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Pesticide residues in agricultural products pose a significant threat to human health. Herein, a sensitive fluorescence method employing upconversion nanoparticles was developed for detecting organophosphorus pesticides (OPs) based on the principle of enzyme inhibition and copper-triggered o-phenylenediamine (OPD) oxidation. Copper ions (Cu 2+ ) oxidized the colorless OPD to a yellow 2,3-diaminophenazine (oxOPD). The yellow solution oxOPD quenched the fluorescence of upconversion nanoparticles due to the fluorescence resonance energy transfer. The high affinity of Cu 2+ for thiocholine reduced the level of oxOPD, resulting in almost no fluorescence quenching. The addition of dimethoate led to the inhibition of acetylcholinesterase activity and thus prevented the formation of thiocholine. Subsequently, Cu 2+ oxidized OPD to form oxOPD, which attenuated the fluorescence signal of the system. The detection system has a good linear range of 0.01 ng/mL to 50 ng/mL with a detection limit of 0.008 ng/mL, providing promising applications for rapid detection of dimethoate., 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 Ltd. All rights reserved.)

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.)

Food analysis plays a critical role in assessing human health risks and monitoring food quality and safety. Currently, there is a pressing need for a reliable, portable, and quick recognition element for point-of-care testing (POCT) to better serve the demands of on-site food analysis. Aptamer-modified paper-based analytical devices (Apt-PADs) have excellent characteristics of high portability, high sensitivity, high specificity, and on-site detection, which have been widely used and concerned in the field of food safety. The article reviews the basic components and working principles of Apt-PADs, and introduces their representative applications detecting food hazards. Finally, the advantages, challenges, and future directions of Apt-PADs-based sensing performance are discussed, to provide new directions and insights for researchers to select appropriate Apt-PADs according to specific applications., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2023. Published by Elsevier Inc.)

Co-contamination of multiple mycotoxins produces synergistic toxic effects, leading to more serious hazards. Therefore, the simple, rapid and accurate simultaneous detection of multiple mycotoxins is crucial. Herein, a three-channel aptamer-based lateral flow assay (Apt-LFA) was established for the detection of aflatoxin M 1 (AFM 1 ), aflatoxin B 1 (AFB 1 ) and ochratoxin A (OTA). The multi-channel Apt-LFA utilized gold‑iridium nanozyme to catalyze the chromogenic substrate, which effectively achieved signal amplification. Moreover, the positions and lengths of the complementary sequences were screened by changes in fluorescence intensity. After grayscale analysis, the semi-quantitative results showed that the detection limits of AFM 1 , AFB 1 and OTA were 0.39 ng/mL, 0.36 ng/mL and 0.82 ng/mL. The recoveries of the multiplexed competitive sensors in complex matrices of real samples were 93.33%-97.01%, 95.72%-102.67%, and 106.88%-109.33%, respectively. In conclusion, the assembly principle of the three-channel Apt-LFA is simple, which can provide a new idea for the simultaneous detection of small molecule targets., 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 Ltd.)

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.)

The prevalence of pathogenic bacterial infections with high morbidity and mortality poses a widespread challenge to the healthcare system. Therefore, it is imperative to develop nanoformulations capable of adaptively releasing antimicrobial factors and demonstrating multimodal synergistic antimicrobial activity. Herein, an NIR-activated multifunctional synergistic antimicrobial nanospray MXene/ZIF-90@ICG was prepared by incorporating ZIF-90@ICG nanoparticles onto MXene-NH 2 nanosheets. MXene/ZIF-90@ICG can on-demand release the antimicrobial factors MXenes, ICG, and Zn 2+ in response to variations in pH and ATP levels within the bacterial infection microenvironment. Under NIR radiation, the combination of MXenes, Zn 2+ , and ICG generated a significant amount of ROS and elevated heat, thereby enhancing the antimicrobial efficacy of PDT and PTT. Meanwhile, NIR excitation could accelerate the further release of ICG and Zn 2+ , realizing the multimodal synergistic antibacterial effect of PDT/PTT/Zn 2+ . Notably, introducing MXenes improved the dispersion of the synthesized antimicrobial nanoparticles in aqueous solution, rendering MXene/ZIF-90@ICG a candidate for application as a nanospray. Importantly, MXene/ZIF-90@ICG demonstrated antimicrobial activity and accelerated wound healing in the constructed in vivo subcutaneous Staphylococcus aureus infection model with NIR activation, maintaining a favorable biosafety level. Therefore, MXene/ZIF-90@ICG holds promise as an innovative nanospray for adaptive multimodal synergistic and efficient antibacterial applications with NIR activation.

