Design and Synthesis of a Water-Based Nanodelivery Pesticide System for Improved Efficacy and Safety.

Developing an environmentally friendly and safe nanodelivery system is crucial to improve the efficacy of pesticides and minimize environmental and health risks. However, preparing a completely water-based nanopesticide without using harmful solvents is a technical challenge. In this study, a water-based nanodelivery pesticide system was constructed to improve the efficacy and safety of Emamectin Benzoate (EB). A specific surfactant, 29-(4-(5-hydroxynonan-5-yl)phenoxy)-3,6,9,12,15,18,21,24,27-nonaoxanonacosan-1-ol (SurEB) was designed and synthesized to form a water-based nanodelivery system (EBWNS) with EB. Molecular dynamics simulations revealed the self-assembly and interaction forces between SurEB and EB in water, providing insights into the formation mechanism of EBWNS nanoparticles. The nanodelivery system showed the prolonged effectivity of EB with reduced degradation and demonstrated a good control efficacy for multiple target pests, such as red spider mite, beet armyworm larvae (Lepidoptera: Noctuidae), and rice stem borers (Chilo suppressalis). Toxicology tests on various objects demonstrated that the EBWNS has low toxicity for seeds, HaCaT cells, zebrafish, earthworm, and E. coli. This study provides a distinctive perspective for developing environmentally friendly nanopesticide formulations, which clarified a water-based treatment method for specific lipid-soluble pesticides. The water-based nanodelivery pesticide system has the potential to improve the efficacy and safety of pesticides in the process of field applications.

Temperature-Dependent Nanogel for Pesticide Smart Delivery with Improved Foliar Dispersion and Bioactivity for Efficient Control of Multiple Pests.

The use of nanomaterials and nanotechnology to construct a smart pesticide delivery system with target-oriented and controlled-release functions is important to increase the effective utilization rate and minimize environmental residue pollution. A temperature-dependent delivery system can modulate the release of pesticide with temperature to improve the efficacy and precision targeting. A series of poly(N-isopropylacrylamide) (PNIPAM)-based nanogels with high deformability and tunable structure were successfully constructed for smart pesticide delivery and effective pest control. A lambda-cyhalothrin (LC)-loaded Pickering emulsion (LC@TNPE) with a stable gel-like network structure was further formed by the temperature-dependent nanogel to encapsule the pesticide. The foliar wettability, photostability, and controlled-release property of LC@TNPE were effectively enhanced compared to the commercial formulation because of the encapsulation and stabilization of nanogel. The release rate of LC positively correlated with temperature changes and thereby adapted to the trend of pest population increase at higher temperature. The LC@TNPE displayed improved control efficacy on multiple target pests including Plutella xylostella, Aphis gossypii, and Pieris rapae compared with the commercial suspension concentrate and microcapsule suspension, and it showed marked efficacy to control Pieris rapae for an extended duration even at a 40% reduced dosage. Furthermore, the safety was evaluated systematically on cells in vitro and with a nontarget organism. Studies confirmed that the system was relatively safe for HepG2 cells and aquatic organism zebrafish. This research provides an insight into creating an efficient and environmentally friendly pesticide nanoformulation for sustainable agriculture production.

Simple and fast colorimetric detection of lipopolysaccharide based on aptamer and SYBR Green I mediated aggregation of gold nanoparticles.

Lipopolysaccharide (LPS) poses a considerable threat to food safety and human health. A colorimetric assay for LPS detection based on LPS binding aptamer (LBA) and SYBR Green I (SG) mediated aggregation of gold nanoparticles (AuNPs) was established. In the absence of LPS, the LBA was absorbed onto the AuNPs surface which prevented SG-induced aggregation of AuNPs, and the sensing system exhibited red color. When LPS was added, it interacted with the LBA, forming a complex. At higher LPS concentration, many LBAs were exhausted resulting in SG-induced aggregation of AuNPs, and color change from red to blue. The range of colorimetric detection of LPS was linear in 0-12 EU/mL, with a limit of detection of 0.1698 EU/mL. Spiked LPS in real samples and interfering substances were also identified. This assay ingeniously using the fluorescent dye SG as an effective trigger of AuNPs aggregation, is rapid and facile than most of those earlier reported LBA-based LPS assays, and there is potential to be modified to construct assays for other targets.

