pH-responsive Performance Research Articles

Nano-pesticide delivery system based on UiO-66 with pH sensitivity for precise control of Spodoptera frugiperda.

Metal-organic frameworks have the advantages of easy synthesis, high loading capacity and good biocompatibility, making them essential materials for constructing pesticide nano-delivery systems. In this study, a pH-responsive nano-controlled-release formulation Chl@UiO-66 was prepared using UiO-66 as the nano-scale carrier for adsorbing chlorantraniliprole (Chl). The appearance, pesticide loading, release behaviour, insecticidal activity, long-term control efficacy and safety of Chl@UiO-66 for non-target organisms were extensively evaluated. The results showed that the prepared Chl@UiO-66 was a regular octahedron with a uniform particle size of 230 nm and pesticide loading of 15.62%. The release of pesticides under alkaline conditions was superior to that under acidic and neutral conditions, which showed pH-responsive performance. Chl@UiO-66 had an excellent ability to protect pesticides from ultraviolet degradation. Compared with chlorantraniliprole suspension concentrate, Chl@UiO-66 had a better control effect against Spodoptera frugiperda and long-term control efficacy. The prepared nano-controlled-release formulation had low toxicity to zebrafish, earthworms and human BEAS-2B cells. Chl@UiO-66 is a new pesticide formulation with high efficacy and low toxicity that provides a smart controlled-release solution. © 2024 Society of Chemical Industry.

High adsorption capacities for dyes by a pH-responsive sodium alginate/sodium lignosulfonate/carboxylated chitosan/polyethyleneimine adsorbent

Dyes are indispensable for the rapid development of society, but untreated dye wastewater can threaten human health. In this study, an adsorbent (SA/SL/CCS/PEI@MNPs) was synthesized by one-pot method using magnetic nanoparticles (MNPs), sodium alginate (SA), sodium lignosulfonate (SL), carboxylated chitosan (CCS) and polyethyleneimine (PEI). The adsorbent was mesoporous micrometer-sized particles with pore size of 34.92 nm, which was favorable for dynamic column experiments. SA/SL/CCS/PEI@MNPs possessed pH-responsive performance. Under acidic condition, the maximum adsorption capacities for anionic dyes (tartrazine, reactive black-5, indigo carmine) reached >550 mg/g. Under alkaline condition, those for cationic dyes (methylene blue, methyl violet, neutral red) exceeded 1900 mg/g. The function of the various modifiers was investigated. The results indicated that the incorporation of SL, CCS and PEI was able to provide plenty of sulfonate, carboxylate and amino/imine reactive groups so that adsorption capacities of dyes were improved. The adsorption mechanism was explored by FTIR and XPS. At the same time, the adsorption mechanism was more deeply analyzed using molecular dynamics simulations and radial distribution function. It was demonstrated that the dyes adsorption on the SA/SL/CCS/PEI@MNPs was mainly due to electrostatic attraction and π-π interaction. In addition, the adsorbent had good reusability, and the removal still reached over 90 % after five cycles. In conclusion, the adsorbent displayed a broad prospect for the adsorption of organic dyes.

Florfenicol core–shell composite nanogels as oral administration for efficient treatment of bacterial enteritis

