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This article reports on the synthesis of an innovative smart polymer, P5‐QPDMAEMA, opportunely developed with the aim of combining the responsiveness of PDMAEMA polymer and the host‐guest properties of covalently linked pillar[5]arenes. Thanks to a traditional Non‐Induced Phase Separation (NIPS) process performed at various coagulation pH, the blending of P5‐QPDMAEMA with polyethersulfone gave rise to the formation of functional beads for the removal of organic dyes in water. Adsorption tests are carried out on all the produced blend‐based beads by employing two representative dyes, the cationic methylene blue (MB), and the anionic methyl orange (MO). In particular, the P5‐QPDMAEMA based beads, prepared at acidic pH, featured the best MO removal rate (i. e., 91.3 % after 150 minutes starting from a 20 mg ⋅ L−1 solution) and a high selectivity towards the removal of the selected anionic dye. Based on the adsorption kinetics and isotherm calculations, the pseudo‐first order and Freundlich models were shown to be the most suitable to describe the MO adsorption behavior, achieving a maximum adsorption capacity of 21.54 mg ⋅ g−1. Furthermore, zwitterionic beads are obtained by a post‐functionalization of the PDMAEMA and the P5‐QPDMAEMA based beads, to test their removal capability towards both anionic and cationic dyes, as shown. [ABSTRACT FROM AUTHOR]

Thermoresponsive hydrogels based on ionic cellulose/chitosan are widely used various fields, such as smart windows and tissue engineering, while the effect of carbohydrate backbones of cellulose/chitosan on the thermal response and mechanical properties of hydrogels has received less attention so far. Herein, poly(2(dimethylamino)ethyl methacrylate) (PDMAEMA)-grafted cellulose sulfate (P-CS) and PDMAEMA-grafted chitosan sulfate (P-CHS) as research models are successfully synthesized through multi-step reactions. The P-CS and P-CHS polymers are further applied in crosslinked polyacrylamide networks, resulting in the P-CS and P-CHS hydrogels. Compared to P-CS hydrogels, P-CHS hydrogels could obviously block the transmission of visible light when the temperature is changed from 25 to 42 °C. In contrast to P-CHS hydrogels, the P-CS hydrogels change easily from soft and weak state to stiff and strong state according to their mechanical behaviors. These results indicate that different carbohydrate backbones of cellulose and chitosan should have caused distinct aggregation behaviors of corresponding P-CS and P-CHS hydrogels, which are accompanied by different light transmittance and mechanical properties. Thermoresponsive hydrogels using PDMAEMA-grafted ionic cellulose sulfate (P-CS) and chitosan sulfate (P-CHS) are successfully prepared. Distinct carbohydrate backbone displayed different effects on the thermoresponsive and mechanical properties of hydrogels. [ABSTRACT FROM AUTHOR]

The influence of poly(2-dimethylamino)ethyl methacrylate (PDMAEMA) block on the thermo- and pH-responsive behavior of poly(N-isopropyl acrylamide)-block-poly[(2-dimethylamino)ethyl methacrylate)] (PNIPAM-b-PDMAEMA) was studied. The block copolymers were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization by varying the chain length of the second block (PDMAEMA). 1H-NMR and FTIR spectra confirmed the formation of block copolymers PNIPAM21-b-PDMAEMA2 and PNIPAM21-b-PDMAEMA7 with the corresponding molar masses from the GPC data. Thermo- and pH-responsive behavior of block copolymers was investigated in phosphate buffer with various pHs. Interesting results showed that the hydrophilic carboxyl end group and the hydrophobic dodecyl end group of the RAFT agent affected the resulting phase transition temperature (Tc), while the Tc was found to be low in the acidic environment. Moreover, larger particle sizes of PNIPAM21‑b‑PDMAEMA2 were found with a pH of 9. It is noteworthy, that the resulted block copolymers might have the potential use in a drug delivery system.

Dental caries remains one of the most prevalent bacterium-caused chronic diseases affecting both adults and children worldwide. The development of new materials for enhancing its remineralization is one of the most promising approaches in the field of advanced dental materials as well as one of the main challenges in non-invasive dentistry. The aim of the present study is to develop novel hybrid materials based on (PDMAEMA)/Carbomer 940 microgels with in situ deposited calcium phosphates (CaP) and to reveal their potential as a remineralization system for artificial caries lesions. To this purpose, novel PDMAEMA/Carbomer 940 microgels were obtained and their core–shell structure was revealed by transmission electron microscopy (TEM). They were successfully used as a matrix for in situ calcium phosphate deposition, thus giving rise to novel hybrid microgels. The calcium phosphate phases formed during the deposition process were studied by X-ray diffraction and infrared spectroscopy, however, due to their highly amorphous nature, the nuclear magnetic resonance (NMR) was the method that was able to provide reliable information about the formed inorganic phases. The novel hybrid microgels were used for remineralization of artificial caries lesions in order to prove their ability to initiate their remineralization. The remineralization process was followed by scanning electron microscopy (SEM), X-ray diffraction, infrared and Raman spectroscopies and all these methods confirmed the successful enamel rod remineralization upon the novel hybrid microgel application. Thus, the study confirmed that novel hybrid microgels, which could ensure a constant supply of calcium and phosphate ions, are a viable solution for early caries treatment. [ABSTRACT FROM AUTHOR]

In recent years, stimuli-responsive poly(ionic liquids) (PILs) have attracted great attention. The stimuli-dependent properties, particularly the electrical properties, of multiresponsive PILs incorporating functionalized nanoparticles, however, have been less investigated. In this work, we present the synthesis, characterization, and application of PIL films incorporating pH- and thermoresponsive hybrid materials composed of gold nanoparticles functionalized with poly(2-(dimethylamino)ethyl methacrylate) (Au@PDMAEMA). The Au@PDMAEMA nanoparticles exhibit distinct responsiveness to changes in environmental pH and temperature, thereby altering the electrical properties of the PIL films blended with responsive gold nanoparticles (PIL w/Au). This research not only fills a gap in the study of electrical properties of multiresponsive nanoparticle-incorporated PILs but also extends the potential applications of PILs in various fields, including smart sensors and electronic devices.

