Preparation and characterization of pH-responsive metal-polyphenol structure coated nanoparticles

In this paper,tannic acid(TA)and Fe~(3+)were added to form a layer of metal-polyphenol network structure on the surface of the nanoparticles which were fabricated by zein and carbon quantum dots(CQDs)encapsulating phlorotannins(PTN).pH-Responsive nanoparticles were prepared successfully(zein-PTN-CQDs-Fe-~Ⅲ).Further,the formation of composite nanoparticles was confirmed by a series of characterization methods.The zeta-potential and Fourier transform infrared spectroscopy data proved that electrostatic interaction and hydrogen bonding are dominant forces to form nanoparticles.The encapsulation efficiency(EE)revealed that metal-polyphenol network structure could improve the EE of PTN.Thermogravimetric analysis and differential scanning calorimetry experiment indicated the thermal stability of zein-PTN-CQDs-Fe~Ⅲnanoparticles increased because of metal-polyphenol network structure.The pH-responsive nanoparticles greatly increased the release rate of active substances and achieved targeted release.

Preparation of Manganese Oxide Hollow Spheres Using pH-responsive Microgels as Templates

Manganese oxide hollow spheres were prepared by a novel and facile approach using pH- responsive microgels as templates. The final products were thoroughly characterized with X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared, and transmission electron microscopy. The results reveal that the shell thickness of manganese oxide hollow spheres increased with the dosage of KMnO4, which implies that a controllable and feasible strategy for manganese oxide hollow spheres prepa- ration has been established. Further studies on the microgels template showed some of them had an irreversible swelling/deswelling transition due to the uneven cross-link extent. Based on the results, a probable formation mechanism for the hollow spheres was proposed.

pH-responsive mesoporous silica nanoparticles employed in controlled drug delivery systems for cancer treatment

In the fight against cancer, controlled drug delivery systems have emerged to enhance the therapeutic efficacy and safety of anti-cancer drugs. Among these systems, mesoporous silica nanoparticles （MSNs） with a functional surface possess obvious advantages and were thus rapidly developed for cancer treatment. Many stimuli-responsive materials, such as nanopartides, polymers, and inorganic materials, have been applied as caps and gatekeepers to control drug release from MSNs. This review presents an overview of the recent progress in the production of pH-responsive MSNs based on the pH gradient between normal tissues and the tumor microenvironment. Four main categories of gatekeepers can respond to acidic conditions. These categories will be described in detail.

Pharmacokinetics of a ternary conjugate based pH-responsive 10-HCPT prodrug nano-micelle delivery system

A pH-responsive conjugate based 10-hydroxycamptothecin-thiosemicarbazide-polyethene glycol 2000 (10-HCPT-hydro-PEG) nano-micelles were prepared in our previous study. In the present study, ultra-performance liquid chromatography (UPLC-MS) method is developed to investigate its pharmacokinetics and biodistribution in tumor bearing mice. The results demonstrated that the conjugate circulated for a much longer time in the blood circulation system than commercial 10-HCPT injection, and bioavailability was significantly improved compared with 10-HCPT. In vivo biodistribution study showed that the conjugate could enhance the targeting and residence time in tumor site.

CaCO3-Assisted Preparation of pH-Responsive Immune-Modulating Nanoparticles for Augmented Chemo-Immunotherapy

Due to the negative roles of tumor microenvironment(TME)in compromising therapeutic responses of various cancer therapies,it is expected that modulation of TME may be able to enhance the therapeutic responses during cancer treatment.Herein,we develop a concise strategy to prepare pH-responsive nanoparticles via the CaCO3-assisted double emulsion method,thereby enabling effective co-encapsulation of both doxorubicin(DOX),an immunogenic cell death(ICD)inducer,and alkylated NLG919(aNLG919),an inhibitor of indoleamine 2,3-dioxygenase 1(IDO1).The obtained DOX/aNLG919-loaded CaCO3 nanoparticles(DNCaNPs)are able to cause effective ICD of cancer cells and at the same time restrict the production of immunosuppressive kynurenine by inhibiting IDO1.Upon intravenous injection,such DNCaNPs show efficient tumor accumulation,improved tumor penetration of therapeutics and neutralization of acidic TME.As a result,those DNCaNPs can elicit effective anti-tumor immune responses featured in increased density of tumor-infiltrating CD8+cytotoxic T cells as well as depletion of immunosuppressive regulatory T cells(Tregs),thus effectively suppressing the growth of subcutaneous CT26 and orthotopic 4T1 tumors on the Balb/c mice through combined chemotherapy&immunotherapy.This study presents a compendious strategy for construction of pH-responsive nanoparticles,endowing significantly enhanced chemo-immunotherapy of cancer by overcoming the immunosuppressive TME.