To reduce the bitterness of florfenicol, avoid its degradation by gastric acid, and enhance its antibacterial activity against Escherichia coli by targeting and slowly releasing drugs at the site of intestinal infection, with pectin as an anion carrier and chitosan oligosaccharides (COS) as a cationic carrier, florfenicol-loaded COS@pectin core nanogels were self-assembled by electrostatic interaction and then encapsulated in sodium carboxymethylcellulose (CMCNa) shell nanogels through the complexation of CMCNa and Ca2+ to prepare florfenicol core–shell composite nanogels in this study. The florfenicol core–shell composite nanogels were investigated for their formula choice, physicochemical characterization, pH-responsive performances, antibacterial activity, therapeutic efficacy, and in vitro and in vivo biosafety studies. The results indicated that the optimized formula was 0.6 g florfenicol, 0.79 g CMCNa, 0.30 g CaCl2, 0.05 g COS, and 0.10 g pectin, respectively. In addition, the mean particle diameter, polydispersity index, zeta potential, loading capacity, and encapsulation efficiency were 124.0 ± 7.2 nm, –22.9 ± 2.5 mV, 0.42 ± 0.03, 43.4 % ± 3.1 %, and 80.5 % ± 3.4 %, respectively. The appearance, lyophilized mass, resolvability, scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and fourier transform infrared (FTIR) showed that the florfenicol core–shell composite nanogels were successfully prepared. Florfenicol core–shell composite nanogels had satisfactory stability, rheology, and pH-responsiveness, which were conducive to avoid degradation by gastric acid and achieve targeted and slow release at intestinal infection sites. More importantly, florfenicol core–shell composite nanogels had excellent antibacterial activity against Escherichia coli, a satisfactory therapeutic effect, and good palatability. In vitro and in vivo biosafety studies suggested the great promise of florfenicol core–shell composite nanogels. Therefore, the prepared florfenicol core–shell composite nanogels may be helpful for the treatment of bacterial enteritis as a biocompatible oral administration.

Neutrophil-like pH-responsive pro-efferocytic nanoparticles improve neurological recovery by promoting erythrophagocytosis after intracerebral hemorrhage.

Rationale: Intracerebral hemorrhage (ICH) is a devastating cerebrovascular disease resulting from blood extravasating into the brain parenchyma. Escalation of erythrophagocytosis (a form of efferocytosis), avoiding the consequent release of the detrimental erythrocyte lysates, may be a promising target of ICH management. The ADAM17 inhibitor and liver X receptor (LXR) agonist could promote efficient efferocytosis and injury repair. Nevertheless, the poor bioavailability and restriction of the blood-brain barrier (BBB) hinder their application. Therefore, it is needed that biocompatible and smart nanoplatforms were designed and synthesized to realize effective therapy targeting erythrophagocytosis. Methods: We first assessed the synergistic effect of therapeutic GW280264X (an ADAM17 inhibitor) and desmosterol (an LXR agonist) on erythrophagocytosis in vitro. Then a pH-responsive neutrophil membrane-based nanoplatform (NPEOz) served as a carrier to accurately deliver therapeutic GW280264X and desmosterol to the damaged brain was prepared via co-extrusion. Afterwards, their pH-responsive performance was valued in vitro and targeting ability was assessed through fluorescence image in vivo. Finally, the pro-erythrophagocytic and anti-neuroinflammatory ability of the nanomedicine and related mechanisms were investigated. Results: After the synergistical effect of the above two drugs on erythrophagocytosis was confirmed, we successfully developed neutrophil-disguised pH-responsive nanoparticles to efficiently co-deliver them. The nanoparticles could responsively release therapeutic agents under acidic environments, and elicit favorable biocompatibility and ability of targeting injury sites. D&G@NPEOz nanoparticles enhanced erythrophagocytosis through inhibiting shedding of the efferocytotic receptors MERTK/AXL mediated by ADAM17 and accelerating ABCA-1/ABCG-1-mediated cholesterol efflux regulated by LXR respectively. In addition, the nano-formulation was able to modulate the inflammatory microenvironment by transforming efferocytes towards a therapeutic phenotype with reducing the release of proinflammatory cytokines while increasing the secretion of anti-inflammatory factors, and improve neurological function. Conclusions: This biomimetic nanomedicine is envisaged to offer an encouraging strategy to effectively promote hematoma and inflammation resolution, consequently alleviate ICH progression.