Introduction: Triple-negative breast cancer (TNBC) is characterized by higher malignancy and mortality and is prone to distant metastasis, among which bone is the most common site. It's urgent to explore new strategies for the treatment of TNBC and its bone metastases., Methods: A tumor environment responsive vector, poly-(dimethylaminoethyl methacrylate)-SS-poly(ethylene glycol)-SS-poly-(dimethylaminoethyl methacrylate) (PDMAEMA-SS-PEG-SS-PDMAEMA), was constructed to co-delivery transforming growth factor-β1 (TGF-β1) siRNA and forkhead box M1 (FOXM1) siRNA in MDA-MB-231 cells. The preparation, characterization, in vitro release, stability, and transfection efficiency of nanoparticles were measured. Cell viability, migration, and invasion of MDA-MB-231 cells were determined. Cell chemotactic migration and cell heterogeneity adhesion of MDA-MB-231 cells to the human osteoblast-like cell line MG-63 were determined., Results: PDMAEMA-SS-PEG-SS-PDMAEMA self-assembled with siRNA at N/P of 15:1 into nanoparticles with a particle size of 122 nm. In vitro release exhibited redox and pH sensitivity, and the nanoparticles protected siRNA from degradation by RNase and serum protein, remaining stable at 4 °C with similar transfection efficiency with lipo2000. Nanoparticles co-loaded with TGF-β1 siRNA and FOXM1 siRNA inhibited the cell viability, migration and invasion of MDA-MB-231 cells, as well as chemotactic migration and heterogeneous adhesion of MDA-MB-231 cells to MG-63 cells, showing a synergetic effect. After gene silencing on TGF-β1 and FOXM1, the epithelial to mesenchymal transition (EMT) related molecules vimentin mRNA expression decreased while E-cadherin increased., Conclusions: PDMAEMA-SS-PEG-SS-PDMAEMA was suitable for TGF-β1 siRNA and FOXM1 siRNA delivery, exhibiting a synergetic inhibition effect on TNBC and its bone metastases, which might be related to its synergetic inhibition on EMT.

Dental caries remains one of the most prevalent bacterium-caused chronic diseases affecting both adults and children worldwide. The development of new materials for enhancing its remineralization is one of the most promising approaches in the field of advanced dental materials as well as one of the main challenges in non-invasive dentistry. The aim of the present study is to develop novel hybrid materials based on (PDMAEMA)/Carbomer 940 microgels with in situ deposited calcium phosphates (CaP) and to reveal their potential as a remineralization system for artificial caries lesions. To this purpose, novel PDMAEMA/Carbomer 940 microgels were obtained and their core–shell structure was revealed by transmission electron microscopy (TEM). They were successfully used as a matrix for in situ calcium phosphate deposition, thus giving rise to novel hybrid microgels. The calcium phosphate phases formed during the deposition process were studied by X-ray diffraction and infrared spectroscopy, however, due to their highly amorphous nature, the nuclear magnetic resonance (NMR) was the method that was able to provide reliable information about the formed inorganic phases. The novel hybrid microgels were used for remineralization of artificial caries lesions in order to prove their ability to initiate their remineralization. The remineralization process was followed by scanning electron microscopy (SEM), X-ray diffraction, infrared and Raman spectroscopies and all these methods confirmed the successful enamel rod remineralization upon the novel hybrid microgel application. Thus, the study confirmed that novel hybrid microgels, which could ensure a constant supply of calcium and phosphate ions, are a viable solution for early caries treatment.

Abstract Well-defined polymer micelles with core-shell structure are good delivery platform for stabilizing silver nanoparticles (AgNPs) in the field of antimicrobials targeting diseases. The rational construction of the polymer structure, an efficient, facile, and green preparation approach, and comprehensive exploration of the derived AgNPs are necessary, such as size, particle stability, antibacterial activity, and other properties. Herein, we designed and assessed the in vitro antimicrobial activity of AgNPs-decorated copolymer micelles with different copolymer topologies. First, linear or four-arm star triblock copolymers with the similar molecular weight and degree of polymerization were obtained, which consisted of DMAEMA for in situ reduction of silver ions to form AgNPs without external reducing agent. HEMA and PEGMA in micellar shell gave an enhanced stability of AgNPs during blood circulation. The combination of computational modeling and experimental results indicated that both types of micelles could fabricate AgNPs with monodisperse and spherical morphology. Star copolymer micelles stabilized AgNPs had smaller average size, better stability, and higher antibacterial activity than those with linear structure, which may due to higher stability of micelles from star copolymers. Furthermore, the cytotoxicity evaluation test showed that the achieved linear or star copolymers micelles stabilized AgNPs had good biocompatibility. This work provides a facile and universal approach in the rational design of micelles stabilized AgNPs with suitable topology for fighting against a wide range of bacterial infections.

Lignin is a natural renewable biomass resource with great potential for applications, while its development into high value-added molecules or materials is rare. The development of biomass lignin as potential nonviral gene delivery carriers was initiated by our group through the “grafting-from” approach. Firstly, the lignin was modified into macroinitiator using 2-bromoisobutyryl bromide. Then cationic polymer chains of poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) were grown from the lignin backbone using atom transfer radical polymerization (ATRP) to yield lignin-PDMAEMA graft copolymers (LPs) with branched structure. To gain a deep understanding of the relationship between the nonviral gene transfection efficiency of such copolymers and their structural and compositional factors, herein eight lignin-based macroinitiators with different modification degrees (MDs, from 3.0 to 100%) were synthesized. Initiated by them, a series of 20 LPs were synthesized with varied structural factors such as grafting degree (GD, which is equal to MD, determining the cationic chain number per lignin macromolecule), cationic chain length (represented by number of repeating DMAEMA units per grafted arm or degree of polymerization, DP) as well as the content of N element (N%) which is due to the grafted PDMAEMA chains and proportional to molecular weight of the LPs. The in vitro gene transfection capability of these graft copolymers was evaluated by luciferase assay in HeLa, COS7 and MDA-MB-231cell lines. Generally, the copolymers LP-12 (N% = 7.28, MD = 36.7%, DP = 13.6) and LP-14 (N% = 6.05, MD = 44.4%, DP = 5.5) showed good gene transfection capabilities in the cell lines tested. Overall, the performance of LP-12 was the best among all the LPs in the three cell lines at the N/P ratios from 10 to 30, which was usually several times higher than PEI standard. However, in MDA-MB-231 at N/P ratio of 30, LP-14 showed the best gene transfection performance among all the LPs. Its gene transfection efficiency was ca. 11 times higher than PEI standard at this N/P ratio. This work demonstrated that, although the content of N element (N%) which is due to the grafted PDMAEMA chains primarily determines the gene transfection efficiency of the LPs, it is not the only factor in explaining the performance of such copolymers with the branched structure. Structural factors of these copolymers such as grafting degree and cationic chain length could have a profound effect on the copolymer performance on gene transfection efficiency. Through carefully adjusting these factors, the gene transfection efficiency of the LPs could be modulated and optimized for different cell lines, which could make this new type of biomass-based biomaterial an attractive choice for various gene delivery applications.

