Mussel-Inspired Photografting on Colloidal Spheres: A Generalized Self-Template Route to Stimuli-Responsive Hollow Spheres for Controlled Pesticide Release

Current Challenges in Microcapsule Designs and Microencapsulation Processes: A Review

Microencapsulation is an advanced methodology for the protection, preservation, and/or delivery of active materials in a wide range of industrial sectors, such as pharmaceuticals, cosmetics, fragrances, paints, coatings, detergents, food products, and agrochemicals. Polymeric materials have been extensively used as microcapsule shells to provide appropriate barrier properties to achieve controlled release of the encapsulated active ingredient. However, significant limitations are associated with such capsules, including undesired leaching and the nonbiodegradable nature of the typically used polymers. In addition, the energy cost of manufacturing microcapsules is an important factor to be considered when designing microcapsule systems and the corresponding production processes. Recent factors linked to UN sustainability goals are modifying how such microencapsulation systems should be designed in pursuit of "ideal" microcapsules that are efficient, safe, cost-effective and environmentally friendly. This review provides an overview of advances in microencapsulation, with emphasis on sustainable microcapsule designs. The key evaluation techniques to assess the biodegradability of microcapsules, in compliance with recently evolving European Union requirements, are also described. Moreover, the most common methodologies for the fabrication of microcapsules are presented within the framework of their energy demand. Recent promising microcapsule designs are also highlighted for their suitability toward meeting current design requirements and stringent regulations, tackling the ongoing challenges, limitations, and opportunities.

Degradable PDA@PNIPAM-TA Nanocomposites for Temperature- and NIR light-Controlled Pesticide Release

Controlled pesticide delivery systems offer many distinctive advantages over conventional pesticide formulations. In this work, degradable poly(N-isopropylacrylamide) (PNIPAM)-tannic acid (TA) microgels and multifunctional PDA@PNIPAM-TA nanocomposites were prepared in a high-gravity rotating packed bed reactor (RPB) for smart pesticide delivery and release. The as-prepared microgels and nanocomposites showed reversible temperature-dependent swelling/deswelling behavior and irreversible pH-induced degradation. A dynamic contact angle test suggested that the introduction of TA and PDA into the PNIPAM matrix could enhance foliar adhesion and deposition efficiency. The nanocomposites were further used for the encapsulation and delivery of imidacloprid (IMI) to protect it from rapid photolysis and improve its pest-control efficiency. Their thermoresponsive behavior as well as pesticide loading capacity could be tuned by tailoring the PNIPAM-TA shell thickness, which could be varied by the NIPAM amount. The release rate of IMI from the core/shell nanocomposites was positively correlated with environmental temperature and near-infrared (NIR) light, which was adaptive to the positive temperature-dependent toxicity correlation of IMI and the increasing trend of pests under high temperature. The cumulative release of IMI was 23.5% at 25 °C, while it was 81.2% at 40 °C after 24 h of incubation, and the release rate was greatly enhanced under NIR irradiation. The results indicated that the facile control of pesticide release could be realized by regulating environmental conditions. This work also provides an idea for using high-gravity technology to conveniently construct a smart, effective, and environmentally friendly pesticide delivery system for sustainable crop protection.

Oxygen-Tolerant Photografting for Surface Structuring from Microliter Volumes

Here, we report an oxygen-tolerant photografting technique to grow polymer brushes employing microliter volumes of monomer solution under ambient conditions. With the key advantages that include spatial control, initiator/catalyst-free nature, and high oxygen tolerance, a series of homo-, multiblock, and arbitrary patterned polymer brushes were successfully obtained by photografting. Moreover, a dual-functional surface with hydrophilic and hydrophobic properties could easily be realized by one-pot photografting. These results illustrated the practicality and versatility of this strategy, which will allow nonexperts access to polymer brush architectures and broaden the potential applications of polymer brushes.