Objective: Neonatal multisystem inflammatory syndrome (MIS-N) is a unique disease of neonates described in several case reports from all over the world with a myriad of presentations and the emergence of new cases., Study Design: Retrospective case series. Place and Duration of the Study: Department of Paediatrics, Fazaia Medical College, Pakistan Air Force Hospital, Islamabad, Pakistan, from December 2021 to November 2022., Methodology: The study was conducted on neonates who were managed as MIS-N in the neonatal ICU. Data were collected and analysed on SPSS version 24., Results: Patients in this study ranged from newborns to 13 days of age with a mean age of 3.27 ± 4.29 days and average gestational age of 35.18 ± 3.67 weeks. Among these neonates, 7 (63.6%) had bleeding diathesis, 11 (100%) had seizures, 8 (72.2%) presented with haemodynamic instability and shock, and 7 (63.3%) had signs of heart failure. All neonates (100%) had markedly raised SARS-CoV2 IgG antibodies, CRP, ferritin, D-dimers, interleukin 6, procalcitonin, 10 (90.9%) had hypoalbuminemia, and 7 (63.3%) had deranged coagulation profile. Cardiac involvement was seen in all neonates (100%) with raised proBNP and myocardial dysfunction on echocardiography. Pulmonary hypertension was present in 6 (54.4%) neonates. High mortality was observed at 6 (54.5%) among which 4 (66.6%) were premature neonates., Conclusion: MIS-N is a new disease entity which is still under research. There is a high propensity for cardiovascular system involvement and higher mortality among preterm neonates., Key Words: Neonatal multisystem inflammatory syndrome (MIS-N), Multisystem inflammatory syndrome in children (MIS-C), SARS-CoV2 infection, SARS-CoV2 spike protein, SARS-CoV2 IgG antibodies.

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.)

After optimizing the original aptamer sequence by truncation strategy, a magnetic separation-assisted DNAzyme-driven 3D DNA walker fluorescent aptasensor was developed for detecting the food-borne pathogen Cronobacter species. Iron oxide magnetic nanoparticles (MNPs) modified with a hybrid of truncated aptamer probe and DNAzyme strand (AP-E1) denoted as MNPs@AP-E1, were employed as capture probes. Simultaneously, a DNAzyme-driven 3D-DNA walker was utilized as the signal amplification element. The substrate strand (Sub) was conjugated with the gold nanoparticles (AuNPs), resulting in the formation of AuNPs@Sub, which served as a 3D walking track. In the presence of the target bacteria and Mg 2+ , E1-DNAzyme was activated and moved along AuNPs@Sub, continuously releasing the signal probe. Under optimized conditions, a strong linear correlation was observed for Cronobacter sakazakii (C. sakazakii) in the concentration range 10 1 to 10 6 CFU mL -1 , with a low detection limit of 2 CFU mL -1 . The fluorescence signal responses for different Cronobacter species exhibited insignificant differences, with a relative standard deviation of 3.6%. Moreover, the aptasensor was successfully applied to determine  C. sakazakii in real samples with recoveries of 92.86%-108.33%. Therefore, the novel method could be a good candidate for ultra-sensitive and selective detection of Cronobacter species without complex manipulation., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

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.)

Probiotics, like lactic acid bacteria, are non-pathogenic microbes that exert health benefits to the host when administered in adequate quantity. Currently, research is being conducted on the molecular events and applications of probiotics. The suggested mechanisms by which probiotics exert their action include; competitive exclusion of pathogens for adhesion sites, improvement of the intestinal mucosal barrier, gut immunomodulation, and neurotransmitter synthesis. This review emphasizes the recent advances in the health benefits of probiotics and the emerging applications of probiotics in the food industry. Due to their capability to modulate gut microbiota and attenuate the immune system, probiotics could be used as an adjuvant in hypertension, hypercholesterolemia, cancer, and gastrointestinal diseases. Considering the functional properties, probiotics are being used in the dairy, beverage, and baking industries. After developing the latest techniques by researchers, probiotics can now survive within harsh processing conditions and withstand GI stresses quite effectively. Thus, the potential of probiotics can efficiently be utilized on a commercial scale in food processing industries., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Latif, Shehzad, Niazi, Zahid, Ashraf, Iqbal, Rehman, Riaz, Aadil, Khan, Özogul, Rocha, Esatbeyoglu and Korma.)

