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Poly(aspartic acid) (PASP) is an environmentally friendly biopolymer used as a fertilizer synergist and known to increase agricultural yields. The mechanism of PASP enhancement has, however, not been established, although the general hypothesis is that the polymer functions to hold nutrients closer to the root zone. The objective of this study was to determine the physiological and molecular changes that occur when plants are exposed to PASP, with future directions leading to a proposed mode of action. A whole genome transcriptome study was conducted. Arabidopsis thaliana seeds were germinated and grown in sterile plates treated with 250 ppm PASP under continuous light. Total RNA was extracted from whole seedlings and sequenced. The results revealed 462 differentially expressed genes (DEGs), 245 of which were upregulated and 217 downregulated. Gene Ontology, KEGG and MAPman analyses revealed DEGs involved in photosynthesis with 11 light harvesting complexes upregulated (e.g. LHCB1.1, LHCB2.2, LHCA1, LHCB4.2, LHCB2.1, LHCA4, LHCB1.1, LHCB3, LHCA3); the peroxisome pathway had 6 DEGs (CAT1, KAT1 and XDH2) upregulated (CSD1, CSD2 and FSD2) downregulated, the phenylpropanoid biosynthesis pathway had 7 DEGs upregulated. Other key DEGs were associated with the amino acid (e.g. ASN1) and nitrogen metabolism pathways. Physiology assessment results showed significant differences between control and treated plants with a 33 % increase in leaf area, 25 % increase chlorophyll content (p ≤ 0.05) and a 4-fold increase in photosynthetic rate (p ≤ 0.001). This information helps to increase our understanding of the key genes and metabolic pathways associated with plant response to PASP.

Poly(aspartic acid) (pAsp)-based fiber networks were developed via electrospinning and photo-crosslinking. Fiber networks hold the advantage that they exhibit a high surface-to-volume ratio, giving rise to a high water uptake and retention capacity, along with the ability to release moisture under desired circumstances (e.g. reduced relative humidity, mechanical pressure, etc.). Herein, polysuccinimide (PSI), the precursor of pAsp, was modified with 5-norbornene-2-methylamine to obtain crosslinkable norbornene-modified PSI (PSI-NB) with two different degrees of substitution, i.e. 19% and 46%. These derivatives were electrospun into thin uniform fibers after optimization of the processing parameters. The fiber sheets were crosslinked via a thiol-ene step-growth mechanism with three different thiol crosslinkers exploiting UV-A irradiation in the presence of TPO-L as photo-initiator. Using this strategy, fiber networks with diameters ranging between 1.27 ± 0.29 and 2.20 ± 1.05 µm were obtained, as visualized with scanning electron microscopy (SEM). Successful crosslinking was evidenced by a dissolution test in dimethylformamide and through X-ray photoelectron spectroscopy. Finally, the PSI-NB fiber networks were hydrolyzed to obtain pAsp-NB fiber networks by alkaline hydrolysis in a carbonate buffer solution, as confirmed by Fourier-transform infrared spectroscopy. The morphology of the fibers following hydrolysis was visualized by SEM and the average fiber diameters were calculated and compared to the diameters before hydrolysis, generally showing a diameter increase due to swelling of the fibers in aqueous solution. In conclusion, pAsp-based fiber networks were successfully developed and stabilized via photo-crosslinking.

The adsorption mechanism of different polymers containing ionic polyamino acids monomers in the chain structure at the solid–liquid interface was investigated. Initially, the influence of molecular weight and solution pH on simple polyamino acids (poly(L-aspartic acid) and poly(L-lysine) binding was determined. Considering the obtained dependencies, the polymer adsorption layer conformation was proposed in the systems containing block copolymers (both diblock and symmetrical triblock) consisting of polypeptide as well as poly(ethylene glycol) fragments. The presented studies focused on the application of two experimental methods. The polymer adsorption was carried out using the batch method and the adsorbate concentration was determined spectrophotometrically. Then, the turbidimetric measurements were taken. The analysis of the obtained results showed that the adsorption process of block copolymers depends on two factors. Firstly, the solution pH determines both the nature of the interactions of the copolymer structural units with the solid surface and the conformation of the polypeptide chains. The second parameter influencing the adsorption layer structure is the ratio of the lengths of both blocks. Introducing a short PEG fragment into the polymer main chain may improve the polymer adsorption properties by increasing the number of interactions with the adsorbent surface. [ABSTRACT FROM AUTHOR]

