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Hydrogels as wound dressing have attracted extensive attention in past decade because they can provide moist microenvironment to promote wound healing. Herein, this research designed a multifunctional hydrogel with antibacterial property and antioxidant activity fabricated from quaternary ammonium bearing light emitting quaternized TPE-P(DAA-co-DMAPMA) (QTPDD) and poly(aspartic hydrazide) (PAH). The protocatechuic aldehyde (PCA) grafted to the hydrogel through dynamic bond endowed the hydrogel with antioxidant activity and the tranexamic acid (TXA) was loaded to enhance the hemostatic performance. The hydrogel possesses preferable gelation time for injectable application, good antioxidant property and tissue adhesion, improved hemostatic performance fit for wound repairing. Furthermore, the hydrogel has excellent antimicrobial property to both E. coli and S. aureus based on quaternary ammonium structure. The hydrogel also showed good biocompatibility and the in vivo experiments proved this hydrogel can promote the wound repairing rate. This study suggests that TXA/hydrogel with quaternary ammonium structure and dynamic grafted PCA have great potential in wound healing applications. • Quaternary ammonium bearing copolymer QTPDD was synthesized through two step reaction. • The antibacterial hydrogel with biodegradability was prepared QTPDD and PAH. • Protocatechualdehyde with antioxidant activity was grafted onto the hydrogel by dynamic bond. • Tranexamic acid was loaded to the hydrogel to enhance the hemostatic performance of the hydrogel. • The multifunctional hydrogel showed good hemostatic property and enhance the wound healing. [ABSTRACT FROM AUTHOR]

Highlights • An environmentally friendly MPASPs was put forward and synthesized. • PEM and SPA were introduced into PASP to improve the performance of superplasticizer. • The MPASPs could improve the fluidity of cement paste and the strength of cement mortar. • The MPASPs could inhibit early cement hydration while had little effect on later cement hydration. Abstract The environmentally friendly polycarboxylate superplasticizer based on modified poly(aspartic acid) (MPASPs) with varied grafting densities were prepared by partially ring-opening reaction of polysuccinimide (PSI) with polyetheramine M2005 (PEM) and sodium p-aminobenzenesulfonate (SPA) and subsequently hydrolyzing of the remaining imide ring under mildly alkaline conditions. FTIR was used to characterize the MPASPs. The properties of the MPASPs were evaluated by fluidity of cement paste, flexural strength of hardened cement mortar, adsorption amount on cement particle surface, zeta potential of cement paste, XRD and TG-DSC analysis. The results revealed that the MPASPs with proper incorporation of polyether side chains and benzene sulfonic acid groups could improve the fluidity of cement paste and the mechanical property of cement mortar. The fluidity of cement paste doped with MPASP-3 was 197% higher than that of PASP, and the cement mortar with MPASP-3 shown the highest flexural strength at both ages of 7 d and 28 d. The MPASPs could inhibit the early cement hydration while had little effect on later cement hydration. Based on the above results, the dispersion model of MPASPs in cement–water system was also discussed. This study offered a novel environmentally friendly superplasticizer based on a biodegradable green polymer and simple synthesis method. [ABSTRACT FROM AUTHOR]

Poly(aspartic acid) (PASP) hydrogels have gained significant attention in recent years due to their excellent biocompatibility, biodegradability and tunable swelling behavior. This comprehensive review presents an overview of past and current research efforts focusing on PASP hydrogels, their functionalization strategies, processing methods and applications. The chemical functionalization of PASP is addressed, highlighting the ability to tailor the functionalities of PASP for customization. Precise control over functional groups for crosslinking enables the preparation of PASP hydrogels that can respond to environmental triggers, rendering them valuable for applications including, yet not limited to, controlled drug release, tissue engineering and self-healing concrete. Furthermore, the processing methods employed to produce PASP in different forms, such as films, nanoparticles and fibers are described. Finally, the applications of PASP hydrogels are overviewed, highlighting their potential to help improving human health and environmental sustainability by providing an alternative for fossil-based hydrogels. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract The synthesis of a chemically cross-linked polymer hydrogel consisting exclusively of amino acids is described in this paper. A natural amino acid, aspartic acid was polymerized to polysuccinimide which was cross-linked by a tetrapeptide sequence designed for proteolytic degradation, and then the corresponding poly(aspartic acid) hydrogel was obtained by alkaline hydrolysis. The hydrogel dissolved in the presence of trypsin. According to in vitro cellular assays, the degradation products of the hydrogel cross-linked with the peptide were non-cytotoxic and non-cytostatic. The sustained release of an encapsulated macromolecular model drug, FITC-dextran, was triggered by the degradation of the hydrogel induced by trypsin. These results suggest the potential application of the trypsin-responsive hydrogel for drug delivery in the small intestine. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

