechanism of aptamer-functionalized AgNCs biosensors, as well as their specific applications in food safety detection including heavy metal, toxin, and foodborne pathogenic bacteria. Furthermore, a brief conclusion and outlook regarding the prospects and challenges of their applications in food safety were drawn in line with the developments in DNA-AgNCs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Geraniol (Ger) is an essential oil molecule with excellent biological activity. High hydrophobicity and volatility limit its practical application. Cyclodextrins (CDs) are water-soluble cyclic oligosaccharides with hydrophobic cavities. Physical encapsulation of CDs to improve the solubility and stability of essential oil molecules is not satisfactory. Therefore, this study synthesized the γ-CD derivative (γ-CD-Ger) by grafting Ger onto γ-CD using a bromide-mediated method. Compared to the inclusion complexes (γ-CD/Ger) formed by both, the derivatives exhibit better solubility and thermal stability. The derivative has better antibacterial activity when the ratio of γ-CD to Ger was 1:2. In addition, the derivatives did not exhibit cytotoxic and hemolytic properties. These results indicate that this research provides a water-soluble antibacterial agent with a wide range of promising applications and offers new ideas for the application of alcohol hydrophobic molecules in aqueous systems., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

DNA nanostructures, with their fascinating luminescent and detecting capabilities, provide a basis that can accommodate a wide range of applications. The unique electronic configurations, and physical and chemical properties of aptamer-assembled gold nanoclusters (apt-AuNCs) as a novel type of fluorophore have gradually piqued the interest of the scientific community. Bending DNA sequences and other templates/legends as a stabilizing agent with Au metal has produced an abundance of biosensors, along with catalytic and imaging properties. This review article summarizes the synthesis, conjugation tactics, advantages, and sensing mechanisms of AuNCs aptasensor after providing a brief introduction to the topic. Moreover, the application of DNA/aptamer functionalization has been briefly discussed in the fields of food safety and quality, catalysis, clinical diagnosis, cancer cell bioimaging, detection of cancer cell indicators, and therapy. We also concluded the current obstacles and made recommendations about the future prospects of AuNCs for fundamental research and applications in line with the developments in DNA/aptamer-AuNCs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Tetracycline (TC) poses a great threat to food and environmental safety due to its misuse in animal husbandry and aquaculture. Therefore, an efficient analytical method is needed for the detection of TC to prevent possible hazards. Herein, a cascade amplification SERS aptasensor for sensitive determination of TC was constructed based on aptamer, enzyme-free DNA circuits, and SERS technology. The capture probe and signal probe were obtained by binding DNA hairpins H1 and H2 to the prepared Fe 3 O 4 @hollow-TiO 2 /Au nanochains (Fe 3 O 4 @h-TiO 2 /Au NCs) and Au@4-MBA@Ag nanoparticles, respectively. The dual amplification of EDC-CHA circuits significantly facilitated the sensitivity of the aptasensor. Additionally, the introduction of Fe 3 O 4 simplified the operation of the sensing platform due to its superb magnetic capability. Under optimal conditions, the developed aptasensor exhibited a distinct linear response to TC with a low limit of detection of 15.91 pg mL -1 . Furthermore, the proposed cascaded amplification sensing strategy exhibited excellent specificity and storage stability, and its practicability and reliability were verified by TC detection of real samples. This study provides a promising idea for the development of specific and sensitive signal amplification analysis platforms in the field of food safety., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Aptasensors being versatile sensing platforms presented higher sensitivity toward target detection. However, lacking theoretical basis of recognition between most targets and their corresponding aptamers has impeded their applications. Herein, we conducted a study to explore the binding mechanism of aptamer to kanamycin (Kana) and developed rapid fluorescent aptasensing methods. Based on the fluorescence polarization results, base mutations were performed at different sites of the aptamer. The key binding nucleotides of Kana was identified as T7, T8, C13 and A15 by using isothermal titration calorimetry (ITC). The Kmut3 (2.18 μM) with