Hypothesis: Worm-like micelles triggered by carbon dioxide (CO2), as an abundant, inert, and green stimulus have recently attracted much interest. These materials have many potential applications, including heat transfer, rheological control, personal protection and enhanced oil recovery (EOR). An ideal CO2-responsive worm-like micelle reveals a reversible transition state (from sol to gel state and vice versa) in response to environmental changes. The most important feature of these systems during these transitions is that CO2 does not accumulate in the system upon repeated cycles. Herein, we prepared two types of materials based on 3-(dimethylamino)-1-propylamine sodium dodecyl sulfate (DMAPA-SDS) as a small molecule, and poly(2-(dimethylamino)ethyl methacrylate-b-polymethyl mthacrylate)-SDS [(PDMAEMA-b-PMMA)-SDS] as a macromolecule to examine possible formation of CO2-responsive worm-like micelles. Methods: Amine groups in the structure of DMAPA and PDMAEMA-b-PMMA can be protonated and ionized to quaternary ammonium salts by CO2 bubbling and interact with SDS to possibly form a worm-like micelle through non-covalent electrostatic attraction. The viscosity and structural features of aqueous solutions were evaluated before and after being exposed to CO2 by rheometry and 1H NMR, respectively. The rheometry results showed shear thinning and gel-like behaviors at high shear rates and frequencies, respectively. Findings: The results showed that for a DMAPA-SDS small molecule an ideal reversible CO2-responsive worm-like micelle was formed and a sol-to-gel transition was observed, whereas in using a macromolecule an irreversible agglomeration occurred. The absence of reversible sol-gel transitions and the presence of heavy agglomeration for the (PDMAEMA-b-PMMA)-SDS macromolecule was attributed to entanglements of its long polymer chains. Therefore, DMAPA-SDS as small molecule with its ideal CO2-responsive worm-like micelle has potential in different useful applications, particularly in EOR.

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen often associated with biofilm infections. This study evaluated the capacity for biofilm destruction of a novel combination of cationic polymer micelles formed from poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA-PCL-PDMAEMA) triblock copolymer either alone, or loaded with silver nanoparticles (M_AgNPs). Pre-formed P. aeruginosa biofilms were incubated with either blank micelles, AgNO3, or M_AgNPs. Biofilm biomass (crystal violet assay), metabolic activity (Alamar blue reduction), structure (SEM) and viability (CLSM after Live/Dead staining, or plating for CFU) were checked. The results showed that the micelles alone loosened the biofilm matrix, and caused some alterations in the bacterial surface. AgNO3 killed the bacteria in situ leaving dead biofilm bacteria on the surface. M_AgNPs combined the two types of activities causing significant biofilm reduction, and alteration and death of biofilm bacteria. Therefore, the applied PDMAEMA-based micelles appear to be a successful candidate for the treatment of P. aeruginosa biofilm infections. [ABSTRACT FROM AUTHOR]

Inorganic–organic hybrid materials offer a wide variety of intriguing properties by combining their different characteristics and (chemical/physical) behavior, and the resulting smart materials find potential applications in areas such as energy technologies and drug delivery systems. Especially responsive two-dimensional carbides that belong to the class of MXenes benefit from this additional functionality in combination with their unique mechanical and electronic properties and bare potential for use as catalysts and sensors. Here, we therefore graft a stimuli-responsive polymer (poly-(2-(dimethyl-amino)-ethyl methacrylate (PDMAEMA)) from the surface of a Ti-based two-dimensional carbide (MXene) using the OH groups on the MXene surface as a linker for the organic molecules. Successful fabrication of the hybrid material as well as covalent bonding between the inorganic component and the thermoresponsive polymer is shown by X-ray powder diffraction, IR and X-ray photoelectron spectroscopy, thermal analysis, and electron microscopy. We further demonstrate a reversible change of conductivity of thin films of this smart hybrid material using temperature as an external stimulus and enhance the mechanistic understanding by density functional theory (DFT) calculations. Such systems could therefore be used as temperature sensors in chemical reactions or microelectronics. [ABSTRACT FROM AUTHOR]

In this work, the antimicrobial action of partially quaternized poly(2-(dimethylamino)ethyl methacrylate) (PQDMAEMA) copolymers using different alkyl halides is presented. The poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) homopolymer was synthesized by group transfer polymerization, followed by the modification of its tertiary amine groups, using bromoethane, iodoethane, bromohexane and bromoethanol, to introduce permanent cationic, quaternary ammonium salt moieties, randomly distributed along the polymer chains. In all cases, the degree of quaternization was low, at ~10 mol%, as verified by proton nuclear magnetic resonance spectroscopy to preserve the thermo-responsive character of the PDMAEMA precursor polymer. The biocidal activity of the lightly quaternized PQDMAEMA copolymers against Escherichia coli and Staphylococcus aureus was evaluated by calculating the minimum inhibitory concentration (MIC) as well as the minimum bactericidal concentration (MBC) of the polymers and by comparing them to the respective values of the precursor non-quaternized PDMAEMA homopolymer. The antibacterial mechanism of action in the solution was studied by zeta potential measurements, scanning electron microscopy and protein leakage tests signifying the disruption of the outer membrane of the bacterial cells to release their periplasmic proteins.

Non-lamellar lyotropic liquid crystalline (LLC) lipid nanoparticles contain internal multidimensional nanostructures such as the inverse bicontinuous cubic and the inverse hexagonal mesophases, which can respond to external stimuli and have the potential of controlling drug release. To date, the internal LLC mesophase responsiveness of these lipid nanoparticles is largely achieved by adding ionizable small molecules to the parent lipid such as monoolein (MO), the mixture of which is then dispersed into nanoparticle suspensions by commercially available poly(ethylene oxide)–poly(propylene oxide) block copolymers. In this study, the Reversible Addition-Fragmentation chain Transfer (RAFT) technique was used to synthesize a series of novel amphiphilic block copolymers (ABCs) containing a hydrophilic poly(ethylene glycol) (PEG) block, a hydrophobic block and one or two responsive blocks, i.e., poly(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl acrylate) (PTBA) and/or poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA). High throughput small angle X-ray scattering studies demonstrated that the synthesized ABCs could simultaneously stabilize a range of LLC MO nanoparticles (vesicles, cubosomes, hexosomes, inverse micelles) and provide internal particle nanostructure responsiveness to changes of hydrogen peroxide (H2O2) concentrations, pH and temperature. It was found that the novel functional ABCs can substitute for the commercial polymer stabilizer and the ionizable additive in the formation of next generation non-lamellar lipid nanoparticles. These novel formulations have the potential to control drug release in the tumor microenvironment with endogenous H2O2 and acidic pH conditions.