Construction and characterization of ethyl cellulose-based nano-delivery system for phenamacril.

Fungicide-resistant Fusarium has become a threaten to wheat production. Novel fungicide formulations can improve the efficacy of active ingredient and minimize the emergence of resistance. Encapsulation of fungicides in biodegradable carriers, especially, in polysaccharide, is a feasible approach to develop environment-friendly and efficient formulation. This study focused on the synthesis of ethyl cellulose-based phenamacril nano-delivery system by combining emulsion-solvent evaporation and high-pressure homogenization technology to improve the control of fusarium head blight in wheat. Emulsifier 125 and Tersperse 2500 were screened from eleven commonly used surfactants. Emulsifier 125 and Tersperse 2500 in a ratio of 2:1 and phenamacril nanocapsules with the mean particle size of 152.5 ± 1.3 nm were prepared. These showed excellent storage stability and wettability on crop leaves. A bioassay comparing the nanocapsules with a commercial preparation against Fusarium graminearum showed significantly improved biological activity. This formulation could be used to effectively not only to control fusarium head blight but also delay the occurrence of resistance.

Nano-EMB-SP improves the solubility, foliar affinity, photostability and bioactivity of emamectin benzoate.

BACKGROUND: Emamectin benzoate (EMB), a frequently used biopesticide, is poorly soluble in water, making it difficult to wet the leaf surface, is prone to degrade in sunlight and readily loses its bioactivity. Traditional methods such as organic solvent application, pH adjustment and addition of photoprotectants either increase the economic and environmental costs or barely achieve the desired goal. We hypothesized that nanotechnology could improve the solubility, foliar affinity, photostability and bioactivity of EMB. This research set out to prepare a nano-EMB solid powder (nano-EMB-SP) and test this hypothesis. RESULTS: Nano-EMB-SP was prepared using a self-emulsifying method combined with carrier solidification. The mean particle size and Polydispersity index (PDI) of nano-EMB-SP were 14.64 nm and 0.24, respectively. A scanning electron microscopy image showed that EMB nanoparticles were mainly spherical or ellipsoidal in shape. Without organic solvent, the aqueous solubility of EMB in nano-EMB-SP was 4500 mg L-1 , at least 14-fold that of the EMB soluble granule (EMB-SG), which is solubilized by pH adjustment. Excellent foliar affinity of EMB was achieved by nano-EMB-SP, which completely wet and penetrated the superhydrophobic surface of cabbage (Brassica oleracea L.) leaf. Without photoprotectants, up to 82% of EMB content can be protected from ultraviolet (UV) damage in nano-EMB-SP. The combined effects of excellent photostability and foliar affinity of nano-EMB-SP led to the bioactivity of EMB being almost unchanged before and after UV radiation. CONCLUSION: Nano-EMB-SP is an eco-friendly and efficient way to improve the solubility, foliar affinity, photostability and bioactivity of EMB. This research provides a good approach to improving the efficacy of poorly soluble and UV-sensitive pesticides. © 2022 Society of Chemical Industry.

Polylactic acid nanoparticles for co-delivery of dinotefuran and avermectin against pear tree pests with improved effective period and enhanced bioactivity.

Pesticide compounding technology for disease and pest control emerges as an effective way to increase the effectiveness of pesticides while reducing pesticides resistance. Nanomaterials and encapsulation technology have offered a new insight into preparing efficient pesticide formulations, especially constructing a co-delivery nanoparticle for synergistic pesticides. In this study, a dinotefuran/avermectin co-delivery nanoparticles (DACNPs) against pear tree pests with polylactic acid (PLA) as the wall material were constructed by double-emulsion method combined with high-pressure homogenization technique. The drug content of the DACNPs was 39.1% with an average size of 245.7 ± 4.2 nm and the mean polymer dispersity index (PDI) value was 0.123. The DACNPs showed high foliar retention and good spread performance on target leaves due to the nanoscale effect. The obtained DACNPs showed a better control effect on Grapholitha molesta Busck and Psylla chinensis Yang et Li compared with the commercial formulations, which could significantly prolong the effective duration and enhance the bioactivity with lower amounts and application frequency of pesticides. This study may provide new insights into developing novel pesticide formulations to improve the utilization rate of pesticides, reduce environmental pollution and minimize the cost of farming.