With biocompatibility and biodegradability, self-healing hydrogels prepared from biopolymers show great advantages in bioengineering and bioscience as drug delivery carrier. In this research, the biodegradable hydrogel was constructed based on poly(amino acid) of poly(aspartic acid) (PAsp) and pectin for in vivo antitumor applications as DOX release carrier. The PAsp bearing hydrazide groups and isopropyl groups (PAPH) was synthesized by ring opening of polysuccinimide (PSI) by isopropylamine and hydrazine, and used to fabricate fully biodegradable hydrogel with oxidized pectin (OPec) through dynamic acylhydrazone bond cross-linking. The regulatable mechanical strength of the hydrogel could adapt its bioapplication, and the excellent biocompatibility ensured biosafety in biomedical areas. Furthermore, the pectin backbone and the PAsp endowed the hydrogel with biodegradability both by enzyme and in vivo. The PAPH/Opec hydrogel as DOX carrier inhibited the tumor growth with the tumor weight 80% lower than the control group and reduced the in vivo toxicity of the DOX. As a result, this biodegradable PAPH/Opec hydrogel could find show great potential as sustained drug delivery vehicle in biomedical areas. [ABSTRACT FROM AUTHOR]

The onset of osteoporosis leads to a gradual decrease in bone density due to an imbalance between bone formation and resorption. To achieve optimal drug efficacy with minimal side effects, targeted drug delivery to the bone is necessary. Previous studies have utilized peptides that bind to hydroxyapatite, a mineral component of bone, for bone‐targeted drug delivery. In this study, a hydroxyapatite binding (HAB) tag is fused to 30Kc19α‐Runt‐related transcription factor 2 (RUNX2) for bone‐targeting. This recombinant protein can penetrate the nucleus of human mesenchymal stem cells (hMSCs) and act as a master transcription factor for osteogenesis. The HAB tag increases the binding affinity of 30Kc19α‐RUNX2 to mineral deposition in mature osteoblasts and bone tissue, without affecting its osteogenic induction capability. In the osteoporosis mouse model, intravenous injection of HAB‐30Kc19α‐RUNX2 results in preferential accumulation in the femur and promotes bone formation while reducing toxicity in the spleen. These findings suggest that HAB‐30Kc19α‐RUNX2 may be a promising candidate for bone‐targeted therapy in osteoporosis. [ABSTRACT FROM AUTHOR]

Concrete is currently the most used man-made construction material. Unfortunately it is prone to defects, such as cracks. Crack repair is possible by incorporation of superabsorbent polymers (SAPs) which can fill a crack by swelling and promote formation of healing products. However, SAPs are usually acrylate-based and not biodegradable. Present work focuses on development of SAPs based on poly(aspartic acid) (PASP), which is a biobased and biodegradable alternative of acrylate-based polymers. The developed SAP was incorporated in mortar and the effect on the mortar properties was studied. When adding 1 m% SAP, a decrease in strength was observed, similar to commercially available acrylate-based SAPs. The SAPs showed an efficient and immediate sealing effect in cracked mortar, reflected by a reduction in water permeability over 50%. Hence, the developed biobased SAP shows good sealing properties and could be used as a sustainable alternative for acrylic SAPs in concrete repair. [ABSTRACT FROM AUTHOR]

In this work, nanoparticles of the chitosan-poly((α,β)-DL-aspartic acid) polyelectrolyte complex (PEC) were synthesized. The purpose is to develop a biodegradable, biocompatible, and non-toxic polymeric platform as a vehicle for the encapsulation of hydrophilic drugs. The ionotropic gelation method, using solutions of chitosan and poly((α,β)-DL-aspartic acid sodium salt), allowed synthesizing particles with diameters of 142.1 ± 2.9 nm determined by DLS, while by FESEM particle diameters in the 60–200 nm range were observed. A preliminary trial showed that encapsulation of isoniazid, a hydrophilic drug to treat tuberculosis, is possible with encapsulation efficiency in the range of 5.3–5.8%. [ABSTRACT FROM AUTHOR]

