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Manipulating molecular and supramolecular interactions within cellulose nanocrystals (CNCs) to introduce different levels of assemblies combined with multiple functionalities is required for the development of degradable smart materials from renewable resources. To attain hierarchical structures and stimuli-responsive properties, a new class of liquid crystalline cellulosic hybrid materials is synthesized. Herein, main-chain rigid-rod-like oxidized cellulose (CNC-COOH) is prepared from a Cellulose Whatman filter paper (Cellulose W.P.) by acid hydrolysis and oxidized using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO). Thermotropic LC molecule, 4-cyano-4'-hydroxybiphenyl with a 12-methylene spacer (CB12-OH) is grafted onto the carboxylic acid group of CNC-COOH

The self-assembly of liquid crystals (LCs) in small volumes is mediated by the anchoring conditions of the constituent mesogens at the confining surfaces. In hierarchically ordered systems such as ...

The development of hydrogels and their application in various fields, such as in medical dilators and scaffolds for cartridge regeneration, are restricted by their low modulus because of the trade-...

We demonstrate sequential ring-opening metathesis polymerization (ROMP) of norbornene bearing n-alkyloxycyanobiphenyl (NBCB12) and norbornene bearing poly(dl-lactide) (NBPLA) to synthesize low poly...

Leukaemia stem cells (LSCs) underlie cancer therapy resistance but targeting these cells remains difficult. The Wnt-β-catenin and PI3K-Akt pathways cooperate to promote tumorigenesis and resistance to therapy. In a mouse model in which both pathways are activated in stem and progenitor cells, LSCs expanded under chemotherapy-induced stress. Since Akt can activate β-catenin, inhibiting this interaction might target therapy-resistant LSCs. High-throughput screening identified doxorubicin (DXR) as an inhibitor of the Akt-β-catenin interaction at low doses. Here we repurposed DXR as a targeted inhibitor rather than a broadly cytotoxic chemotherapy. Targeted DXR reduced Akt-activated β-catenin levels in chemoresistant LSCs and reduced LSC tumorigenic activity. Mechanistically, β-catenin binds multiple immune-checkpoint gene loci, and targeted DXR treatment inhibited expression of multiple immune checkpoints specifically in LSCs, including PD-L1, TIM3 and CD24. Overall, LSCs exhibit distinct properties of immune resistance that are reduced by inhibiting Akt-activated β-catenin. These findings suggest a strategy for overcoming cancer therapy resistance and immune escape.

Optically driven ordering transitions are rarely observed in macromolecular systems, often because of kinetic limitations. Here, we report a series of block co-oligomers (BCOs) that rapidly order and disorder at room temperature in response to optical illumination, and the absence thereof. The system is a triblock where rigid azobenzene (Azo) mesogens are attached to each end of a flexible siloxane chain. UV-induced trans-to-cis Azo isomerization, and

This review describes the recent progress made in designing stimuli-responsive, functional, side-chain, end-on mesogen attached liquid crystalline polymers (LCPs). Developments in synthetic methodologies including controlled and living techniques provide an easy access to well-defined liquid crystalline polymers. For example, the synthesis of linear liquid crystalline block copolymers (LCBCPs), block copolymers with a linear, coil–coil, non-LC block and an end-on mesogen attached LC block, provides a route to polymers with morphology and properties akin to conventional block copolymers. However, synthesis of topologically branched LCBCPs with a branched coil–coil non-liquid LC block and an end-on mesogen attached LC block is used to manipulate the phase behavior, morphology and alignment kinetics of the resultant polymer. Furthermore, synthesis of branched liquid crystalline random copolymers wherein the branched coil–coil non LC unit and end-on mesogen LC unit are statistically distributed results in never-before-seen helical and curved interfaces with new and enhanced properties. Finally, synthetic strategies to incorporate organic dye molecules into a variety of liquid crystalline polymer frameworks produce new optically active and adaptive soft materials. In the Outlook section, the need for topologically diverse synthetic and naturally derived liquid crystalline polymer architectures along with processing tools and field directed assemblies to produce functional materials and their applications are discussed.

We describe the influence of competing self-organizing phenomena on the formation of cholesteric mesophase in liquid crystalline brush block terpolymers (LCBBTs) and liquid crystalline random brush terpolymers (LCRBTs) containing chromonic molecules. A library of LCBBTs and LCRBTs are synthesized using ring-opening metathesis polymerization (ROMP) of norbornene side-chain functionalized monomers comprising cholesteryl mesogen (NBCh9), chromonic xanthenone (NBXan), and poly(ethylene glycol) (NBMPEG). Compression molded films of LCRBTs containing chromonic molecules display multilevel hierarchical structure in which cholesteric mesophase co-exists with π–π stacking of the chromonic mesophase along with PEG microphase segregated domains. This is unexpected as conventional LCBCPs and LCBBCs that lack chromonic molecules do not form cholesteric mesophases. The presence of π–π interactions modifies the interface at the IMDS so that both chromonic and cholesteric mesophases coexist leading to the manifestation of cholesteric phase for the first time within block architecture and is very reminiscent of previously published LCRBCs without chromonic molecules. The key to the observed hierarchical assembly in these LCBBTs containing chromonic molecules lies in the interplay of LC order, chromonic π–π stacking, PEG side chain microphase segregation, and their supramolecular cooperative motion. This unique “single component” polymer scaffold transforms our capacity to attain nanoscale hierarchies and optical properties from block architecture similar to nanoscale mesophases resulting in random architecture.

