pH-responsive Block Copolymer Research Articles

PH-Responsive Micellar Nanoparticles for the Delivery of a Self-Amplifying ROS-Activatable Prodrug.

The objective of this study is to enhance the therapeutic efficacy of the anticancer drug, camptothecin (CPT) via a nanoparticle (NP) formulation using a novel amphiphilic biopolymer. We have designed a dimeric prodrug of CPT with the ability to self-amplify and respond to reactive oxygen species (ROS). For this, we incorporated the intracellular ROS generator cinnamaldehyde into a ROS-cleavable thioacetal (TA) linker to obtain the dimeric prodrug of CPT (DCPT(TA)). For its efficient NP delivery, a pH-responsive block copolymer of acetalated dextran and poly(2-ethyl-2-oxazoline) (AcDex-b-PEOz) was synthesized. The amphiphilic feature of the block copolymer enables its self-assembly into micellar NPs and results in high prodrug loading capacity and a rapid release of the prodrug under acidic conditions. Upon cellular uptake by HeLa cells, DCPT(TA)-loaded micellar NPs induce intracellular ROS generation, resulting in accelerated prodrug activation and enhanced cytotoxicity. These results indicate that this system holds significant potential as an effective prodrug delivery strategy in anticancer treatment.

Thermal, pH, and Photo Multistimuli Responsive Block Copolymer Self-Assembly Nanoparticles for Drug Delivery Using Visible-Light-Induced PET-RAFT

Thermal, pH, and Photo Multistimuli Responsive Block Copolymer Self-Assembly Nanoparticles for Drug Delivery Using Visible-Light-Induced PET-RAFT

PEO-b-PNBA in-situ functionalized mesoporous silica films and their light- and pH-controlled ionic mesopore accessibility

Multistimuli-responsive, in-situ functionalized mesoporous silica films were fabricated by evaporation-induced self-assembly through physical entrapment of the functional template poly(ethylene oxide)-b-poly(2-nitrobenzyl acrylate) (PEO-b-PNBA). The light-cleavable and pH-responsive block copolymer PEO-b-PNBA simultaneously serves as structure-directing agent and for in-situ polymer functionalization of the generated mesopore space. The use of different PEO-b-PNBA compositions results in highly filled hybrid mesoporous silica films with different pore sizes, porosity, and polymer chain sequence within the mesopores. Based on these structural variations and the polymer chain sequence the ionic permselectivity of the silica-polymer hybrid thin films is adjusted. The side chains of the template PNBA block can be deprotected upon irradiation, hereby releasing pH-responsive carboxylic acid groups. The irradiation energy and irradiation time-dependent deprotection allows gradually controlled charge regulation in mesopores. This approach of in-situ functionalization using multistimuli-responsive PEO-b-PNBA block copolymers facilitates the fabrication of multi-responsive hybrid mesoporous silica films and bears high potential for the production of complex, hierarchical, multifunctional mesoporous materials. This fabrication method including direct functionalization of mesoporous structures is of high interest for many applications based on controlled molecular transport in nanoscale pores, such as sensing, separation, or catalysis.

Preparation of pH-responsive block copolymers for separation of cephalosporin antibiotics by open-tubular capillary electrochromatography

Stimuli-responsive block copolymers have exhibited their feasibility for drug delivery and analysis of biomolecules. However, study of the electrophoretic behavior of antibiotics by open tubular capillary electrochromatography (OT-CEC) based on smart block copolymers coatings is still a substantial challenge. Herein, we reported an OT-CEC protocol for analysis of cephalosporin antibiotics with pH-responsive block copolymers as coatings. By using the reversible addition-fragmentation chain-transfers radical polymerisation technique, the smart poly(styrene-maleic anhydride-acrylic acid) (P(St-MAn-AA)) was synthesized and subsequently chemical bonded onto the inner walls of amino-grafted capillaries. The pH induced changes in the stretch/curl states of P(St-MAn-AA) chains were used to generate an adjustable hydrophobic/hydrophilic interaction and hydrogen bonds between the polymer coatings and the analytes. The OT-CEC performance was evaluated by varying the monomer ratios, polymer coating amounts and layers, buffer concentrations and pH values. Baseline separation of the three-test antibiotics was achieved at pH 8.0. The proposed OT-CEC technique was further applied to the determination of rat serum antibiotics in the metabolic processes. The present work demonstrates an enhancement in antibiotics separation efficiency, and shows a great potential for the preparation of stimuli-responsive block copolymers coatings and in OT-CEC analysis of real samples in living bio-systems.