Well-defined, semi-degradable polyester/polymethacrylate block copolymers, based on ε-caprolactone (CL), d,l-lactide (DLLA), glycolide (GA) and N,N′-dimethylaminoethyl methacrylate (DMAEMA), were synthesized by ring-opening polymerization (ROP) and atom transfer radical polymerization. Comprehensive degradation studies of poly(ε-caprolactone)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PCL-b-PDMAEMA) on hydrolytic degradation and enzymatic degradation were performed, and those results were compared with the corresponding aliphatic polyester (PCL). The solution pH did not affect the hydrolytic degradation rate of PCL (a 3% Mn loss after six weeks). The presence of a PDMAEMA component in the copolymer chain increased the hydrolysis rates and depended on the solution pH, as PCL-b-PDMAEMA degraded faster in an acidic environment (36% Mn loss determined) than in a slightly alkaline environment (27% Mn loss). Enzymatic degradation of PCL-b-PDMAEMA, poly(d,l-lactide)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PLA-b-PDMAEMA) and poly(lactide-co-glycolide-co-ε-caprolactone)-block-poly(N,N′-dimethylaminoethyl methacrylate) (PLGC-b-PDMAEMA) and the corresponding aliphatic polyesters (PCL, PLA and PLGC) was performed by Novozyme 435. In enzymatic degradation, PLGC degraded almost completely after eleven days. For polyester-b-PDMAEMA copolymers, enzymatic degradation primarily involved the ester bonds in PDMAEMA side chains, and the rate of polyester degradation decreased with the increase in the chain length of PDMAEMA. Amphiphilic copolymers might be used for biomaterials with long-term or midterm applications such as nanoscale drug delivery systems with tunable degradation kinetics.

Synthesis, physicochemical characterization, and the enzymatic degradation of the amphiphilic miktoarm star-shaped polymers is reported herein. First, star-shaped macroinitiators, based on N,N′-dimethylaminoethyl methacrylate (DMAEMA) and glycerol dimethacrylate (GDMA) ((PDMAEMA)n-PGDMA), were synthesized. Due to the presence of hydroxyl groups in the macroinitiator core, polyesters such as poly(ɛ-caprolactone) (P(ɛ-CL)), polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were synthesized using ring opening polymerization (ROP). Comprehensive degradation studies on enzymatic degradation, using a lipase from Pseudomonas cepacia, were performed. Enzymatic degradation was monitored by weight measurements and nuclear magnetic resonance spectroscopy (1H NMR). The fastest degradation rate was observed for the polymer with the lowest molecular weight. Amphiphilic miktopolymers may find application as biomaterials for long- or mid-term period drug-delivery systems.

Detection of cyanide ion (CN−) and design of new sensors with high sensitivity and selectivity are interesting topics in recent developments. Cyanide ions lead to immediate dissolution of gold nanoparticles (AuNPs) and distinct color changes from red to transparent colorless solution. The presence of any material e.g. stabilizer may affect dissolution mechanism and hence sensing properties. Here, we represent a novel sensor (Au-PDA) based on the AuNPs coated with poly (N,N-dimethylaminoethyl methacrylate) (PDMAEMA) for the detection of CN− with tunable sensitivity. PDMAEMA bearing tertiary amine groups not only induced stimuli-responsivity to the prepared Au-PDA as the sensor, but also influenced the sensing performance like linear response range and limit of detection (LOD). The detection process with the increase in CN− concentration in wide range of pHs as well as high ionic strength of the medium was monitored by reduction of the localized surface plasmon resonance band of AuNPs at 530 nm. In the optimized condition, this sensing approach exhibited excellent selectivity in contrary to other anions and cations. The highest sensitivity was obtained in basic media (i.e. pH 9) with a LOD of 4.7 × 10−6 μM and two linear ranges from 10−5-10−3 μM and 0.04–320 μM. The tunable sensitivity could be considered as the strength point of such sensor with lowest LOD for detection of CN− and such a controlled stimuli-responsivity will open up a promising route toward adjustable detection of other chemicals. Image 1 • Cyanide sensor based on Au-PDMAEMA stimuli-responsive nanoparticles. • A new approach for tunable chemical-sensing properties. • Dissolution mechanism of gold nanoparticles for cyanide ion detection. • Controlled range of limit of detection by pH and ionic strength. [ABSTRACT FROM AUTHOR]

• New interfaces with self-healing characteristics based on double network. • Self-healing behaviour in simulated biological fluids is highlighted. • Confirm the possibility of using this kind of hydrogel as a drug delivery system. In the last years, responsive hydrogels have been widely studied due to their capacity to interact with the biological environment in a pre-programmed manner. Another aspect worth considering when synthesizing intelligent hydrogels is the introduction of self – healing characteristics, which can sustain the recovery of a material to its original shape. The study was developed as an extension of an ongoing investigation regarding new interpenetrated gels (IPNs) based on poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(itaconic anhydride-co-3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5] undecane) (PITAU) and it was focused on highlighting not only the rheological properties and the behaviour in simulated biological fluids, but also to confirm the possibility of using this kind of hydrogel as a drug delivery system. The semi-IPN structure was achieved by crosslinking DMAEMA into a preformed network of PITAU. The IPNs swelling kinetics and self-healing capacity evaluated by visual observation and oscillatory rheology were investigated. The potential of these IPNs gels to act as drug delivery systems has been explored by loading them with ibuprofen, and the in vitro drug release has been evaluated. The in vivo investigation was conducted in order to demonstrate the biocompatibility of the studied gels after systemic administration in mice. The new synthesised IPNs exhibit self-healing characteristics with promising capacity to be used as a controlled drug delivery system. [ABSTRACT FROM AUTHOR]

The present work aims to assess: (a) The effectiveness of nylon nonwoven fabrics containing antimicrobial substance and grafted with PMAA, PDMAEMA and the blended fabric containing the above mentioned two types of nonwoven fabrics for metal ions (Cu2+, Pb2+) and chromate (Cr2O7)2- recovery from wastewater; (b) The amount of the ion-exchanger used; and (c) The desired quality of product water (breakthrough point) on the operating capacity of textile under investigation. The main objective of this study is to investigate the possibilities of the final effluent in order to comply with the National Environmental Regularity standard for wastewater discharge into the public sewage network. The Cu2+and Pb2+ removal efficiency by the above mention textile types was studied by batch adsorption and column runs methods. It was found, in case of applying batch adsorption method that, the maximum removal of Cu2+ (92%) takes place when nylon grafted with PMAA nonwoven fabric was used. The application of blended nonwoven grafted with PMAA and PDMAEMA fabric paves the way for high sorption (79%) of Cu2+ from wastewater. The Cu2+ removal with grafted with PDMAEMA nonwoven fabric slightly increased relative to control fabric. The maximum ion removal % of Pb2+ (80-82%) was attained upon using all three types of grafted textiles, irrespective of the types of grafted polymer. Column method was used for determination of Cu2+ and Pb2+ removal efficiency by using the three types of grafted nylon-6 nonwoven fabrics. The copper and lead free effluents, breakthrough points and breakthrough capacities for the ion-exchangers under investigation were obtained Chromate removal efficiency by using Nylon non woven antimicrobial fabrics grafted with PDMAEMA was studied. For this anion exchanger fabric chromate free effluent, chromate breakthrough point and breakthrough capacity were also obtained. [ABSTRACT FROM AUTHOR]