lower dissociation constants (Kd), one-third of the native aptamer (6.91 μM), was also obtained. In addition, the lower K + concentration and temperature were found to be conducive to Kana binding. Circular dichroism (CD) results revealed that the binding of Kana can trigger the change of base stacking force and helix force. On the aforementioned basis, a fluorescent sensor was designed with the native aptamer and Kmut3 as recognition elements. The comparison results proved that the Kmut3 presented a 3 times lower limit of detection of 59 nM compared to the native aptamer (148 nM). Notably, this developed aptasensor can be finished in 45 min and was convenient to operate., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Histamine is a significant biomarker to assess the freshness of fish products. In this study, a novel MOF-based SERS sensor for histamine determination was synthesized by wrapping PVP-capped Au nanoflowers with a ZIF-67 shell (Au NFs@ZIF-67). The highly branched Au NFs core exhibited a strong electromagnetic field enhancement effect and provided an ultra-sensitive SERS fingerprint spectrum, while ZIF-67 shell was the contributor to enrich the target and stabilize the substrate. The morphology of the core-shell structures can be easily controlled by the concentrations of the capping agent PVP and MOF precursor Co ion. Consequently, 4-MBA pre-grafted on the optimized SERS substrate can act as the Raman internal standard (IS) to eliminate signal fluctuations through standardizing all spectra against its peak at 1074 cm -1 . Moreover, as the specific receptor for histamine molecules, 4-MBA helped reach the low detection sensitivity, where the SERS intensity ratio, I 1172 /I 1074 presented a good linear relationship towards the histamine concentrations (10 -3 -10 -7  M) with the LOD of 0.87 × 10 -7  M (R 2  = 0.9930). Furthermore, the application in monitoring fish spoilage process demonstrated the feasibility and reliability of the developed sensor. This work provided a facile strategy to construct MOF-based SERS substrate as a potential platform for the shelf-life prediction of fish products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The development of new antimicrobial agents is important to combat infections caused by pathogenic bacteria. Herein, Hydroxypropyl chitosan (HPCS), a hydrophilic modified product of chitosan (CS), was employed as a carrier of the photosensitizer chlorin e6 (Ce6) through an amide bond to obtain the products (HPCS-Ce6 conjugates) with a degree of substitution (DS) ranging from 2.95% to 5.25%. The UV-vis absorption spectra and 1 H NMR spectra confirmed the successful synthesis of the products. The products have a better and more stable reactive oxygen species (ROS) generation capacity and higher bacterial affinity than Ce6. At a very low dose (1.8 μg/mL), the highest DS product (HPCS-Ce6-3) can effectively kill Staphylococcus aureus (S. aureus) under 660 nm irradiation. In addition, the HPCS-Ce6 conjugates showed high biocompatibility in the CCK-8 test. The HPCS-Ce6 conjugates could be a photodynamic antibacterial agent with good water solubility, high biocompatibility, and antibacterial activity., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Fluorescent biosensors and imaging devices have gained fervent consideration due to their prime functionality in biological. Among fluorescent nanomaterial (FNMs), the ultra-small gold nanoclusters (AuNCs) have gained promising attention with respect to extra-ordinary properties of bright fluorescence, economical synthesis, higher photostability, and biocompatibility, and deep tissue penetration. Therefore, the prior decades comprehended the revolutions in the field of real-time monitoring devices, nanotechnology-based biosensing, and bioimaging sensors. The present review primarily focuses on metal NCs (MNCs) and their advantages, a brief introduction of AuNCs along with history prospective and development, fundamental aspects regarding AuNCs quality and fluorescence, limitations and advantages of AuNCs, sensing mechanism, expected synthesis principle, and summarized the recent progress of AuNCs probe over the last 3 years (2019-2021) with their respective detection and bioimaging mechanism and synthesis principle. Moreover, the present work also serves as a novel stratagem for the preparation and potential applications of multifunctional AuNCs nano-systems responsiveness for various analytes detection and cell bioimaging with respective examples. At last, we described the challenges associated with the application of AuNCs based on recent signs of progress., (Copyright © 2022. Published by Elsevier B.V.)