Recent Development of Versatile Polyphenol Platforms in Fertilizers and Pesticides

The utilization of agrochemicals has been of significant importance in both the cultivation and disease control of crops. The development of advanced agrochemicals that are both effective and eco-friendly has been made possible through the use of slow delivery platforms and surface modification technology. Inspired by the nature of mussel adhesion, polyphenolic platforms with versatile properties have been extensively employed in various applications, including agro-food, owing to their ability to flexibly modulate chemical and surface characteristics. This mini-review highlights the development of polyphenols, such as polydopamine and tannic acid, in the field of agrochemicals, particularly in the design and production of novel fertilizers and pesticides. The synthetic approach, active ingredient release performance, foliar adhesion, and design of polyphenolic-based agrochemicals in recent years have been discussed to explore their potential applications and limitations. We believe that utilizing versatile polyphenolic materials and their characteristics for agro-food applications can provide innovative ideas and suggestions for developing novel agrochemicals suitable for modern and sustainable horticulture and agriculture.

Preparation and Properties of Photoresponsive Pendimethalin@Silica-cinnamamide/γ-CD Microspheres for Pesticide Controlled Release

Photocontrolled pesticide delivery systems have broad prospects for application in agriculture. Here, a novel photoresponsive herbicide delivery system was fabricated by functionalizing silica microsphere surfaces with cinnamamide and encapsulating the silica-cinnamamide with γ-cyclodextrin (γ-CD) to form a double-layered microsphere shell loaded with pendimethalin (pendimethalin@silica-cinnamamide/γ-CD). The microspheres showed remarkable loading capacity for pendimethalin (approximately 30.25% w/w) and displayed excellent photoresponsiveness and controlled release. The cumulative drug release rate exceeded 80% over 72 h under UV or sunlight irradiation. The herbicidal activity of the microspheres against Echinochloa crusgalli (L.) Beauv. was almost the same as that of pendimethalin under UV or sunlight. A bioactivity survey confirmed that the pendimethalin@silica-cinnamamide/γ-CD microspheres exhibited longer duration weed control than commercial pendimethalin. Allium cepa chromosomal aberration assays demonstrated that the microspheres showed lower genotoxicity than pendimethalin. These advantages indicate that pendimethalin@silica-cinnamamide/γ-CD microspheres constitute an environmentally friendly herbicidal formulation.

Development of emamectin benzoate-loaded liposome nano-vesicles with thermo-responsive behavior for intelligent pest control

Pesticides play an important role in agricultural disease and pest control. However, the low utilization efficiency and environmentally unfriendly disadvantages of conventional pesticide formulations cause substantial environmental and ecological damage. Constructing intelligent controlled-release pesticide systems via nanotechnology is a feasible way to overcome these defects. In this research, an emamectin benzoate-loaded liposome nano-vesicle (EB-Lip-NV) with a multicompartment structure and thermo-responsive characteristics was developed to accurately control nocturnal pests and improve insecticidal activity. EB-Lip-NV is an unusual low-temperature rapid-release system based on phase transitions of the liposome membrane. Compared with the conventional water-soluble granule (SG), the EB-Lip-NV exhibited higher control activity on Spodoptera exigua. More importantly, the control efficacy of Spodoptera exigua at 20 °C was around 1.4 times that at 40 °C because of low temperature-induced rapid release. This controlled-release behavior of EB-Lip-NV in response to temperature change could effectively control the population of nocturnal pests. In addition, the toxicity of the EB-Lip-NV towards zebrafish was lower than that of SG by above 50%. This study provides a new strategy for constructing intelligent controlled-release pesticide systems with improving utilization rate and reducing harm to the environment and non-target organisms.