Abstract It is known that an efficient gene therapy vector must overcome several steps to be able to express the gene of interest: (I) enter the cell by crossing the cell membrane; (II) escape the endo-lysosomal degradation pathway; (III) release the genetic material; (IV) traffic through the cytoplasm and enter the nucleus; and last (V), enable gene expression to synthetize the protein of interest. In recent years, we and others have demonstrated the potential of poly(2‑(N , N ′‑dimethylamino)ethylmethacrylate) (PDMAEMA) as a gene therapy vehicle. Further optimization of gene transfer efficiency requires the understanding of the intracellular pathway of PDMAEMA. Therefore the goal of this study was to determine the cellular entry and intracellular trafficking mechanisms of our PDMAEMA vectors and determine the gene transfer bottleneck. For this, we have produced rhodamine-labeled PDMAEMA polyplexes that were used to transfect retinal cells and the cellular localization determined by co-localization with cellular markers. Our vectors quickly and efficiently cross the cell membrane, and escape the endo-lysosomal system by 24 h. We have observed the PDMAEMA vectors to concentrate around the nucleus, and the DNA load to be released in the first 24 h after transfection. These results allow us to conclude that although the endo-lysosomal system is an important obstacle, PDMAEMA gene vectors can overcome it. The nuclear membrane, however, constitutes the bottleneck to PDMAEMA gene transfer ability. Highlights • PDMAEMA polyplexes enter by clathrin-mediated endocytosis in RPE cells • PDMAEMA polyplexes are able to escape the endo-lysosomal system. • The main bottleneck to an efficient transfection in RPE cells is the nuclear entry. [ABSTRACT FROM AUTHOR]

This article explores the adsorption kinetics of positively charged hard and soft silica nanoparticles (NPs) on supported lipid bilayers (SLBs) with an anionic surface charge. The softness of the NPs is adjusted by varying the grafting density of covalently bound Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes. The adsorption process, which is irreversible, can be described by a Langmuir-like adsorption model, where the desorption term is replaced by a term representing repulsive interactions, while the adsorption term is the classical one governed by its rate constant that quantifies how quickly a particle becomes bound to the SLBs. This occurs because further NP adsorption leads to a surface charge conversion that prevents additional particles from covering the SLB interface. NP adsorption is favored by electrostatic attraction and increases the adsorption kinetics. However, the latter decreases with increasing grafting density of the polyelectrolyte layer, ultimately preventing adsorption at a critical grafting density. This results from the interaction between the brush-grafted particle and the supported lipid bilayer depends on the counterion density in the contact area. This reduces the polymer flexibility in the brush, preventing it from making direct contact. Overall, the NP adsorption is favored, but counterions limit the extent of adsorption on a molecular scale, reaching the osmotic limit regime. [Display omitted] [ABSTRACT FROM AUTHOR]

Poly(2-(dimethylamino)ethyl methacrylate)-grafted bentonite, marked as Bent-PDMAEMA, was designed and prepared by a surface-initiated atom transfer radical polymerization method for the first time in this study. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA) were applied to characterize the structure of Bent-PDMAEMA, which resulted in the successful synthesis of Bent-PDMAEMA. As a cationic adsorbent, the designed Bent-PDMAEMA was used to remove dye Orange I from wastewater. The adsorption property of Bent-PDMAEMA for Orange I dye was investigated under different experimental conditions, such as solution pH, initial dye concentration, contact time and temperature. Under the optimum conditions, the adsorption amount of Bent-PDMAEMA for Orange I dye could reach 700 mg·g−1, indicating the potential application of Bent-PDMAEMA for anionic dyes in the treatment of wastewater. Moreover, the experimental data fitted well with the Langmuir model. The adsorption process obeyed pseudo-second-order kinetic process mechanism.

Nanodiamonds (NDs) can considerably improve the mechanical and thermal properties of polymeric composites. However, the tendency of NDs to aggregate limits the potential of these non-toxic, mechanically- and chemically-robust nanofillers. In this work, tough, flexible, and stimuli-responsive polyelectrolyte films composed of cross-linked poly(butyl acrylate-co-dimethylaminoethyl methacrylate) (P(BA-co-DMAEMA)) were prepared by photopolymerization. The effects of the added carboxylate-functionalized NDs on their mechanical and stimuli-responsive properties were studied. When the negatively charged NDs were added to the polymerization media directly, the mechanical properties of the films changed only slightly, because of the uneven distribution of the aggregated NDs in the films. In order to disperse and distribute the NDs more evenly, a prepolymerized polycation block copolymer complexing agent was used during the photopolymerization process. This approach improved the mechanical properties of the films and enhanced their thermally-induced, reversible phase-transition behavior.

In this study, diblock copolymers poly(methyl methacrylate)—block—poly (2-dimethylaminoethyl methacrylate) (pMMA-b-pDMAEMA) are investigated for the steric stabilization of latex particles and the subsequent use of these latex particles as Pickering emulsifiers. Solution properties of the diblock copolymers highlight that the pDMAEMA block length influences the critical micelle concentration (CMC) and micelle hydrodynamic diameter in response to changes in pH and the pKa. The block length can also be used as a way to control the particle size of sterically stabilized polystyrene latex particles prepared via emulsion polymerization. The suspension properties of these latex particles are also presented. Emulsion studies using these latex particles as emulsifiers show that both continuous phase pH and electrolyte concentration affect emulsion stability to coalescence. At high pH, stable emulsions are formed due to the affinity of the particles to the interface. At low pH, protonation of the amine groups reduces the affinity and thus droplet coalescence is observed. Increasing the electrolyte concentration improves emulsion stability, but causes an increase in droplet size due to adsorption of flocculated/aggregated particles. Finally, it is shown that these latex particles can be used in conjunction with membrane emulsification techniques to produce emulsions with low polydispersity.

Hexavalent chromium (Cr(VI)) is a highly toxic pollutant which widely exists in industrial wastewater. Here, an adsorbent, corn stalk fibers (CSF) grafted poly(dimethylaminoethyl methacrylate) (PDMAEMA), was prepared via atom transfer radical polymerization (ATRP). Polyvinyl alcohol (PVA) was used to enrich the hydroxyl groups of CSF, thus increasing PDMAEMA grafting density. Compared with the general grafting, the adsorption capacity of high-density grafting CSF increased from 56 to 145 mg/g. The PDMAEMA chains stretched in the water like brushes, resulting in very fast adsorption rate—about 10 min to achieve adsorption equilibrium. The adsorbent was stable and would not be oxidized by Cr(VI), and the adsorption performance was still excellent after 20 cycles. [ABSTRACT FROM AUTHOR]

