Polysuccinimide Research Articles

Electrospun polysuccinimide scaffolds containing different salts as potential wound dressing material.

In this research, we applied electrospinning to create a two-component biodegradable polymeric scaffold containing polysuccinimide (PSI) and antibacterial salts. Antibacterial agents for therapeutical purposes mostly contain silver ions which are associated with high environmental impact and, in some cases, may cause undesired immune reactions. In our work, we prepared nanofibrous systems containing antibacterial and tissue-regenerating salts of zinc acetate or strontium nitrate in different concentrations, whose structures may be suitable for developing biomedical wound dressing systems in the future. Several experiments have been conducted to optimize the physicochemical, mechanical, and biological properties of the scaffolds developed for application as wound dressings. The scaffold systems obtained by PSI synthesis, salt addition, and fiber formation were first investigated by scanning electron microscopy. In almost all cases, different salts caused a decrease in the fiber diameter of PSI polymer-based systems (<500 nm). Fourier-transform infrared spectroscopy was applied to verify the presence of salts in the scaffolds and to determine the interaction between the salt and the polymer. Another analysis, energy-dispersive X-ray spectroscopy, was carried out to determine strontium and zinc atoms in the scaffolds. Our result showed that the salts influence the mechanical properties of the polymer scaffold, both in terms of specific load capacity and relative elongation values. According to the dissolution experiments, the whole amount of strontium nitrate was dissolved from the scaffold in 8 h; however, only 50% of the zinc acetate was dissolved. In addition, antibacterial activity tests were performed with four different bacterial strains relevant to skin surface injuries, leading to the appearance of inhibition zones around the scaffold discs in most cases. We also investigated the potential cytotoxicity of the scaffolds on human tumorous and healthy cells. Except for the ones containing zinc acetate salt, the scaffolds are not cytotoxic to either tumor or healthy cells.

Synthesis and Performance Evaluation of Modified Polyaspartic-Acid-Based Scale Inhibitor

This paper focuses on the selection and application of scale inhibitor by studying the problem of pipeline scaling in geothermal well development. Adding scale inhibitor can effectively reduce the treatment cost and achieve a good scale resistance effect, but the commonly used polyaspartic acid scale inhibitor has problems such as poor scale inhibition effect and large use limitations. Therefore, a new modified polyaspartic acid scale inhibitor (His-Tyr-SA-PASP) was prepared using polysuccinimide (PSI) as the raw material and histidine (His), tyrosine (Tyr), and sulfonic acid (SA) as the modification reagent. When the dosage of His-Tyr-SA-PASP was 8 mg/L, the scale inhibition rate of CaCO3 was 94.40%. In addition, the scale inhibition effect of His-Tyr-SA-PASP on CaCO3 was better than that of PASP. At the same time, under the condition of a static experiment at 75 °C, according to the ion concentration of water samples in different scale zones, this paper also identified the ratio of four composite scale inhibitors. When the dosage of compound scale inhibitor was 100 mg/L, Sodium of Polyaspartic Acid–Diethylene Triamine Penta (Methylene Phosphonic Acid)–2-Phosphonobutane-1,2,4-Tricarboxylic Acid–Amino Trimethylene Phosphonic Acid–Copolymer of Maleic and Acrylic Acid = (10:10:5:1:9), (15:10:5:2.5:2.5), (12.5:5:10:1:6.5), and (15:5:10:4:1) and the scale inhibition rate was more than 95%. Under the condition of a dynamic experiment, the optimized composite scale inhibitor still showed a scale inhibition rate of more than 90%. It provides a useful reference for the practical application of water treatment in geothermal wells and has the prospect of industrial application.