Nanomaterials and nanotechnology for the delivery of agrochemicals: strategies towards sustainable agriculture.

Nanomaterials (NMs) have received considerable attention in the field of agrochemicals due to their special properties, such as small particle size, surface structure, solubility and chemical composition. The application of NMs and nanotechnology in agrochemicals dramatically overcomes the defects of conventional agrochemicals, including low bioavailability, easy photolysis, and organic solvent pollution, etc. In this review, we describe advances in the application of NMs in chemical pesticides and fertilizers, which are the two earliest and most researched areas of NMs in agrochemicals. Besides, this article concerns with the new applications of NMs in other agrochemicals, such as bio-pesticides, nucleic acid pesticides, plant growth regulators (PGRs), and pheromone. We also discuss challenges and the industrialization trend of NMs in the field of agrochemicals. Constructing nano-agrochemical delivery system via NMs and nanotechnology facilitates the improvement of the stability and dispersion of active ingredients, promotes the precise delivery of agrochemicals, reduces residual pollution and decreases labor cost in different application scenarios, which is potential to maintain the sustainability of agricultural systems and improve food security by increasing the efficacy of agricultural inputs.

Advances in Controlled-Release Pesticide Formulations with Improved Efficacy and Targetability.

Pesticides are commonly used in modern agriculture and are important for global food security. However, postapplication losses due to degradation, photolysis, evaporation, leaching, surface runoff, and other processes may substantially reduce their efficacy. Controlled-release formulations can achieve the permeation-regulated transfer of an active ingredient from a reservoir to a target surface. Thus, they can maintain an active ingredient at a predetermined concentration for a specified period. This can reduce degradation and dissipation and other losses and has the potential to improve efficacy. Recent developments in controlled-release technology have adapted the concepts of intelligence and precision from the pharmaceutical industry. In this review, we present recent advances in the development of controlled-release formulations and discuss details of the preparation methods, material improvements, and application technologies.

Plasmonic gold nanostructures for biosensing and bioimaging.

As one kind of noble metal nanostructures, the plasmonic gold nanostructures possess unique optical properties as well as good biocompatibility, satisfactory stability, and multiplex functionality. These distinctive advantages make the plasmonic gold nanostructures an ideal medium in developing methods for biosensing and bioimaging. In this review, the optical properties of the plasmonic gold nanostructures were firstly introduced, and then biosensing in vitro based on localized surface plasmon resonance, Rayleigh scattering, surface-enhanced fluorescence, and Raman scattering were summarized. Subsequently, application of the plasmonic gold nanostructures for in vivo bioimaging based on scattering, photothermal, and photoacoustic techniques  has been also briefly covered. At last, conclusions of the selected examples are presented and an outlook of this research topic is given.

Simultaneous detection of telomerase and miRNA with graphene oxide-based fluorescent aptasensor in living cells and tissue samples.

Telomerase and microRNAs (miRNAs) as important biomarkers are closely related to cancers. Simultaneous detection of telomerase activity and miRNAs would be beneficial to improve the specificity and reliability. Here, we establish a telomerase and miRNA-21 (miR-21) simultaneous sensing platform with graphene oxide-based fluorescent aptasensors (GOFA) including graphene oxide (GO), template strand (TS) primer and fluorophore-labeled telomerase/miR-21 oligonucleotides. Owing to π-π stacking interaction, TS primer and telomerase/miR-21 probes would be loaded onto GO, resulting in fluorescence quenching. However, in the presence of the telomerase or miR-21, the double-stranded oligonucleotides would be away from the GO surface attribute to the hybridization between the extended TS primers and telomerase probe as well as miR-21 and miR-21 probe, leading to obvious fluorescence recovery. We found that GOFA could simultaneously detect telomerase activity and miR-21 with low background signal, high sensitivity and simplified operation. Moreover, GOFA could be used for accurately detecting telomerase activity and miRNA in living cells and cancer patient tissue sample. This sensing platform shows great potential in improving the accuracy in clinical diagnosis of cancer.

Zeolitic imidazolate framework-based biosensor for detection of HIV-1 DNA.