While curcumin has a broad range of beneficial properties such as anticancer, antioxidant and antibacterial activities, its poor solubility, low stability and non-selectivity toward tumor cells often limit its applications. Herein, we described the preparation and characterization of a new fully biocompatible graft copolymer from folic acid/amylose-functionalized poly(aspartic acid) (FA-PAsp-Am) as an effective nanocarrier using a simple aminolysis method. The inclusion complex formation ability of amylose (Am) with curcumin (Cur) as well as its glycotargeting ability when it grafted to the polyaspartic acid (PAsp) backbone as a side chain, could impart more selectivity to tumor cells, promote the solubility of curcumin and improve its stability against UV–Visible irradiation, as demonstrated by UV–Visible exposure test results. The obtained data from FT-IR, H-NMR, Fluorescence, SEM, DLS and UV–Visible techniques confirmed the successful synthesis of the polymer nanocarrier. The observed nanofiber like morphology (20 nm width by SEM) of the nanocarrier and the host-guest interaction of curcumin with the amylose helices facilitate the high efficiency of the drug loading. The influence of pH, on the curcumin release behavior also was assessed. Furthermore, the antioxidant ability of curcumin was largely maintained after the loading in the FA-PAsp-Am system. These properties collectively make the folic acid (FA) functionalized poly(aspartic acid)-graft-amylose@curcumin of potential interest for various biomedical applications such as targeted drug delivery systems. [ABSTRACT FROM AUTHOR]

Poly(amino acid) based self-healing hydrogels have important application in biomedications. In this research, the catechol pendant groups were imported to poly(aspartic acid) based self-healing hydrogel to improved skin adhesion and ROS scavenging performance. The poly(succinimide) (PSI) was reacted with 3,4-dihydroxyphenylalanine (DA) and then hydraziolyzed to import catechol group and hydrazide group respectively, which are responsible for mussel inspired tissue adhesion and dynamic coupling reactivity. The dopamine modified poly(aspartic hydrazide) (PDAH) was reacted with PEO 90 dialdehyde (PEO 90 DA) to prepare hydrogels, and the resultant hydrogel showed good biocompatibility both in vitro and in vivo. The skin adhesion strength of the mussel inspired hydrogel increased notably with enhanced radical scavenging efficiency fit for in vivo wound repairing applications. The PDAH/PEO 90 DA hydrogel also showed sustained albumin release profile and the in vivo wound repairing experiment proved the mouse Epidermal Growth Factor (mEGF) loaded hydrogel as wound dressing material accelerated the wound repairing rate. [Display omitted] • The PSI was reacted with dopamine and hydrazine to synthesis catechol bearing poly(aspartic hydrazide) PDAH. • The PDAH was reacted with PEO 90 DA to fabricate hydrogels through dynamic hydrazone bonds. • The catechol bearing self-healing hydrogel showed enhanced ROS scavenging performance and tissue adhesion. • The hydrogel with mEGF loading accelerated the wound repairing rate in mice model. [ABSTRACT FROM AUTHOR]

A novel multifunctional nanosystem formed by magnetite nanoparticles coated with pH-responsive poly(aspartic acid) hydrogel was developed. Magnetite nanoparticles (Fe 3 O 4 ) have been intensively investigated for biomedical applications due to their magnetic properties and dimensions similar to the biostructures. Poly(aspartic acid) is a water-soluble, biodegradable and biocompatible polymer, which features makes it a potential candidate for biomedical applications. The nanoparticles surface modification was carried out by crosslinking polysuccinimide on the magnetite nanoparticles surface and hydrolyzing the succinimide units in mild alkaline medium to obtain the magnetic poly(aspartic acid) hydrogel. The surface modification in each step was confirmed by DRIFTS, TEM and zeta potential measurements. The hydrodynamic diameter of the nanosystems decreases as the pH value decreases. The nanosystems showed high colloidal stability in water and no cytotoxicity was detected, which make these nanosystems suitable for biomedical applications. [ABSTRACT FROM AUTHOR]

Macromolecular co-assemblies built up in aqueous solutions, by using a linear polypeptide, poly(aspartic acid) (PAS), and a globular protein, bovine serum albumin (BSA), have been studied. The main interest was to identify the optimum conditions for an interpenetrated complex formation in order to design materials suitable for biomedical applications, such as drug delivery systems. BSA surface possesses several amino- and carboxylic groups available for covalent modification, and/or bioactive substances attachment. In the present study, mixtures between PAS and BSA were investigated at 37 °C in dilute aqueous solution by viscometry, dynamic light scattering and zeta potential determination, as well as in solid state by AFM microscopy and dielectric spectroscopy. The experimental data have shown that the interpolymer complex formation occurs for a PAS/BSA molar ratio around 0.541. [ABSTRACT FROM AUTHOR]