Polyaspartic acid modified by fluorescent carbon quantum dots as an environmentally friendly scale inhibitor for calcium sulphate

Polysuccinimide (PSI), as the precursor of polyaspartic acid (PASP), can easily react with amino (NH2) groups under mild conditions. A novel scale inhibitor, designed as PASP/N-CDs, is synthesised through the ring-opening reaction of PSI with nitrogen-doped carbon quantum dots (N-CDs). XPS, TEM, FT-IR and Raman spectroscopy are used to analyse the micro structure and spectral characteristics of synthesised inhibitors. The efficiency of PASP/N-CDs in inhibiting calcium sulphate (CaSO4) scale is tested through static scale inhibition experiments. The comparative analysis reveals a significant enhancement in the scaling resistance of PASP/N-CDs over PASP, particularly noticeable at reduced concentrations. The scale inhibition efficiency of PASP/N-CDs reaches nearly 100 % at 5 mg/L. The underlying mechanism of scale inhibition in PASP/N-CDs is investigated using SEM and XRD. It indicates that the PASP/N-CDs inhibits the formation of CaSO4 scale via a combination of chelation, adsorption, and lattice distortion.

Polysuccinimide-based nanoparticle: A nanocarrier with drug release delay and zero burst release properties for effective theranostics of cancer

We have developed a novel pH-responsive delivery system consisting of oleylamine-modified polysuccinimide (PSI) nanoparticles (NPs) whereby NPs remained stable and started to release bioactive agents after 8.5 h with maximal release acquired after 36 h under physiological pH. Our NPs did not exhibit any burst release of drug, which is a key advantage in anti-cancer targeted drug delivery system. Here, the NPs function as a carrier for bioactive agents such as Curcumin and IR-780 dye whereby the former exerts its intrinsic anti-cancer abilities, the latter confers photothermal treatment application and bimodal imaging ability using photoacoustic and fluorescence imaging. In vitro and in vivo results establish that administration of folate receptors targeting PSI-NPs in U87MG model effected in a substantial decrease in tumour and photothermal laser exposure at 808 nm further ablated tumours to an almost total eradication. Our dual loaded targeted NPs demonstrated selectivity through enhanced accumulation and retention in tumours as indicated by multi-spectral optoacoustic tomography (MSOT) and fluorescence imaging (FI). Loading of Curcumin and IR-780 into PSI-NPs improved its bioavailability, allowing Curcumin to be administered into the circulation system and retention in tumours which led to the simultaneous application for a successful targeted, synergistic photothermal treatment and bimodal imaging using MSOT and FI.

Formation of Three-Dimensional Polysuccinimide Electrospun Fiber Meshes Induced by the Combination of CaCl2 and Humidity.

Even though electrospinning is getting more and more attention, the preparation of 3D nanofibrous meshes is still a big challenge that limits the application of electrospun materials, especially in tissue engineering. To overcome this problem, several solutions are introduced but most of them focus on the postprocessing of the electrospun meshes. This paper presents a straightforward novel method that utilizes the joint effect of the addition of CaCl2 and the relative environmental humidity (RH), which can induce the random 3D formation of polysuccinimide (PSI) electrospun fibers with different such as wrinkled or ribbon-like structures. Although the effect of humidity and inorganic salt additives on the micro and macrostructure of electrospun fibers is known, the connection between the two in this manner has never been presented. To investigate the effect, fibers with different PSI and CaCl2 concentrations at different humidity RH levels are prepared, and their microstructure is visualized with high-resolution scanning electron microscopy (SEM). To reveal the nature of the interaction between the polymer and the CaCl2, Fourier-transformed infrared (FTIR), X-ray diffraction (XRD), and thermogravimetry (TGA) measurements are carried out and 3D nanofibrous structures are obtained.

Development of Efficient Sodium Alginate/Polysuccinimide-Based Hydrogels as Biodegradable Acetaminophen Delivery Systems.

Efficient drug delivery systems are essential for improving patient outcomes. Acetaminophen (AP), which is a kind of oral administration, is a commonly used pain reliever and fever reducer. However, oral administration carries various health risks, especially overdose and frequent use; for instance, AP is administered approximately 4 times per day. Therefore, the aim of this study is to develop an efficient delivery system for once-daily administration by combining sodium alginate and polysuccinimide (PSI) hydrogels to delay the release of analgesic AP. PSI is a biodegradable polymer that can be used safely and effectively in drug delivery systems because it is eliminated by hydrolysis in the intestine. The use of PSI also improves the mechanical properties of hydrogels and prolongs drug release. In this study, hydrogel characterizations such as mechanical properties, drug dissolution ability, and biodegradability were measured to evaluate the hydrolysis of PSI in the intestine. Based on the results, hydrogels could be designed to improve the structural mechanical properties and to allow the drug to be completely dissolved, and eliminated from the body through PSI hydrolysis in the intestines. In addition, the release profiles of AP in the hydrogels were evaluated, and the hydrogels provided continuous release of AP for 24 h. Our research suggests that sodium alginate/PSI hydrogels can potentially serve as biodegradable delivery systems for AP. These findings may have significant implications for developing efficient drug delivery systems for other classes of drugs.

