Amphiphilic Cationic Polymers Research Articles

Cationic Amphiphilic Comb-Shaped Polymer Emulsifier for Fabricating Avermectin Nanoemulsion with Exceptional Leaf Behaviors and Multidimensional Controlled Release.

The development of intelligent multifunctional nanopesticides featuring enhanced foliage affinity and hierarchical target release is increasingly pivotal in modern agriculture. In this study, a novel cationic amphiphilic comb-shaped polymer, termed PEI-TA, was prepared via a one-step Michael addition between low-molecular-weight biodegradable polyethylenimine (PEI) and tetradecyl acrylate (TA), followed by neutralization with acetic acid. Using the emulsifier PEI-TA, a positively charged avermectin (AVM) nanoemulsion was prepared via a phase inversion emulsification process. Under optimal formulation, the obtained AVM nanoemulsion (defined as AVM@PEI-TA) demonstrated exceptional properties, including small size (as low as 67.6 nm), high encapsulation efficiency (up to 87.96%), and high stability toward shearing, storage, dilution, and UV irradiation. The emulsifier endowed AVM@PEI-TA with a pronounced thixotropy, so that the droplets exhibited no splash and bounce when they were sprayed on the cabbage leaf. Owing to the electrostatic attraction between the emulsifier and the leaf, AVM@PEI-TA showed improved leaf adhesion, better deposition, and higher washing resistance in contrast to both its negatively charged counterpart and AVM emulsifiable concentrate (AVM-EC). Compared to the large-sized particles, the small-sized particles of the AVM nanoemulsion more effectively traveled long distances through the vascular system of veins after entering the leaf apoplast. Moreover, the nanoparticles lost stability when exposed to multidimensional stimuli, including pH, temperature, esterase, and ursolic acid individually or simultaneously, thereby promoting the release of AVM. The release mechanisms were discussed for understanding the important role of the emulsifier in nanopesticides.

Polyoxometalate-Polymer Directed Macromolecular Architectonics of Silver Nanoparticles as Effective Antimicrobials.

A novel inorganic-organic-inorganic ternary bioactive material formulated on antimicrobial peptide-based polymer has been reported. Supramolecular approach has been employed to incorporate molecularly crowded tyrosine-based polymer stabilized silver nanoparticles into membrane bound vesicles exploiting polyoxometalate-triggered surface templating strategy. Utilizing the covalent reversible addition fragmentation chain transfer (RAFT) polymerization and exploiting templated supramolecular architectonics at biopolymer interface, the bioactive ternary polymeric nanohybrids have been designed against Shigellosis leveraging the antibacterial activities of silver nanoparticle, cationic amphiphilic tyrosine polymer and inorganic polyoxometalate. The detail investigation against Shigella flexneri 2a cell line demonstrates that the collaborative mechanism of the ternary hybrid composite enhances the bactericidal activity in comparison to only polyoxometalate and polymer stabilized silver nanoparticle with an altered mechanism of action which is established via detailed biological analysis.

Aggregation behavior of cationic amphiphilic polymers and their application in metal-free leather retanning

The manufacture of metal-free leather is considered to be favorable for environment compared to conventional technology of chrome tanning. However, metal-free leather crust presents some disadvantages for further processing, like low isoelectric point (pI) and high hydrophilicity. Applying cationic amphiphilic polymer retanning agent is expected to overcome the disadvantages. The aggregation behavior of this polymer, which is influenced by its charged nature, will greatly affect the leather properties. However, the structure-function relationship has not been clarified yet. Here we synthesized a series of cationic amphiphilic acrylic polymers, Poly(SMA-co-DMA)s (PSDs), with increasing protonation degrees (PSD-40 %, PSD-60 %, PSD-80 %, PSD-100 %) and applied them to metal-free leather retanning. Experiments and molecular dynamics simulations show that PSD with higher protonation degree exhibits smaller aggregate size and better dispersion in water. PSD retanning significantly promotes the uptake of anionic fatliquors by leather (>90 %) because PSD enhances the pI of leather. PSD-40 % cannot be uniformly dispersed in water. PSD-60 %, PSD-80 % and PSD-100 % possess suitable particle size (45–90 nm) to penetrate into leather fibrils and form hydrophobic films, thereby greatly improving the hydrophobicity of leather. The hydrophobicity of leather increases with decreased protonation degree of PSD. Moreover, the fiber dispersion and organoleptic properties of leather are positively correlated with leather hydrophobicity because of the separating and lubricating effects of the amphiphilic PSD.