Poly(aspartic acid) (PASP) derivatives with adjustable pH-dependent solubility were synthesized and characterized to establish the relationship between their structure and solubility in order to predict their applicability as a basic material for enteric coatings. Polysuccinimide, the precursor of PASP, was modified with short chain alkylamines, and the residual succinimide rings were subsequently opened to prepare the corresponding PASP derivatives. Study of the effect of the type and concentration of the side groups on the pH-dependent solubility of PASP showed that solubility can be adjusted by proper selection of the chemical structure. The Henderson–Hasselbalch (HH) and the extended HH equations were used to describe the pH-dependent solubility of the polymers quantitatively. The estimate provided by the HH equation is poor, but an accurate description of the pH-dependent solubility can be found with the extended HH equation. The dissolution rate of a polymer film prepared from a selected PASP derivative was determined by fluorescence marking. The film dissolved rapidly when the pH was increased above its pK a . Cellular viability tests show that PASP derivatives are non-toxic to a human cell line. These polymers are thus of great interest as starting materials for enteric coatings. Statement of Significance Poly(amino acid) type biocompatible polymers were synthesized for future use as pharmaceutical film coatings. To this end, we tailored the pH-dependent solubility of poly(aspartic acid) (PASP). It was found that both the solubility and the pK a values of the modified PASP depended strongly on composition. Fluorescent marking was used to characterize the dissolution of a chosen PASP derivative. In acidic media only a negligible amount of the polymer dissolved, but dissolution was very fast and complete at the pH values that prevail in the small intestine. As a consequence, enteric coatings based on such PASP derivatives may be used for drug delivery in the gastrointestinal tract. [ABSTRACT FROM AUTHOR]

A series of 14 cationic derivatives of poly(aspartic acid) i.e. cationic polyaspartamides with different (dialkylamino)alkyl and alkyl or hydroxyalkyl side groups was synthesized by nucleophilic addition on polysuccinimide. The resulting polyaspartamides have moderate amphiphilic properties. Relationships between the structure and ratio of side groups and in vitro properties of polyaspartamides, including their cytotoxic and membrane-damaging activity towards human cell lines, primary skin fibroblasts and erythrocytes, were established and discussed. Cationic polyaspartamides vary in their DNA-binding, condensing and nuclease-protecting characteristics depending on the concentration ratio of (dialkylamino)alkyl and alkyl or hydroxyalkyl side groups. Effective cell transfection was achieved upon polyaspartamide-mediated plasmid DNA delivery in serum-free medium in the presence of chloroquine. Effect of serum proteins adsorption onto polyaspartamide based polyplexes, and the role of concentration of polyplexes in culture medium in their colloidal stability and transfection process were demonstrated. Synthesized polyaspartamides are biocompatible and long-acting gene carriers, which are applied to cells after dilution and without washing, thus providing transfection level comparable to that of commercial transfection reagent. [ABSTRACT FROM AUTHOR]

The development of wound dressings with antibacterial activities and simultaneous pro-healing functions are always urgent in treating bacterial wound infection. Herein, a novel multifunctional self-healing hydrogel was designed and prepared by crosslinking quaternary ammonium/boronic acid modified poly(aspartic acid) and poly (vinyl alcohol) polymers with targeted peptide MP196- conjugated polydopamine. The formation of this hydrogel not only improves the biocompatibility of quaternary poly(aspartic acid), but also enhances antibacterial efficacy by pH-triggering dissociation under the low pH bacterial microenvironment. Moreover, precise photothermal treatment can be achieved. In vitro study suggested high synergistic antibacterial efficiency(∼100 %) under near-infrared light, significantly higher than a single antibacterial strategy (66.0–82.6 %). In vivo study suggested infected wounds treated with the hydrogel showed an optimal healing rate(92.0 %) after 7 days. The survival rate of the bacteria in the epidermal tissues was reduced to 2.3 %. Besides, the suitable self-healing property of this hydrogel facilitated its application in the diversity of wound shapes. Thus, the novel poly(aspartic acid) hydrogel might be a promising candidate for precise therapy of bacteria-infected wounds. [Display omitted] • Precise antibacterial therapy was introduced into a poly(aspartic acid) hydrogel. • The MP196 short peptide endowed PDA with targeted photothermal ability. • The hydrogel possessed both intrinsic and photothermal bactericidal effects. • The synergistic antibacterial effect promoted wound healing within 7 days. [ABSTRACT FROM AUTHOR]

The present investigation is focused on evaluation of self-assembling ability in aqueous solutions of two water soluble polymers: poly(aspartic acid) (PAS) and Pluronic F127 (PL). The intermolecular complexes, realized between polyacid and neutral copolymer surfactant in different ratios, have been studied by combining various characterization techniques as rheology, DLS, spectroscopy, microscopy, chemical imaging, and zeta potential determination, measurements performed in static and/or dynamic conditions. In static conditions, when the equilibrium state between PAS/PL polymeric pair was reached, and depending on the polymers mixture composition, and of experimental rheological conditions, positive or negative deviations from the additive rule are registered. Conformational changes of the macromolecular chains and correspondingly physical interactions are generated between PL and PAS for self-assembly and the formation of interpolymer complex as suprastructure with micellar configuration. The phenomenon was better evidenced in case of 1/1 wt ratio between the two polymers. In dynamic conditions of determination, during “in situ” evaluation of the hydrodynamic diameter, zeta potential and conductivity, when the equilibrium state is not reached and as result either the intermolecular bonds are not achieved, the self-assembling process is not so obvious evidenced. [ABSTRACT FROM AUTHOR]

Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by a solid–liquid phase separation technique, cryogelation, to achieve a supermacroporous interconnected pore structure. The precursor polymer of PASP, polysuccinimide (PSI) was cross-linked below the freezing point of the solvent and the forming crystals acted as templates for the pores. Dimethyl sulfoxide was chosen as solvent instead of the more commonly used water. Thus larger temperatures could be utilized for the preparation and the drawback of increase in specific volume of water upon freezing could be eliminated. The morphology of the hydrogels was characterized by scanning electron microscopy and interconnectivity of the pores was proven by the small flow resistance of the gels. Compression tests also confirmed the interconnected porous structure and the complete re-swelling and shape recovery of the supermacroporous PASP hydrogels. The prepared hydrogels are of interest for several biomedical applications as scaffolding materials because of their cytocompatibility, controllable morphology and pH-responsive character. [ABSTRACT FROM AUTHOR]

Core–shell structured micelles produced from an amphiphilic block copolymer are promising drug delivery vehicles because their hydrophobic core can encapsulate hydrophobic drugs through hydrophobic interactions and their hydrophilic shell can prolong their circulation in the blood. However, the low cargo capacity and the lack of stability in the blood are major problems associated with micellar drug delivery systems. Poly(amino acid) or its derivatives, especially poly(glutamic acid) or poly(aspartic acid) or poly( l -lysine), are widely used as micelle-forming materials because of their remarkable advantages such as easy biodegradability, good biocompatibility and availability of side functional groups. In this review, the structures, synthesis and characteristics of the amphiphilic poly(amino acid) based micelles are initially described, then the driving forces, which may determine the drug loading capacity, and the variants which affect the stability of drug-loaded micelles in blood post-injection are summarized. Furthermore, the strategies for increasing the drug loading capacity and improve the stability in blood are also described. [ABSTRACT FROM AUTHOR]

Owing to their unique properties such as low cytotoxicity and excellent biocompatibility, poly(aspartic acid) (PAsp) and polysaccharides are good candidates for the development of new biomaterials. In order to construct better gene delivery systems by combining polysaccharides with PAsp, in this work, a general strategy is described for preparing series of polysaccharide- graft -PAsp (including cyclodextrin (CD), dextran (Dex) and chitosan (CS)) gene vectors. Such different polysaccharide-based vectors are compared systematically through a series of experiments including degradability, pDNA condensation capability, cytotoxicity and gene transfection ability. They possess good degradability, which would benefit the release of pDNA from the complexes. They exhibit significantly lower cytotoxicity than the control ‘gold-standard’ polyethylenimine (PEI, ∼25 kDa). More importantly, the gene transfection efficiency of Dex- and CS-based vectors is 12–14-fold higher than CD-based ones. This present study indicates that properly grafting degradable PAsp from polysaccharide backbones is an effective means of producing a new class of degradable biomaterials. [ABSTRACT FROM AUTHOR]

In situ gelling poly(aspartic acid) thiomers are investigated to demonstrate their potential application in the development of injectable formulations. The chemical stability of the thiomer solutions is measured against air to determine the maximum storage time of the solution before injection. Hydrogels exhibit considerably large storage moduli after the chemical oxidation of the low-viscosity thiomer solution. The gelation time can be controlled within 2–6 min, which is advantageous for injection because the thiomer solution and the oxidising agent can be mixed safely in a two-chamber system before injection into the desired site of the body. [ABSTRACT FROM AUTHOR]

Stable pH-sensitive poly(aspartic acid) (PASP) hydrogel in nanofibrous structure was successfully manufactured. Firstly, polysuccinimide (PSI), the intermediate of PASP, was synthesized by thermal polymerization of aspartic acid and electrospun into nanofibrous mat. Secondly, imide rings on the main chains of PSI were partly opened to form crosslinking points by amino groups of ethylenediamine. Eventually, the residual imide rings of PSI were opened to obtain PASP hydrogel nanofibers by hydrolysis. The PASP hydrogel nanofibers exhibited significant hydrogel characteristics with fast swelling, high water absorption and pH-sensitivity. Durability test showed the morphological robustness and stability of PASP hydrogel nanofibers. The swelling ratio of pH-sensitive PASP hydrogel nanofibers ranged from 14.8 g/g to 128.1 g/g with the pH values increasing from 1.0 to 10.0. [ABSTRACT FROM AUTHOR]

Highlights: [•] Evaluation of poly(aspartic acid) and Pluronic F127 self-assembling capability. [•] pH and temperature effect on interpolymeric complex formation. [•] Establishing the best ratio for interpolymeric complex formation. [Copyright &y& Elsevier]

Pluronic F127/poly(aspartic acid) mixtures were investigated in dilute solutions by viscometry and dynamic light scattering. The two polymers were chosen due to well known applications in biomedical field, taking into account the final purpose (the use of the complex structure as drug delivery systems). The central item was to identify the possibility of complexation between the poly(carboxylic acid) and a non-ionic polymer and to investigate the conditions of the interpolymer complex formation. The ability of Pluronic F127 to form micelle is well known. Poly(aspartic acid), as a polycarboxylic acid with resemblance with polyacrylic acid, can act as dispersant, antiscalant, superabsorber, being also able to form micelles. Due to its functional groups, -COOH and -NH2, poly(aspartic acid) can make physical and/or chemical bonds with other macromolecular compounds. The intrinsic viscosity and the dynamic light scattering data obtained for PLU/PAS mixtures at 25 °C have shown that interpolymer complex formation occurs around 1/1 wt. ratio between the two polymers. [ABSTRACT FROM AUTHOR]

