Generation of Patterned Neuronal Networks on Cell‐Repellant Poly(oligo(ethylene glycol) Methacrylate) Films

The utilization of non‐biofouling poly(oligo(ethylene glycol) methacrylate) (pOEGMA) films as a background material for the generation of neuronal patterns is reported here. Our previously reported method, which was surface‐initiated, atom transfer radical polymerization of OEGMA, and subsequent activation of terminal hydroxyl groups of pOEGMA with disuccinimidyl carbonate, was employed for the generation of activated pOEGMA films on glass. Poly‐L ‐lysine was then microcontact‐printed onto the activated polymer films, followed by backfilling with poly(ethylene glycol) moieties. E18 hippocampal neurons were cultured on the chemically patterned substrate, and the resulting neuronal networks were analyzed by phase‐contrast microscopy and whole‐cell patch clamp method. The results indicated that the pOEGMA films played an important role in the generation of good‐quality neuronal patterns for up to two weeks without any negative effects to neurons.     

Photo‐Degradable,Protein–Polyelectrolyte Complex‐Coated,Mesoporous Silica Nanoparticles for Controlled Co‐Release of Protein and Model Drugs

The fabrication of photo‐degradable, protein–polyelectrolyte complex (PPC)‐coated, mesoporous silica nanoparticles (MSNs) and their controlled co‐release of protein and model drugs is reported. Random copolymers composed of oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA), and a photolabile o‐nitrobenzyl‐containing monomer, 5‐(2′‐(dimethylamino)ethoxy)‐2‐nitrobenzyl methacrylate (DENBMA), are first anchored onto the MSNs and then quaternary aminated, to obtain positively charged P(OEGMA‐co‐TENBMA) which exhibits photo‐induced charge conversion characteristics. PPCs consisting of P(OEGMA‐co‐TENBMA) and the protein bovine serum albumin (BSA) are utilized as capping agents for the nanopores of the MSNs. Upon UV irradiation, charge conversion of P(OEGMA‐co‐TENBMA) can lead to the disruption of PPCs on MSNs and co‐release of BSA and rhodamine B by electrostatic repulsion.     

Synthesis and micellization of thermoresponsive galactose‐based diblock copolymers

Thermoresponsive double hydrophilic diblock copolymers poly(2‐(2′‐methoxyethoxy)ethyl methacrylate‐co‐oligo(ethylene glycol) methacrylate)‐b‐poly(6‐O‐methacryloyl‐D ‐galactopyranose) (P(MEO₂MA‐co‐OEGMA)‐b‐PMAGP) with various compositions and molecular weights were obtained by deprotection of amphiphilic diblock copolymers P(MEO₂MA‐co‐OEGMA)‐b‐poly(6‐O‐methacryloyl‐1,2:3,4‐di‐O‐isopropylidene‐D ‐galactopyranose) (P(MEO₂MA‐co‐OEGMA)‐b‐PMAlpGP), which were prepared via reversible addition‐fragmentation chain transfer (RAFT) polymerization using P(MEO₂MA‐co‐OEGMA) as macro‐RAFT agent. Dynamic light scattering and UV–vis studies showed that the micelles self‐assembled from P(MEO₂MA‐co‐OEGMA)‐b‐PMAlpGP were thermoresponsive. A hydrophobic dye Nile Red could be encapsulated by block copolymers P(MEO₂MA‐co‐OEGMA)‐b‐PMAGP upon micellization and released upon dissociation of the formed micelles under different temperatures. The galactose functional groups in the PMAGP block have specific interaction with HepG2 cells, and P(MEO₂MA‐co‐OEGMA)‐b‐PMAGP has potential applications in hepatoma‐targeting drug delivery and biodetection. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,characterization, and properties of tunable thermosensitive amphiphilic dendrimer‐star copolymers with Y‐shaped arms