Synergistic properties of polysuccinimide/poly(lactic acid) co-electrospun and blended-electrospun nanofibers

One of the greatest challenges in tissue engineering and tissue scaffold development is tissue integration. If cells cannot adhere, infiltrate, and migrate through the implant, the immune system will develop a fibrous capsule around it, isolating it, and rendering it useless. To solve this complex issue, researchers directed their attention towards blend and composite materials. Poly(lactic acid) PLA is a popular polymer used for biomedical applications having several advantages such biocompatibility, chemical stability, and cost-effectiveness. Concurrently, hydrophobicity, poor cell adhesion, and slow biodegradation limit application possibilities. On the other hand, polysuccinimide (PSI) is versatile polymer with excellent cell adhesion, biocompatibility, and a fast biodegradation. The objective of this work is to develop electrospun meshes composed of a fast (PSI) and slow (PLA) degrading component. The fabricated blend-electrospun meshes have a pronounced 3D structure compared to the co-electrospun meshes. Average fibre diameters were 580 ± 140 and 650 ± 110 nm for the co-electrospun and blend-electrospun meshes then after cross-linking the meshes diameters increased to 890 ± 300 and 750 ± 150 nm respectively. Both meshes exhibited increased hydrophilicity compared to pure PLA meshes (125°) especially after the cross-linking (Co-spun: 119°, Blend-spun: 78°). The co-electrospun PSI/PLA demonstrated an increased specific loading capacity suggesting a synergistic relationship between the two polymer fibres. In contrast however, the blend mesh performed poorly. The in vitro degradation assessment confirmed that the PSI component degrades in under a week while the PLA component of the composite was still stable even after 4 weeks. To conclude, both meshes have their own advantages which could be exploited for different applications.

Manipulating Physicochemical Properties of Biosensor Platform with Polysuccinimide-Silica Nanocomposite for Enhanced Protein Detection.

As point-of-care testing (POCT) is becoming the new paradigm of medical diagnostics, there is a growing need to develop reliable POCT devices that can be conveniently operated in a minimally invasive manner. However, the clinical potential of POCT diagnostics is yet to be realized, mainly due to the limited and inconsistent amount of collected samples on these devices, undermining their accuracy. This study proposes a new biosensing platform modified with a functional polysuccinimide (PSI)-silica nanoparticle (SNP) composite system that can substantially increase the protein conjugation efficiency by modulating physicochemical interaction with proteins by several hundred percent from an unmodified device. The efficacy of this PSI-SNP system is further validated by applying it on the surface of a microneedle array (MN), which has emerged as a promising POCT device capable of accessing interstitial fluid through minimal penetration of the skin. This PSI-SNP MN is demonstrated to detect a wide array of proteins with high sensitivity on par with conventional whole serum analysis, validated by in vivo animal testing, effectively displaying broad applicability in biomedical engineering.

Studies of a novel bone-targeted nano drug delivery system with a HAP core-PSI coating structure for tanshinol injection