Abstract: A dually responsive nanocarrier with multilayer core–shell architecture was prepared based on Fe3O4@SiO2 nanoparticles coated with mPEG-poly(l-Asparagine). Imidazole groups (pKa ∼6.0) were tethered to the side chains of poly(l-Asparagine) segments by aminolysis. These nanoparticles were expected to be sensitive to both magnetic field and pH environment. The obtained materials were characterized with FTIR, dynamic light scattering, ζ-potential, TEM, TGA and hysteresis loop analysis. It was found that this Fe3O4@SiO2–polymer complex can form nano-scale core–shell–corona trilayer particles (∼250nm) in aqueous solution. The Fe3O4@SiO2, poly(l-Asparagine) and mPEG segments serve as a super-paramagnetic core, a pH-sensitive shell, and a hydrophilic corona, respectively. An antitumor agent, doxorubicin (DOX), was successfully loaded into the nanocarrier via combined actions of hydrophobic interaction and hydrogen bonding. The drug release profiles displayed a pH-dependent behavior. DOX release rate increased significantly as the ambient pH dropped from the physiological pH (7.4) to acidic (5.5). This is most likely due to protonation and a change in hydrophilicity of the imidazole groups in the poly(l-Asparagine) segments. This new approach may serve as a promising platform to formulate magnetic targeted drug delivery systems. [Copyright &y& Elsevier]

Abstract: In the present paper we report for the first time the development of redox-responsive biocompatible polymer gels. Double cross-linked poly(aspartic acid) hydrogels were prepared using two different cross-linking agents simultaneously. One of the cross-linkers was diaminobutane (DAB), the other cystamine (CYS). The relative amounts of DAB and CYS molecules were varied over a wide range while the total amount of cross-linker molecules (DAB+CYS) was kept constant. DAB provides stable cross-links, whereas CYS contains disulfide bonds, which can be broken by reduction. The cleavage of disulfide cross-links results in enhanced swelling and a significant decrease in the elastic modulus of the gels. These novel types of stimuli-responsive gels are promising candidates for new swelling controlled release matrices. [Copyright &y& Elsevier]

Abstract: The stability of a polymer hybridized liposome (PHL) was examined with the microfluidic and thermal state of anchored alkyl chains, and with dissolution against deoxycholate (DOC). Poly(asparagine) grafted with octadecylamine (PAsn-g-C18), poly(aspartic acid) grafted with octadecylamine (PAsp-g-C18), and poly(aspartic acid) grafted with phytosphingosine (PAsp-g-PHS) were synthesized. The microfluidity of the membrane of the PHL was evaluated by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and the phase transition temperature (T c) was measured by differential scanning calorimetry (DSC). The membrane fluidity of liposomes was increased by the inclusion of amphiphilic graft polymers. The phase transition temperature of liposomes increased by the anchoring of PAsn-g-C18, while the inclusion of PAsp-g-C18 or PAsp-g-PHS lowered the T c. The surface charge of PHL of PAsn-g-C18 was changed by the cationic lipid content. The structural stability of the PHL was affected by variation of the hydrophilic backbone or the hydrophobic moiety of the polymer and PHL of PAsn-g-C18 was most stable against DOC. An increased degree of substitution of the graft copolymer led to better stability of the PHL. It was found that the polymer characteristics affect the physicochemical strength of the PHL structure, resulting in different degrees of stability enhancement. [Copyright &y& Elsevier]

Abstract: The thermal degradation of sodium polyaspartate (PAspNa) and of its precursor - polysuccinimide (PSI) - was investigated using three different techniques: thermal analysis (TA), Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). These online coupled techniques can comprise a very useful tool for the investigation of the thermal decomposition and its mechanisms and allow having simultaneous information about the decomposition process itself as well as of the evolving substances. PSI and sodium-polyaspartate present complex thermal decomposition processes (two to five stages). Also, thermal stability of PSI is low in comparison to that of PAspNa. Finally, weight losses were 72.53% for PSI and 46.73% in the case of PAspNa. [Copyright &y& Elsevier]

Abstract: The purpose of this study is to investigate the temperature influence on the complex formation in aqueous solutions of mixtures between a nonionic polymer, i.e., poly(ethylene glycol) (PEG), and a polyelectrolyte type polymer, namely poly(aspartic acid) (PAS). The PAS/PEG/water colloidal systems were studied as a function of the PEG chain length at different temperatures: 22°C, 26°C, 30.7°C and 37°C, temperatures corresponding to the storage and use conditions of the systems. The changes of the electrokinetic and rheological properties were revealed and correlated with the information given by Fourier Transform Infra-Red Spectroscopy (FTIR) studies in order to underline the interpenetration process between PAS and PEG macromolecular chains. The study evidences the unfavorable effect of the temperature upon interpolymeric complex formation. Both homopolymers are biocompatible and their resulting interpolymeric complex can be regarded as a network with potential bioapplications. [Copyright &y& Elsevier]