The modified natural biopolymers, recognized as environmentally friendly flocculants, are gaining tremendous attention in the field of water treatment. In this study, a novel hybrid flocculant with antibacterial activity, cinnamic acid (CA) conjugated N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (HTCC) derivative (HTCC-CA), was prepared via quaternary ammonium and amide reactions. The characterization, flocculation, and antibacterial activities were carried out to access the structural properties and potential application. The results of UV-vis, FT-TR, and 1 H NMR confirmed the successful synthesis of HTCC-CA1-3 derivatives. XRD and TGA revealed the lower crystallinity and thermal stability of HTCC-CA1-3 derivatives than chitosan (CS). Bacterial flocculation and antibacterial tests indicated the excellent flocculation effect of HTCC-CA1-3 derivatives and showed high antibacterial activity for Escherichia coli suspension. Moreover, the mechanism of action of the derivatives was investigated via zeta potential measurements and scanning electron microscope, which can be summed up as the effective interaction between charges. The results proved that HTCC-CA derivatives are promising agents for wastewater treatment., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The present study emphasizes improving the overall yield, productivity and quality of xanthan by Xanthomonas campestris using different carbon sources via optimizing the fermentation media and kinetic modelling work. After optimization, six carbon sources and one nitrogen source were selected for xanthan production in 5 L bioreactor. Kinetic modelling was applied to assess the experimental fermentation data and to check its influence on scale-up production. In this work, xanthan production reached 40.65 g/L with a growth-associated rate constant (α) of 2.831, and highest specific growth rate (μm) of 0.37/h while using maltose as the sole carbon source. Furthermore, rheological properties were determined, and Herschel-Bulkley model was employed to assess the experimental data. Interestingly, xanthan obtained from sucrose and glucose showed the highest yield stress (τ 0 ) of 12.50 ± 0.31 and 7.17 ± 0.21. Moreover, the highest xanthan molecular weight of 3.53 × 10 7 and 3.25 × 10 7  g/mol were also found with sucrose and glucose. At last, the proposed mechanism of sugar metabolism and xanthan biosynthesis pathway were described. Conclusively, maltose appeared as the best carbon source for maximum xanthan production: while sucrose and glucose gave qualitatively best results. In short, this systematically modelled approach maximizes the potential output and provides a solid base for continuous cultivation of xanthan at large-scale production., (Copyright © 2021. Published by Elsevier B.V.)

In this study, cinnamic acid (CA) conjugated hydroxypropyl chitosan (HPCS) derivatives (HPCS-CA) with different degrees of substitution (DS) were successfully synthesized. The reaction was divided into two steps: the first step was to modify chitosan (CS) to HPCS, and the second step was to graft CA onto HPCS. Structural characterization and properties were carried out employing elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, nuclear magnetic resonance (NMR) spectra, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The solubility test revealed the better water solubility of derivatives than CS. In addition, in vitro antibacterial and antibiofilm tests were performed. As expected, HPCS-CA derivatives exhibited good antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The MIC and MBC of HPCS-CA derivatives could reach 256 μg/mL and 512 μg/mL, respectively. Confocal laser scanning microscopy (CLSM) analysis proved the inhibitory effect of HPCS-CA derivatives on S. aureus and E. coli biofilms by disrupting the formation of biofilms, reducing the thickness of biofilms, and the number of live bacteria. These results suggest the potential applicability of HPCS-CA derivatives in the treatment of biofilm-associated infections and provide a practical strategy for the design of novel CS-based antibacterial materials., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Recently, food industries are directing on the promotion of innovative food matrices fortified with bioactive compounds in order to enhance the consumer's health. Octenyl succinic anhydride modified starches (OSA-MS) such as Hi-cap100 (HCP) and purity gum 2000 (PUG) were used to fabricate emulsions co-entrapped with borage seed oil (BSO), resveratrol (RES) and curcumin (CUR), which were further spray dried to obtain powders. The fabricated microcapsules loaded with BSO, RES, and CUR displayed excellent dissolution performance, high encapsulation efficiency (≈93.05%) as well as semi-spherical shape, revealed via scanning electron microscopy (SEM). We also evaluated the impact of storage time (4 weeks) and temperature (40 °C) on the physicochemical characterization of OSA-MS coated microcapsules. Microcapsules coated with HCP exhibited greater oxidative stability, lower water activity and moisture contents rather than PUG coated microcapsules during storage because of its good film-forming properties. Addition of CUR enhanced the oxidative stability and retention of bioactive compounds. HCP microcapsules loaded with BSO + RES + CUR presented supreme retention of RES (70.32%), CUR 81.6% and γ-linolenic acid (≈ 96%). Our findings showed that CUR acted as an antioxidant agent; also, lower molecular weight OSA-MS as wall material could be used for the entrapment of bioactive compounds and promotion of innovative food products., (Copyright © 2021. Published by Elsevier B.V.)