Curcumin (Cur) is a natural pigment with excellent biological activity. The poor stability and insolubility of Cur in water severely limit its application. Therefore, to overcome these dilemmas which are big hindrances in their application, a novel derivative (COCS-Cur) was prepared by the esterification reaction of carboxylated chitosan (COCS) and Cur. The structure and properties of conjugate were determined through a series of characterizations. The derivatives had excellent solubility as well as stability. In addition, antioxidant and photodynamic antibacterial experiments proved that COCS-Cur had the excellent free radical scavenging ability and photodynamic antibacterial activity. The derivatives presented a better antibacterial effect on Staphylococcus aureus (S. aureus) than Escherichia coli (E. coli). Noteworthy, the COCS-Cur derivatives showed no obvious toxicity which makes them a stronger contender and potential antimicrobial agent or functional nutrient for application in the food industry., 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 Ltd. All rights reserved.)

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.)

Herein, for the first time, the CRISPR-Cas12a system is combined with aptamer, cascaded dynamic DNA network circuits, and Fe 3 O 4 @hollow-TiO 2 @MoS 2 nanochains (Fe 3 O 4 @h-TiO 2 @MoS 2 NCs) to construct an efficient sensing platform for tetracycline (TC) analysis. In this strategy, specific recognition of the target is transduced and amplified into H1-H2 duplexes containing the specific sequence of Cas12a-crRNA through an aptamer recognition module and the dual amplification dynamic DNA network. Subsequently, the obtained activated Cas12a protein non-specifically cleaves the adjacent reporter gene ssDNA-FAM to dissociate the FAM molecule from the quencher Fe 3 O 4 @h-TiO 2 @MoS 2 NCs, resulting in the recovery of the fluorescence signal and further signal amplification. Particularly, the synthesized multifunctional Fe 3 O 4 @h-TiO 2 @MoS 2 NCs composites also exhibit superb magnetic separability and photocatalytic degradation ability. Under optimal conditions, the aptasensor displays a distinct linear relationship with the logarithm of TC concentration, and the limit of detection is as low as 0.384 pg mL -1 . Furthermore, the results of spiked recovery confirm the viability of the proposed aptasensor for TC quantification in real samples. This study extends the application of the CRISPR-Cas12a system in the field of analytical sensing and contributes new insights into the exploration of reliable tools for monitoring and treating hazards in food and environment., (© 2023 Wiley-VCH GmbH.)

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.)

Fluorescent gold (Au) nanostructures have emerged as burgeoning materials to fabricate nanomaterial assemblies which play a vital role in improving the detection sensitivity and specificity for various biomolecules. In this work, a fluorescence labelled (Rhodamine-B-Isothiocyanate) silica shell with Au metal core (AuNPs@PVP@RITC@SiO 2 ) and a graphene-Au nanostar nanocomposite (rGO-AuNS) are presented as a metal enhanced fluorescence (MEF) material and Raman signal enhancer, respectively. Their composite (AuNPs@PVP@RITC@SiO 2 NPs/rGO-AuNS) was employed as a dual-mode fluorescence (FL) and surface-enhanced Raman scattering (SERS) nanoprobe for selective and sensitive detection of T-2 toxin. To comprehend the dual-modality, a core-shell nanostructure, AuNPs@PVP@RITC@SiO 2 , was functionalized with an aptamer (donor) and adsorbed on the surface of rGO-AuNS through electrostatic forces and π-π stacking which act as a FL quencher and SERS signal enhancer. When exposed to T-2 toxin, the apt-AuNPs@PVP@RITC@SiO 2 NPs move away from the surface of rGO-AuNS, resulting in the restoration of FL and reduction of the SERS signal. There was distinct linearity between the T-2 toxin concentration and the dual FL and SERS signals with lower limits of detection (LOD) of 85 pM and 12 pM, as compared to the previous methods, respectively. The developed FL and SERS aptasensor presented excellent recovery ratio and RSD in wheat and maize, respectively, as compared with the standard ELISA method. The complementary performances of the developed stratagem revealed a high correlation between the FL and SERS sensing modes with exquisite detection properties.