Abstract: The interpenetrated macromolecular chains complexation between poly(aspartic acid) and poly(vinyl alcohol) in aqueous solution it was investigated. The interpolymer complexation process was evaluated through dynamic rheology. The aspects concerning the stability of the tested homopolymers and the prepared interpolymeric complex there were achieved from the evaluation of the aqueous solutions’zeta potential and also by determining the pH influence upon the zeta potential and the conductivity. The data obtained through the rheological dynamic measurements were correlated with the composition of the polymeric mixture, the dependence of zeta potential and conductivity. The study reveals the conditions for the formation of interpenetrated polymeric complex as being a ratio of 70wt.% PAS to 30wt.% PVA at 22°C and 50/50 PAS/PVA ratio at 37°C temperature. From the pH influence upon the zeta potential values it was evidenced the PAS aqueous solution does not reach the isoelectric point. At the same time, PVA solution and the complex PAS/PVA reaches the isoelectric point at strongly acid pH. The better stability of PAS, PVA and their mixture in solution is recorded in the alkaline domain (7.5≤pH≥12). The conductivity increases with the rising of the PAS content, pH and temperature. Other characteristics of the prepared interpenetrated polymeric structure, as for example thermal stability, there are also presented. [Copyright &y& Elsevier]

Abstract: In order to obtain nontoxic functional polymer gels for biomedical applications, chemically crosslinked poly(aspartic acid) gels have been prepared using 1,4-diaminobutane as crosslinker. The presence of COOH and amino groups on the network chains renders these gels pH sensitive. Due to the specific hydrophobic–hydrophilic balance, these gels show a significant volume transition at a well-defined pH close to the pK value of uncrosslinked poly(aspartic acid). Since the magnitude of volume change critically depends on the degree of crosslinking, it is an important task to determine the topological characteristics of these networks. A novel method based on potentiometric acid–base titration has been developed to assess the crosslinking ratio, excluding physical crosslinks and entanglements. It turned out that only 25% of all crosslinker molecules forms real crosslinks between the poly(aspartic acid) chains; the rest react with one of its functional groups and forms short pendant side chains. At a nominal crosslinking ratio of 0.1, the number average molecular mass between crosslinks is found to be M c =2300. [Copyright &y& Elsevier]

Abstract: A novel pH-sensitive semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared by using konjac glucomannan (KGM) and poly(aspartic acid) (PAsp) with trisodium trimetaphosphate (STMP) as the cross-linking agent. The effects of component ratio, cross-linking density (STMP concentration), pH and ionic strength on the swelling properties of hydrogels were investigated. The structure of the semi-IPN hydrogels were characterized by fourier transform infrared spectroscopy (FT-IR), surface area analyzer and scanning electron microscopy (SEM). The equilibrium swelling characteristics were investigated at 37°C in buffer solutions of pH 2.2 and 7.4 as simulated gastric and intestinal fluids, respectively. At pH 2.2, the release amount of 5-Fluorouracil (5-FU) incorporated into the hydrogels was about 23% within 180min, while this value approached to 95% at pH 7.4. These results showed that the semi-IPN hydrogels could be a suitable polymeric carrier for site-specific drug delivery in the intestine. [Copyright &y& Elsevier]

Abstract: The purpose of this programme was to synthesize and analyze new bioconjugates of interest for the potential inhibition of the influenza virus, using poly(aspartimide) as a polymer support. The macromolecular targets were obtained by attaching various sialic acid-linker-amine compounds to poly(aspartimide). 1H and 13C NMR studies were then performed to analyze the degree of incorporation of the sialic acid-linker-amine compounds within the poly(aspartimide). These studies illustrated that the incorporation was dependent on the nature of the spacer between the sugar and the amine functionality. Thus aliphatic spacers favoured the inclusion of sialic acid onto the polymer support whereas compounds having only an aromatic moiety between the sialic acid and the amine could not be easily incorporated. [Copyright &y& Elsevier]

Abstract: The compatibility between poly(aspartic acid) and poly(ethylene glycol) for the formation of an interpolymer complex (IPC) was investigated by dynamic rheology and evaluation of zeta potential values. The homogeneity of the realized IPC was observed by near infrared chemical imagistic (NIR-CI) technique. The data were sustained and underlined by the assessment of the compatibility between the polymeric compounds. [Copyright &y& Elsevier]