The development of antibacterial agents with high bacteria-binding capability and antibacterial efficiency is highly desirable. Herein, cationic polysaccharide chitosan (CS) was combined with photosensitizer Chlorin e6 (Ce6) to construct a novel photodynamic antibacterial agent (CS-Ce6 conjugates) for combating gram-positive bacteria Staphylococcus aureus (S. aureus) and gram-negative bacteria Escherichia coli (E. coli). CS-Ce6 conjugates with different degrees of substitution (DS) were synthesized and characterized by a spectroscopic method and organic elemental analysis to understand the relationship between structure and antibacterial effect. CS-Ce6 conjugates revealed good reactive oxygen species (ROS) generation ability and photodynamic antibacterial effect. Meanwhile, they both were positively correlated with DS in the range of 4.81% ~ 11.56% resulting in stronger photodynamic antibacterial ability. These findings highlight that CS-Ce6 conjugates have the potential as an effective photodynamic bactericidal agent in the antibacterial field., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The emerging aptamer, developed through the systematic evolution of ligands by exponential enrichment (SELEX) process, has revolutionized and facilitated the discoveries in basic research. Among all SELEX technology, Capture-SELEX is a variant of the in vitro selection process, which is suitable for isolating aptamers against small molecules. Capture-SELEX library was developed to enable the immobilization of the oligonucleotides instead of the target molecules during the aptamer selection process. The review provides an update on the recent-advances in this new screening method with particular emphasis on key points of capture protocol and its applications. The limitations and the prospects of the Capture-SELEX are also discussed. We hope that present review will inspire more researchers to understand the selection problems from the perspective of Capture-SELEX. Moreover, it will open new pave to improve the efficiency and success of screening to meet the growing demand for aptasensor discovery in small molecules., (Copyright © 2021. Published by Elsevier B.V.)

The objectives of the present study are to synthesize a series of chitosan oligosaccharide-O-Terpenol (COS-O-Ter) derivatives and their implication to evaluate in vitro antibacterial activity. Herein, a general strategy is described for preparing COS-O-Ter derivatives, including substitution and deprotection reactions. The structures of COS-O-Ter derivatives were characterized by FT-IR, 1 H NMR, XRD, TGA, and elemental analysis. COS-O-Ter derivatives revealed the excellent solubility and in vitro antibacterial activity. Moreover, their antibacterial activities were more sensitive to Staphylococcus aureus (S. aureus) than Escherichia coli (E. coli) indicating the effective potential application of COS-O-Ter derivatives as natural antibacterial agents. The aforementioned study opens a pave to expand the application scope of COS and its derivatives in the food and pharmaceutical industries., (Copyright © 2021. Published by Elsevier Ltd.)

L-Fuculose and D-ribulose are kinds of rare sugars used in food, agriculture, and medicine industries. These are pentoses and categorized into the two main groups, aldo pentoses and ketopentoses. There are 8 aldo- and 4 ketopentoses and only fewer are natural, while others are rare sugars found in a very small amount in nature. These sugars have great commercial applications, especially in many kinds of drugs in the medicine industry. The synthesis of these sugars is very expensive, difficult by chemical methods due to its absence in nature, and could not meet industry demands. The pentose izumoring strategy offers a complete enzymatic tactic to link all kinds of pentoses using different enzymes. The enzymatic production of L-fuculose and D-ribulose through L-fucose isomerase (L-FI) and D-arabinose isomerase (D-AI) is the inexpensive and uncomplicated method up till now. Both enzymes have similar kinds of isomerizing mechanisms and each enzyme can catalyze both L-fucose and D-arabinose. In this review article, the enzymatic process of biochemically characterized L-FI & D-AI, their application to produce L-fuculose and D-ribulose and its uses in food, agriculture, and medicine industries are reviewed., Competing Interests: Declaration of competing interest The authors declare that they do not have any conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this study, we prepared a series of edible blend films of xanthan and curdlan by mixing different ratios of these two biopolymers. Characterization techniques like FTIR, XRD, TGA and SEM analysis were applied to investigate the newly formed films. Moreover, mechanical properties, moisture absorbance properties and water solubility of these films were also determined. The obtained results demonstrated that the strong intermolecular hydrogen bonding was observed between xanthan and curdlan at pH 5. At this pH, the xanthan-curdlan hydrogel retained the original structure of xanthan and sustained self-aggregation of xanthan chains via hydrogen bonding, which led to strong intermolecular bonding between xanthan and curdlan. Furthermore, the 5:5 and 4:6 ratios of xanthan and curdlan showed greater interaction in the blend films that resulted in their excellent miscibility. Moreover, highest tensile strength of 28.13 and 26.45 MPa were also found in the same rational of XG/CG blend films. In addition, it was observed that the curdlan incorporation improved the water solubility properties of XG/CG blend films. Conclusively, this