An aminopeptidase N-based color-convertible fluorescent nano-probe for cancer diagnosis.

Specific cancer diagnosis at an early stage plays a significant role in preventing cancer metastasis and reducing cancer mortality. Thus, exploring specific and sensitive fluorescent probes to realize early cancer diagnosis is an urgent need in clinic. Aminopeptidase N (APN/CD13), overexpressed in numerous malignant tumors, is an important tumor biomarker associated with cancer progression, invasion, and metastasis. In this study, a novel fluorescent molecule APN-SUB, capable of monitoring APN in real time, is encapsulated in a pH-responsive block copolymer (termed APN-SUB nanoprobe) for cancer diagnosis. APN-SUB contains a fluorophore center and a trigger moiety (leucine group), which is covalently conjugated on the fluorophore with an amide bond. The hydrolysis of the amide bond in APN-SUB activated by APN leads to a red shift of maximum fluorescence emission wavelength from 495 nm to 600 nm, realizing dual-color transformation from green to red. Moreover, the APN-SUB nanoprobe with pH-responsiveness is prepared to improve the accumulation and the release rate in the tumor region. It is worth noting that the APN-SUB nanoprobe exhibits good performance for APN imaging, namely, superior limit of detection (0.14 nU mL-1), excellent selectivity and strong photostability. More importantly, the APN-SUB nanoprobe can be successfully employed as a color-convertible fluorescent probe for cancer diagnosis by tracking the activity of APN with high specificity and sensitivity in vivo, demonstrating its potential value for cancer diagnosis.

Networking of Block Copolymer Nanoassemblies via Digital Light Processing Four-Dimensional Printing for Programmable Actuation

Controls over stimuli-responsive functional materials and programmable shape deformations are key features in the four-dimensional (4D) printing of soft actuators. Instead of using random copolymers, homopolymers, or natural polymers, this paper reports the first use of amphiphilic, photocurable, and pH-responsive block copolymer (BCP) nanoassemblies in digital light processing (DLP) 4D printing to fabricate smart and programmable soft actuators. Programmable actuation was studied via a bottom-up approach: (1) designed synthesis of pH-responsive BCPs, (2) nanoassembly structures of BCPs, and (3) networking of nanoassemblies via the photocuring process in DLP. As a proof-of-concept, bilayered grippers, ring-shaped actuators, and octopus-like actuators were programmed to produce a range of bending angles and actuation patterns. pH-responsive BCP nanoassemblies were also combined with commercially available three-dimensional printing liquid resin (PlasClear) to produce stimulus-responsive printing ink that was successfully used for 4D printing applications. Thus, smart and programmable materials were developed for 4D printing applications.

Amphiphilic Janus Magnetoplasmonic Nanoparticles: pH-Triggered Self-Assembly and Fluorescence Modulation