Antibiotic contamination is becoming a prominent global issue. Therefore, sensitive, specific and simple technology is desirable the demand for antibiotics detection. Biosensors based on split aptamer has gradually attracted extensive attention for antibiotic detection due to its higher sensitivity, lower cost, false positive/negative avoidance and flexibility in sensor design. Although many of the reported split aptamers are antibiotics aptamers, the acquisition and mechanism of splitting is still unknow. In this review, six reported split aptamers in antibiotics are outlined, including Enrofloxacin, Kanamycin, Tetracycline, Tobramycin, Neomycin, Streptomycin, which have contributed to promote interest, awareness and thoughts into this emerging research field. The study introduced the pros and cons of split aptamers, summarized the assembly principle of split aptamer and discussed the intermolecular binding of antibiotic-aptamer complexes. In addition, the recent application of split aptamers in antibiotic detection are introduced. Split aptamers have a promising future in the design and development of biosensors for antibiotic detection in food and other field. The development of the antibiotic split aptamer meets many challenges including mechanism discovery, stability improvement and new biosensor development. It is believed that split aptamer could be a powerful molecular probe and plays an important role in aptamer biosensor.

Food safety has always been a hot issue of social concern, and biosensing has been widely used in the field of food safety detection. Compared with traditional aptamer-based biosensors, aptamer-based riboswitch biosensing represents higher precision and programmability. A riboswitch is an elegant example of controlling gene expression, where the target is coupled to the aptamer domain, resulting in a conformational change in the downstream expression domain and determining the signal output. Riboswitch-based biosensing can be extensively applied to the portable real-time detection of food samples. The numerous key features of riboswitch-based biosensing emphasize their sustainability, renewable, and testing, which promises to transform engineering applications in the field of food safety. This review covers recent developments in riboswitch-based biosensors. The brief history, definition, and modular design (regulatory mode, reporter, and expression platform) of riboswitch-based biosensors are explained for better insight into the design and construction. We summarize recent advances in various riboswitch-based biosensors involving theophylline, malachite green, tetracycline, neomycin, fluoride, thrombin, naringenin, ciprofloxacin, and paromomycin, aiming to provide general guidance for the design of riboswitch-based biosensors. Finally, the challenges and prospects are also summarized as a way forward stratagem and signs of progress., (© 2022 Institute of Food Technologists®.)

Chitosan is a green, low-cost natural polymer material. The bioactivity of chitosan can be enhanced by coupling with essential oil chemicals, which can broaden the range of applications. Essential oil-chitosan (EOCS), the chitosan modified by essential oil components, which has been widely used as a multi-perspective in numerous filed of food and life in recent years. Herein, the synthesis, characterization, and recent application of EOCS are reviewed. Synthetic methods include 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated modification, free radical-induced modification, enzyme-catalyzed modification, bromide-mediated modification, and method of forming Schiff-base directly. The successful synthesis of derivatives can be demonstrated by UV, FT-IR, TLC, and NMR. EOCSs can be used as preservative coatings, packaging materials, and antibacterial agents in the food industry, as well as drug delivery and wound treatment in biomedicine. In addition, EOCSs are also used in other industries, such as environmental protection, metal corrosion inhibition, as well as plant pest control., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2022 Elsevier Ltd. 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.)