ZIF-8(zinc-methylimidazolate framework-8), one of the zeolitic imidazolate frameworks (ZIFs), as quenching platforms for detection of HIV-1 DNA, which was identified to be effective for highly sensitive detection of HIV-1 DNA. The enhanced fluorescence signal has a relationship with the ssDNA concentration, the detection limit is as low as 1.2 nmol L-1 with good selectivity. This study is an important step toward rational design of materials to achieve specific interactions between biomolecules and synthetic particle surfaces.

A mini-review on functional nucleic acids-based heavy metal ion detection.

Recent years have witnessed great progress in developing functional nucleic acids (FNAs)-based sensors for the detection of heavy metal ion. In this review, four types of the FNAs that most widely-used in heavy metal ions detection were briefly introduced and a dozen of recently published review articles which summarized those FNAs-based sensors were introduced. Particularly, according to the degree of automation and system integration, those FNAs-based sensors which belong to the lab-on-a-chip (LOC) category were reviewed in more detail by classifying them into six types such as microfluidic LOC system, microchip, lateral flow dipstick, personal glucose meter, microfluidic paper-based analytical devices (µPADs) and disc-based analytical platform. After gave a brief description of the sensing strategies, properties, advantages or disadvantages of these FNAs-based sensors, existing problems and future perspectives were also discussed.

Colorimetric detection of bisphenol A based on unmodified aptamer and cationic polymer aggregated gold nanoparticles.

In this study, a colorimetric method was exploited to detect bisphenol A (BPA) based on BPA-specific aptamer and cationic polymer-induced aggregation of gold nanoparticles (AuNPs). The principle of this assay is very classical. The aggregation of AuNPs was induced by the concentration of cationic polymer, which is controlled by specific recognition of aptamer with BPA and the reaction of aptamer and cationic polymer forming "duplex" structure. This method enables colorimetric detection of BPA with selectivity and a detection limit of 1.50 nM. In addition, this colorimetric method was successfully used to determine spiked BPA in tap water and river water samples.

Sensitive fluorescent assay for copper (II) determination in aqueous solution using copper-specific ssDNA and Sybr Green I.

This paper reports a fluorescent turn-off assay for sensitive detection of Cu(2+) in an aqueous solution by using a copper-specific ssDNA Cu100 and Sybr Green I. By monitoring the fluorescence changes arose from different interactions of Sybr Green I with Cu100 and Cu100/Cu(2+) complex, the Cu(2+) could be linearly detected from 5.57 to 250 ppb, with a detection limit of 5.57 ppb. The feasibility of this assay was demonstrated by detecting Cu(2+) in certified reference materials and spiked water samples with satisfactory results.

Fluorescent detection of Hg2+ and Pb2+ using GeneFinder™ and an integrated functional nucleic acid.

This paper reports a simple fluorescent assay for the determination of Hg(2+) and Pb(2+) by using a DNA intercalator GeneFinder™ (GF) and an integrated functional nucleic acid (FNA). In the absence of Hg(2+) and Pb(2+), GF intercalated with the FNA and released moderate strong fluorescence. While in the presence of Hg(2+) or Pb(2+), the FNA would be induced to form T-Hg(2+)-T or G-quadruplex structure, interacted with which the GF would exhibit extremely strong or very weak fluorescence. By monitoring the fluorescence changes upon addition of these two ions, the Hg(2+) and Pb(2+) could be selectively detected as low as 3.23 ppb and 2.62 ppb. As the main advantage of this assay is simplicity and the feasibility was demonstrated by detecting Hg(2+) and Pb(2+) in spiked water samples, this assay holds great potential for the development of a cost effective and useful tool for environmental monitoring.

Selection of a DNA aptamer for cadmium detection based on cationic polymer mediated aggregation of gold nanoparticles.