Contrast-enhanced X-ray computed tomography plays an important role in cancer imaging and disease progression monitoring. Imaging using radiopaque nanoparticle platforms can provide insights on the likelihood of nanoparticle accumulation and can enable image-guided therapies. Perfluorooctyl bromide (PFOB)-loaded nanocapsules designed for this purpose were stabilized using an in-house synthesized PEGylated polycaprolactone-based copolymer (PEG-b-PCL(Ch)) and compared with commercial polycaprolactone employing a Quality-by-Design approach. PFOB is a dense liquid, weakly polarizable, and immiscible in organic and aqueous solvents; thus, carefully designed formulations for optimal colloidal stabilization to overcome settling-associated instability are required. PFOB-loaded nanocapsules exhibited high PFOB loading due to the intrinsic properties of PEG-b-PCL(Ch). Settling and caking are major sources of instability for PFOB formulations. However, the PEG-b-PCL(Ch) copolymer conferred the nanocapsules enough steric impediment and polymer shell elasticity to settle without significant caking, increasing the overall colloidal stability of the formulation. Furthermore, a clear relationship between nanocapsule physical properties and X-ray attenuation was established. Nanocapsules were able to enhance the X-ray contrast in vitro as a function of PFOB loading. This nanocapsule-based platform is promising for future translational studies and image-guided tumor therapy due to its enhanced contrastability and optimal colloidal stability.

Stimuli-responsive polymer gels have received considerable attention due to their singular mechanical properties, which make them materials of choice for niche applications. Polymer gels comprising either physical or chemical cross-links can undergo controlled and reversible shape changes in response to an applied field. The stimulus or external field applied may include thermal, electrical, magnetic, pH, UV/visible light, ionic or metallic interactions or combinations thereof. The shape change can manifest itself in two-dimensional actuation, bending motion, or three-dimensional actuation, volume change. This reversible contraction and expansion of polymer gels as well as their mechanical properties are similar to that of biological muscles. This review will describe and critique some of the recent advances in the field of stimuli-responsive polymer gels including the design of new classes of polymeric gels, controlled actuation in response to external stimuli, and ability to tailor material properties for different applications.

We report the synthesis of new functional cholesteric–azobenzene side-chain liquid crystalline copolymers and terpolymers, their temperature-responsive mesophase behavior, and stimuli responsive photonic properties from 400 nm to the near infra-red region of the electromagnetic spectra. Polynorbornene copolymers are synthesized using norbornene based n-alkyloxy cholesteryl (NBCh9) and norbornene based n-alkyloxy azobenzene moiety bearing different terminal functional groups (NBAz12-X, X = H, CN, CH3O, and NO2) by ring opening metathesis polymerization with modified second-generation Grubbs catalyst. Polynorbornene terpolymers of NBCh9, NBAz12-X, and norbornene bearing poly (ethylene glycol) (NBMPEG) are synthesized in a similar way. The copolymers and terpolymers self-assemble to form cholesteric mesophases (N*) primarily from cholesterol molecules which forms the major phase and within which (1) azobenzene moieties serve as a molecular switch to tune the helical pitch of the cholesteric mesophase leading to wavelength modulation from the visible to near infrared range and (2) PEG provides internal plasticizing ability and mechanical integrity for easy processing of free-standing films. Unlike other azo based homopolymers and azo/cholesterol-based copolymers, this new copolymer and terpolymer platform exhibits unprecedented temperature-responsive optical properties for applications in thermochromic materials, thermal/photoresponsive switches, sun protecting glazing, photopatterning and temperature sensing labels.

A potentially universal approach is presented for enzyme attachment to cellulose that significantly enhances enzyme stability while retaining high activity, and involves no chemical functionalization of cellulose. Bovine serum albumin (BSA) was interlocked in cellulose to form a protein-friendly surface (named BSA-Paper), while also providing COOH and NH2 groups for subsequent attachment of enzymes. The desired enzyme is then mixed with additional BSA and interlocked on BSA-Paper. The second BSA layer dilutes and crosslinks the enzyme for improved stability. Laccase was tested as a model enzyme for interlocking on BSA-Paper, and was found to retain over 100 % activity and was 240 times more stable at 25 °C (half life=180 d) than laccase. This new approach was also tested with a few other enzymes with encouraging results, thus providing a potentially universal method for stabilization of enzymes on cellulose with retention of high activities.

The fabrication of mechanically robust nanoporous polymeric membrane materials with aligned, accessible functionalized nanopores is extremely important for many applications. We report a general and modular synthesis, structure/morphology and properties of nanoporous membranes from norbornene backbone based triblock copolymers containing functionalized amine monomers in the central block, and side-chain liquid crystalline and side-chain polylactide end blocks. The composition, sequence of monomer addition, overall molecular weight, norbornene backbone and thiol–ene crosslinking chemistries are chosen and optimized to produce functional and easily aligned pores within the membrane. These membranes are shown to retain their morphology before and after crosslinking as well as hydrolysis of polylactide side chains. The functional groups on the pores are shown to be chemically accessible as evidenced by spectroscopic techniques and subjecting the membranes to the uptake of arsenate ions as a model application.