We report amphiphilicity-driven self-assembly of polymer-coated magnetoplasmonic Janus nanoparticles (JNP) that result in well-defined colloidal ensembles with controllable size, morphology, and dimension. The amphiphilic JNP building blocks were prepared by coating fluorescent dye-conjugated pH-responsive block copolymer (BCP) and hydrophilic polymers on plasmonic and magnetic side of the JNPs, respectively. Our results have demonstrated a direct correlation between the amphiphilicity of the JNP building block and the structural parameters of corresponding ensembles. It was found that the increase in the relative ratio of pH-responsive hydrophobic BCP and hydrophilic polymer grafts on two different parts of the JNP led to a morphological transition of assemblies from micellar cluster to lamellae to vesicle. It provides insight into the colloidal self-assembly of functional nanocrystal. Furthermore, the coating of well-defined BCP grafts on the gold nanoparticle (AuNP) of the JNPs offers the possibilities to finely tune the interparticle distance and precisely position dye molecules at the gap between neighboring JNPs in the ensembles, and the pH-sensitivity of the BCP allows to control the interparticle distance as a function of pH. Such dye-encoded magnetoplasmonic ensembles can serve as a well-defined platform to study the metal–fluorophore interaction, leading to an improved fundamental understanding of metal-enhanced fluorescence (MEF) process. The fluorescent magnetoplasmonic ensembles with defined morphologies (i.e., multimers and vesicles) are of broad interest for biomedical applications that require synergistic multifunctionalies such as theranostics and biosensors.

PH-sensitive packaging of cationic particles by an anionic block copolymer shell

Cationic non-viral vectors show great potential to introduce genetic material into cells, due to their ability to transport large amounts of genetic material and their high synthetic versatility. However, designing materials that are effective without showing toxic effects or undergoing non-specific interactions when applied systemically remains a challenge. The introduction of shielding polymers such as polyethylene glycol (PEG) can enhance biocompatibility and circulation time, however, often impairs transfection efficiency. Herein, a multicomponent polymer system is introduced, based on cationic and hydrophobic particles (P(nBMA46-co-MMA47-co-DMAEMA90), (PBMD)) with high delivery performance and a pH-responsive block copolymer (poly((N-acryloylmorpholine)-b-(2-(carboxy)ethyl acrylamide)) (P(NAM72-b-CEAm74), PNC)) as shielding system, with PNAM as alternative to PEG. The pH-sensitive polymer design promotes biocompatibility and excellent stability at extracellular conditions (pH 7.4) and also allows endosomal escape and thus high transfection efficiency under acidic conditions. PNC shielded particles are below 200 nm in diameter and showed stable pDNA complexation. Further, interaction with human erythrocytes at extracellular conditions (pH 7.4) was prevented, while acidic conditions (pH 6) enabled membrane leakage. The particles demonstrate transfection in adherent (HEK293T) as well as difficult-to-transfect suspension cells (K-562), with comparable or superior efficiency compared to commercial linear poly(ethylenimine) (LPEI). Besides, the toxicity of PNC-shielded particles was significantly minimized, in particular in K-562 cells and erythrocytes. In addition, a pilot in vivo experiment on bone marrow blood cells of mice that were injected with PNC-shielded particles, revealed slightly enhanced cell transfection in comparison to naked pDNA. This study demonstrates the applicability of cationic hydrophobic polymers for transfection of adherent and suspension cells in culture as well as in vivo by co-formulation with pH-responsive shielding polymers, without substantially compromising transfection performance.Graphical

Potential-induced wetting and dewetting in pH-responsive block copolymer membranes for mass transport control.