Towards recycling purpose:Converting PET plastic waste back to terephthalic acid using pH-responsive phase transfer catalyst

Converting polyethylene terephthalate(PET)wastes to its monomer and valuable chemicals via ecofriendly chemical method is still a challenge task.Previously,phase transfer catalysts used for alkaline hydrolysis were soluble in reaction media and hardly separated after reaction.Here,we reported several pH-responsive catalysts combined alkyl quaternary ammonium units with heteropolyacid anion for achieving stepwise product/catalyst separation and catalyst recycling.The properties of homogeneous/heterogeneous transfer behavior allow catalyst to be easily separated from reaction media by adjusting of pH value.Among them,[C_(16)H_(33)N(CH_(3))_(3)]_(3)PW_(12)O_(40)(abbreviated as[CTA]_(3)PW)exhibits the highest activity and the most suitable pH responsive values.Such a pH triggered switchable catalytic system not only shows good performance for depolymerization of pure PET,but also some real PET wastes such as coloured trays and PE/PET complex films could be completely degraded into terephthalic acid.Additionally,the reaction kinetics and activation energy of PET alkaline hydrolysis also studied with and without pH-responsive[CTA]_(3)PW.

Ultrasmall pH-responsive silicon phthalocyanine micelle for selective photodynamic therapy against tumo

Targeted photodynamic therapy(TPDT)based on the photosensitizers responsive for tumor micr oenvironment is promising because of the better anti-tumor effect and less phototoxicity against normal tissue than the traditional PDT.Nanoparticle based stimuli responsive photo-sensitizers have been widely explored for TPDT.Based on the acidic microenvironments in solid tumors,an ultrasmall pH-responsive silicon phthalocyanine nanomicelle(PSN)(smaller than 10 nm)was designed for selective PDT of tumor.PSN had high drug loading efficacy(more than 28%)and exhibited morphological transitions,enhanced fuorescence and improved singlet∞x-ygen yield under acidic environments.PSN was renal dlearable and could rapidly accumulate and be retained at tumor sites,achieving a tumor-inhibiting ffect better than phthalocyanine micelle without pH response.Tumors of mice treated with PSN for PDT were completely ablated without recurrence.Thus,we have developed a phthalocyanine-based pH responsive micelle with excellent tumor targeting ability,which is expected to realize the selective PDT of tumor.

Preparation of Hollow-Porous Rosin-Based Polyurethane Microspheres with pH-Responsive Characteristics

Preparation of polymer microspheres from naturally occurring resource is a challenge.Here,a rosin-based polyol(RAG)was used to prepare polyurethane resin(RPU)firstly,and then act as both self-assembled precursor and emulsifier,rosin based polyurethane microspheres(RPUMs)were prepared.In the process of self-emulsification,the RPU formed vesicles by self-assembly.The outer shell of the vesicle consisted of hydrophilic segments,while the inner shell contained the hydrophobic phase.After cross-linking the RPU and removal of the solvent in the core,the porous-hollow microspheres with pH-sensitive were obtained.The microspheres were characterized by optical microscope(OM),scanning electron microscopy(SEM)and transmission electron microscope(TEM).The effect of type and amount of the hydrophilic chain extender,and solvent on the morphology,particle size and distribution,and buffer volume of the microspheres were determined.The best conditions for synthetic RPUMs were as follows:n_(NCO)/n_(OH)=1,n_(RAG):n_(1-(2-hydroxyethyl)piperazine)=4:6,with azodiisobutyronitrile level of 1.0 wt.%,based on reactive monomers,mixing speed of both emulsification and polymerization at 400 r·min-1,the RPUMs synthesized had porous-hollow structure with a buffer volume of 1.6 mL.