We report on the synthesis and properties of cholesteric liquid crystalline random terpolymers with comblike architecture as a modular platform for preparation of stimuli-responsive photonic elastomers. Ring-opening metathesis of norbornene monomers bearing n-alkyloxy cholesteryl (Ch9), n-alkoxy cyanobiphenyl (CB6 or CB12), and poly(ethylene glycol) (PEG) side chains is efficient and quantitatively yields low polydispersity random terpolymers. This terpolymer scaffold self-assembles to form cholesteric mesophases (N*) in which microphase-segregated domains of PEG side chains are randomly embedded. The cholesteric mesophase provides a 1D photonic band gap structure at optical wavelengths, which is maintained during chemical cross-linking of the norbornene backbone to form elastomers. The presence of cyanobiphenyl mesogens leads to an increase in the helical pitch of the cholesteric mesophase, resulting in a red-shift of the reflectivity relative to the pure cholesteric mesophase. By contrast, the presence ...

Cytochrome c-poly(acrylic acid) (cyt c-PAA) conjugates with 34-fold enchancement in peroxidase turnover number (kcat) are reported. Cyt c-PAA conjugates were prepared by carbodiimide coupling. PAA with molecular weight (Mw) ranging from 1.8k to 250k g mol-1 were employed, and the effect of PAA Mw on peroxiodase kinetics was assessed. The kcat value increased with increased Mw of PAA, ranging from 0.077(±0.002) s-1 in the absence of PAA to 2.66(±0.08) s-1 for the conjugate of cyt c with 250k PAA. Enzymatic activity studies over pH 6-8 indicated improved activity for cyt c-PAA conjugates at neutral or slightly alkaline pH. Examination of the cyt c heme spectroscopy in the presence of H2O2 revealed that formation of compound III, a reactive intermediate that leads to enzyme inactivation, was supressed in cyt c-PAA conjugates. Thus, we suggest the kcat enhancement can be attributed to acidification of the pH microenvironment and inhibition of the formation of a reactive intermediate that deactivates cyt c during the catalytic cycle.

We previously reported the development of an amphiphilic brush-like block copolymer composed of polynorbornene-cholesterol/polyethylene glycol (P(NBCh9-b-NBPEG)) that self-assembles in aqueous media to form long circulating nanostructures capable of encapsulating doxorubicin (DOX-NPs). Biodistribution studies showed that this formulation preferentially accumulates in tumor tissue with markedly reduced accumulation in the heart and other major organs. The aim of the current study was to evaluate the in vivo efficacy and toxicity of DOX containing self-assembled polymer nanoparticles in a mouse xenograft tumor model and compare its effects with the hydrochloride non-encapsulated form (free DOX). DOX-NPs significantly reduced the growth of tumors without inducing any apparent toxicity. Conversely, mice treated with free DOX exhibited significant weight loss, early toxic cardiomyopathy, acute toxic hepatopathy, reduced hematopoiesis and fatal toxicity. The improved safety profile of the polymeric DOX-NPs can be explained by the low circulating concentration of non-nanoparticle-associated drug as well as the reduced accumulation of DOX in non-target organs. These findings support the use of P(NBCh9-b-NBPEG) nanoparticles as delivery platforms for hydrophobic anticancer drugs intended to reduce the toxicity of conventional treatments.

Biomimetic mineralization of collagen fibrils is an essential process because the mineralized collagen fibers constitute the basic building block of natural bone. To overcome the limited availability and high cost of the noncollagenous proteins (NCPs) that regulate the mineralization process of collagen, commercially available analogues were developed to replicate sequestration and templating functions of NCPs. The use of branched polymers in intrafibrillar mineralization applications has never been explored. In this work, two novel carboxyl-rich brushlike polymers, a carboxylated polyethylene glycol terpolymer (PEG-COOH) and a polyethylene glycol/poly(acrylic acid) copolymer (PEG-PAA), were synthesized and modified to mimic the sequestration function of NCPs to induce intrafibrillar mineralization of collagen fibrils. It was found that these synthetic brushlike polymers are able to induce intrafibrillar mineralization by stabilizing the amorphous calcium phosphate (ACP) nanoprecursors and subsequently facilitating the infiltration of ACP into the gap zone of collagen microfibrils. Moreover, the weight ratios of mineral to collagen in the mineralized collagen fibrils in the presence of these brushlike polymers were 2.17 ± 0.07 for PEG-COOH and 2.23 ± 0.03 for PEG-PAA, while it is only 1.81 ± 0.21 for linear PAA. Plausible mineralization mechanisms using brushlike polymers are proposed that offer significant insight into the understanding of collagen mineralization induced by synthetic NCP analogues.

A modular, general method for trapping enzymes within the voids of paper, without chemical activation of cellulose, is reported. Glucose oxidase and peroxidase were crosslinked with poly(acrylic acid) via carbodiimide chemistry, producing 3-dimensional networks interlocked in cellulose fibers. Interlocking prevented enzyme activity loss and enhanced the washability and stability.