Vanillin (VLN) is generally used in bakery food products as an aroma enhancer and flavoring agent. Hence it is important to develop a powerful and rapid tool to monitor the concentration of VLN levels concerning food safety. In this paper, a simple sensor was proposed by electropolymerized Aspartic acid (ASP) modified on Graphene and Graphite composite paste electrode (PASPMGN/CPE) for the detection of VLN by differential pulse voltammetry (DPV). PASPMGN/CPE ranked to have high electrocatalytic kinetics towards electro‐oxidation of VLN, in optimized conditions. The electrochemical process of VLN is portrayed to be irreversible and adsorption‐controlled kinetics by the cyclic voltammetry (CV) method. The surface features were studied using Field Emission Scanning Electron Microscopy (FE‐SEM), Energy Dispersive X‐ray Spectroscopy (EDX), Electrochemical Impedance Spectroscopy (EIS) and CV. From DPV results, the oxidative peak current showed linear growth toward the concentration of VLN ranging from 1.0 μM to 15.0 μM with a limit of detection and quantification of 4.85 μM and 16.2 μM. The modified sensor attained to be highly selective with common possible interferents. PASPMGN/CPE was efficient in detecting VLN in vanilla pods, essence and bakery product samples. [ABSTRACT FROM AUTHOR]

The innovation of N fertilizer and N management practices is essential to maximize crop yield with fewer N inputs. A long-term field fertilization experiment was established in 2015 on the North China Plain (NCP) to determine the effects of a control treatment (CN) and the eco-friendly material poly(aspartic acid)-coated urea (PN), applied as a one-time basal application method, on winter wheat yield and N use efficiency at four N application rates: 0 (N0), 63 (N63), 125 (N125), and 188 (N188) kg N ha1. The results indicated that compared to CN, PN resulted in a significant increase in wheat yield by 9.6% and 9.2% at N63 and N125, respectively, across the three experimental years, whereas no significant (p < 0.05) difference was detected at N188. Leaf area duration (LAD), crop growth rate (CGR), and dry matter accumulation (DMA) increased with increasing N rates, while PN significantly increased LAD and CGR by 5.1%-16.4% and 5.4%-64.3%, respectively, during the anthesis-ripening growth stage and DMA by 13.7% and 10.1% at N63 and N125, respectively, after the anthesis stage compared to CN. During the grain-filling stage, PN significantly increased the kernel maximum grain-filling rate (Gmax) by 21.7% and the kernel weight at the maximum grain-filling rate (Wmax) by 6.7% at N125 compared to CN. Additionally, compared to CN, PN significantly improved the stover and grain N content at harvest and increased NUT, NPFP, and NAE by 5.7%-40.1%, 2.5%-23.3%, and 3.9%-42.8%, respectively, at N63-N125. Therefore, PN applied using a single basal nitrogen fertilizer application method showed promising potential in maintaining a stable wheat yield and increasing N use efficiency with a 33% urea cut (approximately 63 kg N ha-1) compared to CN at the current wheat yield level on the NCP. [ABSTRACT FROM AUTHOR]

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]

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]

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]

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]

Mineralization by exposure of organic templates to supersaturated solutions is used by many living organisms to generate specialized materials to perform structural or protective functions. Similarly, it was suggested that improved robustness acquired through mineralization under natural conditions could be an important factor for virus survival outside of a host for better transfection of cells. Here, inspired by this fact, we developed a nonviral tricomponent polyplex system for gene delivery capable of undergoing mineralization. First, we fabricated anionic polyplexes carrying pDNA by self-assembly with a lipid-modified cationic polymer and coating by poly(aspartic acid). Then, we submitted the polyplexes to a two-step mineralization reaction to precipitate CaCO 3 under various supersaturations. We carried out detailed morphological studies of the mineralized polyplexes and identified which parameters of the fabrication process were influential on transfection efficiency. We found that mineralization with CaCO 3 is efficient in promoting transfection efficiency as long as a certain Ca 2+ /CO 3 lower limit ratio is respected. However, calcium incubation can also be used to achieve similar effects at higher concentrations depending on polyplex composition, probably due to the formation of physical cross-links by calcium binding to poly(aspartic acid). We proposed that the improved robustness and transfection efficiency provided by means of mineralization can be used to expand the possible applications of polyplexes in gene therapy.2- lower limit ratio is respected. However, calcium incubation can also be used to achieve similar effects at higher concentrations depending on polyplex composition, probably due to the formation of physical cross-links by calcium binding to poly(aspartic acid). We proposed that the improved robustness and transfection efficiency provided by means of mineralization can be used to expand the possible applications of polyplexes in gene therapy.

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]