Amyloid-Like Protein Aggregation Toward Pesticide Reduction

Pesticide overuse is a major global problem and the cause of this problem is noticeable pesticide loss from undesired bouncing of sprayed pesticide droplets and rain erosion. This further becomes a primary source of soil and groundwater pollution. Herein, the authors report a method that can enhance pesticide droplet deposition and adhesion on superhydrophobic plant leave surfaces by amyloid-like aggregation of bovine serum albumin (BSA). Through the reduction of the disulfide bond of BSA by tris(2-carboxyethyl) phosphine hydrochloride (TCEP), the amyloid-like phase transition of BSA is triggered that rapidly affords abundant phase-transitioned BSA (PTB) oligomers to facilitate the invasion of the PTB droplet into the nanostructures on a leaf surface. Such easy penetration is further followed by a robust amyloid-mediated interfacial adhesion of PTB on leaf surface. As a result, after mixing with pesticides, the PTB system exhibits a remarkable pesticide adhesion capacity that is more than 10 times higher than conventional fixation of commercial pesticides. The practical farmland experiments show that the use of PTB aggregation could reduce the use of pesticides by 70-90% while ensuring yield. This work demonstrates that current pesticide dosage in actual agriculture production may be largely reduced by utilizing eco-friendly amyloid-like protein aggregation.

Redox- and Enzyme-Responsive Macrospheres Gatekept by Polysaccharides for Controlled Release of Agrochemicals

Stimuli-responsive materials afford researchers an opportunity to synthesize controlled-release carriers with various potential applications, especially for reducing the abuse of chemical reagents in farmland soil. To enhance the efficiency of agrochemical utilization, redox- and enzyme-responsive macrospheres were prepared by self-assembling β-cyclodextrin-modified zeolite and ferrocenecarboxylic acid (FcA)-grafted carboxymethyl cellulose (CMC). Scanning electron microscopy and Brunauer-Emmett-Teller analysis revealed that pores of zeolite were sealed by the surface coupling of FcA-modified CMC via the formation of an inclusion complex. Salicylic acid (SA) was loaded as a model agrochemical. The release of SA from macrospheres could be triggered in the presence of hydrogen peroxide (oxidant) and cellulase (enzyme); and the corresponding release percentages, 85.2 and 80.4%, were much higher than those of the control sample without responsive groups in water (12.6%) after 12 h. A release kinetic study showed that cellulase could promote carrier dissolution more effectively than the oxidant. The results demonstrate that the dual-responsive macrospheres are promising as a smart and effective carrier for the controlled release of agrochemicals.

Fabrication of gelatin microspheres containing ammonium hydrogen carbonate for the tunable release of herbicide

The major challenge in utilizing pesticides lies in identifying the precise application that would improve the efficiency of these pesticides and decline their environmental and health hazards at the same time. Such application requires the development of specific formulations that enable controlled, stimuli-responsive release of the pesticides. Gelatin is a relatively cheap material characterized by temperature-sensitivity and abundant amino acid groups, which makes it suitable for the storage and controlled release of pesticides. In this study, gelatin microspheres were prepared by emulsion and cross-linking, then they were loaded with 2,4-dichlorophenoxyacetic acid sodium (2,4-D Na) as a model herbicide. To achieve temperature-tunable release of 2,4-D Na from the microspheres, NH₄HCO₃ was added to the formulations at different concentrations. The prepared formulations were characterized by SEM, FTIR, and size distribution analyzes, and their drug loading capacities were determined. Based on bioassay experiments, the 2,4-D Na-NH₄HCO₃-loaded gelatin microspheres can effectively control the spread of dicotyledonous weeds. Therefore, the strategy proposed herein can be used to develop novel, effective herbicide formulations.

Infrared-Light-Responsive Controlled-Release Pesticide Using Hollow Carbon Microspheres@Polyethylene Glycol/α-Cyclodextrin Gel

Controlled release of pesticides by light regulation is one of the most viable strategies recently developed for the highly efficient utilization of agrochemicals. Herein, we report an infrared-light-responsive pesticide delivery system for the controlled release of imidacloprid (IMI) by preparation of functional hollow carbon microspheres (HCMs). After IMI loading and surface functionalization with polyethylene glycol (PEG) and α-cyclodextrin (α-CD), IMI was sequestered in the pesticide system (denoted as HCMs/IMI/PEG/α-CD) as a result of the formation of a PEG/α-CD gel network. Upon the irradiation of infrared light, HCMs with high photothermal conversion efficiency (42.8%) raised the local temperature effectively, leading to the collapse of the gel network and the release of IMI. In comparison to the amount of pesticide release (29%) under sunlight, it could reach 77% driven by infrared light, which was an intriguing improvement. Consequently, HCMs/IMI/PEG/α-CD under infrared light showed significantly higher pest control efficacy on corn borers by 125% than itself alone. This work provides a promising method to intentionally regulate pesticide release and enhance utilization efficiency.