Novel and well‐defined amphiphilic dendrimer‐star copolymer poly(ε‐caprolactone)‐block‐(poly(2‐(2‐methoxyethoxy)ethylmethacrylate‐co‐oligo(ethylene glycol) methacrylate))₂ with Y‐shaped arms were synthesized by the combination of ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The investigation of thermal properties and the analysis of crystalline morphology indicate that the high‐branched structure of dendrimer‐star copolymers with Y‐shaped arms and the presence of amorphous P(MEO₂MA‐co‐OEGMA) segments together led to the complete destruction of crystallinity of the PCL segments in the dendrimer‐star copolymer. In addition, the hydrophilicity–hydrophobicity transition of the dendrimer‐star copolymer film can be achieved by altering the external temperatures. The amphiphilic copolymers can self‐assemble into spherical nanomicelles in water. Because the lower critical solution temperature of the copolymers can be adjusted by varying the ratio of MEO₂MA and OEGMA, the tunable thermosensitive properties can be observed by transmittance, dynamic laser light scattering, and transmission electron microscopy (TEM). The release rate of model drug chlorambucil from the micelles can be effectively controlled by changing the external temperatures, which indicates that these unique high‐branched amphiphilic copolymers have the potential applications in biomedical field. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,Self‐Assembly,and Multi‐Stimuli Responses of a Supramolecular Block Copolymer

A supramolecular block copolymer is prepared by the molecular recognition of nucleobases between poly(2‐(2‐methoxyethoxy)ethyl methacrylate‐co‐oligo(ethylene glycol) methacrylate)‐SS‐poly(ε‐caprolactone)‐adenine (P(MEO₂MA‐co‐OEGMA)‐SS‐PCL‐A) and uracil‐terminated poly(ethylene glycol) (PEG‐U). Because the block copolymer is linked by the combination of covalent (disulfide bond) and noncovalent (A U) bonds, it not only has similar properties to conventional covalently linked block copolymers but also possesses a dynamic and tunable nature. The copolymer can self‐assemble into micelles with a PCL core and P(MEO₂MA‐co‐OEGMA)/PEG shell. The size and morphologies of the micelles/aggregates can be adjusted by altering the temperature, pH, salt concentration, or adding dithiothreitol (DTT) to the solution. The controlled release of Nile red is achieved at different environmental conditions.

     

Synthesis of Thermo‐Responsive Polymers With Both Tunable UCST and LCST

New water‐soluble block copolymers of 2‐(2‐methoxyethoxy)ethyl methacrylate (MEO₂MA), oligo(ethylene glycol) methacrylate (OEGMA), and N‐(3‐(dimethylamino) propyl) methacrylamide (DMAPMA) (poly(OEGMA‐co‐MEO₂MA)‐b‐poly(DMAPMA)) were prepared via sequential reversible addition‐fragmentation chain transfer (RAFT) polymerization. Selective quaternization of poly(DMAPMA) block gives poly(OEGMA‐co‐MEO₂MA)‐b‐poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide), such block copolymer exhibits double thermo‐responsive behavior in water, poly(MEO₂MA‐co‐OEGMA) block shows a lower critical solution temperature (LCST), and poly((3‐[N‐(3‐methacrylamidopropyl)‐N,N‐dimethyl]ammoniopropane sulfonate)‐co‐N‐(3‐(dimethylamino) propyl) methacrylamide) block shows a upper critical solution temperature (UCST). Both of LCST and UCST can be controlled: LCST could be tuned by the fraction of OEGMA units in poly(OEGMA‐co‐MEO₂MA), and UCST was found to be dependent on the degree of quaternization (DQ).

     

Synthesis,characterization, and temperature‐responsive behaviors of novel hybrid amphiphilic block copolymers containing polyhedral oligomeric silsesquioxane

Organic/inorganic hybrid amphiphilic block copolymer poly(methacrylate isobutyl POSS)‐b‐poly(N‐isopropylacrylamide‐co‐oligo(ethylene glycol) methyl ether methacrylate) (PMAPOSS‐b‐P(NIPAM‐co‐OEGMA)) was synthesized via reversible addition–fragmentation chain transfer polymerization. The self‐assembly behavior of this block copolymer in aqueous solution was investigated by dynamic light scattering (DLS) and transmission electron microscopy. The results indicate that the novel block copolymer can self‐assemble into spherical micelles with PMAPOSS segment as the hydrophobic part and P(NIPAM‐co‐OEGMA) segment as the hydrophilic part. The temperature‐responsive characteristics of the assemblies were tested by UV–Vis spectra and DLS. Some factors such as the concentration, molecular weight, and copolymer generation that may affect the cloud point were studied systematically. The results reveal that this copolymer exhibits a sharp and intensive lower critical solution temperature (LCST). The essentially predetermined LCST can be conveniently achieved by adjusting the content of NIPAM or OEGMA domain. In addition, these novel hybrid micelles can undergo an association/disassociation cycle with the heating and cooling of solution and the degree of reversibility displaying a tremendous concentration dependence, as a novel organic/inorganic hybrid material with distinctive virtues can be potentially used in biological and medical fields, especially in drug nanocarriers for targeted therapy. Copyright © 2014 John Wiley & Sons, Ltd.     