Preparation of pH-responsive membranes with amphiphilic copolymers by surface segregation method

Novel pH-responsive membranes were prepared by blending pH-responsive amphiphilic copolymers with polyethersulfone(PES) via a nonsolvent-induced phase separation(NIPS) technique. The amphiphilic copolymers bearing Pluronic F127 and poly(methacrylic acid)(PMAA) segments, abbreviated as PMAA n–F127–PMAA n,were synthesized by free radical polymerization. The physical and chemical properties of the blend membranes were evaluated by scanning electron microscopy(SEM), Fourier transform infrared(FTIR) spectrum, water contact angle, Zeta potential and X-ray photoelectron spectroscopy(XPS). The enrichment of hydrophilic PMAA segments on the membrane surfaces was attributed to surface segregation during the membrane preparation process. The blend membranes had signi ficant p H-responsive properties due to the conformational changes of surface-segregated PMAA segments under different pH values of feed solutions. Fluxes of the blend membranes were larger at low p H values of feed solutions than that at high pH values. The pH-responsive ability of the membranes was enhanced with the increase of the degree of PMAA near-surface coverage.

Preparation and Properties of pH-Responsive Intelligent Medical Dressing Based on Bacterial Cellulose/Polyacrylic Acid

Bacterial cellulose/polyacrylic acid (BC/PAA) pH-responsive hydrogels were prepared by free-radical polymerization (in situ) using BC as the raw material and AA as the monomer. The hydrogels were loaded with curcumin (Cur) to prepare pH-responsive intelligent medical dressings. The preparation process of the hydrogels was optimized by a single factor and response surface experiment using their swelling degree as an index. The structures of BC/PAA pH-responsive hydrogels were characterized by scanning electron microscope (SEM), Fourier Transform Infrared spectrometer (FTIR), X-ray diffraction (XRD), and tensile tester, and the swelling properties, mechanical properties, bacteriostatic properties, and drug release behavior were investigated. The results showed that the BC/PAA pH-responsive hydrogel has a three-dimensional network structure with the swelling rate up to 1600 g/g, compressive strength of up to 8 KPa, and good mechanical properties, and the drug release behavior was in line with the logistic dynamics model, and it has good inhibitory effects on common pathogens of wound infection: E. coli, S. aureus, and P. aeruginosa.

Nature-Inspired pH-Responsive Hydrogels with Rapid and High Contrast Changes in Color,Fluorescence,and Shape Simultaneously

To realize single-stimulus-induced simultaneous multi-behaviors in hydrogels is still quite challenging nowadays.Herein,an intelli gent pH-responsive hydrogel(BP4VA/PAS)with rapid and high contrast changes in color,fluorescence,and shape simultaneously is reported The BP4VA/PAS hydrogel is fabricated by incorporating styryl anthracene derivative(BP4VA)into copolymer networks(PAS)of acrylamide and sodium 4-styrene sulfonate.Under acid conditions,the protonation of BP4VA generates a rapid change with high color contrast from yellow to red and a fluorescence switch between bright green and weak red emission.At the same time,the electrostatic interactions between 2H-BP4VA^(2+)and sulfonate anions suspended on PAS trigger BP4VA/PAS hydrogels to shrink.Upon alkaline treatment,the 2H-BP4VA^(2+)/PAS hydrogel deproto nates and recovers to its original color,fluorescence,and shape.Furthermore,utilizing rapid and remarkable pH-responsive properties o BP4VA/PAS hydrogels,we successfully demonstrated its applications in biomimicry,camouflage,and multistage information encryption.Collec tively,this work provided an elegant strategy to develop intelligent hydrogels in applications of biomimetic smart materials and information en cryption.