Abstract: A block copolymer poly(2-ethyl-2-oxazoline)-block-poly(aspartic acid) (PEOz-b-PAsp) was synthesized and investigated as the carrier of antifungal drug amphotericin B (AmB). Polyion complex (PIC) micelles with clear core–shell structures were identified by TEM, which revealed that the PAsp segment became hydrophobic after it interacted with AmB. PEOz-b-PAsp increased not only the solubility of AmB but also simultaneously the drug potency. The prolonged release of AmB from micelles effectively inhibited the growth of Candida albicans even after three days of administration. Moreover, the in vitro cytotoxicity of AmB-loaded micelles was less than that of Fungizone®, which is a powerful antifungal antibiotic that is adopted to treat various fungal infections. The PEOz-b-PAsp PIC micelles with lower cytotoxicity and higher potency than Fungizone® represent a potential means of encapsulating basic/amphoteric drugs. [Copyright &y& Elsevier]

Abstract: Two-dimensional (2D) correlation FTIR spectroscopy was used to investigate the dynamic mechanism of poly(aspartic acid) during the heating process. According to the 2D asynchronous correlation spectra, the Con band of Amide I was separated into three peaks at 1637, 1645 and 1677cm−1, assigned to α helical, random coil and β antiparallel conformation, respectively. And α helical structure would transform into the more ordered and stable conformation of β antiparallel in heating. In the region of 3700–2700cm−1, the H-contained groups were analyzed; the loosening of hydroxyl is found to change prior to the NH-related hydrogen bonds and the conformational reorganization of hydrocarbon chains. [Copyright &y& Elsevier]

Abstract: Chemically cross-linked poly(aspartic acid) (PASP) gels were prepared by the hydrolysis of poly(succinimide) (PSI). The latter was prepared by thermal polycondensation of aspartic acid. The PSI chains were cross-linked by natural amines and amino acid derivatives such as putrescin, spermine, spermidine, lysine and cystamine to obtain biodegradable, biocompatible, amino acid-based hydrogels. The volume of the synthesized unhydrolyzed PSI gels changes abruptly at a well-defined pH that results in ring opening, while the hydrolyzed gels show a volume phase transition around the pK values of PASP. The unidirectional stress–strain behavior of the gels as well as the dependence of equilibrium swelling degree on the pH was carefully studied and the most important network parameters were determined by a modified version of the Brannon–Peppas–Peppas theory. [Copyright &y& Elsevier]

Abstract: Chemically crosslinked poly(aspartic acid) (PASP) gels were prepared by the hydrolysis of polysuccinimide (PSI). This latter was prepared by thermal polycondensation of aspartic acid. The PSI chains were crosslinked by 1,4-diaminobutane. The consecutive reactions of hydrolysis and swelling kinetics of PSI- and PASP-based gels were studied at different pH values. Two distinct swelling mechanisms were proposed. The cooperative diffusion coefficient has been found to be three orders of magnitude higher in pH 14 solution than at pH 8. [Copyright &y& Elsevier]

A novel sand-fixing agent-poly(aspartic acid) and its composites were synthesized to improve sand particles compressive strength and anti-wind erosion properties. The relationship between the concentration of sand-fixing agent and the sand-fixing properties was studied by three kinds of aging tests. Some composites were choose to improve the sand-fixing property and the composition of 40% xanthan gum and 60% ethyl cellulose were chosen to compare sand-fixing property with lignosulfonate. The results showed that the sand-fixing and water-retaining properties of xanthan gum and ethyl cellulose composites were better than that of lignosulfonate. The biodegradability experiment showed that the PASP and its composites were environment-friendly products and the field test showed that the PASP composites could improve wind erosion disturbance. [Copyright &y& Elsevier]

Abstract: In this study, a novel salt-, pH- and temperature-responsive semi-interpenetrating network (semi-IPN) hydrogel, composed of poly(aspartic acid) (PAsp) and poly(acrylic acid) (PAAc), was prepared. PAsp/PAAc semi-IPN hydrogel being ionic in nature, the swelling behavior was significantly influenced by various swelling medium. The structure of the triply responsive hydrogel was studied by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), and the salt-, temperature- and pH-sensitivities were investigated through measuring equilibrium swelling ratios in various environmental solutions. The results indicate that there is a structure of polyelectrolyte complex in the hydrogel, and that the responsive behaviors of this hydrogel to alternating changes in inorganic salt (different physiological bio-fluids), pH and temperature are improved because of the incorporation of PAsp. In addition, during the repeatable swelling and shrinkage period, the semi-IPN hydrogel shows suitable mechanical strength. The salt-, pH- and temperature-responsive hydrogel will have wider applications in biomedical areas. [Copyright &y& Elsevier]

Abstract: The rheological behavior of multiwall carbon nanotubes (MWCNTs) with polyelectrolyte dispersants (poly(acrylic acid) and poly(aspartic acid)) was investigated. The zeta potential of MWCNT slurries with adding dispersants and the optimum amount of dispersants for MWCNT slurries were measured. The Krieger–Dougherty equation was fitted to experimental data with varying solid loadings. The fitted results of MWCNT slurries showed the high intrinsic viscosity and the low maximum solid loading because of the high aspect ratio and the strong van der Waals force of MWCNTs. Poly(acrylic acid) stabilized MWCNT slurries had a lower maximum solid loading and a higher intrinsic viscosity (φm=0.16, [η]=43) compared to poly(aspartic acid) stabilized MWCNT slurries (φm=0.21, [η]=41.47). These differences may be caused by the different chemical structures of dispersants. [Copyright &y& Elsevier]