Abstract: Poly[2‐(N,N‐dimethyl amino) ethyl methacrylate] (PDMAEMA)‐based nanogels (NGs) have attracted widespread interest as promising nanocarriers for drug/gene delivery, due to their versatile polyelectrolyte properties, multiple responsive functions, and acid‐swellable behaviors. However, the PDMAEMA NGs prepared by conventional methods often suffer from nonuniform particle shapes and sizes, intractable residues of surfactants, as well as inherent cytotoxicity and low circulation stability of cationic polymer particles. Herein, a facile and one‐pot liposome‐templated polymerization method is developed to prepare PEGylated liposome–coated PDMAEMA nanogels (PDMAEMA@liposome NGs). The results indicate that the liposome not only acts as polymerization template to obtain PDMAEMA NGs with controlled and predetermined size, but also anchors stealthy lipid molecules on the surface of NGs to improve the biocompatibility, enhance hemodynamic stability. In brief, the procedure provided here offers a robust and easy‐to‐implement approach to develop a polyelectrolyte–lipid hybrid nanoplatform with combined beneficial features of PDMAEMA NGs and stealthy liposomes, potentially providing a promising drug delivery vehicle for chemotherapy. [ABSTRACT FROM AUTHOR]

Nowadays, stimuli-responsive materials have attracted much attention because of their potential applications in various fields, specifically when a plasmonic nanoparticle is chemically bonded to a polymeric chain. On the other hand, preparation of assemblable anisotropic gold nanoparticles is an interesting challenge and also, synthetic methods and tunability of the plasmonic properties are usually multi-step and complicated. Here, poly( N,N- dimethylaminoethyl methacrylate) (PDMAEMA) was used as a stimuli-responsive polymer substrate for in-situ reduction of chloroauric acid (HAuCl 4 ) and synthesis of smart Au-PDMAEMA nanocomposites with anisotropic shapes. pH- and temperature-sensitive PDMAEMA played its role as a reducing, stabilizing and shape controlling agent to produce triangular gold nanoparticles with tunable UV–Vis absorption domain. Effect of some structural parameters like molar ratio of reducing group to Au ions, addition type and seed-mediated growth methods were studied comprehensively. Responsivity of Au-PDMAEMA nanocomposites to some stimuli like temperature and pH and also their reversibility were examined. Optical investigations revealed reversible and reproducible shifts between UV–Vis (550 nm) and near-IR (700 nm) absorptions by triggering with pH and temperature. The introduced strategy may facilitate synthesis of smart plasmonic nanoparticles with multi-responsivity. Assembly and disassembly of triangular plate-like nanoparticles with several stimulants may open up new fields due to their orientation/packing toward self-assembly. [ABSTRACT FROM AUTHOR]

The interpenetrating polymer networks (IPNs) are promising materials due to their unique properties. In this context, in the present study, new IPN structures based on poly(dimethylaminoethyl methacrylate) (PDMAEMA) and poly(itaconic anhydride- co -3,9-divinyl-2,4,8,10-tetraoxaspiro[5.5] undecane) (PITAU) were synthesized. The double network was prepared by synthesizing and crosslinking (with N , N ′-methylenebis(acrylamide)) PDMAEMA in the presence of a preformed PITAU network. The effect of the two components upon some properties such us: viscoelasticity, thermal stability and swelling behavior of the new prepared gels were deeply investigated. The viscoelastic parameters indicated stronger networks for PDMAEMA/PITAU hydrogels as compared with PDMAEMA. The thermal parameters also indicate that the IPNs are more stable than PDMAEMA. The IPNs present an increased sensitivity to temperature and pH, the equilibrium swelling degree being strongly influenced by them. This behaviour highlights the possibility of controlling the release of therapeutic agents by swelling and deswelling cycles of the IPNs at different pH and temperatures, depending on composition and the application envisaged. [ABSTRACT FROM AUTHOR]

Hypothesis Surfactant-free emulsion polymerization has become favorable due to circumventing instability issues reasonably. Incorporation of an appropriate hydrophilic macroRAFT, could provide controlled in-situ self-assembly via copolymerization with hydrophobic monomers into polymer particles. So far, this approach has mostly been studied in dispersion systems and further studies are needed in emulsions. Beside the corresponding mechanistic studies, the prepared latex particles would potentially exhibit smart behaviors by choosing stimuli-responsive monomers. Experiments Poly(styrene- co -methyl methacrylate) latexes were prepared by utilizing pH-responsive polydimethylaminoethyl methacrylate as the hydrophilic segment through polymerization induced self-assembly (PISA). A systematic study on the effect of MMA amount, role of smart spiropyran ethylacrylate (SPEA) comonomer and the synthesized macroRAFT for inducing efficient assembly has been performed comparatively for the first time. Findings SEM and DLS analyses showed the effect of MMA content on the obtaining of spherical particles with bimodal or monodisperse size distributions in both series of samples. Kinetic studies through conversion measurements along with GPC analysis revealed that the incorporation of MMA and SPEA strongly affected the efficiency of in-situ self-assembly, particle formation and RAFT-controllability on molecular weights. Ultimately, acido/basochromism, pH-responsivity and UV-responsivity of the prepared latexes were verified and the results showed their facile and fast multi-responsivity. [ABSTRACT FROM AUTHOR]

We report on the synthesis and characterization of amphiphile copolymers derived from poly( N , N -dimethylaminoethyl methacrylate) (PDMAEMA) generated by the stepwise quaternization of PDMAEMA, first with 1-hexadecyl bromide (HDB) and then with benzyl chloride (BC). Amphiphile copolymers consisting of hydrophile blocks separated by hydrophobe units were thus prepared in a predictable manner. The chemical structure of the hydrophobically modified polycations was confirmed by FTIR and 1 H NMR spectroscopy, and by elemental analysis. The behavior in salt-free aqueous solutions was investigated by viscometry at 25 °C, rheological investigations at different temperatures, and by SAXS measurements. The steady shear measurements revealed an aggregation during the flow at moderate shear rates, the amplitude of this phenomenon depending on the hydrophobic/hydrophilic balance. The clusters are formed due to the intermolecular interactions and they grow as the shear rate is approaching 1 s −1 . For the temperatures between 45 °C and 65 °C, the shear forces determine an expansion of the macromolecules that tend to orient in the flow direction and favor either a better interaction of the hydrophilic groups with the water molecules, or the manifestation of hydophobic interactions. The associative properties and the micelles geometry were tuned by the content and distribution of the hexadecyl groups. [ABSTRACT FROM AUTHOR]

Perennial problems of adsorption in wastewater treatment include adsorbent recycling, generation of waste sludge and secondary pollution because harmful concentrated acids, bases or strong chelators are often used for adsorbent regeneration and adsorbate recovery. We report, for the first time, an eco-friendly regeneration concept demonstrated with a CO 2 -responsive octopus-like polymeric adsorbent. Various heavy metals can be scavenged at very high Q e by such adsorbent through coordination. Most importantly, the rapid and complete regeneration of the adsorbent and recovery of the heavy metal ions can be readily achieved by CO 2 bubbling within a few minutes under mild conditions, i.e. , room temperature and atmospheric pressure. The adsorbent can then be restored to its adsorptive state and reused upon removal of CO 2 by simply bubbling another gas. This eco-friendly, effective, ultra-fast and repeatable CO 2 -triggered regeneration process using CO 2 -responsive adsorbent with versatile structure, morphology or form can be incorporated into a sustainable closed-loop wastewater treatment process to solve the perennial problems. [ABSTRACT FROM AUTHOR]