BIOCOMPATIBLE P(TM co SA-CAA) HYDROGELS WITH pH RESPONSIVE AND ENHANCED MECHANICAL PERFORMANCE

In recent years, development of hydrogel that combines biocompatibility, pH responsive and mechanical performance has attracted the attention of researchers. A novel biocompatible hydrogel, composed of P(TM co SA) and P(TM co CAA) was synthesized by a simple admixture and heating process. The results show that with increasing levels of SA-CAA monomer concentration, an increase in tensile strength and elongation at breakpoint was observed and optimal at the ratios P(TM co SA CAA). Tensile strenght and young’s modulus registered an impressive increase of 43% and 40% respectively. These improvements are attributed to strong synergistic hydrogen bonding interactions between the TM and SA-CAA chains. During the experiment, maximum increase in weight was also achieved at pH 10 NaOH solution, it is show the pH-responsive hydrogels. The investigation of P(TM co SA-CAA) hydrogel mechanism showed that more homogenous dispersed through crosslinks dominated by β-sheets from Amide I structures. Furthermore, the SA-CAA molecules contributed to the biocompatibility, pH responsive and mechanical performance of P(TM co SA-CAA) hydrogels. Conclusively, its P(TM co SA-CAA) hydrogels clearly demonstrated the relevance of the provide a bioresponsive material for biomedical applications, such as tissue engineering, regenerative medicine and pH-sensitive drug delivery.

High mechanical and self-healing carboxymethyl chitosan-hyaluronic acid hybrid hydrogel via multiple dynamic covalent bonds for drug delivery

Therapeutic drugs for human cardiovascular disease require specific carriers. Hydrogels have a porous structure, plasticity, and biocompatibility, and are ideal carriers for cardiovascular drugs. Moreover, for their intended functions, hydrogels also need to have high mechanical properties, self-healing properties, good pH-responsive performance, and other properties. Here, based on the interactions between multiple dynamic covalent bonds, we effectively synthesized hybrid hydrogels of carboxymethyl chitosan (C-CS), aldehyde-modified hyaluronic acid (OHA), polyvinyl alcohol (PVA), and boric acid (BA). The multiple covalent bonds reinforce each other, endowing the hydrogels with high mechanical properties, self-healing properties and pH responsiveness. In addition, the whole preparation process does not require crosslinking agents and the operation process is simple. The results show that the 5% PVA + C-CS + OHA + BA hydrogel has high mechanical properties (tensile stress 40.07 KPa; compressive stress 553.38 KPa), good self-healing performance (up to 92%) and excellent pH responsive performance. In addition, the hydrogel has high drug-loading capacity (117.54 mg/g) and sustained-release performance. In conclusion, this hybrid hydrogel can potentially be used as a drug carrier for clinical treatment.

Bioinspired engineered proteins enable universal anchoring strategy for surface functionalization

HypothesisConventional coating strategies and materials for bio-applications with protective, diagnostic, and therapeutic functions are commonly limited by their arduous preparation processes and lack of on-demand functionalities. Herein, inspired by the ‘root-leaf’ structure of grass, a series of novel polyacrylate-conjugated proteins can be engineered with sticky bovine serum albumin (BSA) protein as a ‘root’ anchoring layer and a multifunctional polyacrylate as a ‘leaf’ functional layer for the facile coating procedure and versatile surface functionalities. ExperimentsThe engineered proteins were synthesized based on click chemistry, where the ‘root’ layer can universally anchor onto both organic and inorganic substrates through a facile dip/spraying method with excellent stability in harsh solution conditions, thanks to its multiple adaptive molecular interactions with substrates that further elucidated by molecular force measurements between the ‘root’ BSA protein and substrates. The ‘leaf’ conjugated-polyacrylates imparted coatings with versatile on-demand functionalities, such as resistance to over 99% biofouling in complex biofluids, pH-responsive performance, and robust adhesion with various nanomaterials. FindingsBy synergistically leveraging the universal anchoring capabilities of BSA with the versatile physicochemical properties of polyacrylates, this study introduces a promising and facile strategy for imparting novel functionalities to a myriad of surfaces through engineering natural proteins and biomaterials for biotechnical and nanotechnical applications.