Tanshinol (Tan) has good therapeutic effects on osteoporosis, fracture, and bone trauma repair. However, it is easily oxidised, has low bioavailability and a short half-life. To solve these problems, the study aimed to develop a novel bone-targeted nano-sustained-release drug delivery system PSI-HAPs for the systemic administration of Tan. This proposed system has hydroxyapatite (HAP) as the core to load drug and polysuccinimide (PSI), PEG-PSI (Polyethylene glycol, PEG), and ALN-PEG-PSI (Alendronate sodium, ALN) as the coating materials to form nanoparticles. The article examines the various PSI-HAPs’ entrapping efficiency (EE, %), drug loading capacity (DLC, %), and distribution to determine the best PSI-HAP formulation in vivo. The in vivo experiment showed that the ALN-PEG-PSI-HAP (ALN-PEG/PSI molar ratio = 1:20) was the best preparation due to its higher distribution on bone (120 h) and lower distribution in the other tissues. The determined preparation was a uniformly spherical or sphere-like nanoparticle with a negative zeta potential. Additionally, it exhibited pH-sensitive drug release in PBS based on an in vitro drug release test. The proposed PSI-HAP preparations were prepared in the water solution using a facile preparation process without ultrasound, heating, and other conditions, which can significantly affect the stability of drugs.

Different implantable electrospun meshes for simultaneous application of prednisone and doxorubicin

Electrospinning is widely applied to prepare nanofibers that provide high specific surfaces, enhanced bioavailability of poorly water-soluble drugs, moreover, enable several administration routes such as implantation. In this perspective, biocompatible poly(vinyl alcohol) (PVA), polysuccinimide (PSI), and ε-polycaprolactone (PCL) based implantable scaffolds were developed by electrospinning to improve the bioavailability of incorporated or conjugated prednisone (Pred) and doxorubicin (Dox). Besides physicochemical characterization, the effect of the loaded amount of Prednisone on the mechanical properties of the fibers as well as their drug release profile were investigated. The drug release measurement revealed that the release profile highly depends on the polarity of the applied polymer as well as the environmental pH. Concerning electrospun meshes incorporating prednisone, the anti-inflammatory effect was monitored by measuring the release of a wide spectrum of cytokines by MDA-MB-231 cells. Besides the loading of doxorubicin, the chemical conjugation to polysuccinimide was successfully carried out which provided prolonged release as well as increased cellular uptake. Based on the different drug release profiles, poly(vinyl alcohol), polysuccinimide, and ε-polycaprolactone fibrous meshes can be used to prepare a potential multi-layered drug-containing implantable scaffold, which can provide both burst and prolonged release of prednisone and doxorubicin. The anti-inflammatory effect of prednisone could be beneficial to avoid rejection after implantation while incorporation or conjugation of doxorubicin into polysuccinimide fibers provides sufficient cytotoxicity and enhanced cellular uptake of MDA-MB-231 cells.

High-Temperature-Resistant Scale Inhibitor Polyaspartic Acid-Prolineamide for Inhibiting CaCO3 Scale in Geothermal Water and Speculation of Scale Inhibition Mechanism

An excellent high-temperature-resistant scale inhibitor, polyaspartic acid-prolineamide (PASP-Pro), was synthesized by polysuccinimide (PSI) and L-prolineamide (L-Pro), and then characterized by 1H-NMR and FTIR analysis. The inhibition performance of PASP-Pro on CaCO3 precipitation was studied at different temperatures through static tests; at the same time, the influence of PASP-Pro on the crystallization process of CaCO3 was investigated by combining the electrical conductivity test of CaCO3 solution with different CaCO3 scale characterizations. The suitable synthesis and evaluation conditions for PASP-Pro were obtained, and a possible multi-stage scale inhibition mechanism of PASP-Pro for CaCO3 scale was then suggested. PASP-Pro has better thermal stability and high-temperature scale inhibition performance (exceeds 87% after pretreatment at 150 °C) than PASP. In addition, PASP-Pro exhibited a promising anti-scaling property by inhibiting the crystallization of CaCO3; the induction period and the nucleation period of the CaCO3 crystallization process were prolonged nearly four times. It was found from XRD patterns that vaterite, an unstable crystalline phase, gradually emerged with the addition of the scale inhibitors, and the aragonite crystals are clearly observed in SEM images. Finally, the possible multi-stage scale inhibition mechanism of PASP-based inhibitors was proposed, including coating impurities, electrostatic repulsion, and inhibiting dehydration and rearrangement of CaCO3 crystallization.