The applications of lipases in esterification, amidation, and transesterification have broadened their potential in the production of fine compounds with high cumulative values. Mostly, the catalytic triad of lipases is covered by either one or two mobile peptides called the "lid" that control the substrate channel to the catalytic center. The lid holds unique conformational allostery via interfacial activation to regulate the dynamics and catalytic functions of lipases, thereby highlighting its importance in redesigning these enzymes for industrial applications. The structural characteristic of lipase, the dynamics of lids, and the roles of lid in lipase catalysis were summarized, providing opportunities for rebuilding lid region by biotechniques (e.g., metagenomic technology and protein engineering) and enzyme immobilization. The review focused on the advantages and disadvantages of strategies rebuilding the lid region. The main shortcomings of biotechnologies on lid rebuilding were discussed such as negative effects on lipase (e.g., a decrease of activity). Additionally, the main shortcomings (e.g., enzyme desorption at high temperatre) in immobilization on hydrophobic supports via interfacial action were presented. Solutions to the mentioned problems were proposed by combinations of computational design with biotechnologies, and improvements of lipase immobilization (e.g., immobilization protocols and support design). Finally, the review provides future perspectives about designing hyperfunctional lipases as biocatalysts in the food industry based on lid conformation and dynamics., (© 2022 Institute of Food Technologists®.)

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.)

Aptamers are short single-stranded DNA or RNA oligonucleotides isolated from randomized libraries, presenting high affinity and specificity toward targets with similar to antibodies. Recently, aptamers have demonstrated their outstanding application potential ranging from biosensors, bioimaging, and therapeutics due to various advantages including low immunogenicity, ease of large-scale synthesis, low batch-to-batch variation, easily chemical modification, and programmability. However, the current overall success rate of aptamer is far from being satisfactory, and still needs to overwhelm the major obstacle in affinity, specificity, and stability for practical application. The efficient strategy of manipulating the binding performance of aptamers, and improving their performance in practical application is of great significance. Herein, we review the challenges and advances in manipulating the binding performance (e.g., affinity, specificity, and stability) of aptamers to obtain high-quality aptamers by comprehensive analyzing their structure and properties. This mainly includes interfering with the SELEX protocol to obtain excellent parental aptamers, engineering aptamers in post-SELEX process and matching the optimal working microenvironment. Moreover, the perspectives of future direction are also summarized. We hope to provide researchers with alternative strategies for enhancing the performance of aptamers in practical applications and promoting the explosive development of aptamers in related fields., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The monitoring of small-molecule thiols (especially glutathione) has attracted widespread attention due to their involvement in numerous physiological processes in living organisms and cells. In this work, a dual-mode nanosensor was designed to detect small-molecule thiols, which is based on the "on-off" switch of fluorescence resonance energy transfer (FRET) and surface-enhanced Raman scattering (SERS). Briefly, DNA was modified by Cy5 (signal probe) and disulfide bonds (recognition element). Gold nanoflowers (AuNFs) were used as the fluorescence-quenching and SERS-enhancing substrate. However, small-molecule thiols can cleave disulfide bonds and release short Cy5-labeled chains, causing the recovery of the fluorescence signal and a decrease of the SERS signal. The nanosensor showed a sensitive response to small-molecule thiols represented by GSH, with a linear range of 0.01-3 mM and a detection limit of 913 nM. In addition, it competed with other related biological interferences and presented good stability and better selectivity towards small-molecule thiols. Most importantly, the developed nanosensor had been successfully applied to in situ imaging and quantitative monitoring of the concentration of small-molecule thiols which changed during T-2 toxin-induced apoptosis in HeLa cells. Meanwhile, nanosensors are also versatile with their potential applications and can be easily extended to the detection and imaging of other human cell lines. The proposed method combines the dual advantages of fluorescence and SERS, which has broad prospects for in situ studies of physiological processes involving small-molecule thiols in biological systems.

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.)

Acyclic guanosine analogues, a class of widely used antiviral drugs, can cause chronic toxicity and virus resistance. Therefore, it is essential to establish rapid and accurate methods to detect acyclic guanosine analogues. In this study, five acyclic guanosine analogues (acyclovir, famciclovir, ganciclovir, penciclovir, and valaciclovir) were used as positive targets to obtain broad-spectrum aptamers through Capture-SELEX technology. Real-time quantitative PCR (Q-PCR) was used to monitor the aptamer SELEX process. After the sixteen rounds of selection against mixed targets, sequences were obtained by high-throughput sequencing (HTS). Furthermore, a broad-spectrum aptamer, named CIV6, was found as the higher performance aptamer that was suitable for five acyclic guanosine analogues by graphene oxide (GO) polarization and fluorescence assay. Finally, the aptamer CIV6 was used to construct GO fluorescence assay to detect five acyclic guanosine analogues. The limits of detection (LOD) of acyclovir, famciclovir, ganciclovir, penciclovir, and valaciclovir were 0.48 ng·mL -1 , 0.53 ng·mL -1 , 0.50 ng·mL -1 , 0.56 ng·mL -1 , and 0.38 ng·mL -1 , respectively., (© 2021. Springer-Verlag GmbH Germany, part of Springer Nature.)