We explore the morphology and phase behavior of a recently introduced architecture of liquid crystalline brushlike block copolymer (LCBBC) as functions of composition and molecular weight. Low-polydispersity materials were prepared by ring-opening metathesis polymerization of n-alkyloxycyanobiphenyl and poly(dl-lactide) (PLA) functionalized norbornene monomers. Well-ordered block copolymer mesophases were observed with transitions from spheres to hexagonally packed cylinders, lamellae, inverse cylinders, and inverse spheres on increasing the weight fraction of the liquid crystalline block, fLC, from 0.15 to 0.85. The microdomain spacing displays a power-law scaling with molecular weight with an exponent of 0.6, L0 ∼ MW0.6. The simple occurrence of microdomains with curved interfaces, spherical and cylindrical, and the sublinear scaling of microdomain spacing with molecular weight set this system clearly apart from bottlebrush block copolymers. We observe a peculiar morphology dependence of the liquid crys...

A novel amphiphilic cholesterol-based block copolymer comprised of a polymethacrylate bearing cholesterol block and a polyethylene glycol block with reducible disulfide bonds (PC5MA-SS-PEO) was synthesized and evaluated as a redox-sensitive nanoparticulate delivery system. The self-assembled PC5MA-SS-PEO nanoparticles (SS-NPs) encapsulated the anticancer drug doxorubicin (DOX) with high drug loading (18.2% w/w) and high encapsulation efficiency (94.9%). DOX-encapsulated PC5MA-SS-PEO self-assembled nanoparticles (DOX-encapsulated SS-NPs) showed excellent stability and exhibited a rapid DOX release in response to dithiothreitol reductive condition. Importantly, following internalization by lung cancer cells, the reducible DOX-encapsulated SS-NPs achieved higher cytotoxicity than the non-reducible thioester NPs whereas blank nanoparticles were non-cytotoxic. Furthermore, in vivo imaging studies in tumor-bearing severe combined immunodeficiency (SCID) mice showed that the nanoparticles preferentially accumulated in tumor tissue with remarkably reduced accumulation in the healthy non-target organs. The results indicated that the SS-NPs may be a promising platform for cancer-cell specific delivery of hydrophobic anticancer drugs. From the Clinical Editor The use of nanocarriers for drug delivery against tumors has been under intense research. One problem of using carrier system is the drug release kinetics at tumor site. In this article, the authors continued their previous study in the development of an amphiphilic cholesterol-based block copolymer with redox-sensitive modification, so that the payload drug could be released in response to the microenvironment. The interesting results should provide a new direction for designing future novel nanocarrier systems.

An example of a highly stable and functional bienzyme–polymer conjugate triad assembled on a topologically orthogonal support, layered graphene oxide (GO), is reported here. Glucose oxidase (GOx) and horseradish peroxidase (HRP) catalytic dyad were used as the model system for cascade biocatalysis. Poly(acrylic acid) (PAA) was used to covalently conjugate these enzymes, and then the conjugate has been subsequently adsorbed onto GO. The resultant nanobiocatalysts are represented as GOx-HRP-PAA/GO. Their morphology and structural characteristics were examined by transmission electron microscopy (TEM), agarose gel electrophoresis, circular dichroism (CD), and zeta potential. These robust conjugates remarkably functioned as active catalysts under biologically challenging conditions such as extreme pHs, high temperature (65 °C), and in the presence of a chemical denaturant. In one example, GOx-HRP-PAA/GO presented doubling of the Kcat (TON) (68 × 10–2 s–1) at pH 7.0 and room temperature, when compared to the c...

We examine the influence of confining gold nanoparticles on the overall nanoscale morphology, mechanical and electrochemical properties of nanocomposite ion gels. Stimuli-responsive ion gels are generated via the synthesis of gold nanoparticles (AuNPs) within a thiol-functionalized liquid crystalline brush-like block copolymer (LCBBC) and subsequent gelation in ionic liquids. AuNPs are prepared by in situ reduction of the gold ions and stabilized by direct anchoring through coordination bonds with the thiol-functionalized LCBBC. The resulting LCBBC/AuNP nanocomposite comprises a hierarchical structure in which polymer-coated AuNPs are dispersed in a microsegregated LCBBC matrix that further contains both liquid crystalline (LC) and block copolymer ordering. More importantly, this LCBBC/AuNP nanocomposite is solubilized in an ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate, to form a nanocomposite ion gel. At 5 wt% concentration, LCBBC/AuNP nanocomposite ion-gel exhibits interesting characteristics including excellent mechanical strength (∼103 Pa), good optical properties with higher ionic conductivity (∼10−2 S cm−1) and long-term electrochemical stability over a larger potential range compared to the plain LCBBC ion gel. Thus, nanocomposite ion gels present tunable optical, thermal and mechanical properties by virtue of their polymer architecture, morphology and functionality. These are versatile and modular hybrid materials to design nanocomposite ion gels with multiple functionalities for applications in electrochemical devices, photonics, and opto-electronics.

New nanocomposite hydrogels from liquid crystalline brush-like block copolymers (LCBBCs) and gold nanorods (AuNRs) were synthesized and characterized. The hydrogels protected and stabilized AuNRs, which presented peroxidase-like activity and catalysed the oxidation of a substrate in the presence of H2O2 and elicited a sensitive chromogenic response. This reusable, table-top stable, free-standing nanocomposite hydrogel platform can be used to develop a simple and reproducible method to detect H2O2.