A Polymer Defect Passivator for Efficient Hole‐Conductor‐Free Printable Mesoscopic Perovskite Solar Cells

AbstractDue to the low cost and excellent potential for mass production, printable mesoscopic perovskite solar cells (p‐MPSCs) have drawn a lot of attention among other device structures. However, the low open‐circuit voltage (VOC) of such devices restricts their power conversion efficiency (PCE). This limitation is brought by the high defect density at perovskite grain boundaries in the mesoporous scaffold, which results in severe nonradiative recombination and is detrimental to the VOC. To improve the perovskite crystallization process, passivate the perovskite defects, and enhance the PCE, additive engineering is an effective way. Herein, a polymeric Lewis base polysuccinimide (PSI) is added to the perovskite precursor solution as an additive. It improves the perovskite crystallinity and its carbonyl groups strongly coordinate with Pb2+, which can effectively passivate defects. Additionally, compared with its monomer, succinimide (SI), PSI serves as a better defect passivator because the long‐chained macromolecule can be firmly anchored on those defect sites and form a stronger interaction with perovskite grains. As a result, the champion device has a PCE of 18.84%, and the VOC rises from 973 to 1030 mV. This study offers a new strategy for fabricating efficient p‐MPSCs.

Fabrication of micro/nano spherulitic hierarchical energetic materials via noncrystallographic branching induced by polymer additives: A case study of 2,2′,4,4′,6,6′-hexanitrostilbene (HNS)

In this work, the micro/nano spherulitic hierarchical 2,2′,4,4′,6,6′-hexanitrostilbene (HNS) with the excellent specific surface area was prepared for the first time, which was expected to overcome the agglomeration problems of nanoscale HNS. In detail, poly(N-isopropyl acrylamide) (PNIPAM), polysuccinimide (PSI), and polyvinylpyrrolidone (PVP) were selected as additives to induce forming spherulitic HNS. Leaflike crystals were obtained in the presence of PNIPAM, while spherulitic HNS could be fabricated in the presence of PSI or PVP. And the prepared spherulitic HNS owned nearly 6 times the specific surface area of the raw HNS, with decreased impact sensitivity and advanced melting and decomposition temperatures, demonstrating a good desensitization effect, and a favorable energy release of the hierarchical structure. Moreover, morphological changes under the effect of the molecular weight and concentration of PVP were explored. The approximated morphological evolution of spherulitic HNS was consistent with the classical spherulitic growth by noncrystallographic branching. Furthermore, it was verified that preferential adsorption of PVP and PSI on the HNS inhibits the growth steps of the (200) face and introduces stress to generate crystal defects, which triggers noncrystallographic branching and further spherulitic growth. Overall, the strategy of fabricating micro/nano spherulitic hierarchical energetic materials via polymer-additive induced noncrystallographic branching is promising to solve the problems of nanoscale energetic materials in agglomeration and microscale bulk crystals in low activity.

Characterization of Electrospun Polysuccinimide-Dopamine Conjugates and Effect on Cell Viability and Uptake.

Biocompatible nanofibrous systems made by electrospinning have been studied widely for pharmaceutical applications since they have a high specific surface and the capability to make the entrapped drug molecule amorphous, which increases bioavailability. By covalently conjugating drugs onto polymers, the degradation of the drug as well as the fast clearance from the circulation can be avoided. Although covalent polymer-drug conjugates have a lot of advantages, there is a lack of research focusing on their nano-formulation by electrospinning. In this study, polysuccinimide (PSI) based electrospun fibrous meshes conjugated with dopamine (DA) are prepared. Fiber diameter, mechanical properties, dissolution kinetics and membrane permeability are thoroughly investigated, as these are crucial for drug delivery and implantation. Dopamine release kinetics prove the prolonged release that influenced the viability and morphology of periodontal ligament stem cells (PDLSCs) and SH-SY5Y cells. The presence of dopamine receptors on both cell types is also demonstrated and the uptake of the conjugates is measured. According to flow cytometry analysis, the conjugates are internalized by both cell types, which is influenced by the chemical structure and physical properties. In conclusion, electrospinning of PSI-DA conjugates alters release kinetics, meanwhile, conjugated dopamine can play a key role in cellular uptake.

Characterization of a conjugated polysuccinimide-carboplatin compound.