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 abuse of ribavirin, an antiviral drug, in poultry breeding can cause quality degradation and drug resistance. So it is of great importance to establish a simple and effective method for detecting ribavirin in foods. In this work, aptamers that could especially bind to ribavirin with high affinity were obtained by the Capture-SELEX method. After 15 rounds of enrichment, ssDNA library pool was enriched and then analyzed by high-throughput sequencing. The seven most enriched sequences were selected as candidate aptamers for affinity and specificity characterization. Among the candidate aptamers, APT-1 was proved to be the optimal aptamer. The dissociation constant (K d ) values of APT-1 obtained by the two methods of colorimetric and fluorescence were 34.34 ± 6.038 nmol L -1 , 61.19 ± 21.48 nmol L -1 , respectively. To study the binding mechanism of the selected aptamer, molecular docking was conducted and results indicated that hydrogen bonds were formed at binding sites located at G37, T38, A40, T53 and A54. Furthermore, to confirm the practicability of the selected aptamer, a fluorescence assay was designed, showing the liner range within 1.0-50 ng mL -1 and the low detection limit of 0.67 ng mL -1 . Besides, the aptamer was applied for the detection of ribavirin in chicken samples and the recoveries ranged from 87.26% to 105.57%, which showed great application potential in food safety.

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.)

A new chitosan oligosaccharide derivative (COS-N-Ger), based on geraniol (Ger) modificated onto the NH 2 position of chitosan oligosaccharide (COS) via a facile method, was prepared and employed to evaluate in vitro antibacterial activity. The structures of COS-N-Ger derivatives were confirmed by FT-IR, 1 H, 13 C NMR, and elemental analysis. The characterization results showed successful synthesis of derivatives and the degrees of substitution (DS) of COS-N-Ger1-3 were from 0.260 to 0.283 with the yields up to 78 %. The in vitro antibacterial activity evaluation results presented a significant inhibition effect of COS-N-Ger1-3 derivatives on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as compared to COS. Moreover, their antibacterial activities were dose-dependent and more sensitive to S. aureus than E. coli. The results provide reliable theoretical supports for exploring the application of COS derivatives in the food industry as new potential antibacterial agents., (Copyright © 2020. Published by Elsevier Ltd.)

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.)

Background: High mortality among premature and very low birth weight (VLBW) babies necessitates the need to formulate and use scoring systems like CRIB score to predict the mortality in this vulnerable group. Objective of the study was to determine the strength of Clinical Risk Index For Babies (CRIB) score in detecting neonatal mortality in babies presenting with very low birth weight so that timely intervention can be done. It was a cross-sectional study, conducted at NICU, Children Hospital, Pakistan Institute of Medical Sciences Islamabad (PIMS) in nine months starting from First July 2017., Methods: A total of two hundred and fifty-four (n=254) new-borns with birth weight of between 500-1500 grams and gestational age lesser than 35 weeks were included in the study. CRIB score was calculated in all neonates and its association was assessed with mortality during NICU stay. Recorded data was analysed for demographic variables. Means and standard deviation was calculated for numeric variables. Chi-square test was applied to find p-value for the correlation between the main variables., Results: 54.3% (n=138) patients were males and 45.7% (n=116) were females. Mean gestational age was 33.3 weeks±1.04 SD and mean birth weight of study population was 1129.9 grams±210.6 SD. Mean CRIB score among the study population was 6.3±3.1SD and overall mortality was found to be 54.7% (n=139). Mean CRIB score was found to be 8.27±2.1 SD among mortality group and it was 3.87±3.4 SD among newborns who were discharged (p<0.05). Mortality was present in 4.3% (n=4) of neonates with CRIB score between 1 to 5, 87.1% (n=121) who had CRIB score between 6 to 10 and 100% (n=14) of neonates who had CRIB score level 11-15 (p<0.05), so a significantly higher percentage mortality was noted among neonates with higher CRIB scores., Conclusions: According to our study mean CRIB score is a significant predictor of neonatal mortality.