The demand for selection of aptamers against various small chemical molecules has substantially increased in recent years. To incubate and separate target-specific aptamers, the conventional SELEX procedures generally need to immobilize target molecules on a matrix, which may be impotent to screen aptamers toward small molecules without enough sites for immobilization. Herein we chose Cd(II) as a model of a small molecule with less sites, and proposed a novel SELEX strategy of immobilizing ssDNA libraries rather than target molecules on a matrix, for selection of aptamers with high affinity to Cd(II). After eleven rounds of positive and negative selection, twelve T and G-rich of nonrepeating ssDNA sequences were identified, of which the Cd-4 aptamer displayed the highest binding affinity to Cd(II). The secondary structures of these sequences revealed that a stem-loop structure folded by the domain of their 30-random sequence is critical for aptamers to bind targets. Then the interaction between the selected Cd-4 aptamer and Cd(II) was confirmed by CD analysis, and the binding specificity toward other competitive metal ions was also investigated. The dissociation constant (Kd) of Cd-4 aptamer was determined as 34.5 nM for Cd(II). Moreover, the Cd-4 aptamer was considered a recognition element for the colorimetric detection of Cd(II) based on the aggregation of AuNPs by cationic polymer. Through spectroscopic quantitative analysis, Cd(II) in aqueous solution can be detected as low as 4.6 nM. The selected Cd-4 aptamer will offer a new substitute for the detection of Cd(II) or other applications like recovery of cadmium from polluted samples.

Label-free fluorescent sensor for lead ion detection based on lead(II)-stabilized G-quadruplex formation.

A label-free fluorescent DNA sensor for the detection of lead ions (Pb(2+)) based on lead(II)-stabilized G-quadruplex formation is proposed in this article. A guanine (G)-rich oligonucleotide, T30695, was used as a recognition probe, and a DNA intercalator, SYBR Green I (SG), was used as a signal reporter. In the absence of Pb(2+), the SG intercalated with the single-stranded random-coil T30695 and emitted strong fluorescence. While in the presence of Pb(2+), the random-coil T30695 would fold into a G-quadruplex structure and the SG could barely show weak fluorescence, and the fluorescence intensity was inversely proportional to the involving amount of Pb(2+). Based on this, a selective lead ion sensor with a limit of detection of 3.79 ppb (parts per billion) and a detection range from 0 to 600 ppb was constructed. Because detection for real samples was also demonstrated to be reliable, this simple, low-cost, sensitive, and selective sensor holds good potential for Pb(2+) detection in real environmental samples.

Ultrasensitive resonance scattering (RS) spectral detection for trace tetracycline in milk using aptamer-coated nanogold (ACNG) as a catalyst.

This paper reports an ultrasensitive resonance scattering (RS) method to detect tetracycline (TET) in milk based on the competition of aptamers between nanogold and TET, aggregation of naked nanogold, nanocatalytic Fehling reaction, and RS signals of catalytic product Cu2O cubic. The detection principle was confirmed by the nanoparticle size analyzer (NANOS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The variations of RS intensity had good linear correlation with TET concentrations, and the limit of detection was calculated as 11.6 nM. The proposed method was successfully applied for analysis of TET in milk, with total recoveries ranging from 105 to 109%.

Nanoparticles assembled by aptamers and crystal violet for arsenic(III) detection in aqueous solution based on a resonance Rayleigh scattering spectral assay.

Aptamer-assembled nanomaterials have captured much attention from the field of analytical chemistry in recent years. Although they have been regarded as a promising tool for heavy metal monitoring, report involving aptamer-based biosensors for arsenic detection are rare. Herein we developed a highly sensitive and selective aptamer biosensor for As(iii) detection based on a Resonance Rayleigh Scattering (RRS) spectral assay. Prior to As(iii) detection, we firstly assembled a variety of nanoparticles with different sizes via controlling the concentration of arsenic-binding aptamers in crystal violet (CV) solutions. The results of photon correlation spectroscopy (PCS) and scanning probe microscope (SPM) testified that the introduction of As(iii) had indeed changed the size of nanoparticles, which caused a great variation in the RRS intensity at 310 nm. In the presence of 100 ppb As(iii), a maximum decline in the ratio of RRS intensity was achieved for large nanoparticles assembled from 200 nM of aptamers and CV molecules, where the average size of nanoparticles had decreased from 273 nm to 168 nm. In the case of small nanoparticles, the maximum increase ratio of the RRS intensity was obtained when the concentration of aptamer was over 600 nM. Combined with an RRS spectral assay, an effective biosensor has been developed for As(iii) detection, using the above large and small nanoparticles as the target recognition element. The present biosensor has a detection limit as low as 0.2 ppb, a dynamic range from 0.1 ppb to 200 ppb, and high selectivity over other metal ions. Such an efficient biosensor will play an important role in environmental detection.