Magnetic fields are useful for directing block copolymer (BCP) self-assembly, but to date such a field alignment has required large fields (>5 T) necessitating the use of superconducting magnets. We report an approach that circumvents this limitation by introducing labile reactive mesogens into a liquid crystalline (LC) BCP based on a norbornene backbone with a poly(lactide) minority block that forms hexagonally packed cylinders. The free mesogens co-assemble with the smectic A mesophase of the BCP and enable alignment at fields as low as 0.5 T. The remarkable field response originates from the combined effects of enhanced mobility and decreased segregation strength, and the presence of large micron-scale grains in the system. We demonstrate a robust alignment of mesogen-blended samples using simple permanent magnets. The etching of poly(lactide) yields nanoporous films, while the spatially selective microdomain immobilization by UV-induced crosslinking through a photomask provides a versatile mechanism for creating alignment patterns. We anticipate that the nanoporous materials as generated here may find application in membrane fabrication or BCP lithography, while the ability to spatially pattern alignment is promising for the design of mechanical metamaterials exploiting the shape memory effect of LC elastomers.

Higher loading of enzymes on electrodes and efficient electron transfer from the enzyme to the electrode are urgently needed to enhance the current density of biofuel cells. The two-dimensional nature of the electrode surface limits the enzyme loading on the surface, and unfavorable interactions with electrode surfaces cause inactivation of the enzyme. Benign biohydrogels are designed here to address enzyme degradation, and the three-dimensional nature of the biohydrogel enhanced the enzyme density per unit area. A general strategy is demonstrated here using a redox active enzyme glucose oxidase embedded in a bovine serum albumin biohydrogel on flexible carbon cloth electrodes. In the presence of ferricyanide as a mediator, this bioelectrode generated a maximum current density (jmax) of 13.2 mA·cm-2 at 0.45 V in the presence of glucose with a sensitivity of 67 μA·mol-1·cm-2 and a half-life of >2 weeks at room temperature. A strong correlation of current density with water uptake by the biohydrogel was observed. Moreover, a soluble mediator (sodium ferricyanide) in the biohydrogel enhanced the current density by ∼1000-fold, and citrate-phosphate buffer has been found to be the best to achieve the maximum current density. A record 2.2% of the loaded enzyme was electroactive, which is greater than the highest value reported (2-fold). Stabilization of the enzyme in the biohydrogel resulted in retention of the enzymatic activity over a wide range of pH (4.0-8.0). We showed here that biohydrogels are excellent media for enzymatic electron transfer reactions required for bioelectronics and biofuel cell applications.

The interaction of fields with condensed matter during phase transitions produces a rich variety of physical phenomena. Self-assembly of liquid crystalline block copolymers (LC BCPs) in the presence of a magnetic field, for example, can result in highly oriented microstructures due to the LC BCP's anisotropic magnetic susceptibility. We show that such oriented mesophases can be produced using low-intensity fields (4 T) and superconducting magnets required to date. Low-intensity field alignment is enabled by the addition of labile mesogens that coassemble with the system's nematic and smectic A mesophases. The alignment saturation field strength and alignment kinetics have pronounced dependences on the free mesogen concentration. Highly aligned states with orientation distribution coefficients close to unity were obtained at fields as small as 0.2 T. This remarkable field response originates in an enhancement of alignment kinetics due to a reduction in viscosity, and increased magnetostatic energy due to increases in grain size, in the presence of labile mesogens. These developments provide routes for controlling structural order in BCPs, including the possibility of producing nontrivial textures and patterns of alignment by locally screening fields using magnetic nanoparticles.

Enzymes are biological catalysts, which accelerate chemical or physical reactions in vivo and in vitro with very high selectivity, specificity, and efficiency. This chapter focuses on how enzymes and water- soluble polymers interact and how the synthetic polymers can enhance the physical, chemical, and biological properties of enzymes. Hemoglobin does not function as an enzyme in biological environments but its peroxidase-like activity is widely used in biosensors, and the oxidation of polycyclic aromatic hydrocarbons. Both glucose oxidase and horseradish peroxidase are industrially important enzymes and used in various applications such as sensing of glucose, biofuel cell applications and biocatalysis. Polyacrylic acid is a hydrophilic polymer with one COOH group per monomer being available for conjugation with the amine groups on enzyme surfaces. The larger the enzyme, the longer the length of the polymer required to fully wrap the enzyme, as derived from simple geometry considerations.

Synthesis and characterization of highly stable and functional bienzyme-polymer triads assembled on layered graphene oxide (GO) are described here. Glucose oxidase (GOx) and horseradish peroxidase (HRP) were used as model enzymes and polyacrylic acid (PAA) as model polymer to armor the enzymes. PAA-armored GOx and HRP covalent conjugates were further protected from denaturation by adsorption onto GO nanosheets. Structure and morphology of this enzyme-polymer-nanosheet hybrid biocatalyst (GOx-HRP-PAA/GO) were confirmed by agarose gel electrophoresis, zeta potential, circular dichroism, and transmission electron microscopy. The armored biocatalysts retained full enzymatic activities under challenging conditions of pH (2.5-7.4), warm temperatures (65°C), and presence of chemical denaturants, 4mM sodium dodecyl sulfate, while GOx/HRP physical mixtures without the armor had very little activity under the same conditions. Therefore, this novel combination of two orthogonal approaches, enzyme conjugation with PAA and subsequent physical adsorption onto GO nanosheets, resulted in super stable hybrid biocatalysts that function under harsh conditions. Therefore, this general and powerful approach may be used to design environmentally friendly, green, biocompatible, and biodegradable biocatalysts for energy production in biofuel cell or biobattery applications.