Potentiating the Immune Responses of HBsAg-VLP Vaccine Using a Polyphosphoester-Based Cationic Polymer Adjuvant.

Virus-like particle (VLP)-based vaccines are required to be associated with a suitable adjuvant to potentiate their immune responses. Herein, we report a novel, biodegradable, and biocompatible polyphosphoester-based amphiphilic cationic polymer, poly(ethylene glycol)-b-poly(aminoethyl ethylene phosphate) (PEG-PAEEP), as a Hepatitis B surface antigen (HBsAg)-VLP vaccine adjuvant. The polymer adjuvant effectively bound with HBsAg-VLP through electrostatic interactions to form a stable vaccine nanoformulation with a net positive surface charge. The nanoformulations exhibited enhanced cellular uptake by macrophages. HBsAg-VLP/PEG-PAEEP induced a significantly higher HBsAg-specific IgG titer in mice than HBsAg-VLP alone after second immunization, indicative of the antigen-dose sparing advantage of PEG-PAEEP. Furthermore, the nanoformulations exhibited a favorable biocompatibility and in vivo tolerability. This work presents the PEG-PAEEP copolymer as a promising vaccine adjuvant and as a potentially effective alternative to aluminum adjuvants.

Smart Copolymer Surface Derived from Geminized Cationic Amphiphilic Polymers for Reversibly Switchable Bactericidal and Self-Cleaning Abilities.

Bacterial adhesion and colonization on material surfaces pose a serious problem for healthcare-associated devices. Cationic amphiphilic polymer brushes are usually used as surface coatings in antibacterial materials to endow an interface with excellent bactericidal efficiency, but they are easily contaminated, which puts a great limitation on their application. Herein, novel antibacterial copolymer brush surfaces containing geminized cationic amphiphilic polymers (pAGC8) and thermoresponsive poly(N-isopropylacrylamide) polymers (pNIPAm) have been synthesized. Surface functionalization of polymer brushes was investigated by X-ray photoelectron spectroscopy, spectroscopic ellipsometry, atomic force microscopy, and water contact angle measurements. A proportion of AGC8 and NIPAm units in copolymer brushes has been adjusted to obtain a high-efficiency bactericidal surface with minimal interference to its self-cleaning property. The killing and releasing efficiency of the optimized surface simultaneously reached up to above 80% for both Staphylococcus aureus and Escherichia coli bacteria, and the bactericidal and self-cleaning abilities are still excellent even after three kill-release cycles. Such a novel copolymer brush system provides innovative guidance for the development of high-efficiency antibacterial materials in biomedical application.

Synergy effect of bactericidal and antifouling with structure reversion and hydrolysis of cationic amphiphilic copolymer PHMA-b-PCBMAE to zwitterionic copolymer