Multiple Roles of Mesoporous Silica in Safe Pesticide Application by Nanotechnology: A Review

Pollution related to pesticides has become a global problem due to their low utilization and non-targeting application, and nanotechnology has shown great potential in promoting sustainable agriculture. Nowadays, mesoporous silica-based nanomaterials have garnered immense attention for improving the efficacy and safety of pesticides due to their distinctive advantages of low toxicity, high thermal and chemical stability, and particularly size tunability and versatile functionality. Based on the introduction of the structure and synthesis of different types of mesoporous silica nanoparticles (MSNs), the multiple roles of mesoporous silica in safe pesticide application using nanotechnology are discussed in this Review: (i) as nanocarrier for sustained/controlled delivery of pesticides, (ii) as adsorbent for enrichment or removal of pesticides in aqueous media, (iii) as support of catalysts for degradation of pesticide contaminants, and (iv) as support of sensors for detection of pesticides. Several scientific issues, strategies, and mechanisms regarding the application of MSNs in the pesticide field are presented, with their future directions discussed in terms of their environmental risk assessment, in-depth mechanism exploration, and cost-benefit consideration for their continuous development. This Review will provide critical information to related researchers and may open up their minds to develop new advances in pesticide application.

Surface Grafting "Band-Aid" for "Everyone": Filter Paper-Assisted Surface-Initiated Polymerization in the Presence of Air

We report herein a facile and generalized approach to the modification of solid surfaces with polymer brushes under ambient conditions: filter paper-assisted surface-initiated Cu0 -mediated controlled radical polymerization (PSI-CuCRP). The polymerization solution wetted filter paper is sandwiched between a copper plate and an initiator-modified substrate, which allows the creation of a surface-initiated polymerization (SIP) "band-aid" so that everyone can perform the surface grafting selectively with good control over the quality of the polymer brushes employing low concentration and microliter amounts of the monomer solution. The versatility of this method is demonstrated by grafting different homo-, block-, and multicomponent polymer brushes by using the same activation system and reaction conditions, the polymerization process can be precisely controlled to yield uniform polymers and show high chain-end functionality which is exemplified by in situ tetra-copolymerization. The combination of photolithography and paper cutting enables to prepare arbitrary three-dimensional patterned polymer brushes on the surface.

A Discrete Multi-Physics Model to Simulate Fluid Structure Interaction and Breakage of Capsules Filled with Liquid under Coaxial Load

This paper investigated the mechanical response (including breakage and release of the internal liquid) of single core–shell capsules under compression by means of discrete multi-physics. The model combined Smoothed Particle Hydrodynamics for modelling the fluid and the Lattice Spring Model for the elastic membrane. Thanks to the meshless nature of discrete multi-physics, the model can easily account for the fracture of the capsule’s shell and the interactions between the internal liquid and the solid shell. The simulations replicated a parallel plate compression test of a single core–shell capsule. The inputs of the model were the size of the capsule, the thickness of the shell, the geometry of the internal structure, the Young’s modulus of the shell material, and the fluid’s density and viscosity. The outputs of the model were the fracture type, the maximum force needed for the fracture, and the force–displacement curve. The data were validated by reproducing equivalent experimental tests in the laboratory. The simulations accurately reproduced the breakage of capsules with different mechanical properties. The proposed model can be used as a tool for designing capsules that, under stress, break and release their internal liquid at a specific time.