Poly((2-dimethylamino)ethyl methacrylate) (PDMAEMA) nanogels were synthesized via surfactant-free free-radical polymerization technique in aqueous conditions utilizing N,N’ -methylene-bis-acrylamide (MBA) as a crosslinking agent. The PDMAEMA nanogels were subsequently quaternized with acryloyl chloride in order to yield mucoadhesive materials which incorporate two mucoadhesive concepts; electrostatic interactions and covalent bond forming acrylate groups. The native PDMAEMA nanogels were found to exhibit good mucoadhesive properties on ex vivo bovine conjunctival tissues, which was found to increase proportionally with the degree of quaternization. With a view to determine the ocular drug delivery capabilities of the materials, both quaternized and native nanogels were loaded with pilocarpine hydrochloride via an absorption method, and their in vitro release profiles were analysed. The nanogels were found to exhibit a high loading capacity (>20% of total weight) and a sustained release over 6 h. [ABSTRACT FROM AUTHOR]

ABSTRACT Functional cationic polymers carrying mannose moieties were synthesized in a facile manner by employing RAFT polymerization. Initially, a protected carbohydrate based monomer, [2-(2,3,4,6-tetra- O-acetyl-α- d-mannopyranosyloxy)ethyl methacrylate (AcManEMA)], was prepared by the O-glycosylation of 2-hydroxyethyl methacrylate (HEMA). Subsequently, a macroRAFT agent of poly[2-(dimethyl)amino ethyl methacrylate] (PDMAEMA) was generated, and a further chain extension polymerization with AcManEMA was carried out in dioxane to form a acetylated mannose cationic diblock copolymer, PDMAEMA- b-PAcManEMA. It was attained in high yields and displayed low dispersity ( Ð). Acetylated mannose moieties on the polymer were deprotected with sodium methoxide and the amines from the DMAEMA block were protonated to yield a cationic diblock glycopolymer, PDMAEMA- b-PManEMA. The cationic property of polymers were characterized by mixing with a negatively charged siRNA duplex and a pDNA, and aggregates of 102 and 233 nm were obtained, respectively. Agarose gel shift assay revealed that the polymers were able to retain the nucleic acids as large polymer complexes. Lectin binding assay proved that the mannose residue on the polymers were only able to bind specifically with ConA. PNA lectin was employed as a control and did not show specific binding. The cationic glycopolymer could be advantageous in targeted nucleic acids delivery in specific cells. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44947. [ABSTRACT FROM AUTHOR]

A systematic investigation to fine-tune the cloud point of thermoresponsive poly[2-(dimethylamino)ethyl methacrylate) (p(DMAEMA)) aqueous solutions in a broad temperature interval is reported. For this research, p(DMAEMA)s of different molar mass are quaternized at distinct degrees with methyl iodide to obtain an expanded library of poly[DMAEMA- co-poly[2-(methacryloyloxy) ethyl] trimethylammonium iodide]s. Turbidity measurements show that depending on the molar mass of p(DMAEMA) and its degree of quaternization, the cloud point of the corresponding aqueous solutions can be adjusted within a rather broad temperature range from 23 to 70 °C. The cloud point and dynamics of the aggregation behavior of these polymers in the aqueous medium are also investigated by dynamic the light scattering. Furthermore, it is also found that the relationship between the molar mass and the cloud point of the respective aqueous solutions obeys an Arrhenius-type model. [ABSTRACT FROM AUTHOR]

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) samples were synthesizedviaaqueous atom transfer radical polymerization with DPnof 35, 151, 390, and 546 and dispersity of 1.13, 1.17, 1.20, and 1.18, respectively. All samples were exposed to temperature and pH variations at different concentration of polymer and salt (NaCl). Results indicated that cloud point (Tcl) can be controlled by changing DPn, polymer concentration, and ionic strength of solution. According to results,Tclof the PDMAEMA chains shifted to lower temperatures with increasing solution pH at all molecular weight ranges due to deprotonation of tertiary amine groups in polymer structure. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, higher polymer concentration acted as driving force to decrease cloud point of samples and formation of aggregates that was more predominant for higher molecular weights at alkaline media.Tclof PDMAEMA chains decreased with increasing ionic strength even at low pH values for low molecular weight polymers. [ABSTRACT FROM PUBLISHER]

The introduction of the DNA into mammalian cells remains a challenge in gene delivery, particularly in vivo. Viral vectors are unmatched in their efficiency for gene delivery, but may trigger immune responses and cause severe side-reactions. Non-viral vectors are much less efficient. Recently, our group has suggested that a star-shaped structure improves and even transforms the gene delivery capability of synthetic polycations. In this contribution, this effect was systematically studied using a library of highly homogeneous, paramagnetic nano-star polycations with varied arm lengths and grafting densities. Gene delivery was conducted in CHO-K1 cells, using a plasmid encoding a green fluorescent reporter protein. Transfection efficiencies and cytotoxicities varied systematically with the nano-star architecture. The arm density was particularly important, with values of approximately 0.06 arms/nm2 yielding the best results. In addition, a certain fraction of the cells became magnetic during transfection. The gene delivery potential of a nano-star and its ability to render the cells magnetic did not have any correlations. End-capping the polycation arms with di(ethylene glycol) methyl ether methacrylate (PDEGMA) significantly improved serum compatibility under transfection conditions; such nano-stars are potential candidates for future in vivo testing. [ABSTRACT FROM AUTHOR]

Zwitterion-functionalized polycations are ideal gene carriers with long circulation, high cellular uptaking and low cell viability. However, the trade-off between the DNA condensation efficiency and the cell viability must be addressed. The purpose of this study is to provide a microscopic insight into the DNA condensation process and to explore the effect of a zwitterionic block of zwitterion-functionalized polycation, which is of great significance in designing novel gene delivery systems. Poly[2-(dimethylamino)ethyl methacrylate-b-(sulfobetaine methacrylate)] (PDMAEMA-b-PSBMA) copolymers were synthesized and used as the model systems. Different from the conventional concept that the PSBMA zwitterionic block act only as the 'stealthy' groups, the subtle differences in physical and colloidal characteristics between the polycation/DNA polyplexes show that the PSBMA segment is capable of wrapping DNA attributed to the quaternary ammonium cations, without compromising the DNA condensation capability. On the other hand, the incorporation of PSBMA block reduces the surface charge of the polyplexes, which substantially result in the inefficient transfection and the reduced cytotoxicity. [ABSTRACT FROM AUTHOR]