MOF-based magnetic microrobot swarms for pH-responsive targeted drug delivery

Metal-organic frameworks(MOFs)hold significant potential as vehicles for drug delivery due to their expansive specific surface area,biocompatibility,and versatile attributes.Concurrently,magnetically actuated micro/nano-robots(MNRs)offer distinct advantages,such as untethered and precise manipulation.The fusion of these technologies presents a promising avenue for achieving non-invasive targeted drug delivery.Here,we report a MOF-based magnetic microrobot swarm(MMRS)for targeted therapy.Our approach overcomes limitations associated with a single MNR,including limited drug loading and the risk of loss during manipulation.We select Zeolitic Imidazolate Framework-8(ZIF-8)as the drug vehicle for its superior loading potential and p H-sensitive decomposition.Our design incorporates magnetic responsive components into the one-pot synthesis of Fe@ZIF-8,enabling collective behaviors under actuation.Tuning the yaw angle of alternating magnetic fields and nanoparticles'amount,the MMRSs with controllable size achieve instantaneous transformation among different configurations,including vortex-like swarms,chain-like swarms,and elliptical swarms,facilitating adaptation to environmental variations.Transported to the subcutaneous T24 tumor site,the MMRSs with encapsulated doxorubicin(DOX)automatically degrade and release the drug,leading to a dramatic reduction of the tumor in vivo.Our investigation signifies a significant advancement in the integration of biodegradable MOFs into microrobot swarms,ushering in new avenues for accurate and non-invasive targeted drug delivery.

Employing pH-responsive RNA triplex to control CRISPR/Cas9-mediated gene manipulation in mammalian cells

The clustered regularly interspersed short palindromic repeats/CRISPR-associated protein 9(CRISPR/Cas9)system is an RNA-guided platform for highly efficient and specific genome targeting in diverse organisms,which has been exploited for various applications in gene manipulation.Compared with the constantly active CRISPR/Cas9 function,conditional control of its activity can improve the performance of the system with reduced side effects and high spatiotemporal precision.The pH-responsive triplex RNA was successful used in CRISPR-derived RNA/trans-activating crRNA(crRNA/tracrRNA)of CRISPR/Cas9,thus affecting RNA/dead Cas9(dCas9)complex to target DNA in vitro and in vivo.This design of triplex RNA opens a new window towards the broad involvement of eukaryotic cells for conditional control of CRISPR/Cas9function.?2024 Published by Elsevier B.V.on behalf of Chinese Chemical Society and Institute of Materia Medica,Chinese Academy of Medical Sciences.

Carbon dots-enhanced pH-responsive lubricating hydrogel based on reversible dynamic covalent bondings

Due to the various pH liquid environment in nature,the pH-responsive lubricating hydrogel is widely investigated and developed for tissue interface substitute.However,the applied liquid environment will lead to poor mechanical property and weaken the pH-responsive capability.In this work,a carbon dotsenhanced pH-responsive lubricating hydrogel is developed by combining a pH-responsive section of dynamic PVA-borax network into a PAAm covalent polymer network.The formed hydrogel presents a partial gel-sol transition under controlled pH environments.At low pH environments(<6.0),the formed lubricating layer originated from dynamic disassembly of PVA-borax hydrogel,and brings the lubricating properties on the hydrogel surface.Moreover,the mechanical strength and lubrication properties are well promoted by introducing the carbon dots into the hydrogel,the blue sol layer can be observed more visually under the fluorescence microscope.The pH-response also exhibits well reversibility.The prepared hydrogel broadens the idea for designing pH-responsive soft materials for soft lubricating actuator or robot.