Wetting and dewetting behavior in channel-confined hydrophobic volumes is used in biological membranes to effect selective ion/molecular transport. Artificial biomimetic hydrophobic nanopores have been devised utilizing wetting and dewetting, however, tunable mass transport control utilizing multiple transport modes is required for applications such as controllable release/transport, water separation/purification and energy conversion. Here, we investigate the potential-induced wetting and dewetting behavior in a pH-responsive membrane composed of a polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) when fabricated as a hierarchically-organized sandwich structure on a nanopore electrode array (NEA), i.e. BCP@NEA. At pH < pKa(P4VP) (pKa ∼ 4.8), the BCP acts as an anion-exchange membrane due to the hydrophilic, protonated P4VP cylindrical nanodomains, but at pH > pKa(P4VP), the P4VP domains exhibit charge-neutral, hydrophobic and collapsed structures, blocking mass transport via the hydrophobic membrane. However, when originally prepared in a dewetted condition, mass transport in the BCP membrane may be switched on if sufficiently negative potentials are applied to the BCP@NEA architecture. When the hydrophobic BCP membrane is introduced on top of 2-electrode-embedded nanopore arrays, electrolyte solution in the nanopores is introduced, then isolated, by exploiting the potential-induced wetting and dewetting transitions in the BCP membrane. The potential-induced wetting/dewetting transition and the effect on cyclic voltammetry in the BCP@NEA structures is characterized as a function of the potential, pH and ionic strength. In addition, chronoamperometry and redox cycling experiments are used to further characterize the potential response. The multi-modal mass transport system proposed in this work will be useful for ultrasensitive sensing and single-molecule studies, which require long-time monitoring to explore reaction dynamics as well as molecular heterogeneity in nanoconfined volumes.

Actively Controllable Solid-Phase Microextraction in a Hierarchically Organized Block Copolymer-Nanopore Electrode Array Sensor for Charge-Selective Detection of Bacterial Metabolites.

Pseudomonas aeruginosa produces a number of phenazine metabolites, including pyocyanin (PYO), phenazine-1-carboxamide (PCN), and phenazine-1-carboxylic acid (PCA). Among these, PYO has been most widely studied as a biomarker of P. aeruginosa infection. However, despite its broad-spectrum antibiotic properties and its role as a precursor in the biosynthetic route leading to other secondary phenazines, PCA has attracted less attention, partially due to its relatively low concentration and interference from other highly abundant phenazines. This challenge is addressed here by constructing a hierarchically organized nanostructure consisting of a pH-responsive block copolymer (BCP) membrane with nanopore electrode arrays (NEAs) filled with gold nanoparticles (AuNPs) to separate and detect PCA in bacterial environments. The BCP@NEA strategy is designed such that adjusting the pH of the bacterial medium to 4.5, which is above the pKa of PCA but below the pKa of PYO and PCN, ensures that PCA is negatively charged and can be selectively transported across the BCP membrane. At pH 4.5, only PCA is transported into the AuNP-filled NEAs, while PYO and PCN are blocked. Structural characterization illustrates the rigorous spatial segregation of the AuNPs in the NEA nanopore volume, allowing PCA secreted from P. aeruginosa to be quantitatively determined as a function of incubation time using square-wave voltammetry and surface-enhanced Raman spectroscopy. The strategy proposed in this study can be extended by changing the nature of the hydrophilic block and subsequently applied to detect other redox-active metabolites at a low concentration in complex biological samples and, thus, help understand metabolism in microbial communities.

Block copolymer coated carbon nanotube membrane anodes for enhanced and multipurpose hybrid capacitive deionization

Carbon nanotube (CNT) membranes are widely used electrode materials in capacitive deionization (CDI) processes, while the limited electrosorption capacity and poor long-term stability need to improve. In this work, a pH-responsive block copolymer (BCP), poly (2-dimethylaminoethyl methacrylate)-block-polystyrene (PDMAEMA-b-PS) is combined with the selective swelling to fabricate a CNT membrane based multipurpose electrode. After BCP coating and selective swelling, the PDMAEMA blocks migrate onto the membrane surface and protonate during the CDI processes, which enhance the attraction between electrode and anions. Therefore, the BCP coated electrodes can be used as high performance anodes in the hybrid CDI (HCDI) module. Experiment results show that the initial solution pH values have significant influence on the CDI performance of the HCDI module. The maximum removal efficiencies of the HCDI module towards NaCl and NaH2PO4 are ~15 mg·g−1 and ~38.7 mg·g−1, respectively. Moreover, the chemical and mechanical stabilities of the anodes are significantly enhanced. No anode oxidation can be observed during CDI processes and the frequently occurred co-ion repulsion effect is suppressed. Considering these advantages, the combination of BCPs and selective swelling will be a promising candidate for the development of HCDI module.