A simple method for interlocking glucose oxidase (GOx) and horseradish peroxidase (HRP) in cellulose fibers using poly(acrylic acid) (PAA) as an armor around the enzyme, without any need for activation of the cellulose support, is reported here. The resulting enzyme paper is an inexpensive, stable, simple, wearable, and washable biosensor. PAA functions as a multifunctional tether to interlock the enzyme molecules around the paper fibers so that the enzymes are protected against thermal/chemical denaturation and not released from the paper when washed with a detergent. The decreased conformational entropy of the interlocked enzyme protected by the nanoarmor is likely responsible for increased enzyme stability to heat and chemical denaturants (retained ≥70 percent enzyme activity after washing with urea or SDS for 30min), and the polymer protects the enzyme against inactivation by proteases, bacteria, inhibitors, etc. The kinetics of the interlocked enzyme were similar to that of the enzyme in solution. The V

Amphiphilic brush-like block copolymers composed of polynorbonene-cholesterol/poly(ethylene glycol) (P(NBCh9-b-NBPEG)) self-assembled to form a long circulating nanostructure capable of encapsulating the anticancer drug doxorubicin (DOX) with high drug loading (22.1% w/w). The release of DOX from the DOX-loaded P(NBCh9-b-NBPEG) nanoparticles (DOX-NPs) was steady at less than 2% per day in PBS. DOX-NPs were effectively internalized by human cervical cancer cells (HeLa) and showed dose-dependent cytotoxicity, whereas blank nanoparticles were noncytotoxic. The DOX-NPs demonstrated a superior in vivo circulation time relative to that of free DOX. Tissue distribution and in vivo imaging studies showed that DOX-NPs preferentially accumulated in tumor tissue with markedly reduced accumulation in the heart and other vital organs. The DOX-NPs greatly improved survival and significantly inhibited tumor growth in tumor-bearing SCID mice compared to that for the untreated and free DOX-treated groups. The results indicated that self-assembled P(NBCh9-b-NBPEG) may be a useful carrier for improving tumor delivery of hydrophobic anticancer drugs.

Several key properties of catalase such as thermal stability, resistance to protease degradation, and resistance to ascorbate inhibition were improved, while retaining its structure and activity, by conjugation to poly(acrylic acid) (PAA, Mw 8000) via carbodiimide chemistry where the amine groups on the protein are appended to the carboxyl groups of the polymer. Catalase conjugation was examined at three different pH values (pH 5.0, 6.0, and 7.0) and at three distinct mole ratios (1:100, 1:500, and 1:1000) of catalase to PAA at each reaction pH. The corresponding products are labeled as Cat-PAA(x)-y, where x is the protein to polymer mole ratio and y is the pH used for the synthesis. The coupling reaction consumed about 60-70% of the primary amines on the catalase; all samples were completely water-soluble and formed nanogels, as evidenced by gel electrophoresis and electron microscopy. The UV circular dichroism (CD) spectra indicated substantial retention of protein secondary structure for all samples, which increased to 100% with increasing pH of the synthesis and polymer mole fraction. Soret CD bands of all samples indicated loss of ∼50% of band intensities, independent of the reaction pH. Catalytic activities of the conjugates increased with increasing synthesis pH, where 55-80% and 90-100% activity was retained for all samples synthesized at pH 5.0 and pH 7.0, respectively, and the Km or Vmax values of Cat-PAA(100)-7 did not differ significantly from those of the free enzyme. All conjugates synthesized at pH 7.0 were thermally stable even when heated to ∼85-90 °C, while native catalase denatured between 55 and 65 °C. All conjugates retained 40-90% of their original activities even after storing for 10 weeks at 8 °C, while unmodified catalase lost all of its activity within 2 weeks, under similar storage conditions. Interestingly, PAA surrounding catalase limited access to the enzyme from large molecules like proteases and significantly increased resistance to trypsin digestion compared to unmodified catalase. Similarly, negatively charged PAA surrounding the catalase in these conjugates protected the enzyme against inhibition by negatively charged inhibitors such as ascorbate. While Cat-PAA(100)-7 did not show any inhibition by ascorbate in the presence of 270 μM ascorbate, unmodified catalase lost ∼70% of its activity under similar conditions. This simple, facile, and rational methodology produced thermostable, storable catalase that is also protected from protease digestion and ascorbate inhibition and most likely prevented the dissociation of the multimer. Using synthetic polymers to protect and improve enzyme properties could be an attractive approach for making "Stable-on-the-Table" enzymes, as a viable alternative to protein engineering.