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.)

The performance of chloramphenicol aptamer, including binding thermodynamics, structure switching, and binding domain, was investigated by isothermal titration calorimetry, circular dichroism, and molecular docking. Then, a new fluorescence aptasensor was developed with signal amplification mediated by exonuclease I-catalyzed reaction and hybridization chain reaction (HCR) for chloramphenicol detection. In this system, the aptamer-binding domain is blocked by the initiator of HCR, the aptamer undergoes structure switching in the presence of chloramphenicol, and DNA dissociation occurs. The released aptamer is subsequently recognized and cleaved by Exo I to set free chloramphenicol. With the Exo I-assisted chloramphenicol recycling, an increasing number of initiators were exposed from the digestion of the initiator-aptamer complex. Then, the chain-like assembly of FAM labeled H1 and H2 through HCR was triggered by the initiator, generating a long DNA polymer. Under optimum conditions, the aptasensor exhibited a log-linear range from 0.001 to 100 nM of chloramphenicol and a detection limit of 0.3 pM. Additionally, the designed biosensing platform was applied to determine chloramphenicol in milk and lake water with high accuracy. The current approach provides a new avenue to develop sensitive aptasensors with the assistance of binding mechanism between aptamer and target compounds. Graphical abstract.

Yersinia enterocolitica remains a threat to public health, and a sensitive detection method is a prerequisite due to its complicated diagnosis associated with slow growth. Recently, aptamer-based detection systems have played a vital role in the development of simple, rapid, sensitive, and specific detection methods. Herein, highly specific ssDNA aptamers were screened against Y. enterocolitica at the different growth stages by whole cell-SELEX. Cells at different growth stages were harvested and incubated with an ssDNA library to get an enriched pool of specific aptamer candidates. After the 10 th round of SELEX, the enriched pool was sequenced and grouped into seven families based on homology and similarity of the secondary structure. Flow cytometry analysis revealed that the aptamers M1, M5, and M7 with K d values of 37.93 ± 7.88 nM, 74.96 ± 21.34 nM, and 73.02 ± 18.76 nM had the highest affinity and specificity to the target, respectively. The selected aptamers showed binding to the different growth stages of Y. enterocolitica with a significant increase in the gated fluorescence. Our aptamer selection strategy is convenient, and the developed aptamer can be useful for an accurate and reliable detection system., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

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.)

Staphylococcal enterotoxin A (SEA) is a worldwide public health problem accounting for the majority of food poisoning which is produced by Staphylococcus aureus , threatening human health and leading to various foodborne diseases. Therefore, it is of great significance to develop a sensitive detection method for SEA to ensure food safety and prevent foodborne diseases in humans. In this study, an adaptive fluorescence biosensor for the detection of staphylococcal enterotoxin A (SEA) was designed and developed by combining DNA silver nanoclusters (DNA-AgNCs) with polypyrrole nanoparticles (PPyNPs). Fluorescent AgNCs, synthesized using aptamers as templates, were used as fluorescence probes, whose fluorescence was quenched by PPyNPs. In the presence of the target SEA, DNA-AgNCs were forced to desorb from the surface of PPyNPs through the binding of SEA with the aptamer-DNA-AgNCs, thereby resulting in fluorescence recovery. Under the optimized conditions, the relative fluorescence intensity (FI) showed a linear relationship with the SEA concentration in the range from 0.5 to 1000 ng/mL ( Y = 1.4917 X + 0.9100, R 2 = 0.9948) with a limit of detection (LOD) of 0.3393 ng/mL. The sensor was successfully used to evaluate the content of SEA in milk samples, and the recovery efficiency of SEA was between 87.70% and 94.65%. Thus, the sensor shows great potential for application in food analysis. In short, the proposed platform consisted of an aptamer fluorescent sensor that can be used for the ultrasensitive detection of various toxins by taking advantage of the excellent affinity and specificity of corresponding aptamers., Competing Interests: The authors declare no conflicts of interest.