PH-Dependent Structure of Block Copolymer Micelles Featuring a Polyampholyte Corona: A Combined Experimental and Theoretical Approach

Herein, we describe the preparation as well as experimental and theoretical investigations of block copolymer micelles based on amphiphilic, pH-responsive block copolymers featuring bipyridine liga...

New side chain design for pH-responsive block copolymers for drug delivery

New molecular motifs that can act as pH-regulating triggers for amphiphilic, pH-sensitive block copolymers are investigated. Inspired by the mechanism of action of pH-indicators, such as methyl orange, and natural amino acids, we designed these copolymers where either 4-Amino-4′-dimethylaminoazobenzene, AZB (pKa 3.4, an amine derivative of methyl orange), isoleucine, Ile (pKa 2.37 for carboxylic acid), or a statistical mixture of both were appended as side chains to the hydrophobic block to act as pH-triggers. These new side chain motifs were identified with an aim to enhance the self-assembling properties of the block copolymers in terms of particle size and stability, drug encapsulation, and release. As the parent polymer, poly (ethylene) glycol-block- poly (carbonate) (PEG-b-PC) of number average molecular weight 12.1 kDa was used. We observed that PEG-b-PC block copolymers, when engineered with AZB or Ile-type of pH-regulators appended as side chains to PC blocks, formed self-assembled, spherical nanoparticles with hydrodynamic diameters ranging from 114 to 137 nm depending on copolymer composition. Critical aggregation concentrations (CAC) of the block copolymers were found to be governed by the type and content of side chains. We explored the use of these newly designed block copolymer assemblies as drug carriers using gemcitabine (GEM) as a model cytotoxic drug generally used for pancreatic ductal adenocarcinoma (PDAC). We showed that AZB and Ile decorated copolymeric nanocarriers were able to encapsulate GEM at 13.8–28.8 % loading content and release the drug in a pH-dependent pattern. Drug-loaded nanocarriers showed cellular entry into PDAC cells in vitro and were found to exert cytotoxicity against these cells. Neither the block copolymers bearing AZB or Ile-type pH-responsive triggers, nor their self-assembled nanoparticles showed any cytotoxicity at usable concentrations, thereby reflecting the potentials of these molecular motifs for designing stimuli-responsive drug delivery nanosystems.

Synthesis of pH-Responsive Block Copolymer By ATRP

The block copolymer, poly(4-vinylpyridine)-b-poly(tert-butylmethacrylate) (P4VP-b-PtBMA), was synthesized by atom transfer radical polymerization (ATRP) in two steps. Firstly, macroinitiator P4VP-Cl was prepared via ATRP with the conversion of monomer 66.3%. The result of GPC illustrated that the Mn of P4VP-Cl could be controlled by adjusting polymerization conditions. Then, P4VP-b-PtBMA was synthesized by ATRP using P4VP-Cl as macroinitiator. The effects of polymerization reaction parameters such as solvent and polymerization time on the M n and M W/M n were investigated. Then the pH-responsive block copolymer poly(4- vinylpyridine)-b-poly(methacrylic acid) (P4VP-b-PMAA) was obtained by hydrolyzing the P4VP-b-PtBMa copolymer.

Ion Gating in Nanopore Electrode Arrays with Hierarchically Organized pH-Responsive Block Copolymer Membranes.