xanthan/curdlan nexus with excellent mechanical and moisture barrier properties confirm its potential application and prospective use as food packaging material., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Drug nanodelivery systems (DNDSs) are fascinated cargos to achieve outstanding therapeutic results of various drugs or natural bioactive compounds owing to their unique structures. The efficiency of several pharmaceutical drugs or natural bioactive ingredients is restricted because of their week bioavailability, poor bioaccessibility and pharmacokinetics after orally pathways. In order to handle such constraints, usage of native/natural polysaccharides (NPLS) in fabrication of DNDSs has gained more popularity in the arena of nanotechnology for controlled drug delivery to enhance safety, biocompatibility, better retention time, bioavailability, lower toxicity and enhanced permeability. The main commonly used NPLS in nanoencapsulation systems include chitosan, pectin, alginates, cellulose, starches, and gums recognized as potential materials for fabrication of cargos. Herein, this review is centered on different polysaccharide-based nanocarriers including nanoemulsions, nanohydrogels, nanoliposomes, nanoparticles and nanofibers, which have already served as encouraging candidates for entrapment of therapeutic drugs as well as for their sustained controlled release. Furthermore, the current article explicitly offers comprehensive details regarding application of NPLS-based nanocarriers encapsulating several drugs intended for the handling of numerous disorders, including diabetes, cancer, HIV, malaria, cardiovascular and respiratory as well as skin diseases., Competing Interests: Declaration of Competing Interest All authors declared that they have no any kinds of conflicts., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Herein, we reported a simple, flexible and sensitive surface-enhanced Raman scattering (SERS) substrate to detect methyl parathion residues in real life. The substrate was fabricated by filter paper and gold nanoparticles (Au NPs) with excellent reproducibility and stability. First, Au NPs were synthesized by the seed mediated growth method and assembled to the filter paper through immersion. The Raman probe molecule 4-MBA was used to evaluate performance of the substrate for an optimized signal using a portable Raman spectrometer coupled with 785 nm laser. Then, the paper-based substrate was applied to detect methyl parathion standard solution whose detection limit was down to 0.011 μg/cm 2 , and the linear range was between 0.018 μg/cm 2 and 0.354 μg/cm 2 . Afterwards, actual sample (apple) spiked with methyl parathion was taken to verify the practicality of the substrate by a simple way of "press-peel off". The recovery rate was ranged from 94.09% to 98.72%, indicating that this method is reliable in actual sample detection without complicated pretreatment steps. This work demonstrates that the flexible paper-based substrate combined with portable Raman instruments can be potentially applied to on-site detection of hazardous substances in the field of food safety., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The authors describe a fluorescence polarization (FP) aptasensor based on the polymerase chain reaction (PCR) and streptavidin as dual FP amplifiers to detect chloramphenicol residues in food. Briefly, label-free aptamer was incubated with chloramphenicol and the aptamer-chloramphenicol conjugate was used as a template. Subsequently, the FAM-labeled forward primer and biotin-labeled reverse primer were added for PCR to amplify the template and the FAM-labeled primer. The molecular weight of FAM-labeled primer increased rapidly and the corresponding FP also enhanced. Finally, with the introduction of streptavidin, the PCR products and streptavidin were combined with the biotin-streptavidin interactions, resulting in much larger molecular weight. Thus, a dual amplified FP signal was obtained. Under optimal conditions, we were able to achieve a wide linear detection range of 0.001-200 nM. In addition, the designed strategy was applied to detect chloramphenicol in honey samples with high accuracy. Moreover, the strategy can be easily extended to detect other small molecules by changing the corresponding aptamers, which provide a promising avenue for the detection of small molecules by FP., (Copyright © 2019. Published by Elsevier B.V.)

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by fungi on stored grains. The earlier detection methods used for ZEN rely on expensive equipment, time-consuming sample preparation and temperature sensitive antibodies. The current work, proposed a novel strategy based on ZEN aptamer labeled with amine-functionalized magnetic nanoparticle (MNPs) as a capture probe and time-resolved fluorescence (TRFL) nanoparticles labeled with complementary DNA (cDNA) as a signal probe. Under the optimized conditions, TRFL intensity at 544 nm was used to measure ZEN (R 2 = 0.9920) in the range of 0.001-10 ng mL -1 and limits of detection (LOD) for proposed method was 0.21 pg mL -1 . The specificity of bioassay was also determined by using other mycotoxins (OTA, AFB 2 , DON and Patulin) and results showed that the aptamer are specific to recognize only ZEN. The analytical applications of the present bioassay in maize and wheat samples were also examined and results were compared with existing methods. Based on these findings, it is suggested to use current rapid and simple bioassay for the determination of ZEN in food and agricultural products., (Copyright © 2018 Elsevier B.V. All rights reserved.)