A temperature-responsive release cellulose-based microcapsule loaded with chlorpyrifos for sustainable pest control

Controlled pesticide release in response to environmental stimuli by encapsulating pesticide in carrier is a feasible approach to improve the effective utilization rate. Here, a temperature-responsive release microcapsule loaded with chlorpyrifos (CPF@CM) was prepared from n-hexadecane-in-water emulsions via interfacial polymerization. The microcapsule was consisted of nanofibrillated cellulose (NFC) as the shell wall material and isophorone diisocyanate (IPDI) as the crosslinker. The prepared CPF@CM had pesticide-loading efficiency (33.1 wt%) and favorable adhesion on the surface of cucumber and peanut foliage compared with conventional formulation. Additionally, CPF@CM could protect chlorpyrifos against photodegradation effectively. The in vitro release test showed that microcapsule had adjustable controlled-release characteristics with the change in temperature based on phase transition of the n-hexadecane core. Bioassay studies showed that control efficacy of CPF@CM microcapsule against P. xylostella was positively correlated with temperature because of temperature-induced changes in release rate. The acute toxicity of CPF@CM to zebrafish was reduced more than 5-fold compared with that of CPF technical. These results indicated that the microcapsule release system has great potential in the development of an effective and environmentally friendly pesticide formulation.

Stimuli-responsive polydopamine-based smart materials

This review provides in-depth insight into the structural engineering of PDA-based materials to enhance their responsive feature and the use of them in construction of PDA-based stimuli-responsive smart materials.

Synthesis and characterization of dopamine-modified Ca-alginate/poly(N-isopropylacrylamide) microspheres for water retention and multi-responsive controlled release of agrochemicals

The multi-responsive controlled-release system could enhance crop yield while improving utilization efficiency of agrochemicals, and minimize environmental pollution caused by agrochemicals overuse. This work reports a novel Ca-alginate/Poly(N-isopropylacrylamide)@polydopamine (Ca-alginate/PNIPAm@PDA) microsphere to control the agrochemicals release. Microsphere with a semi-interpenetrating network, which contained pH-sensitive Ca-alginate, temperature-sensitive poly(N-isopropylacrylamide) (PNIPAm), and sunlight-sensitive polydopamine (PDA), was characterized by thermogravimetric analysis, zeta potential, Fourier transform infrared spectroscopy, and scanning electron microscopy to prove the successful synthesis. Moreover, the comprehensive performances, including photothermal conversion, water absorbency, water retention, and controlled-release agrochemicals behaviors, were systematically investigated. The results indicated that the composite microsphere was a prosperous water and agrochemicals manager to effectively retain water and control the release of agrochemicals by external stimulation. Consequently, the Ca-alginate/PNIPAm@PDA microsphere with outstanding water-retention and controlled-release capacities is economical and eco-friendly and thus is promising for utilization as water and agrochemicals controlled-release carrier material in agriculture applications.

Melanin-Like Nanomaterials for Advanced Biomedical Applications: A Versatile Platform with Extraordinary Promise

Developing efficient, sustainable, and biocompatible high-tech nanoplatforms derived from naturally existing components in living organisms is highly beneficial for diverse advanced biomedical applications. Melanins are nontoxic natural biopolymers owning widespread distribution in various biosystems, possessing fascinating physicochemical properties and playing significant physiological roles. The multifunctionality together with intrinsic biocompatibility renders bioinspired melanin-like nanomaterials considerably promising as a versatile and powerful nanoplatform with broad bioapplication prospects. This panoramic Review starts with an overview of the fundamental physicochemical properties, preparation methods, and polymerization mechanisms of melanins. A systematical and well-bedded description of recent advancements of melanin-like nanomaterials regarding diverse biomedical applications is then given, mainly focusing on biological imaging, photothermal therapy, drug delivery for tumor treatment, and other emerging biomedicine-related implementations. Finally, current challenges toward clinical translation with an emphasis on innovative design strategies and future striving directions are rationally discussed. This comprehensive and detailed Review provides a deep understanding of the current research status of melanin-like nanomaterials and is expected to motivate further optimization of the design of novel tailorable and marketable multifunctional nanoplatforms in biomedicine.

Mussel-inspired hydrogels: from design principles to promising applications

This review presents the recent progress of mussel-inspired hydrogels from fundamental interaction mechanisms and design principles to promising applications.