Carboplatin, an advanced anticancer drug with excellent efficacy against ovarian cancer, was developed to alleviate the side effects that often occur with cisplatin and other platinum-based compounds. Our study reports the in vitro characteristics, viability, and activity of cells expressing the inducible nitric oxide synthase (iNOS) gene after carboplatin was conjugated with polysuccinimide (PSI) and administered in combination with other widely used anticancer drugs. PSI, which has promising properties as a drug delivery material, could provide a platform for prolonging carboplatin release, regulating its dosage, and improving its side effects. The iNOS gene has been shown to play an important role in both cancer cell survival and inhibition. Herein, we synthesized a PSI-carboplatin conjugate to create a modified anticancer agent and confirmed its successful conjugation. To ensure its solubility in water, we further modified the structure of the PSI-carboplatin conjugate with 2-aminoethanol groups. To validate its biological characteristics, the ovarian cancer cell line SKOV-3 and normal ovarian Chinese hamster ovary cells were treated with the PSI-carboplatin conjugate alone and in combination with paclitaxel and topotecan, both of which are used in conventional chemotherapy. Notably, PSI-carboplatin conjugation can be used to predict changes in the genes involved in cancer growth and inhibition. In conclusion, combination treatment with the newly synthesized polymer-carboplatin conjugate and paclitaxel displayed anticancer activity against ovarian cancer cells but was not toxic to normal ovarian cancer cells, resulting in the development of an effective candidate anticancer drug without severe side effects.

Synthesis, scale inhibition performance evaluation and mechanism study of 3-amino-1-propane sulfonic acid modified polyaspartic acid copolymer

A water-soluble polyaspartic acid derivative scale inhibitor (PASP-Ho) was synthesized from 3-amino-1-propanesulfonic acid (Ho) and polysuccinimide (PSI) as raw materials. The structure of PASP-Ho was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H NMR). The scale inhibition performance of PASP and PASP-Ho was determined by static scale inhibition method. The results show that compared with PASP the scale inhibition performance of PASP-Ho has been greatly improved, especially at low concentrations. The scale inhibition performance of PASP-Ho reaches 100% against CaSO4, which is 54% higher than that of PASP at the dose of 4 mg·L−1; the scale inhibition performance of PASP-Ho against CaCO3 is improved by 42% at the dose of 5 mg·L−1. The crystal surface morphology and crystal structure were characterized by field emission scanning electron microscopy (SEM), X-ray diffraction techniques (XRD), and X-ray photoelectron spectroscopy (XPS), indicating that the addition of PASP-Ho enhanced the chelation and dispersion effect, destroying the surface morphology of the crystal. The scale inhibition mechanism was further deduced by conductivity measurement and density functional theory (DFT). The addition of PASP-Ho can increase the surface energy of CaSO4 and CaCO3 scales, reduce the nucleation rate of crystals and inhibit the formation of scales. The scale inhibition mechanism of PASP-Ho is a combination of chelation, dispersion, threshold effect and lattice distortion, but only a little lattice distortion is exhibited for CaSO4 scale.

Polyaspartic acid-capped (4-[(2-aminoethyl) amino]-4-oxobutanoic acid as an efficient and green gypsum scale inhibitor and its scale inhibition mechanism

Two new yet structurally similar scale inhibitors (PASP-AAB and PASP-AAA), have been successfully synthesized through ring-opening reaction of polysuccinimide (PSI) with inexpensive (4-[(2-aminoethyl) amino]-4-oxobutanoic acid or glycylglycine. Static antiscaling experiments imply they could dramatically improve the antiscaling efficiency of gypsum, better than that of PASP. Moreover, the slightly different nitrogen atom position on the side chain of PASP-AAB and PASP-AAA enables the former efficiently inhibit the gypsum scale at low concentration (2.0 mg/L). In addition, our results indicate the antiscaling performance of PASP-AAB (at 4.0 mg/L) could maintain the excellent efficiency (>99 %) against gypsum for at least 7 days, better than that of some reported polymer-, and phosphorus-based industrial antiscalants. The very efficient gypsum scale inhibition property of PASP-AAB makes it as one of the very effective green antiscalants reported in the literature by now. Detailed mechanism studies reveal that the better calcium scale inhibition performance of PASP-AAB should be attributed to the easier formation of seven-membered chelation ring of side chain with Ca2+. The unprecedented nitrogen substitution effect disclosed in this work provides a new perspective for understanding the structure-activity relationship of the grafting-modified polymeric inhibitor, meaningful for developing other novel green scale inhibitors.