Ternary NiCoTi-layered double hydroxide nanosheets as a pH-responsive nanoagent for photodynamic/chemodynamic synergistic therapy

Combining photodynamic therapy(PDT)with chemodynamic therapy(CDT)has been proven to be a promising strategy to improve the treatment efficiency of cancer,because of the synergistic therapeutic effect arising between the two modalities.Herein,we report an inorganic nanoagent based on ternary NiCoTi-layered double hydroxide(NiCoTi-LDH)nanosheets to realize highly efficient photodynamic/chemodynamic synergistic therapy.The NiCoTi-LDH nanosheets exhibit oxygen vacancy-promoted electron-hole separation and photogenerated holeinduced O_(2)-independent reactive oxygen species(ROS)generation under acidic circumstances,realizing in situ pH-responsive PDT.Moreover,due to the effective conversion between Co^(3+)and Co^(2+)caused by photogenerated electrons,the NiCoTi-LDH nanosheets catalyze the release of hydroxyl radicals(-OH)from H_(2)O_(2)through Fenton reactions,resulting in CDT.Laser irradiation enhances the catalyzed ability of the NiCoTi-LDH nanosheets to promote the ROS generation,resulting in a better performance than TiO_(2)nanoparticles at pH 6.5.In vitro and in vivo experimental results show conclusively that NiCoTi-LDH nanosheets plus irradiation lead to efficient cell apoptosis and significant inhibition of tumor growth.This study reports a new pH-responsive inorganic nanoagent with oxygen vacancy-promoted photodynamic/chemodynamic synergistic performance,offering a potentially appealing clinical strategy for selective tumor elimination.

Manganese-Zeolitic Imidazolate Frameworks-90 with High Blood Circulation Stability for MRI-Guided Tumor Therapy

Zeolitic imidazolate frameworks(ZIFs)as smart drug delivery systems with microenvironment-triggered release have attracted much attention for tumor therapy.However,the exploration of ZIFs in biomedicine still encounters many issues,such as inconvenient surface modification,fast drug release during blood circulation,undesired damage to major organs,and severe in vivo toxicity.To address the above issues,we developed an Mn-ZIF-90 nanosystem functionalized with an originally designed active-targeting and pH-responsive magnetic resonance imaging(MRI)Y1 receptor ligand[Asn28,Pro30,Trp32]-NPY(25-36)for imaging-guided tumor therapy.After Y1 receptor ligand modification,the Mn-ZIF-90 nanosystem exhibited high drug loading,better blood circulation stability,and dual breast cancer cell membrane and mitochondria targetability,further favoring specific microenvironment-triggered tumor therapy.Meanwhile,this nanosystem showed promising T1-weighted magnetic resonance imaging contrast in vivo in the tumor sites.Especially,this nanosystem with fast clean-up had almost no obvious toxicity and no damage occurred to the major organs in mice.Therefore,this nanosystem shows potential for use in imaging-guided tumor therapy.

Chitosan nanoparticles crosslinked by glycidoxypropyltrimethoxysilane for pH triggered release of protein

pH-responsive-chitosan nanoparticles for the control release of protein drug were prepared by combining two-step crosslinking method, in which chitosan was subsequently crosslinked by sodium tripolyphosphate （TPP） and glycidoxypropyltrimethoxysilane （GPTMS）. Compared with TPP crosslinked chitosan particles, the two-step crosslinked nanoparticles were not only pH-responsive but also more stable in wide pH range. Fluorescein isothiocyanate （FITC） labeled anti-human-IgG antibody was used as a model protein drug for evaluating the control release profile of the nano-carrier. The amount of released antibody increased from 5.6% to 50% when the pH of solution shifted from 7.4 to 6.0. The results suggest the possible application of the nanoparticles as pH- responsive drug delivery materials.

Gas-blasting nanocapsules to accelerate carboplatin lysosome release and nucleus delivery for prostate cancer treatment