Fabrication of detonation nanodiamond@sodium alginate hydrogel beads and their performance in sunlight-triggered water release

Agricultural water use accounts for around 70% of total water use in the world. Enhancing agricultural water use efficiency is a key way to cope with water shortage. Here, sunlight-responsive hydrogel beads consisting of sodium alginate (SA) matrix and detonation nanodiamond (DND) were fabricated by an ion gelation technique, which has potential applications in controlled water release. The interaction between the DND and SA matrix was investigated by Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD). UV-vis diffuse reflectance spectra verified DND can absorb solar energy in the UV, visible and even near-infrared regions. DND dispersed in the hydrogel matrix can absorb sunlight and generate heat, increasing the temperature of the matrix and resulting in slow release of water from the elastic beads. In addition, the effects of DND content and pH were systematically studied to evaluate their water adsorption properties. The swelling kinetics of DND@SA hydrogel beads in distilled water could be fitted well with a pseudo-second-order kinetic model. Six consecutive cycles of water release-reswelling indicated that their easy regeneration and reusability. The novel and eco-friendly hydrogel beads should be applicable to on-demand, sequential, and long-term release of water via light exposure.

Interfacial assembly of mussel-inspired polydopamine@Ag core-shell nanoparticles as highly recyclable catalyst for nitroaromatic pesticides degradation

With the abundant use of pesticides in agriculture and grassland farming, water contamination unavoidably occurs due to the leaching of pesticide residues into environment. Now, most of the research on degradation of nitroaromatic pesticides residues has focused on nano catalysis-based method, however, effective post-reaction separation and recycling of the tiny nanocatalysts is also a significant technological challenge to be addressed. Herein, we report a simple and versatile strategy for the construction of efficient and recyclable catalysts of polydopamine (PDA)@Ag/polystyrene (PS) films for degradation of pesticides based on multi-purpose PDA microspheres inspired by mussel adhesion. The PDA not only functioned as a scaffold, a reductant as well as a stabilizer for the formation and dispersions of Ag NPs in situ, but also served as an adhesive layer between the nanocatalysts and the substrate. The obtained PDA@Ag/PS films were evaluated for the first time against the catalytic degradation of pendimethalin. Most importantly, the recovery of catalysts can be easily realized by simply pulling out PS substrate from the reaction mixture and the catalytic activity of the nanofilms was found to be equally efficient for seven catalytic cycles. Considering their excellent catalytic activity and recyclability in the degradation of nitroaromatic pesticides, the PDA@Ag/PS films have great potential applications in the fields of environment protection, soil contamination remediation, and sewage treatment. Also, by virtue of the remarkable reducing and stabilizing ability and adhesive versatility of PDA, this approach can be extended to the deposition of various metals and semiconducting NPs, which can be stably anchored on a diverse range of solid substrates regardless of physiochemical and morphology.

Environmental behavior of coated NMs: Physicochemical aspects and plant interactions

The application of nanomaterials (NMs) depends on several characteristics, including polydispersity, shape, surface charge, and composition, among others. However, the specific surface properties of bare NMs induce aggregation, reducing their utilization. Thus, different surface coverages have been developed to avoid or minimize NMs aggregation, making them more stable for the envisioned applications. Carbon-based NMs are usually coated with metals, while metal-based NMs are coated with natural organic compounds including chitosan, dextran, alginate, or citric acid. On the other hand, the coating process is expected to modify the surface properties of the NMs; several coating agents add negative or positive charges to the particles, changing their interaction with the environment. In this review, we analyze the most recent literature about coating processes and the behavior of coated NMs in soil, water, and plants. In particular, the behavior of the most commercialized metal-based NMs, such as TiO₂, ZnO, CeO₂, CuO, Ag, and Au, and carbon-based NMs are discussed in this review. The available articles about the effects of coated NMs in plants are discussed. Up to now, there is no uniformity in the information to ensure that the surface coverage increases or decreases the effects of NMs in plants. While some parameters are increased, others are decreased. Since the data is contradictory in some cases, the available literature does not allow researchers to determine what concentrations benefit the plants. This review highlights current results and future perspectives on the study of the effects of coated NMs in the environment.