Effect of Cross-Linker Length on the Absorption Characteristics of the Sodium Salt of Cross-Linked Polyaspartic Acid.

For the development of biodegradable superabsorbent polymers, the effect of the cross-linking length on the absorption characteristics of the Na salt of polyaspartic acid (PAspNa) was demonstrated using different concentrations of diamine cross-linking agents bearing carbon chains of different lengths, viz., ethylenediamine, 1,6-hexamethylenediamine, 1,8-diaminooctane, 1,10-diaminodecane, and 1,12-diaminododecane were used as cross-linking agents. The absorption of PAspNa was measured in deionised water and in a 0.9% aqueous NaCl solution. Under the conditions tested, when the alkyl chain of PAspNa was too short or too long, the absorbency was low and the cross-linking length was optimum. The success of the cross-linking reaction was confirmed by FT-IR spectroscopy. The degree of cross-linking was estimated and the ideal concentration for maximum water absorption was determined by elemental analysis. The sample obtained by cross-linking 1,8-diaminooctane at a concentration of 0.11 g/g polysuccinimide (PSI) showed the highest absorption. The thermal properties of each material were determined by dynamic scanning calorimetry. Therefore, the length of the cross-linking agent was found to strongly influence water absorption.

An Implantable Magneto-Responsive Poly(aspartamide) Based Electrospun Scaffold for Hyperthermia Treatment

When exposed to an alternating magnetic field, superparamagnetic nanoparticles can elicit the required hyperthermic effect while also being excellent magnetic resonance imaging (MRI) contrast agents. Their main drawback is that they diffuse out of the area of interest in one or two days, thus preventing a continuous application during the typical several-cycle multi-week treatment. To solve this issue, our aim was to synthesise an implantable, biodegradable membrane infused with magnetite that enabled long-term treatment while having adequate MRI contrast and hyperthermic capabilities. To immobilise the nanoparticles inside the scaffold, they were synthesised inside hydrogel fibres. First, polysuccinimide (PSI) fibres were produced by electrospinning and crosslinked, and then, magnetitc iron oxide nanoparticles (MIONs) were synthesised inside and in-between the fibres of the hydrogel membranes with the well-known co-precipitation method. The attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) investigation proved the success of the chemical synthesis and the presence of iron oxide, and the superconducting quantum interference device (SQUID) study revealed their superparamagnetic property. The magnetic hyperthermia efficiency of the samples was significant. The given alternating current (AC) magnetic field could induce a temperature rise of 5 °C (from 37 °C to 42 °C) in less than 2 min even for five quick heat-cool cycles or for five consecutive days without considerable heat generation loss in the samples. Short-term (1 day and 7 day) biocompatibility, biodegradability and MRI contrast capability were investigated in vivo on Wistar rats. The results showed excellent MRI contrast and minimal acute inflammation.

Polyaspartic acid grafted dopamine polymer chelated Fe 3+ for magnetic resonance imaging visual photothermal therapy agent

This study aims to explore the potential of polyaspartic acid grafted dopamine copolymer (PAsp- g-DA) chelated Fe 3+ for magnetic resonance imaging (MRI) visual photothermal therapy. Polyaspartic acid grafted copolymer of covalently grafted dopamine and polyethylene glycol (PAsp- g-DA/PEG) was obtained by the ammonolysis reaction of poly succinimide (PSI), and then chelated with Fe 3+ in aqueous solution. The relaxivity in vitro, magnetic resonance imaging enhancement in vivo and photothermal conversion effect at 808 nm were investigated. The results showed that polymeric iron coordination had good near-infrared absorption and photothermal conversion properties, good magnetic resonance enhancement effect, and good longitudinal relaxation efficiency under different magnetic field intensities. In summary, this study provides a new magnetic resonance visual photothermal therapeutic agent and a new research idea for the research in related fields.