A scalable approach for developing large area polymer films, with stimuli responsive vertically aligned nanopores is reported. Magnetic fields are used to create highly aligned hexagonally packed block copolymer cylindrical microdomains with order parameters exceeding 0.95. Selective etch removal of material yields nanoporous films which demonstrate reversible pore closure on heating.

We report on the development of a liquid crystalline block copolymer with brush-type architecture as a platform for creating functional materials by magnetic-field-directed self-assembly. Ring-opening metathesis of n-alkyloxy cyanobiphenyl and polylactide (PLA) functionalized norbornene monomers provides efficient polymerization yielding low polydispersity block copolymers. The mesogenic species, spacer length, monomer functionality, brush-chain length, and overall molecular weight were chosen and optimized to produce hexagonally packed cylindrical PLA domains which self-assemble and align parallel to an applied magnetic field. The PLA domains can be selectively removed by hydrolytic degradation resulting in the production of nanoporous films. The polymers described here provide a versatile platform for scalable fabrication of aligned nanoporous materials and other functional materials based on such templates.

End-capping by covalently binding functional groups to the ends of polymer chains offers potential advantages for tissue engineering scaffolds, but the ability of such polymers to influence cell behavior has not been studied. As a demonstration, polylactide (PLA) was end-capped with lithium carboxylate ionic groups (hPLA13kLi) and evaluated. Thin films of the hPLA13kLi and PLA homopolymer were prepared with and without surface texturing. Murine osteoblast progenitor cells from collagen 1α1 transgenic reporter mice were used to assess cell attachment, proliferation, differentiation, and mineralization. Measurement of green fluorescent protein expressed by these cells and xylenol orange staining for mineral allowed quantitative analysis. The hPLA13kLi was biologically active, increasing initial cell attachment and enhancing differentiation, while reducing proliferation and strongly suppressing mineralization, relative to PLA. These effects of bound lithium ions (Li(+) ) had not been previously reported, and were generally consistent with the literature on soluble additions of lithium. The surface texturing generated here did not influence cell behavior. These results demonstrate that end-capping could be a useful approach in scaffold design, where a wide range of biologically active groups could be employed, while likely retaining the desirable characteristics associated with the unaltered homopolymer backbone.

Immature manufacturing and sub-optimal control of quality attributes hinder the effective translation of nanoformulations for cancer treatment, being partially responsible for the scarce number of products on the market. The effect of the method of preparation on the performance of complex formulations such as bio-responsive nanomedicines needs further understanding. In this study, we investigated the the influence of the method of preparation on the characteristics and bio-responsiveness of doxorubicin-loaded redox-sensitive nanoparticles (DOX-SS-NPs), formed by a biocompatible cholesterol-based amphiphilic block copolymer (PC5MA-SS-PEO). Two commonly used preparation techniques: (1) cosolvent removal and (2) an O/W emulsion method were compared and the in vitro and in vivo performance of promising formulations was assessed. Besides particle size distribution and drug loading, the response of the nanoparticles to reducing environments and subsequent release kinetics and cytotoxicity were also affected by the method of preparation. The investigation and understanding of this extensive influence, led to a DOX-SS-NPs formulation with significant in vivo efficacy and an improved safety profile when evaluated against free doxorubicin (DOX-HCl) and the commercial pegylated liposomal form (Doxil®). Our findings highlight the importance of formulation optimization and support the use of systematic approaches like Quality by Design to the development of bio-responsive nanomedicines for cancer treatment.

We synthesized new amphiphilic brush liquid crystalline block copolymers (brush-chol-BCP) comprised of polymethacrylates bearing polyethylene oxide (PEO) in one block and polymethacrylates bearing a cholesterol mesogen with a hemitelechelic thiol end group. Polymethacrylate bearing PEO (PMA-g-PEO) was first synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) and used as a macro-chain transfer agent to prepare block copolymer (PMA-g-PEO)-b-PC5MA-thioester (brush-chol-BCP-thioester). Brush-chol-BCP-thiol was obtained by the reduction of a thioester to thiol in the presence of butylamine. Gold nanoparticles (AuNPs) were prepared in situ with the brush-chol-BCP-thiol template via the reduction of gold ions and were stabilized by directly anchoring to the brush-chol-BCP-thiol chains through the coordination bonds with the thiol groups in the copolymer. The hydrophobic anticancer drug doxorubicin (DOX) was successfully encapsulated into AuNP-templated brush-chol-BCP-thiol via physical entrapment to form dual-encapsulated NPs with a high drug loading of 21.4% (w/w) and a high encapsulation efficiency of 85.6%. The dual-encapsulated NPs had an average size of 157 nm, spherical shape, excellent stability, and a sustained drug release pattern. More importantly, the dual-encapsulated NPs could be effectively internalized by human cervical cancer cells (Hela) and showed dose-dependent cytotoxicity, while the blank nanoparticles were non-cytotoxic at the tested concentrations. The results indicate that the brush-chol-BCP-thiol and their nanoparticles are promising carriers for dual encapsulation and delivery of an anticancer drug and metal nanoparticles.