Polydopamine Surface Chemistry: A Decade of Discovery

Polydopamine is one of the simplest and most versatile approaches to functionalizing material surfaces, having been inspired by the adhesive nature of catechols and amines in mussel adhesive proteins. Since its first report in 2007, a decade of studies on polydopamine molecular structure, deposition conditions, and physicochemical properties have ensued. During this time, potential uses of polydopamine coatings have expanded in many unforeseen directions, seemingly only limited by the creativity of researchers seeking simple solutions to manipulating surface chemistry. In this review, we describe the current state of the art in polydopamine coating methods, describe efforts underway to uncover and tailor the complex structure and chemical properties of polydopamine, and identify emerging trends and needs in polydopamine research, including the use of dopamine analogs, nitrogen-free polyphenolic precursors, and improvement of coating mechanical properties.

Synthesis and Insecticidal Activity of Enzyme-Triggered Functionalized Hollow Mesoporous Silica for Controlled Release

In the present study, enzymatic responsive controlled release formulations (CRFs) were fabricated. The CRFs were achieved by anchoring mechanically interlocked molecules using α-cyclodextrin onto the surface pore rims of hollow mesoporous silica (HMS). The CRFs were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The results showed that the CRFs had extraordinary loading ability for chlorantraniliprole (42% w/w) and could effectively preserve chlorantraniliprole against degradation under thermal conditions and UV radiation. The CRFs have been proven to be enzyme-sensitive. The release ratio of chlorantraniliprole from CRFs can be accelerated observably when external α-amylase was introduced. The persistence of CRFs was evaluated by regular sampling feeding experiment using Plutella xylostella as the target insect. The results showed that the larval mortality of P. xylostella was much higher than that of Coragen under all concentrations after 14 days, which proved that CRFs had remarkable persistence.

Preparation and Physicochemical Characteristics of Thermo-Responsive Emamectin BenzoateMicrocapsules

Thermo-responsive release emamectin benzoate microcapsules were successfully prepared with a polydopamine (PDA)-g-poly(N-isopropylacrylamide) (PNIPAm) multifunctional layer. Preparation of emamectin benzoate microcapsules was first studied by emulsion interfacial-polymerization using PDA as a wall material. Then the amino-terminated PNIPAm was grafted on the PDA layer by its amino group in aqueous solution. Physicochemical characterization of microcapsules was obtained by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). Kinetic study of emamectin benzoate release showed that the microcapsules exhibit sustained- and controlled-release properties. The multifunctional layer can release emamectin benzoate easily when the temperature was below the lower critical solution temperature (LCST). In contrast, when the temperature increased above the LCST, the release rate was reduced. The results indicated that these microcapsules with excellent thermo-sensitivity would be promising in the research field of pesticide microcapsules.

Facile synthesis of polymeric fluorescent organic nanoparticles based on the self-polymerization of dopamine for biological imaging

Polymeric fluorescent organic nanoparticles (polymer-FONs) have raised considerable research attention for biomedical applications owing to their advantages as compared with fluorescent inorganic nanoparticles and small organic molecules. In this study, we presented an efficient, facile and environment-friendly strategy to produce polymer-FONs, which relied on the self-polymerization of dopamine and polyethyleneimine (PEI) in rather mild conditions. To obtain the final polymer-FONs, aldehyde group-containing copolymers (named as poly(UA-co-PEGMA)) were synthesized by reversible addition-fragmentation chain-transfer polymerization using polyethylene glycol methyl ether methacrylate (PEGMA) and 1-undecen-10-al (UA) as monomers. The dopamine was conjugated onto poly(UA-co-PEGMA) through a multicomponent reaction between UA and dopamine to obtain poly(UA-co-PEGMA)-DA, which was further utilized for preparation of polymer-FONs through self-polymerization of dopamine and PEI. ¹H nuclear magnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy and fluorescence spectroscopy were employed to characterize the structure, morphology, compositions and optical properties of these polymer-FONs. Cell viability and cell uptake behavior results suggested that these polymer-FONs possess good biocompatibility and can be potentially utilized for biomedical applications. More importantly, the method can be also applied to fabricate many other multifunctional polymer-FONs with great potential for biomedical applications.