In this study, cationic amphiphilic copolymers of poly(hexadecyl methacrylate)-b-poly(carboxybetaine methacrylate ester) (PHMA-b-PCBMAE) with hydrophobic unit of 100 were synthesized, which can be self-assembled as core-shell nanoparticles with PCBMAE as core and PHMA as shell in chloroform. In response to the change of solvent polarity from chloroform to methanol, the reversion ability of core-shell structure occurred to cationic amphiphilic polymers of PHMA100-b-PCBMAE40, PHMA100-b-PCBMAE50, PHMA100-b-PCBMAE75 and PHMA100-b-PCBMAE100 in an ascending order, which was verified by 1H NMR results. Coatings embedded with the cationic copolymers with PHMA:PCBMAE block ratios of 100:75 and 100:100 showed remarkably decreased water contact angle and protein adsorption amount due to the resulted zwitterionic copolymers upon hydrolysis in aqueous solution. Moreover, dynamic recording of the bactericidal activity against E. coli and S. aureus showed that it took ∼18 h for the copolymers PHMA100-b-PCBMAE75 and PHMA100-b-PCBMAE100 to take effect in bacteria killing and foulant repelling, and the bacteria left on the coating surfaces were <1.0 % in 24 h. The bactericidal results were in good accord with the trend of the nanoparticle reversion ability, indicating that higher PCBMAE contents of the cationic diblock copolymer facilitated core-shell reversion and subsequent hydrolysis to zwitterionic copolymer. Moreover, the regenerable surfaces of the coating furtherly ensured the sustainable bactericidal and antifouling activities.

Evaluation of the Efficiency of Random and Diblock Methacrylate-Based Amphiphilic Cationic Polymers against Major Bacterial Pathogens Associated with Cystic Fibrosis.

Cystic fibrosis (CF) is associated with repeated lung bacterial infection, mainly by Pseudomonas aeruginosa, Staphylococcus aureus, and Mycobacterium abscessus, all known to be or becoming resistant to several antibiotics, often leading to therapeutic failure and death. In this context, antimicrobial peptides and antimicrobial polymers active against resistant strains and less prompt to cause resistance, appear as a good alternative to conventional antibiotics. In the present study, methacrylate-based copolymers obtained by radical chemistry were evaluated against CF-associated bacterial strains. Results showed that the type (Random versus Diblock) and the size of the copolymers affected their antibacterial activity and toxicity. Among the different copolymers tested, four (i.e., Random10200, Random15000, Random23900, and Diblock9500) were identified as the most active and the safest molecules and were further investigated. Data showed that they inserted into bacterial lipids, leading to a rapid membranolytic effect and killing of the bacterial. In relation with their fast bactericidal action and conversely to conventional antibiotics, those copolymers did not induce a resistance and remained active against antibiotic-resistant strains. Finally, the selected copolymers possessed a preventive effect on biofilm formation, although not exhibiting disruptive activity. Overall, the present study demonstrates that methacrylate-based copolymers are an interesting alternative to conventional antibiotics in the treatment of CF-associated bacterial infection.

Synthesis and anti-bacterial/fungal activities of amphiphilic polysiloxanes primary ammonium salts

Amphiphilic cationic polymers are currently used as antimicrobial agents to disrupt microbial membranes with long-termed stability and low bio-toxicity. However, there are few studies on the relationship between molecular structure and antimicrobial properties of amphiphilic polymers containing primary amine salts against fungi. In this work, a series of polysiloxanes graft primary ammonium salts (PDMS-g-AH) with tunable molecular weights (3 kDa, 5 kDa, 8 kDa, and 10 kDa) and grafting ratios (50% and 75%) were synthesized via thiol-ene “click reaction”, and the effect of their structural parameters on the broad-spectrum inhibition of bacteria (Escherichia coli and Staphylococcus albus) and pathogenic fungi (Candida albicans), especially on two phytopathogenic fungi (Fusarium oxysporum f. sp. cubense race 4 (Foc4) and Rhizoctonia solani (R. solani)) were systematically assessed. The aggregation of polymers in water was characterized by the critical micelle concentration (CMC) values, zeta potentials, and particle sizes and distributions. All PDMS-g-AH had positive zeta-potential values and exhibited high micellar stability in water. At the same time, the aggregation characteristics of polymers are affected by the structure and molecular weight of polymers. Small aggregates and high zeta-potentials interacted easily with the microbial cell membranes, which affected the antimicrobial activity together. These results indicated that the block type of PDMS-g-AH, i.e., PDMS-b-AH, showed better antimicrobial activities than the random type (PDMS-co-AH), and the optimal antimicrobial activities were obtained for moderate polymer chain length (about 5 kDa). This work reveals the relationship between the chemical structure of PDMS-g-AH, their aggregation behavior in water as well as interaction with biological membranes during the sterilization process, which provides the potential applications as fungicidal agents for effectively controlling plant diseases, such as rice sheath blight and banana Fusarium wilt.