Herein we investigate the influence of competing self-organizing phenomena on the hierarchical self-assembly of liquid crystalline brush block copolymers (LCBBCs). A library of LCBBCs are synthesized using ring-opening metathesis polymerization (ROMP) of norbornene side-chain functionalized monomers comprising (1) cholesteryl mesogen with nine methylene spacer and (2) semicrystalline poly(ethylene glycol) (PEG). The self-assembly of LCBBCs with variations in LC block content (7–80 wt %) are investigated in their melt state. All LCBBCs show two distinct thermal transitions corresponding to PEG semicrystalline phase and LC mesophases. Interestingly, the LCBBCs display a multilevel hierarchical structure evidenced by the results from X-ray scattering and transmission electron microscopy (TEM): (1) smectic A (SmA) mesophases (d = 3–7 nm) by the assembly of cholesteryl side chains and (2) microphase segregation into lamellar or cylinder (d = 40–75 nm) resulting from the incompatibility between LC moieties and ...

Here we report a general methodology to attain novel hierarchical nanostructures using new polymer scaffolds that self-assemble to form cholesteric 1D photonic mesophases existing in conjunction with microphase segregated domains. To achieve this, a series of liquid-crystalline random brush copolymers (LCRBC) consisting of cholesteryl liquid crystalline (LC) mesogen and brushlike PEG as side chain functionality are synthesized. At room temperature, all LCRBCs exhibits microphase segregation of PEG side chains on length scale of 10–15 nm, whereas LC domain forms smectic mesophase (3–7 nm LC layers). Interestingly, upon heating a cholesteric mesophase is exclusively observed for copolymer containing 78 and 85 wt % of LC content (LCRBC78 and LCRBC85, respectively) existing along with microphase segregated PEG domains. Moreover, the phase behavior of these copolymers studied by temperature-controlled small-angle X-ray scattering (SAXS) suggests the order–disorder transition for the microphase segregated struc...

We report a general and modular approach for the synthesis of multi enzyme–polymer conjugates (MECs) consisting of five different enzymes of diverse isoelectric points and distinct catalytic properties conjugated within a single universal polymer scaffold. The five model enzymes chosen include glucose oxidase (GOx), acid phosphatase (AP), lactate dehydrogenase (LDH), horseradish peroxidase (HRP) and lipase (Lip). Poly(acrylic acid) (PAA) is used as the model synthetic polymer scaffold that will covalently conjugate and stabilize multiple enzymes concurrently. Parallel and sequential synthetic protocols are used to synthesise MECs, 5-P and 5-S, respectively. Also, five different single enzyme–PAA conjugates (SECs) including GOx–PAA, AP–PAA, LDH–PAA, HRP–PAA and Lip–PAA are synthesized. The composition, structure and morphology of MECs and SECs are confirmed by agarose gel electrophoresis, dynamic light scattering, circular dichroism spectroscopy and transmission electron microscopy. The bioreactor comprising MEC functions as a single biocatalyst can carry out at least five different or orthogonal catalytic reactions by virtue of the five stabilized enzymes, which has never been achieved to-date. Using activity assays relevant for each of the enzymes, for example AP, the specific activity of AP at room temperature and 7.4 pH in PB is determined and set at 100%. Interestingly, MECs 5-P and 5-S show specific activities of 1800% and 600%, respectively, compared to 100% specific activity of AP at room temperature (RT). The catalytic efficiencies of 5-P and 5-S are 1.55 × 10−3 and 1.68 × 10−3, respectively, compared to 9.11 × 10−5 for AP under similar RT conditions. Similarly, AP relevant catalytic activities of 5-P and 5-S at 65 °C show 100 and 300%, respectively, relative to native AP activity at RT as the native AP is catalytically inactive at 65 °C. The catalytic activity trends suggest: (1) MECs show enhanced catalytic activities compared to native enzymes under similar assay conditions and (2) 5-S is better suited for high temperature biocatalysis, while both 5-S and 5-P are suitable for room temperature biocatalysis. Initial cytotoxicity results show that these MECs are non-lethal to human cells including human embryonic kidney [HEK] cells when treated with doses of 0.01 mg mL−1 for 72 h. This cytotoxicity data is relevant for future biological applications.

Synthesis and characterization of highly stable and functional bienzyme-polymer triads assembled on layered graphene oxide (GO) are described here. Glucose oxidase (GOx) and horseradish peroxidase (HRP) were used as model enzymes and polyacrylic acid (PAA) as model polymer to armor the enzymes. PAA-armored GOx and HRP covalent conjugates were further protected from denaturation by adsorption onto GO nanosheets. Structure and morphology of this enzyme-polymer-nanosheet hybrid biocatalyst (GOx-HRP-PAA/GO) were confirmed by agarose gel electrophoresis, zeta potential, circular dichroism, and transmission electron microscopy. The armored biocatalysts retained full enzymatic activities under challenging conditions of pH (2.5-7.4), warm temperatures (65°C), and presence of chemical denaturants, 4mM sodium dodecyl sulfate, while GOx/HRP physical mixtures without the armor had very little activity under the same conditions. Therefore, this novel combination of two orthogonal approaches, enzyme conjugation with PAA and subsequent physical adsorption onto GO nanosheets, resulted in super stable hybrid biocatalysts that function under harsh conditions. Therefore, this general and powerful approach may be used to design environmentally friendly, green, biocompatible, and biodegradable biocatalysts for energy production in biofuel cell or biobattery applications.