Well‐defined succinylated chitosan‐O‐poly(oligo(ethylene glycol)methacrylate) for pH‐reversible shielding of cationic nanocarriers

A novel type of well‐defined graft copolymer, succinylated chitosan‐O‐poly(oligo(ethylene glycol)methacrylate) (SC‐POEGMA), was developed for pH‐reversible poly(ethylene glyocol) (PEG) shielding of cationic nanocarriers. Chitosan‐O‐POEGMA (CS‐POEGMA) was first synthesized via single electron transfer‐living radical polymerization of oligo(ethylene glyol) methacrylate (OEGMA) using O‐brominated chitosan (CS‐Br) as a macromolecular initiator and Cu(I)Br/1,1,4,7,10,10‐hexamethyltriethylenetetramine as a catalyst. The subsequent succinylation of the chitosan backbone gave the titled copolymers. The content of POEGMA in CS‐POEGMA could be widely modulated by varying the degree of bromination and feed ratio of OEGMA to CS‐Br, without compromising the amino density of chitosan backbone. The hierarchical assembly between SC‐POEGMA and trimethylated chitosan‐O‐poly(ε‐caprolactone) (TMC‐PCL) micelles was further studied. At pH 7.4, the stoichiometric interactions between SC and TMC segments to form polyampholyte–polyelectrolyte complexes led to the formation of PEG‐shielded micelles. The hierarchially assembled micelles could be disassembled into the pristine TMC‐PCL micelles, when the medium pH was below a certain pH (pH_φ). By varying the degree of succinylation of SC‐POEGMA, the pH_φ value could be facilely modulated from 6.5 to 3.5 to meet the needs for specific biomedical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis,self‐assembly,fluorescence, and thermosensitive properties of star‐shaped amphiphilic copolymers with porphyrin core

Star‐shaped amphiphilic poly(ε‐caprolactone)‐block‐poly(oligo(ethylene glycol) methyl ether methacrylate) with porphyrin core (SPPCL‐b‐POEGMA) was synthesized by combination of ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Star‐shaped PCL with porphyrin core (SPPCL) was prepared by bulk polymerization of ε‐caprolactone (CL) with tetrahydroxyethyl‐terminated porphyrin initiator and tin 2‐ethylexanote (Sn(Oct)₂) catalyst. SPPCL was converted into SPPCLBr macroinitiator with 2‐bromoisobutyryl bromide. Star‐shaped SPPCL‐b‐POEGMA was obtained via ATRP of oligo(ethylene glycol) methyl ether methacrylate (OEGMA). SPPCL‐b‐POEGMA can easily self‐assemble into micelles in aqueous solution via dialysis method. The formation of micellar aggregates were confirmed by critical micelle formation concentration, dynamic light scattering, and transmission electron microscopy. The micelles also exhibit property of temperature‐induced drug release and the lower critical solution temperature (LCST) was 60.6 °C. Furthermore, SPPCL‐b‐POEGMA micelles can reversibly swell and shrink in response to external temperature. In addition, SPPCL‐b‐POEGMA can present obvious fluorescence. Finally, the controlled drug release of copolymer micelles can be achieved by the change of temperatures. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Stimuli‐Responsive A‐b‐(B‐co‐C) Diblock Terpolymers Bearing Polyampholyte Sequences

Summary: Diblock terpolymers that consist of homopolymer and statistical copolymer (polyampholyte) building blocks are synthesized by group transfer polymerization. Two types of block tepolymers are explored in aqueous media: the amphiphilic poly{[(diethylamino)ethyl methacrylate]‐co‐(methacrylic acid)}‐block‐poly(methyl methacrylate) and the double hydrophilic poly[oligo(ethylene glycol) methacrylate]‐block‐poly{[(diethylamino)ethyl methacrylate]‐co‐(methacrylic acid)}. The first terpolymer self‐assembles in aqueous media to form responsive micelles that change their corona charge sign upon switching pH. The second terpolymer exhibits a multi‐responsive behavior. It forms neutral, positive, or negative micelles depending on a combination of different environmental conditions such as temperature, pH, and ionic strength.

P(DEAEMA‐co‐MAA)‐b‐PMMA pH‐sensitive micelles.     