A Cationic Amphiphilic AIE Polymer for Mitochondrial Targeting and Imaging.

Mitochondria are important organelles that play key roles in generating the energy needed for life and in pathways such as apoptosis. Direct targeting of antitumor drugs, such as doxorubicin (DOX), to mitochondria into cells is an effective approach for cancer therapy and inducing cancer cell death. To achieve targeted and effective delivery of antitumor drugs to tumor cells, to enhance the therapeutic effect, and to reduce the side effects during the treatment, we prepared a cationic amphiphilic polymer with aggregation-induced emission (AIE) characteristic. The polymer could be localized to mitochondria with excellent organelle targeting, and it showed good mitochondrial targeting with low toxicity. The polymer could also self-assemble into doxorubicin-loaded micelles in phosphate buffer, with a particle size of about 4.3 nm, an encapsulation rate of 11.03%, and micelle drug loading that reached 0.49%. The results of in vitro cytotoxicity experiments showed that the optimal dosage was 2.0 μg/mL, which had better inhibitory effect on tumor cells and less biological toxicity on heathy cells. Therefore, the cationic amphiphilic polymer can partially replace expensive commercial mitochondrial targeting reagents, and it can be also used as a drug loading tool to directly target mitochondria in cells for corresponding therapeutic research.

Self-Assembly in water of C60 fullerene into isotropic nanoparticles or nanoplatelets mediated by a cationic amphiphilic polymer

HypothesisTo disperse high concentration of C60 fullerene in water, we propose to use an emulsification-evaporation process in the presence of an amphiphilic polymer whose chemical structure has been chosen for inducing specific interaction with fullerene The viscosity enhancement provided by self-assembly of the amphiphilic polymers in water should result in high stability of the suspensions. The organic solvent has also to been chosen so as to maximize the initial fullerene concentration. ExperimentsThe concentrations of polymer and fullerene, the solvent type and the volume fraction of the organic phase have been varied. Their influence on the concentration of the fullerene dispersions and on the size and shape of the resulting nanoparticles have been investigated by UV–Visible spectroscopy, light scattering and cryo-transmission electron microscopy experiments. FindingsThe resulting nanoparticles consist of aggregates of C60 fullerene stabilized by the cationic polymer with morphologies/sizes tunable through fullerene and polymer concentration. At high fullerene concentration, nanoplatelets are obtained that consist in thin 2D nanocrystals. Their suspensions are very stable with time due to the viscosity of the dispersing aqueous medium. The concentration of fullerene nanoparticles dispersed in water is as high as 8 g/L which corresponds to an upper limit that has never been reached so far.

Amphiphilic cationic triblock polymers for p53-mediated triple-negative breast cancer gene therapy

Polycationic vectors are a promising class of gene delivery systems. To improve delivery efficiency and reduce cytotoxicity, hydrophobic modification has been proposed as an effective way. Herein, we synthesized a class of terpolymer vectors with various hydrophobicities as well as multiple biodegradable disulfide bonds and cationic side chains. The chemical structure and hydrophobic modification ratio of polymers were characterized. The amphiphilic vectors were able to condense pDNA to form flexible and uniform nanoparticles with a size of 60–85 nm. The shielding effect of hydrophobic side chains led to a lower zeta potential and reduced cytotoxicity. The endocytosis efficiency of amphiphilic vectors was significantly increased and the endocytosis pathway shifted from mainly via the clathrin pathway to clathrin/caveolae/lipid raft co-mediated endocytosis. The amphiphilic vectors demonstrated significantly higher transfection efficiency. In addition, the hydrophobic structural domain of polymers could improve serum stability, alleviating the serum inhibition commonly seen in cationic polymers. Then, we tested the tumor-suppressor gene wtp53 delivered by the amphiphilic vectors in triple-negative breast cancer models both in vitro and in vivo. Tumor cell cycle arrest and apoptosis were triggered through the regulation of downstream cell cycle proteins and apoptosis proteins, inhibiting tumor growth with an excellent safety profile.