Inspired by biological ion channels, artificial nanopore-based architectures have been developed for smart ion/molecular transport control with potential applications to iontronics and energy conversion. Advances in nanofabrication technology enable simple, versatile construction methods, and post-fabrication functionalization delivers nanochannels with unique ion transport-control attributes. Here, we characterize a pH-responsive, charge-selective dual-gating block copolymer (BCP) membrane composed of polystyrene-b-poly(4-vinylpyridine) (PS48400-b-P4VP21300), capable of self-organizing into highly ordered nanocylindrical domains. Because the PS-b-P4VP membrane exhibits pH-dependent structural transitions, it is suitable for designing intelligent pH-gated biomimetic channels, for example, exhibiting on-off transport switching at pH values near the pKa of P4VP with excellent anion permselectivity at pH < pKa. Introducing the BCP membrane onto nanopore electrode arrays (BCP@NEAs) allows the BCP to serve as a pH-responsive gate controlling ion transfer into the NEA nanopores. Such selectively transported and confined ions are detected by using a 100 nm gap dual-ring nanoelectrode structure capable of enhancing current output by efficient redox cycling with an amplification factor >102. In addition, BCP@NEAs exhibit extraordinary pH-gated ion selectivity, resulting in a 3380-fold current difference between anion and cation probes at pH 3.0. This hierarchically organized BCP-gated NEA system can serve as a template for the development of other stimulus-responsive ion gates, for example, those based on temperature and ligand gating, thus exploiting the intrinsic advantages of NEAs, such as enhanced sensitivity based on redox cycling, which may lead to technological applications such as engineered biosensors and iontronic devices.

Block Copolymers of Poly(ε-caprolactone) with pH-Responsive Side-Chain Amino Acid Moieties

To prepare amphiphilic block copolymers consisting of biocompatible and biodegradable segments, herein we report synthesis of diblock copolymers having e-caprolactone (e-CL) repeating units in one block and amino acid-based acrylate monomers in another segment. The block copolymers were prepared by a combination of metal-free ring-opening polymerization (ROP) of e-CL and reversible addition-fragmentation chain transfer (RAFT) polymerization of tert-butyloxycarbonyl (Boc)-alanine/Boc-leucine based acrylate monomers. The ROP of e-CL was initiated with diphenyl phosphate (DPP) as a metal-free catalyst in conjunction with a heterofunctional initiator, benzyl-2-hydroxyethyl carbonotrithioate, produced trithiocarbonate terminated poly(e-caprolactone) (PCL). This was further employed as macro-chain transfer agent for the synthesis of side chain amino acid containing block via RAFT. Deprotection of Boc group pendants from the block copolymers under acidic conditions at room temperature provided pH responsive block copolymers with positively charged cationic primary amine functionalities. Furthermore, self-assembling nature of these block copolymers in aqueous medium was examined through dynamic light scattering (DLS) and field emission-scanning electron microscopy (FE-SEM).

PH-responsive nanomicelles of poly(ethylene glycol)-poly(ε-caprolactone)-poly(L-histidine) for targeted drug delivery

Here, a novel pH-responsive block copolymer, poly (ethylene glycol)-poly(ε-caprolactone)-poly(L-histidine) (PEG-PCL-PHis), was synthesized and designed for anti-cancer drug delivery with excellent biocompatible, biodegradable, and strong drug loading efficiency. 1H-NMR, IF-IR, and GPC were used to characterize the structure of the PEG-PCL-PHis copolymer. In addition, the morphology, particle size, Zeta potential, and critical micelle concentration (CMC) of different degree of polymerization were determined by transmission electron microscopy (TEM), dynamic light scattering granulometer (DLS), and fluorescence spectrometer, respectively. The strong affinity between the core of micelles and hydrophobic drug was manifested with 15.09% drug loading content and 84.65% entrapment efficiency. In vitro release of DOX from the block copolymer micelle demonstrated, the PEG-PCL-PHis copolymer micelle has stable and durable drug releasing ability accompanied with pH-sensitivity. From the mechanism of cellular uptake the micelles, the pathway of drug release was captured by confocal laser scanning microscope. These experiments demonstrated the safe delivery for anticancer medicine through this novel copolymer. In conclusion, the PEG-PCL-PHis copolymer micelle has great potential to become a safe drug carrier for cancer chemotherapy.