Synthesis of amphiphilic functional terpolymers towards preparation of high flux, anti-fouling, micropollutant-capturing ultrafiltration membranes

Traditional method for modification of PVC ultrafiltration membrane depends mainly on blending, but inevitably suffers from additive leakage and poor compatibility between components. Herein, we synthesized amphiphilic functional terpolymers with adjustable chemical structures through in-situ copolymerization of vinyl chloride, acrylonitrile, and dimethyl aminoethyl acrylate, subsequently prepared the terpolymer ultrafiltration membranes by non-solvent induced phase separation. The novel terpolymers endow the membranes with amphiphilic and pH-responsive performances. Compared with the blend membrane, the copolymer had the more stable covalent bonding, and then its hydrophilic segments could anchor and enrich stably to the membrane surface without diffusing into the aqueous phase. As a result, the copolymer membrane not only effectively overcame the disadvantages of blend membrane, but also showed excellent antifouling and permeable properties. Its water flux significantly increases to 469.41 L/(m2·h·bar) from 35.67 L/(m2·h·bar) of pure PVC membrane while the adsorption capacity for bovine serum proteins was reduced. Meanwhile, the copolymer membranes exhibited strong pH-dependent adsorption for anionic dyes and heavy metal ions. The maximum adsorption capacities occurred respectively at pH values of 3.5 and 6.0. In addition, the copolymer membrane can be regenerated by desorbing the adsorbed anionic dyes and heavy metal ions respectively at pH 10 and pH 3.5. This research provides a new strategy for facile preparation of amphiphilic functional ultrafiltration membranes and effective removal of micropollutants.

Construction of pH-responsive polydopamine coated magnetic layered hydroxide nanostructure for intracellular drug delivery

In recent years, using magnetic nanocomposites for controlled release of drugs and target-specific drug delivery has great potential in exploring a new method for cancer chemotherapy. Nevertheless, the low loading rate of insoluble drugs greatly restricts their efficacy and clinical application. Here, an efficient magnetic nanostructure combining Fe3O4 nanoparticles and layered double hydroxide (LDH) was developed and used for tumor cell inhibition. LDH was first deposited on Fe3O4 nanoparticles (Fe3O4@LDH), curcumin (Cur) was then loaded and polydopamine (PDA) eventually formed a PDA-coating on Fe3O4@Cur-LDH via self-polymerization. The Fe3O4@Cur-LDH/PDA nanostructure showed a suitable nano-meter size, excellent magnetic property, and high drug loading rate (up to 38 %). In vitro release results implied that Fe3O4@Cur-LDH/PDA nanostructure had good pH-responsive performance and excellent controlled-release behaviors due to the introduction of PDA. The cellular experiments demonstrated that Fe3O4@Cur-LDH/PDA nanostructure had good biocompatibility. In addition, Fe3O4@Cur-LDH/PDA entered into the cells mainly through endocytosis and had excellent inhibition on HepG2 cell viability in a concentration-dependent manner. Therefore, Fe3O4@Cur-LDH/PDA nanostructure has a prospective application in cancer therapy as a controlled drug delivery system.

Intelligent-Responsive Enrofloxacin-Loaded Chitosan Oligosaccharide–Sodium Alginate Composite Core-Shell Nanogels for On-Demand Release in the Intestine