Antimicrobial activities of amphiphilic cationic polymers and their efficacy of combination with novobiocin

Today, drug-resistant bacteria represent a significant problem worldwide. In fact, bacteria are becoming resistant even to newly developed antibiotics. Therefore, there is an urgent need to develop antibiotics to which bacteria cannot become resistant. In this study, antimicrobial polymers to which bacteria cannot develop resistance were prepared from 6-aminohexyl methacrylamide and N-isopropyl acrylamide. The polymers with molecular weights of the order of 105 showed little antimicrobial activity against Staphylococcus aureus and Escherichia coli as well as low toxicity. On the other hand, polymers with lower molecular weights (of the order of 104) did show antimicrobial activity against S. aureus and E. coli. These polymers were combined with novobiocin to investigate the combined usage effects against E. coli. The combined usage of novobiocin and the low-molecular-weight polymers reduced the minimum inhibitory concentration, which was less than 0.0625 μg/mL against E. coli. This result indicates that the combination is useful for increasing the efficacy of antibiotics and broadening their antimicrobial spectrum. Furthermore, the results showed the possibility that the antimicrobial polymers serve not only as antibiotics to which bacteria have not developed resistance but also as adjuvants for other antibiotics.

Mechanistic Study of Membrane Disruption by Antimicrobial Methacrylate Random Copolymers by the Single Giant Vesicle Method.

Cationic amphiphilic polymers have been a platform to create new antimicrobial materials that act by disrupting bacterial cell membranes. While activity characterization and chemical optimization have been done in numerous studies, there remains a gap in our knowledge on the antimicrobial mechanisms of the polymers, which is needed to connect their chemical structures and biological activities. To that end, we used a single giant unilamellar vesicle (GUV) method to identify the membrane-disrupting mechanism of methacrylate random copolymers. The copolymers consist of random sequences of aminoethyl methacrylate and methyl (MMA) or butyl (BMA) methacrylate, with low molecular weights of 1600-2100 g·mol-1. GUVs consisting of an 8:2 mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol), sodium salt (POPG) and those with only 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were prepared to mimic the bacterial (Escherichia coli) or mammalian membranes, respectively. The disruption of bacteria and mammalian cell membrane-mimetic lipid bilayers in GUVs reflected the antimicrobial and hemolytic activities of the copolymers, suggesting that the copolymers act by disrupting cell membranes. The copolymer with BMA formed pores in the lipid bilayer, while that with MMA caused GUVs to burst. Therefore, we propose that the mechanism is inherent to the chemical identity or properties of hydrophobic groups. The copolymer with MMA showed characteristic sigmoid curves of the time course of GUV burst. We propose a new kinetic model with a positive feedback loop in the insertion of the polymer chains in the lipid bilayer. The novel finding of alkyl-dependent membrane-disrupting mechanisms will provide a new insight into the role of hydrophobic groups in the optimization strategy for antimicrobial activity and selectivity.

Screening and Matching Amphiphilic Cationic Polymers for Efficient Antibiosis.