In recent years, there has been an effort toward creating and utilizing novel biodegradable polymeric materials. As products become available, it is necessary to concurrently search for novel biodegradation catalysts and further investigate the properties of known biodegradation enzymes. Regarding the latter, we recently reported the crystal structure of a dimeric enzyme, Sphingomonas sp. KT-1 PahZ1, capable of degrading poly(aspartic acid), a green alternative to non-biodegradable polycarboxylates. However, the role of the dimeric state in catalytic function remained unclear. Here we report PahZ1 KT-1 constructs with either single or multiple mutation(s) at the dimer interface yield active monomers. Our data indicates PahZ1 KT-1 monomers and dimers catalyze PAA degradation at equivalent rates. Unfolding experiments reveal differences where the activation energy for monomers is ~ 46 kJ mol−1 lower than for dimers despite similar thermodynamic properties. Characterization of this biodegradation enzyme and others is critical for future protein engineering efforts toward polymer remediation. [Display omitted] • Sphingomonas sp. KT PahZ1 Monomers were generated to elucidate the role of dimerization in structure, function, and stability • PahZ1 monomers and dimers exhibit indistinguishable catalytic activity as it relates to poly(aspartic acid) degradation • PahZ1 monomers and dimers exhibit similar free energy changes for spontaneous unfolding • Stopped-flow fluorescence methods demonstrate that PahZ1 monomer unfolding occurs with an activation energy that is decreased ~46 kJ mol−1 relative to dimer species • Monomer species are observed to completely recover enzyme activity after heat- or chemical-induced unfolding, whereas wild-type dimers do not [ABSTRACT FROM AUTHOR]

[Display omitted] • Phenylboronic ester based self-healing hydrogel was prepared from PASP and PVA. • The self-healing hydrogel shows antibacterial and light-emitting property. • The mEGF loaded hydrogel accelerate the wound repairing rate of model mice. • The PASP based antibacterial hydrogels show great promise for tissue engineering. We report here a self-healing hydrogel with antibacterial and light-emitting properties for wound repair. The hydrogel was prepared by reaction of poly(aspartic acid) (PASP) derivatives bearing groups of quaternary ammonium and boronic acid with poly(vinyl alcohol) (PVA). Due to the dynamic nature of boronic ester bonds, bacteria-killing activity of quaternary ammonium, and light-emitting activity of phenylboronic ester, the resultant hydrogels featured self-healing, antibacterial and light-emitting properties. The hydrogels show controlled release behavior of mouse epidermal growth factor (mEGF) and the in vivo studies show mEGF loaded hydrogel accelerate the wound repair of model mice and improve skin cell proliferation by prevention of bacterial infections. The PASP based hydrogels would show great promise in bio-applications, in particular for wound dressing and tissue repairing. [ABSTRACT FROM AUTHOR]

• The hydrogel was designed from PAsp with acylhydrazide and ethoxyl groups. • The hydrogels exhibited good mechanical property and self-healing property. • The hydrogels showed good biocompatibility. • The hydrogels have potential in local drug delivery. Self-healing hydrogels were prepared from hydrazide functionalized poly(aspartic acid) (PAsp). The polymer succinimide (PSI) was reacted with hydrazine and ethanolamine successively to obtain water soluble poly(aspartic acid) derivatives with hydrazide functional groups (PAEH). The hydrogel was prepared by cross-linking PAEH with poly(ethylene glycol) dialdehyde (PEG DA) under mild conditions without addition of catalyst. The rheological property and the self-healing property of the hydrogels were investigated intensively. The in vitro toxicity experiment showed the hydrogels have good bio-compatibility and the doxorubicin (DOX)-loaded hydrogels showed controlled release profile. Importantly, the hydrogel can still be degraded based on poly(aspartic acid) backbone. The bio-degradable poly(amino acid) based on self-healing hydrogel could have great potential application in bioscience including tissue repairing, drug loading and release. [ABSTRACT FROM AUTHOR]

A novel interpenetrating network hydrogel for drug controlled release, composed of modified poly(aspartic acid) (KPAsp) and carboxymethyl chitosan (CMCTS), was prepared in aqueous system. The surface morphology and composition of hydrogels were characterized by SEM and FTIR. The swelling properties of KPAsp, KPAsp/CMCTS semi-IPN and KPAsp/CMCTS IPN hydrogels were investigated and the swelling dynamics of the hydrogels was analyzed based on the Fickian equation. The pH, temperature and salt sensitivities of hydrogels were further studied, and the prepared hydrogels showed extremely sensitive properties to pH, temperature, the ionic salts kinds and concentration. The results of controlled drug release behaviors of the hydrogels revealed that the introduction of IPN observably improved the drug release properties of hydrogels, the release rate of drug from hydrogels can be controlled by the structure of the hydrogels and pH value of the external environment, a relative large amount of drug released was preferred under simulated intestinal fluid. These results illustrated high potential of the KPAsp/CMCTS IPN hydrogels for application as drug carriers. [ABSTRACT FROM AUTHOR]