Simple SummaryNovel pharmaceutical formulations are attracting interest in their potential to overcome the poor palatability and strong gastric irritation of enrofloxacin. To overcome the difficulty of treating intestinal Escherichia coli infections, an oral intelligent-responsive chitosan-oligosaccharide (COS)–sodium alginate (SA) composite core-shell nanogel loaded with enrofloxacin was designed and systematically evaluated. Scanning electron microscopy images revealed that enrofloxacin nanogels were incorporated into the nano-sized cross-linked networks. The physical state and molecular interaction among the components of the nanogel and the enrofloxacin were evaluated by Fourier transform infrared spectroscopy. Furthermore, their biocompatible structure, high drug loading efficacy, ideal stability, “on-demand” release at the target site, and antibacterial activity were confirmed. Thus, the present study may serve as a fruitful platform to explore nanogel to resolve the challenge of enrofloxacin formulation development and the fight against intestinal bacterial infections.Enrofloxacin has a poor palatability and causes strong gastric irritation; the oral formulation of enrofloxacin is unavailable, which limits the treatment of Escherichia coli (E. coli) infections via oral administration. To overcome the difficulty in treating intestinal E. coli infections, an oral intelligent-responsive chitosan-oligosaccharide (COS)–sodium alginate (SA) composite core-shell nanogel loaded with enrofloxacin was explored. The formulation screening, characteristics, pH-responsive performance in gastric juice and the intestinal tract, antibacterial effects, therapeutic effects, and biosafety level of the enrofloxacin composite nanogels were investigated. The optimized concentrations of COS, SA, CaCl2, and enrofloxacin were 8, 8, 0.2, and 5 mg/mL, respectively. The encapsulation efficiency, size, loading capacity, zeta potential, and polydispersity index of the optimized formulation were 72.4 ± 0.8%, 143.5 ± 2.6 nm, 26.6 ± 0.5%, −37.5 ± 1.5 mV, and 0.12 ± 0.07, respectively. Scanning electron microscopy images revealed that enrofloxacin-loaded nanogels were incorporated into the nano-sized cross-linked networks. Fourier transform infrared spectroscopy showed that the nanogels were prepared by the electrostatic interaction of the differently charged groups (positive amino groups (-NH3+) of COS and the negative phenolic hydroxyl groups (-COO−) of SA). In vitro, pH-responsive release performances revealed effective pH-responsive performances, which can help facilitate targeted “on-demand” release at the target site and ensure that the enrofloxacin has an ideal stability in the stomach and a responsive release in the intestinal tract. The antibacterial activity study demonstrated that more effective bactericidal activity against E. coli could have a better treatment effect than the enrofloxacin solution. Furthermore, the enrofloxacin composite nanogels had great biocompatibility. Thus, the enrofloxacin composite core-shell nanogels might be an oral intelligent-responsive preparation to overcome the difficulty in treating intestinal bacterial infections.

Reduction and pH-responsive performance of nitroxide radical-containing copolymers probed by EPR spectroscopy

Although stimuli-responsive polymers have appeared as promising materials for drug administration, the effectiveness of these materials on various bioinspired stimuli is still open for dispute. In this work, the stimuli-responsive behaviors of radical-containing nonamphiphilic copolymers were investigated using electron paramagnetic resonance (EPR) spectroscopy while altering the pH and reductant concentration. The concentration of radicals in the aqueous solution had a considerable impact on self-assembly. The nitroxide radicals (hydrophobic) were converted to hydroxylamine (hydrophilic) when ascorbic acid (Asc) was added as a reductant, and the assemblies were switched to dissolution with a rate control behavior. The behavior of morphological change was observed in the acidic pH due to the disproportionation reaction of nitroxide radicals forming cationic species. The acquired results give new insights into the colloidal nanoparticles of nonamphiphilic copolymers and encourage the development of comparable responsive nanoparticles with intriguing drug delivery applications.

Effect of Surface Functionalization and Pore Structure Type on the Release Performance of Mesoporous Silica Nanoparticles