The amphiphilic cationic polymers that mimic antimicrobial peptides have received increasing attention due to their excellent antibacterial activity. However, the relationship between the structure of cationic polymers and its antibacterial effect remains unclear. In our current work, a series of PEG blocked amphiphilic cationic polymers composed of hydrophobic alkyl-modified and quaternary ammonium salt (QAS) moieties have been prepared. The structure-antibacterial activity relationship of these cationic polymers was investigated against E. coli and S. aureus, including PEGylation, random structure, molecular weights, and the content and lengths of the hydrophobic alkyl side chains. The results indicated that PEGylated random amphiphilic cationic copolymer (mPB35/T57) showed stronger antibacterial activity and better biocompatibility than the random copolymer without PEG (PB33/T56). Furthermore, mPB35/T57 with appropriate mole fraction of alkyl side chains (falkyl = 0.38), degree of polymerization (DP = 92), and four-carbon hydrophobic alkyl moieties was found to have the optimal structure that revealed the best antibacterial activities against both E. coli (MIC = 8 μg/mL, selectivity > 250) and S. aureus (MIC = 4 μg/mL, selectivity > 500). More importantly, mPB35/T57 could effectively eradicate E. coli biofilms by killing the bacteria embedded in the biofilms. Therefore, the structure of mPB35/T57 provided valuable information for improving the antibacterial activity of cationic polymers.

Hierarchical Surface Inspired by Geminized Cationic Amphiphilic Polymer Brushes for Super-Antibacterial and Self-Cleaning Properties.

Pathogenic bacteria adhesion and formation of biofilm on the implant are the most common reasons for healthcare-associated device failure. Cationic amphiphilic polymer brushes containing covalently linked quaternary ammonium salts (QASs) are considered to be the most promising bactericidal materials, but these surfaces still suffer from incomplete bactericidal ability and serious microorganism accumulation. With this in mind, a novel kind of hierarchical surface integrating both geminized cationic amphiphilic antibacterial upper layer and zwitterionic antifouling sublayer has been developed in this study. Measurements of X-ray photoelectron spectroscopy, spectroscopic ellipsometry, atomic force microscopy, water contact angle, and surface ζ-potential were performed to investigate the surface functionalization process. The thicknesses and grafting densities of the pAGC8 upper blocks have been optimized to avert the mutual interference among different components. The optimal hierarchical surface exhibits an ultrahigh antibacterial activity and a potent self-cleaning functionality against both Staphylococcus aureus and Escherichia coli bacteria, as well as a certain protein repellence ability. Such a novel hierarchical architecture provides innovative guidance for the construction of super-antibacterial and self-cleaning brushes in many biomedical applications.

Surface Curvature and Aminated Side-Chain Partitioning Affect Structure of Poly(oxonorbornenes) Attached to Planar Surfaces and Nanoparticles of Gold.

Cationic amphiphilic polymers are often used to coat nanoparticles as they increase chemical stability in solution and exhibit membrane disruption activities. Among these, poly(oxonorbornenes) (PONs) are tunable membrane disruptors. They can be constructed with either one amine-terminated side chain and one hydrophobic alkyl side chain (PON-50) or two amine-terminated side chains (PON-100) on each repeat unit and can then be conjugated to gold nanoparticles using O-(2-carboxyethyl)-O'-(2-mercaptoethyl) heptaethylene glycol (HEG) spacers. While the amine content and membrane disruption activity of PONs can be controlled, the detailed structural properties of PONs conjugated to gold nanoparticles remain less understood. To address this, we performed molecular dynamics simulations of PON-50 and PON-100 to determine the nonbonded energies of PON structures as a function of amine composition. We found increasing energetic stabilization with decreasing amine composition. These results were consistent with experimental observations obtained with X-ray photoelectron spectroscopy (XPS) in which PON-100 was found to have the lowest conjugation efficiency to gold surfaces out of a range of PON amination ratios. Computationally obtained energetics suggest that replacing the aliphatic amine groups with aromatic amine groups can reverse this behavior and lead to more stable PON structures with increasing amine content. We also found that the curvature of the gold nanoparticle surface affects interactions between the surface and the amine groups of PON-50. Increasing curvature decreased these interactions, resulting in a smaller effective footprint of the HEG-PON-50 structure.