An Arm‐First Approach to Cleavable Mikto‐Arm Star Polymers by RAFT Polymerization

Redox‐cleavable mikto‐arm star polymers are prepared by an “arm‐first” approach involving copolymerization of a dimethacrylate mediated by a mixture of macroRAFT agents. Thus, RAFT copolymerization of the monomers BMA, DMAEMA, and OEGMA, with the disulfide dimethacrylate cross‐linker (DSDMA), bis(2‐methacryloyl)oxyethyl disulfide, mediated by a 1:1:1 mixture of three macroRAFT agents with markedly different properties [hydrophilic, poly[oligo(ethylene glycol) methacrylate]—P(OEGMA)_8–9; cationizable, poly[2‐(dimethylamino)ethyl methacrylate]—P(DMAEMA); hydrophobic, poly(n‐butyl methacrylate)—P(BMA)] provides low dispersity mikto‐arm star polymers. Good control (Đ < 1.3) is observed for the target P(DMAEMA)/P(OEGMA)/P(BMA) (3:3:1) mikto‐arm star, a double hydrophilic P(DMAEMA)/P(OEGMA) (3:3) mikto‐arm star and a hydrophobic P(BMA) homo‐arm star. However, Đ for the target mikto‐arm stars increases with an increase in either the ratio [DSDMA]:[total macroRAFT] or the fraction of hydrophobic P(BMA) macroRAFT agent. The quaternized mikto‐arm star in dilute aqueous solution shows a monomodal particle size distribution and an average size of ≈145 nm.

     

Electrochemically Induced Formation of Surface‐Attached Temperature‐Responsive Hydrogels. Amperometric Glucose Sensors with Tunable Sensor Characteristics

Employing thermally responsive hydrogels, the design of an amperometric glucose sensor is proposed. The properties of the biosensor can be modulated upon changing the temperature. Homo‐ and copolymers of N‐isopropylacrylamide (NIPAm) and oligo(ethylene glycol) methacrylate (OEGMA) were prepared by electrochemically induced polymerization thus yielding surface‐attached hydrogels. The growth of the films as well as the change in the film thickness in dependence from the temperature were investigated by means of an electrochemical quartz crystal microbalance (EQCM). The layer thickness in the dry state ranged from 20 to 120 nm. The lower critical solution temperature (LCST) of the hydrogel increases with increasing content of the more hydrophilic OEGMA. Hence, the swelling in aqueous electrolyte is composition dependent and can be adjusted by selecting a specific NIPAm to OEGMA ratio. All homo‐ and copolymer films showed good biocompatibility and no fouling could be observed during exposing the surfaces to human serum albumin. For amperometric glucose detection, glucose oxidase was entrapped in the films during electrochemically‐induced polymerization. Both the apparent Michaelis constant (K$\rm{{_{M}^{app}})}$ and the apparent maximum current (i$\rm{{_{max}^{app}})}$ as determined by amperometry could be adjusted both by the film composition as well as the operation temperature.     

Surface Stabilization of Diblock PEG‐PLGA Micelles by Polymerization of N‐Vinyl‐2‐pyrrolidone

This paper presents a new approach to improving the physical stability of biodegradable poly‐(ethylene glycol)‐block‐poly[(DL ‐lactic acid)‐co‐(glycolic acid)] (PEG‐PLGA) micelles. A hydroxyl‐terminated PEG monomethacrylate (PEGmer) macroinitiator was used to prepare a methacrylate‐end‐capped PEG‐PLGA diblock copolymer by the ring‐opening polymerization of D ,L ‐lactide and glycolide. The surface‐exposed methacrylate groups in the shell layer of the micelles can be polymerized with N‐vinyl‐2‐pyrrolidone. The resulting micelles show substantially enhanced stability.     