Based on the excellent physicochemical properties of mesoporous silica nanoparticles (MSN), the application of MSN in drug delivery has become a popular strategy. However, a wide variety of MSN structures and surface modification affect the drug loading and release, thus affecting the effectiveness of drug delivery system. Therefore, the effects of MSN type, pore structure and modified functional groups on drug release properties were investigated in this paper. A series of MSN was synthesized by sol-gel method, and the mesopore type and pore size were adjusted. Their surfaces were modified by amino groups (NH 2 ) and polydopamine (PDA) to change the surface charge. Anticancer Doxorubicin (DOX) was used as a model drug to study effects of different types of MSN on drug loading and release. MSN with hollow structure had a large inner cavity for DOX loading and tiny pore shell to prevent DOX loss, leading to higher loading capacity. MSN with surface-modified amine was positively charged and processed good pH responsiveness and accelerated DOX release. Thus hexagonal pore MSN-NH 2 and MSN-PDA were the anticancer DOX delivery carriers with better combined release performance in terms of pH-responsive performance and sustained release effect. Finally, several kinetic models were measured to fit the in vitro DOX release data and the results showed that release behaviors of different MSNs were more consistent with Korsmeyer-Peppas release kinetic model. All of them were Fick diffusion-controlled except for the second release stage of hollow MSN at pH 7.4, which was non-Fick diffusion release. • A series of MSNs with diverse structures and modification were studied. • Specific surface area, pore volume/type and surface charge affected drug loading. • Diverse kinetic models were employed to investigate mechanism of drug release. • MSNs with modification were drug delivery systems with better release performance.

The synthesis of bacterial cellulose-chitosan zwitterionic hydrogels with pH responsiveness for drug release mechanism of the naproxen

The human digestive and absorption system has a specific pH environment, which makes it difficult to for accurate drug-release. Zwitterionic hydrogel, as a kind of drug carrier, is a feasible response strategy. In this work, a facile method was employed to prepare a series zwitterionic hydrogels composed of BC and chitosan. The composite gels could in-situ formed via Schiff's base reaction between partially oxidated bacterial cellulose and chitosan which exhibited relatively well mechanical properties. Besides, the rich amino and carboxyl groups endowed the hydrogels with excellent pH responsive performance. The minimum swelling rate of the hydrogels appeared at pH 3.5–pH 5.0. In lower or higher pH solutions, the swelling rate was greatly increased. The drug (naproxen) loading of the hydrogels was above 110 mg/g. The release amount of naproxen in the simulated gastric juice was less than intestinal fluid with the sustained release time exceeded 24 h. Through kinetic simulation analysis, the drug release behavior is in accordance with zero-order release model. Such kind of composite hydrogel is suggested to be a potential drug carrier for clinical therapy.

PH-Responsive Nanoparticles for Enhanced Antitumor Activity by High-Intensity Focused Ultrasound Therapy Combined with Sonodynamic Therapy.

BackgroundTherapeutic ultrasound (US) has been extensively explored for its inherent high tissue-penetrating capability and on-demand irradiation without radioactive damage. Although high-intensity focused ultrasound (HIFU) is evolved as such an outstanding US-based approach, its insufficient therapeutic effect and the high-intensity induced potential damage to surrounding normal tissues hindered its development towards practical application. As opposed to high intensity ultrasound, sonodynamic therapy (SDT) is a low intensity US-based method which exhibits certain therapeutic effects against cancer via sonosensitizers-generated reactive oxygen species (ROS) overproduction.MethodsHematoporphyrin monomethyl ether (HMME) loaded CaCO3 nanoparticles (designated as Ca@H) were synthesized by a gas diffusion method. The pH-responsive performance, in vitro SDT, ex vivo HIFU therapy (HIFUT), photoacoustic (PA) imaging and in vivo HIFUT combined with SDT were investigated thoroughly.ResultsCa@H NPs gradually decomposed in acid tumor microenvironment, produced CO2 and released HMME. Both CO2 and HMME enhanced photoacoustic (PA) imaging. The generated CO2 bubbles also enhanced HIFUT by inducing an enlarged ablation area. The tumor ablation efficiency (61.04%) was significantly improved with a combination of HIFU therapy and SDT.ConclusionpH-responsive Ca@H NPs have been successfully constructed for PA imaging-guided/monitored HIFUT combined with SDT. With the assistance of pH-responsive Ca@H NPs, the combination of these two US-based therapies is expected to play a role in the treatment of non-invasive tumor in the future.