Enhancing antibacterial activity of geminized cationic amphiphilic polymer via structure control and self-assembly regulation

A novel geminized amphiphilic polymer containing double cationic head groups and hydrophobic tails in each structural unit (denoted as PAGBn), has been prepared in our study. The self-assembly behavior on the solid/liquid interface was investigated by quartz crystal microbalance with dissipation (QCM-D), steady-state fluorescence, dynamic light scattering (DLS) and transmission electron microscope (TEM). A two-regime buildup can be observed, where the first regime is attributed to the rapid adsorption of polymers, while a rearrangements of pre-adsorbed molecules and their aggregation on the surface dominate the second regime, exhibiting a formation of aggregates in large sizes due to the effect of the charge density and hydrophobes on the self-assembly process. It exhibits a drastically enhanced killing efficiency of ∼99.9% against both of Staphylococcus aureus and Escherichia coli bacteria for PAGBn compared with other traditional single-chained polymers, through the reinforced synergistic effect of electrostatic and hydrophobic interactions, and the formation of large-sized polymer aggregates, encompassing and killing the bacteria more efficiency. Our findings reveal the antibacterial mechanism and the correlation between antibacterial activity and aggregates structure, providing a basis for the development of super-antibacterial materials in the infection resistant applications.

Effect of aging time on the viscoelastic properties of amphiphilic polymer-polyacid supramolecular solution

An amphiphilic polymer-based supramolecular system was formulated by exploring the electrostatic interactions between the cationic amphiphilic polymer and polyacid. The effect of aging time on the viscoelastic properties, salt and temperature tolerance, shear resistance, and viscosity recovery of the system was explored by means of rheological measurements. The intrinsic relationship between the viscoelasticity of the system at different aging times and their dynamic growth was studied by macro-rheological and optical micro-rheological methods. The results show that under the influence of various factors, the viscoelastic properties of the supramolecular system increase significantly with aging. Optical micro-rheological studies demonstrated that the viscoelasticity of the system continues to increase over a period of 30 days. After aging, the viscoelastic results indicate the formation of a strong gel. This study clearly demonstrates that the aging time is a key factor that should be considered in the formulation of supramolecular systems formed by the electrostatic interaction between the cationic amphiphilic polymer and polyacid.

Light-responsive polymersomes with a charge-switch for targeted drug delivery

Unlike the traditional block amphiphilic polymersomes, we herein report a lipid-like amphiphilic polymer that self-assembles into photo-responsive polymersomes for drug delivery. The introduction of a quaternary ammonium moiety not only provides a hydrophilic segment of the polymersomes, but also enables electrostatic adsorption with folic acid, thus achieving the targeting of cancer cells with overexpression of folate receptor. Upon light irradiation, the photocleavage reaction of the o-nitrobenzyl moiety disintegrates polymersomes by changing the polymer structure from cationic amphiphilic state to zwitterionic hydrophilic state, thus realizing photo-triggered drug release. The data showed that anticancer drugs (doxorubicin hydrochloride, DOX·HCl) can be loaded into the hydrophilic cavity of polymersomes and controllably released by photo-induced disintegration of polymersomes. Cellular assay showed that the active targeting of folic acid and photo-triggered release endowed the DOX-loaded polymersomes with a higher cytotoxicity to HeLa cells. Such cationic polymersomes provide a novel strategy for designing effective and intelligent drug carriers, and have potential application as a novel integrated platform for targeted drug delivery.

Amphiphilic cationic polymers as effective substances improving the safety of use of body wash gels

Cationic surfactants have a wide range of applications in the cosmetic industry. The present study is an attempt to determine the effect of an amphiphilic cationic polymer – a cationic derivative of guar gum – on the safety of use of body wash cosmetics. Model body wash gels based on an anionic surfactant, containing 0.05, 0.25 and 0.5% of the studied compound, were subjected to analyses in order to evaluate their skin irritation effect and the ability to solubilize model sebum. Cell culture studies were also carried out. In addition, the effect of the cationized guar gum derivative on the key quality parameters of body wash cosmetics (viscosity and foaming properties) was assessed. The analyses showed that the addition of the cationic guar gum derivative induced a significant increase in the safety of use of the model body wash gels without causing any impairment of the functional properties of the product.