Genetic modification ("transfection") of mammalian cells using non-viral, synthetic agents such as polycations, is still a challenge. Polyplex formation between the DNA and the polycation is a decisive step in such experiments. Star-shaped polycations have been proposed as superior transfection agents, yet have never before been compared side-by-side, e.g., in view of structural effects. Herein four star-shaped polycationic structures, all based on (2-dimethylamino) ethyl methacrylate (DMAEMA) building blocks, were investigated for their potential to deliver DNA to adherent (CHO, L929, HEK-293) and non-adherent (Jurkat, primary human T lymphocytes) mammalian cells. The investigated vectors included three structures where the PDMAEMA arms (different arm length and grafting densities) had been grown from a center silsesquioxane or silica-coated γ-Fe2O3-core and one micellar structure self-assembled from poly(1,2-butadiene)-block PDMAEMA polymers. All nano-stars combined high transfection potential with excellent biocompatibility. The micelles slightly outperformed the covalently linked agents. For method development and optimization, the absolute amount of polycation added to the cells was more important than the N/P-ratio (ratio between polycation nitrogen and DNA phosphate), provided a lower limit was passed and enough polycation was present to overcompensate the negative charge of the plasmid DNA. Finally, the matrix (NaCl vs. HEPES-buffered glucose solution), but also the concentrations adjusted during polyplex formation, affected the results. [ABSTRACT FROM AUTHOR]

The present work describes the acid-triggered condensation of silicic acid, Si(OH)4, as directed by selected polycations in aqueous solution in the pH range of 6.5-8.0 at room temperature, without the use of additional solvents or surfactants. This process results in the formation of silica-polyelectrolyte (S-PE) nanocomposites in the form of precipitate or water-dispersible particles. The mean hydrodynamic diameter (dh) of size distributions of the prepared water-dispersible S-PE composites is presented as a function of the solution pH at which the composite formation was achieved. Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and block copolymers of DMAEMA and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) were used as weak polyelectrolytes in S-PE composite formation. The activity of the strong polyelectrolytes poly(methacryloxyethyl trimethylammonium iodide) (PMOTAI) and PMOTAI-b-POEGMA in S-PE formation is also examined. The effect of polyelectrolyte strength and the OEGMA block on the formation of the S-PE composites is assessed with respect to the S-PE composites prepared using the PDMAEMA homopolymer. In the presence of the PDMAEMA60 homopolymer (Mw = 9400 g/mol), the size of the dispersible S-PE composites increases with solution pH in the range pH 6.6-8.1, from dh = 30 nm to dh = 800 nm. S-PDMAEMA60 prepared at pH 7.8 contained 66% silica by mass (TGA). The increase in dispersible S-PE particle size is diminished when directed by PDMAEMA300 (Mw = 47,000 g/mol), reaching a maximum of dh = 75 nm. S-PE composites formed using PDMAEMA-b-POEGMA remain in the range dh = 20-30 nm across this same pH regime. Precipitated S-PE composites were obtained as spheres of up to 200 nm in diameter (SEM) and up to 65% mass content of silica (TGA). The conditions of pH for the preparation of dispersible and precipitate S-PE nanocomposites, as directed by the five selected polyelectrolytes PDMAEMA60, PDMAEMA300, PMOTAI60, PDMAEMA60-b-POEGMA38 and PMOTAI60-b-POEGMA38 is summarized. [ABSTRACT FROM AUTHOR]

Due to their biodegradable character, polyesters such as polycaprolactone (PCL), poly( d , l -lactide) (PDLLA), and polylactic-co-glycolic acid (PLGA) were widely used as the hydrophobic cores of amphiphilic cationic nanoparticles (NPs) for siRNA delivery. However, fewer researches focused on facilitating siRNA delivery by adjusting the polyester composition of these nanoparticles. Herein, we investigated the contribution of polyester segments in siRNA delivery in vitro by introducing different ratio of DLLA moieties in PCL segments of mPEG-block-PCL-graft-poly(dimethylamino ethyl methacrylate)(PEG-b-PCL-g-PDMAEMA). It was noticed that compared with the other ratios of DLLA moieties, a certain molar ratio (about 70%) of the NPs, named mPEG 45 -P(CL 21 -co-DLLA 48 )-g-(PDMAEMA 29 ) 2 (PECLD-70), showed the highest gene knockdown efficiency but poorest cellular uptake ability in vitro. Further research revealed that NPs with various compositions of the polyester cores showed different physicochemical properties including particle size, zeta potential and stiffness, leading to different endocytosis mechanisms thus influencing the cellular uptake efficiency. Subsequently, we observed that the cells treated by PECLD-70 NPs/Cy5 siRNA complexes exhibited more diffuse Cy5 signal distribution than other NPs by confocal laser scanning microscope, which suggested that siRNA delivered by PECLD-70 NPs/Cy5 siRNA complexes possessed of stronger capabilities in escaping from endosome/lysosome, entering the RNA-induced silencing complex (RISC) and cutting the target mRNA efficiently. The different siRNA release profile was dominated by the degradation rate of polyester segments. Therefore, it could be concluded that the adjustment of hydrophobic core of cationic nanoparticles could significantly affect their transfection behavior and appropriate polyester composition should be concerned in designing of analogous siRNA vectors. [ABSTRACT FROM AUTHOR]

The biomass kraft lignin was modified into lignin-based macroinitiators (LnMI) through esterification of the alcohol and phenol functional groups on lignin backbone with 2-bromo-isobutyric bromide under mild condition. Then a series of cationic amphiphilic lignin-based graft copolymers were synthesized by atom transfer radical polymerization (ATRP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA) starting from the lignin-based macroinitiators. These copolymers, denoted as LnPDMAEMA, had a hyperbranched structure with a hydrophobic backbone of lignin and multiple cationic hydrophilic arms of PDMAEMA. The LnPDMAEMA copolymers were characterized by 1 H NMR and elemental analysis (EA), and studied in terms of their DNA binding capability, formation of nanoparticles with plasmid DNA (pDNA), cytotoxicity, and gene transfection in cultured cells. It was found that all the copolymers could efficiently compact pDNA into nanoparticles with sizes ranging from 100 to 200 nm at N/P ratios of 5 or higher. The cytotoxicity of these copolymers depends greatly on the chain length of PDMAEMA arms, the longer the PAMAEMA chain the higher the cytotoxicity. Luciferase assay was used to study the in vitro gene transfection for the LnPDMAEMA copolymers in different cell lines. The gene transfection efficiency of these copolymers was dependent on the grafted PDMAEMA chain length and N/P ratio. Generally, the transfection efficiency decreased with the increase of PAMAEMA length at N/P ratio of 20 or higher. It is very interesting that one of the LnPDMAEMA copolymers with very short arm length (degree of average DMAEMA units = 5.5) showed excellent in vitro transfection efficiency that was comparable or even higher than that of branched PEI (25K). These novel biomass-based LnPDMAEMA hyperbranched copolymers can be a promising nonviral gene vectors for future gene delivery application. [ABSTRACT FROM AUTHOR]