Preparation and properties study of F-SiO2@MPDA-AuNPs drug nanocarriers

Photothermal material was one of the hot topics in nanomedicine in recent years, which had aroused widespread attention of scholars. In this paper, a kind of core-shell drug nanocarriers with good photothermal properties were prepared, and its photothermal therapeutic effect on tumor cells in vitro was studied. First, fluorescein isothiocyanate (FITC) was encapsulated in silica nanoparticles to form silica fluorescent (F-SiO2) nanoparticles. Then mesoporous dopamine (MPDA) layer were built on the F-SiO2 nanoparticles, the core-shell nanoparticles (F-SiO2@MPDA) with mesoporous shell structure were obtained. Finally, Au nanoparticles (AuNPs) were wrapped on the surface of the layer of MPDA shell by the citrate reduction method, and the F-SiO2@MPDA-AuNPs composite nanoparticles were formed. Then, the fluorescence property, adsorption performance, sustained release property, photothermal property and cytotoxicity of the F-SiO2@MPDA-AuNPs nanoparticles were researched. It was found that F-SiO2@MPDA-AuNPs nanoparticles had good fluorescence performance, high adsorption capacity (DOX, 111.275 mg/g) and pH responsive release performance. When pH = 5.2, the DOX release rate was 39.5% within 7 h under the action of near-infrared light (NIR). In addition, it also had a high photothermal conversion rate (36.95%), and the DOX loaded F-SiO2@MPDA-AuNPs nanoparticles had obvious inhibitory effect on tumor cells in vitro. As a kind of mesoporous drug nanocarriers with photothermal properties, it has potential application value.

Epoxy coating with excellent anticorrosion and pH-responsive performances based on DEAEMA modified mesoporous silica nanomaterials

A pH-responsive epoxy composite coating was obtained by adding a benzotriazole-containing with pH-responsive nanocontainer to the epoxy coating. The release experimental results of benzotriazole in benzotriazole-loaded nanocontainer show that the cumulative release of benzotriazole increases with the decrease of pH value of the 3.5 wt% NaCl solution. The cumulative release of benzotriazole from nanocontainer in 60 h with different pH are 50.6%, 63.1%, 76.3% and 80.2% for pH = 6.8, 6.0, 5.5 and 5.0, respectively, indicating that benzotriazole has obvious release behavior under weak acid condition, which ensures that the coating with nanocontainer can show active repair performance in different acidic environments. Moreover, the EIS results show that the epoxy coating with benzotriazole-loaded nanocontainer exhibits excellent anticorrosion and active repair properties, and the more severe the corrosion environment, the stronger the repair ability of the coating.

Integrated Instillation Technology for the Synthesis of a pH-Responsive Sodium Alginate/Biomass Charcoal Soil Conditioner for Controlled Release of Humic Acid and Soil Remediation.

In this work, pH-responsive gel spheres for controlled release of humic acid (CSGCHs) were prepared by an integrated instillation technology using a composite material of sodium alginate (SA) and charcoal activated carbon (CAC) as a carrier, and their slow-release performance, pH-responsive performance, and soil amendment performance were investigated. The results showed that the prepared CSGCH was uniform in size with obvious base responsiveness. Soil remediation experiments revealed that CSGCH could play a good role in the remediation of different types of soils. After 50 days of remediation, the content of nutrients and organic matter in the soil increased significantly and the pH and salt content of saline soils decreased by 15.2 and 29.8%, respectively. The plant experiment showed that CSGCH could effectively promote the growth of crops. Therefore, the prepared soil conditioner has a great potential value for improving soil conditions and promoting crop growth in agricultural applications.