Food safety is imperative for a healthy life, but pathogens are still posing a significant life threat. "Yersiniosis" is caused by a pathogen named Yersinia enterocolitica and is characterized by diarrheal, ileitis, and mesenteric lymphadenitis types of sicknesses. This neglected pathogen starts its pathogenic activity by colonizing inside the intestinal tract of the host upon the ingestion of contaminated food. Y. enterocolitica remains a challenge for researchers and food handlers due to its growth habits, low concentrations in samples, morphological similarities with other bacteria and lack of rapid, cost-effective, and accurate detection methods. In this review, we presented recent information about its prevalence, biology, pathogenesis, and existing cultural, immunological, and molecular detection approaches. Our ultimate goal is to provide updated knowledge regarding this pathogen for the development of quick, effective, automated, and sensitive detection methods for the systematic detection of Y. enterocolitica ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

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.)

Mycotoxins posit serious threats to human and animal health, and numerous efforts have been performed to detect the multiple toxins by a single diagnostic approach. To best of our knowledge, for the first time, we synthesized an aptamer induced "turn on" fluorescence resonance energy transfer (FRET) biosensor using dual-color gold nanoclusters (AuNCs), l-proline, and BSA synthesized AuNCs (Lp-AuNCs and BSA-AuNCs), with WS 2 nanosheet for simultaneous recognition of aflatoxinB 1 (AFB 1 ) and zearalenone (ZEN) by single excitation. Here, AFB 1 aptamer stabilized blue-emitting AuNCs (AFB 1 -apt-Lp-AuNCs) (at 442 nm) and ZEN aptamer functionalized with red-colored AuNCs (ZEN-apt-BSA-AuNCs) (at 650 nm) were employed as an energy donor and WS 2 nanosheet as a fluorescence quencher. With the addition of AFB 1 and ZEN, the change in fluorescence intensity (F.I) was recorded at 442 and 650 nm and can be used for simultaneous recognition with a detection limit of 0.34 pg mL -1 ( R 2 = 0.9931) and 0.53 pg mL -1 ( R 2 = 0.9934), respectively. Most importantly, the semiquantitative determination of AFB 1 and ZEN can also be realized through photovisualization. The current approach paves a new way to develop sensitive, selective, and convenient metal nanocluster-based fluorescent "switch-on" probes with potential applications in multipurpose biosensing.

A "turn on" time-resolved fluorometric aptasensor is described for the simultaneous detection of zearalenone (ZEN), trichothecenes A (T-2), and aflatoxin B 1 (AFB 1 ). Multicolor-emissive nanoparticles doped with lanthanide ions (Dy 3+ , Tb 3+ , Eu 3+ ) were functionalized with respective aptamers and applied as a bioprobe, and tungsten disulfide (WS 2 ) nanosheets are used as a quencher of time-resolved fluorescence. The assay exploits the quenching efficiency of WS 2 and the interactions between WS 2 and the respective DNA aptamers. The simultaneous recognition of the three mycotoxins can be performed in a single solution. In the absence of targets, WS 2 is easily adsorbed by the mixed bioprobes via van der Waals forces between nucleobases and the WS 2 basal plane. This brings the bioprobe and WS 2 into close proximity and results in quenched fluorescence. In the presence of targets, the fluorescence of the bioprobes is restored because the analytes react with DNA probe and modify their molecular conformation to weaken the interaction between the DNAs and WS 2 . Under the optimum conditions and at an excitation wavelength of 273 nm, the time-resolved fluorescence intensities (peaking at 488, 544 and 618 nm and corresponding to emissions of Dy 3+ , Tb 3+ and Eu 3+ ) were used to quantify ZEN, T-2 and AFB 1 , respectively, with detection limits of 0.51, 0.33 and 0.40 pg mL -1 and a linear range from 0.001 to 100 ng mL -1 . The three mycotoxins can be detected simultaneously without mutual interference. The assay was applied to the quantification of ZEN, T-2 and AFB 1 in (spiked) maize samples. This homogeneous aptamer based assay can be performed within 1 h. Conceivably, it can become an alternative to other heterogeneous methods such as the respective enzyme-linked immunosorbent assays. Graphical abstract Schematic presentation of an aptasensor for simultaneous detection of zearalenone, trichothecenes A and aflatoxin B 1 using aptamer modified time-resolved fluorescence nanoparticles as signalling probes and tungsten disulfide as the quencher. This assay shows lower detection limit and requires no washing steps.