Synthesis of pH-responsive block copolymer micelles via RAFT polymerization induced self-assembly and its application in emulsifier-free emulsion polymerization

The pH-responsive amphiphilic block copolymer micelles based on poly (2-(dimethylamino) ethyl methacrylate) (PDMAEMA) as a flexible corona and poly(hexafluorobutyl acrylate) (PHFBA) as a core have been synthesized by reversible addition-fragmentation chain transfer polymerization induced self-assembly (RAFT-PISA). This core-shell type amphiphilic copolymer micelles possessed the characteristics of pH-response from pendent tertiary amine groups in PDMAEMA chain. The morphology and size of amphiphilic block copolymer micelles were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. The results indicated that the diameter of micelles narrowed down from 160 nm to 20 nm along with the increased pH value from 1.32 to 2.90. However, the diameter of the amphiphilic block copolymer micelles ranged broadly from 20 nm to more than 100 nm at pH ≥ 5.89. The amphiphilic block copolymer micelles were later used as reactors to synthesize cationic fluorinated polyacrylate emulsifier-free emulsion at pH 2.90, using fluorinated monomers and acrylate monomers as mixed monomers. The latex particles were presented as core-shell morphology with diameter of about 220 nm and narrow distribution, as characterized by TEM and DLS. The obtained emulsion with high zeta potential (+57.8 mV) had excellent stability.

Combating Multidrug Resistance through an NIR-Triggered Cyanine-Containing Amphiphilic Block Copolymer.

Nowadays, multidrug resistance is the main challenge during cancer chemotherapy. Photochemical internalization (PCI) has been demonstrated to be a unique and promising approach to overcome multidrug resistance with light-harnessed activation. Here, an amphiphilic pH-responsive block copolymer with IR780 at the junction point [PEG-IR780-PDEAEMA; PEG, poly(ethylene glycol); PDEAEMA, poly((diethylamino)ethyl methacrylate)] has been designed as a perfect drug release platform as well as a functional macromolecular photosensitizer of PCI. PEG-IR780-PDEAEMA was synthesized by the combination of RAFT polymerization and click chemistry and further self-assembled into spherical micelles in aqueous solution. Notably, IR780 moieties were dispersed regularly around the core of the spherical micelles, which led to the diminishment of the aggregation-caused quenching effect of photosensitizers and high singlet oxygen quantum yield. Confocal laser scanning microscopy results showed that a high amount of doxorubicin (DOX) was translocated into the nucleus with NIR light irradiation through the PCI effect. Moreover, DOX-loaded PEG-IR780-PDEAEMA micelles showed much higher phototoxicity under short-time NIR light irradiation than their dark toxicity. Therefore, this DOX-loaded drug release platform based on pH-sensitive IR780-containing block copolymers has the potential to offer an efficient strategy for addressing drug resistance.

PH-Responsive Poly(dimethylsiloxane) Copolymer Decorated Magnetic Nanoparticles for Remotely Controlled Oil-in-Water Nanoemulsion Separation.

A smart and recyclable oil absorber based on pH-responsive block copolymer modified magnetic nanoparticles is constructed for effective separation of oil-in-water emulsions. Superparamagnetic iron(III) oxide (Fe3 O4 ) nanoparticles are designed as the core materials for providing the separation force, and surface modification with poly(4-vinylpyridine-b-dimethyl siloxane-b-4-vinylpyridine) (P4VP-PDMS-P4VP) block copolymer is performed to supply switchable oil wettability. The mean hydrodynamic radius of the nanoparticles increases from 43.8 ± 3.6 to 75.2 ± 5.3 nm when the neutral pH is reduced to 3, due to the protonation and subsequent swelling of P4VP segments at lower pH. The nanoparticles show excellent separation performance and can absorb octadecene up to 78.2 times of their own weight, simply by switching the pH of the oil-in-water emulsion treated with the nanoparticles and using a magnetic field. The different dipole of P4VP-PDMS-P4VP and protonated P4VP-PDMS-P4VP, as confirmed by density functional theory calculations, is responsible for the different oil miscibility and wettability of the nanoparticles.