To improve therapeutic effect and reduce severely side effects of carboplatin(CBP),the gas-generating nanocapsules were developed to accelerate CBP lysosome release and nucleus delivery.CBP/SB-NC was prepared by co-loading CBP and NaHCO 3(SB)in nanocapsules using w/o/w emulsification solvent evaporation.They exhibited vesicle-like spherical morphology,uniform particle size and negative zeta potential.Reaching the tumor site with a relatively high concentration is the first step for CBP delivery and the results showed that CBP/SB-NC could effectively increase drug accumulation at tumor site.After that,the drug delivery carriers need to be internalized into tumor cells and the in vitro cellular uptake ability results showed CBP/SB-NC could be internalized into RM-1 cells more efficient than CBP solution.After internalized by RM-1 cells,the gas-blasting release process was tested in acid environment.It was demonstrated that 5 mg/ml NaHCO 3 was optimal to achieve pH-responsive gas-blasting release.In vitro release results showed that CBP significantly rapid release in acid environment(pH 5.0)compared to neutral pH(pH 7.4)(P<0.05).Meanwhile,TEM and the change of the concentration of H+results exhibited that the explosion of CBP/SB 5-NC was more easily happened in lysosome acid environment(pH 5.0).The blasting release can accelerate CBP lysosome release to cytoplasm.Furthermore,the nucleus delivery results showed CBP/SB 5-NC can promote pH-triggered rapid nucleus delivery.And the results of Pt-DNA adduct assay showed that the binding efficiency between CBP and DNA of CBP/SB 5-NC was higher than CBP solution.At last,in vitro and in vivo anti-tumor efficacy proved that CBP/SB 5-NC could enhance anti-tumor activity for prostate cancer therapy.CBP/SB 5-NC also showed superior safety in vitro and in vivo by hemolysis assay and histopathological study.All of the results demonstrate that CBP/SB 5-NC would be an efficient gas-blasting release formulation to enhance prostate cancer treatment.

Hollow MnO_2/GNPs serving as a multiresponsive nanocarrier for controlled drug release

In this work,hollow manganese dioxide/gold nanoparticle(MnO2/GNPs)hybrid drug nanocarriers were prepared by coupling the gold nanoparticles(GNPs)with hollow structure manganese dioxide(MnO2).Among them,GNPs have been used as near-infrared(NIR)-responsive element for photothermal effect under NIR laser irradiation.The glutathione(GSH)-responsive and p H-responsive performances of drug release were derived from hollow MnO2.Particularly,Doxorubicin hydrochloride(DOX)can be loaded into hollow MnO2/GNPs with the drug loading efficiency up to 82.0%.Moreover,the photothermal effect and GSH-/pH-responsive properties of hollow MnO2/GNPs were investigated.The hollow MnO2/GNPs possessed satisfactory drug release efficiency(ca.87.4%of loaded drug released in 12 h)and have high photothermal conversion efficiency,multiresponsive properties,and degradability.Finally,the kinetics of drug release was discussed in detail.Thus,our finding highlights that the multiresponsive nanocarriers are of great potential in the field of drug controlled release.

Antibacterial hydrogel with pH-responsive microcarriers of slow-release VEGF for bacterial infected wounds repair

Bacterial infection causes wound inflammation and makes angiogenesis difficult.It is urgent to develop effectively antibacterial and pro-vascularizing dressings for wound healing.The hydrogel is developed with pH-responsive drug-releasing microcarriers which were loaded with vascular endothelial growth factor(VEGF)that promotes angiogenesis and actively respond to wound pH for control and prolong VEGF release.The surfaces of the microcarriers were coated with polydopamine which can reduce the silver nanoparticles(AgNPs)in situ,and dynamically crosslink with the polyacrylamide,which forms a stable slow-release system with different release behavior for the VEGF and AgNPs.The hydrogel inhib-ited bacterial formation and accelerated wound healing.With the hydrogel dressing,83.3%±4.29%of the wound heals at day 7,which is 40.9%±8.5%higher than the non-treatment group in defect infected model.The antibacterial properties of hydrogel down-regulate early inflammation-related cytokines,and the release of VEGF in the middle and late phases of wound healing in response to pH changes pro-motes angiogenesis and up-regulate the expression of angiogenesis-associated cytokine.The sequential release of antibacterial agents and pro-vascularizing agents in response to the change in wound microen-vironmental cues facilitate temporally controlled therapy that suites the need of different wound healing phases.Collectively,the hydrogel loaded with multifunctional microcarriers that enable controlled release of AgNPs and VEGF is an effective system for treating infected wounds.