New Linear and Star‐Shaped Thermogelling Poly([R]‐3‐hydroxybutyrate) Copolymers

The synthesis of multi‐arm poly([R]‐3‐hydroxybutyrate) (PHB)‐based triblock copolymers (poly([R]‐3‐hydroxybutyrate)‐b‐poly(N‐isopropylacrylamide)‐b‐[[poly(methyl ether methacrylate)‐g‐poly(ethylene glycol)]‐co‐[poly(methacrylate)‐g‐poly(propylene glycol)]], PHB‐b‐PNIPAAM‐b‐(PPEGMEMA‐co‐PPPGMA), and their subsequent self‐assembly into thermo‐responsive hydrogels is described. Atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide (NIPAAM) followed by poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) and poly(propylene glycol) methacrylate (PPGMA) was achieved from bromoesterified multi‐arm PHB macroinitiators. The composition of the resulting copolymers was investigated by ¹H and ¹³C J‐MOD NMR spectroscopy as well as size‐exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The copolymers featuring different architectures and distinct hydrophilic/hydrophobic contents were found to self‐assemble into thermo‐responsive gels in aqueous solution. Rheological studies indicated that the linear one‐arm PHB‐based copolymer tend to form a micellar solution, whereas the two‐ and four‐arm PHB‐based copolymers afforded gels with enhanced mechanical properties and solid‐like behavior. These investigations are the first to correlate the gelation properties to the arm number of a PHB‐based copolymer. All copolymers revealed a double thermo‐responsive behavior due to the NIPAAM and PPGMA blocks, thus allowing first the copolymer self‐assembly at room temperature, and then the delivery of a drug at body temperature (37 °C). The non‐significant toxic response of the gels, as assessed by the cell viability of the CCD‐112CoN human fibroblast cell line with different concentrations of the triblock copolymers ranging from 0.03 to 1 mg mL^?1, suggest that these PHB‐based thermo‐responsive gels are promising candidate biomaterials for drug‐delivery applications.     

Polymer electrolyte membranes by in situ polymerization of poly(ethylene carbonate‐co‐ethylene oxide) macromonomers in blends with poly(vinylidene fluoride‐co‐hexafluoropropylene)

Salt‐containing membranes based on polymethacrylates having poly(ethylene carbonate‐co‐ethylene oxide) side chains, as well as their blends with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), have been studied. Self‐supportive ion conductive membranes were prepared by casting films of methacrylate functional poly(ethylene carbonate‐co‐ethylene oxide) macromonomers containing lithium bis(trifluorosulfonyl)imide (LiTFSI) salt, followed by irradiation with UV‐light to polymerize the methacrylate units in situ. Homogenous electrolyte membranes based on the polymerized macromonomers showed a conductivity of 6.3 × 10^?6 S cm^?1 at 20 °C. The preparation of polymer blends, by the addition of PVDF‐HFP to the electrolytes, was found to greatly improve the mechanical properties. However, the addition led to an increase of the glass transition temperature (T_g) of the ion conductive phase by ～5 °C. The conductivity of the blend membranes was thus lower in relation to the corresponding homogeneous polymer electrolytes, and 2.5 × 10^?6 S cm^?1 was recorded for a membrane containing 10 wt % PVDF‐HFP at 20 °C. Increasing the salt concentration in the blend membranes was found to increase the T_g of the ion conductive component and decrease the propensity for the crystallization of the PVDF‐HFP component. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 79–90, 2007     

Hierarchically organized micellization of thermoresponsive rod‐coil copolymers based on poly[oligo(ethylene glycol) methacrylate] and poly(ε‐caprolactone)

A series of amphiphilic triblock copolymers, poly[oligo(ethylene glycol) methacrylate]_x‐block‐poly(ε‐caprolactone)‐block‐poly[oligo(ethylene glycol) methacrylate]_x, POEGMA_Co(x), were synthesized. Formation of hydrophobic domains as cores of the micelles was studied by fluorescence spectroscopy. The critical micelle concentrations in aqueous solution were found to be in the range of circa 10^?6 M. A novel methodology by modulated temperature differential scanning calorimetry was developed to determine critical micelle temperature. A significant concentration dependence of cmt was found. Dynamic light scattering measurements showed a bidispersed size distribution. The micelles showed reversible dispersion/aggregation in response to temperature cycles with lower critical solution temperature between 75 and 85 °C. The interplay of the two hydrophobic and one thermoresponsive macromolecular chains offers the chance to more complex morphologies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of lightly crosslinked zwitterionic polymer‐based bioinspired adhesives for intestinal tissue sealing