Janus particles with pH switchable properties for high-efficiency adsorption of PPCPs in water

Pharmaceuticals and personal care products (PPCPs) are emerging pollutants and have received increasing attention in recent years. The regeneration of conventional adsorption materials used to remove PPCPs involves the desorption of secondary organic pollution, which is harmful and problematic. In this work, the impact of pH-responsive magnetic Janus particle catalysts on PPCPs’ performance of high-efficiency adsorption and degradation was studied. Magnetic core-shell Fe3O4@SiO2 nanoparticles were prepared via the STÖBER method. Polylactic acid (PLA) was grafted using a template method, and the polymerization of pH-responsive monomer 2-(diethylamino)ethyl methacrylate (DEAEMA) was initiated to obtain the pH-responsive magnetic Janus particles (Janus-Fe-P). SEM (scanning electron microscopy), particle size analysis, TEM (transmission electron microscopy), and N2 adsorption-desorption tests were used to characterize the morphology, magnetic property, and pH-responsive performance of the Janus-F-P. The Janus-F-P was used in the adsorptions of two kinds of representative PPCPs, i.e., hydrophilic (antipyrine) and hydrophobic (tiamulin), under neutral conditions. Commercially available NORIT CN activated carbon was used for comparison, and the adsorption results showed that the adsorption efficiency of Janus particles was higher than that of activated carbon. Therefore, Janus-F-P could be used to efficiently catalyze the degradation of adsorbed PPCPs in the Fenton/hydroxylamine system. The removal rate of PPCPs was above 85 % after repeated use (5 times).

Study on swelling and drug releasing behaviors of ibuprofen-loaded bimetallic alginate aerogel beads with pH-responsive performance

Bimetallic alginate aerogel beads were prepared by ionotropic gelation method with Ca2+-Ba2+ bimetallic solution and ibuprofen was loaded as a model drug. The swelling and drug releasing behaviors of the beads, especially the influence of barium, were investigated in artificial gastric and intestinal fluids. The results showed that these beads presented higher encapsulation efficiency due to the special structure of aerogel, and barium was beneficial for the more stable structure and drug releasing behavior. The lower swelling capacity of bimetallic beads was observed than monometallic beads. A rapid high-level releasing of ibuprofen was achieved in artificial intestinal fluid, which was up to 96.9% within 1 h, while ibuprofen releasing was avoided in artificial gastric fluid effectively. The drug releasing mechanism of these beads was explored in detail. In the bimetallic crosslinking system, Ba2+ presented a special effect on alginate beads with more sensitive pH response performance. Thus, these beads had more widely potential as a site-specific delivery system, especially for intestinal therapy.

Fabrication of pH-responsive nanoparticles for high efficiency pyraclostrobin delivery and reducing environmental impact

In this work, a pH-responsive pesticide delivery system using mesoporous silica nanoparticles (MSNs) as the porous carriers and coordination complexes of Cu ions and tannic acid (TA-Cu) as the capping agent was established for controlling pyraclostrobin (PYR) release. The results showed the loading capacity of PYR@MSNs-TA-Cu nanoparticles for pyraclostrobin was 15.7 ± 0.5% and the TA-Cu complexes deposited on the MSNs surface could protect pyraclostrobin against photodegradation effectively. The nanoparticles had excellent pH responsive release performance due to the decomposition of TA-Cu complexes under the acid condition, which showed 8.53 ± 0.37%, 82.38 ± 1.67% of the encapsulated pyraclostrobin were released at pH 7.4, pH 4.5 after 7 d respectively. The contact angle and adhesion work of PYR@MSNs-TA-Cu nanoparticles on rice foliage were 86.3° ± 2.7° and 75.8 ± 3.1 mJ/m2 after 360 s respectively, indicating that TA on the surface of the nanoparticles could improve deposition efficiency and adhesion ability on crop foliage. The control effect of PYR@MSNs-TA-Cu nanoparticles against Rhizoctonia solani with 400 mg/L of pyraclostrobin was 85.82% after 7 d, while that of the same concentration of pyraclostrobin EC was 53.05%. The PYR@MSNs-TA-Cu nanoparticles did not show any phytotoxicity to the growth of rice plants. Meanwhile, the acute toxicity of PYR@MSNs-TA-Cu nanoparticles to zebrafish was decreased more than 9-fold compared with that of pyraclostrobin EC. Thus, pH-responsive PYR@MSNs-TA-Cu nanoparticles have great potential for enhancing targeting and environmental safety of the active ingredient.