A Near-Infrared and Temperature-Responsive Pesticide Release Platform through Core-Shell Polydopamine@PNIPAm Nanocomposites

Controlled stimuli-responsive release systems are a feasible and effective way to increase the efficiency of pesticides and help improve environmental pollution issues. However, near-infrared (NIR)-responsive systems for encapsulation of pesticides for controlling release have not been reported because of high cost and load ability of conventional NIR absorbers as well as complicated preparation process. Herein, we proposed polydopamine (PDA) microspheres as a photothermal agent owing to their abundant active sites, satisfactory photothermal efficiency, low cost, and easy fabrication, followed by capping with a PNIPAm thermosensitive polymer shell. In this core-shell PDA@PNIPAm hybrid system, the PDA core provided excellent temperature and NIR-light sensitivity as well as high loading capacity, while the PNIPAm applied as both a thermosensitive gatekeeper and a pesticide reservoir. The structure of the PDA@PNIPAm nanocomposites was characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, dynamic light scattering, and thermogravimetric analysis; the results showed that the nanocomposites had a well-defined core-shell configuration for efficient loading of small pesticide molecules. Moreover, the core-shell PDA@PNIPAm nanocomposites exhibited high loading capacity and temperature- or NIR-controlled release performance. Overall, this system has significant potential in controlled drug release and agriculture-related fields as a delivery system for pesticides with photothermal responsive behavior.

Polystyrene-based Hollow Microsphere Synthesized by γ-ray Irradiation-assisted Polymerization and Self-Assembly and Its Application in Detection of Ionizing Radiation

To simply and multitudinously synthesize hollow microspheres in a pure system is important for relevant research and application. Here, a simple and novel one-pot synthetic strategy to prepare polystyrene (PS) hollow microspheres via irradiation-assisted free-radical polymerizing and self-assembly (IFPS) approach under γ-ray irradiation with no additives introduced into the system is presented. And PS/2,5-Diphenyloxazole (PPO) fluorescent microspheres have been prepared successfully by IFPS reaction, which can be used as scintillators for the detection of ionizing radiation. A linear relationship between emitted luminescence and dose-activity in water is obtained, which suggests that composite microspheres could be used as liquid scintillation in specific environment.

Recent developments in polydopamine: an emerging soft matter for surface modification and biomedical applications

After more than four billion years of evolution, nature has created a large number of fascinating living organisms, which show numerous peculiar structures and wonderful properties. Nature can provide sources of plentiful inspiration for scientists to create various materials and devices with special functions and uses. Since Messersmith proposed the fabrication of multifunctional coatings through mussel-inspired chemistry, this field has attracted considerable attention for its promising and exiciting applications. Polydopamine (PDA), an emerging soft matter, has been demonstrated to be a crucial component in mussel-inspired chemistry. In this review, the recent developments of PDA for mussel-inspired surface modification are summarized and discussed. The biomedical applications of PDA-based materials are also highlighted. We believe that this review can provide important and timely information regarding mussel-inspired chemistry and will be of great interest for scientists in the chemistry, materials, biology, medicine and interdisciplinary fields.

One-Reactant Photografting of ATRP Initiators for Surface-Initiated Polymerization

Self-initiated photografting polymerization is used to couple the polymerizable initiator monomer 2-(2-chloropropanoyloxy)ethyl acrylate to a range of polymeric substrates. The technique requires only UV light to couple the initiator to surfaces. The initiator surface density can be varied by inclusion of a diluent monomer or via selection of initiator and irradiation parameters. The functionality of the initiator surface is demonstrated by subsequent surface-initiated atom transfer radical polymerization. Surfaces are characterized by x-ray photoelectron spectroscopy (XPS), ellipsometry, and atomic force microscopy (AFM), and UV-induced changes to the initiator are assessed by (1) H NMR and gel permeation chromatography (GPC). This is the first time this one-reactant one-step technique has been demonstrated for creating an initiator surface of variable density.