In this report, we have developed a new bioinspired medical adhesive capable of providing a leak‐proof barrier for application to intestinal anastomoses. The newly synthesized adhesive is a terpolymer possessing three different repeating units: (1) A zwitterionic polymer, poly(sulfobetaine methacrylate) (polySBMA), for increased hydrophilicity and biocompatibility, (2) a 3,4‐dihydroxy‐L‐phenylalanine (DOPA) segment which contains the catechol group, and (3) poly(ethylene glycol) dimethacrylate (PEGDMA) for light crosslinking, which will be used to strengthen the polymer adhesion properties by providing debonding resistance. The chemical structure of the terpolymer, poly(N‐methacryloyl‐3,4‐dihydroxyl‐L‐phenylalanine‐co‐sulfobetaine methacrylate‐co‐poly(ethylene glycol) dimethacrylate) (poly(MDOPA‐co‐SBMA‐co‐PEGDMA)), synthesized following a convenient and reproducible radical polymerization was clearly confirmed by ¹H NMR. The terpolymer adhesive displayed the optimal adhesion properties when containing 1.5–2.5 mol % of crosslinker, PEGDMA, according to the measured maximum adhesion strength and work of adhesion, characterized by lap shear strength tests utilizing porcine skin. The adhesive did not show cytotoxicity when tested with human embryonic kidney (HEK293A) cells. Ex vivo anastomosis experiments using porcine intestine demonstrated that the new poly(MDOPA‐co‐SBMA‐co‐PEGDMA) is a promising biomedical adhesive which successfully prevents leakage from the sutured intestinal tissue. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1564–1573     

Synthesis of well‐defined chitosan‐based tricomponent copolymers for constructing multifunctional delivery systems

Chitosan‐based tricomponent copolymers, chitosan‐g‐poly(ε‐caprolactone)‐(g‐poly(oligo(ethylene glycol) methacrylate)) (CS‐PCL‐POEGMA, CPP), are synthesized as multifunctional nanocarriers for antitumor therapy. 2‐Bromoisobutyric acid and PCL are first site‐specifically conjugated onto the hydroxy groups of chitosan backbone through conventional coupling chemistry to give CS‐PCL‐Br using sodium dodecyl sulfate–chitosan complex as an organosoluble intermediate. CPP‐PCL‐Br is further used for initiating the single electron transfer‐living radical polymerization of OEGMA in the mixed solvent of dimethyl sulfoxide and lactic acid, yielding CPP. One‐pot reaction of CPP with a small amount of NaN₃ under the catalysis of Cu(I)Br/tris‐(2‐dimethylaminoethyl)amine converts the bromo ends of POEGMA grafts to azide functionality, which is used for conjugation of folic acid targeting moiety via azide–alkyne click reactions. The resultant tricomponent copolymers can assemble into spherical micelles with the capacity of coincorporating indocyanine green and Doxorubicin through electrostatic and hydrophobic interactions, respectively. The dual‐agent‐loaded micelles display a combined effect for combating HepG2 cells when irradiated with near‐infrared laser. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation of a novel polymer monolith with functional polymer brushes by two‐step atom‐transfer radical polymerization for trypsin immobilization

Novel porous polymer monoliths grafted with poly{oligo[(ethylene glycol) methacrylate]‐co‐glycidyl methacrylate} brushes were fabricated via two‐step atom‐transfer radical polymerization and used as a trypsin‐based reactor in a continuous flow system. This is the first time that atom‐transfer radical polymerization technique was utilized to design and construct polymer monolith bioreactor. The prepared monoliths possessed excellent permeability, providing fast mass transfer for enzymatic reaction. More importantly, surface properties, which were modulated via surface‐initiated atom‐transfer radical polymerization, were found to have a great effect on bioreactor activities based on Michaelis–Menten studies. Furthermore, three model proteins were digested by the monolith bioreactor to a larger degree within dramatically reduced time (50 s), about 900 times faster than that by free trypsin (12 h). The proposed method provided a platform to prepare porous monoliths with desired surface properties for immobilizing various enzymes.     

Temperature‐sensitive hydrogel microspheres formed by liquid–liquid phase transitions of aqueous solutions of poly(N,N‐dimethylacrylamide‐co‐allyl methacrylate)

Poly(N,N‐dimethylacrylamide‐co‐allyl methacrylate) (DMA‐co‐AMA) copolymers were prepared by the copolymerization of N,N‐dimethylacrylamide with allyl methacrylate (AMA). The methacryloyl group of AMA reacted preferentially, and this resulted in pendant allyl groups along the copolymer chains. Aqueous solutions of these DMA‐co‐AMA copolymers were thermoresponsive and showed liquid–liquid phase transitions at temperatures that depended on the AMA content. Hydrogel microspheres were prepared from these thermally phase‐separated liquid microdroplets by the free‐radical crosslinking of the pendant allyl groups. The morphologies of the resulting thermoresponsive microspheres as a function of the reaction temperature and the amount of the initiator were examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1641–1648, 2005