External Crosslinking Research Articles

Biodegradable disulfide crosslinked chitosan/stearic acid nanoparticles for dual drug delivery for colorectal cancer

Herein, redox responsive chitosan/stearic acid nanoparticles (CSSA NPs) (≈200nm) are developed for dual drug delivery. These degradable nanoparticles are prepared based on disulfide (SS) crosslinking chemistry avoiding the use of any external crosslinking agent. CSSA NPs are further loaded with both DOX (hydrophilic) and curcumin (hydrophobic) drugs with ≈86% and ≈82% encapsulation efficiency respectively. This approach of combining anticancer therapeutics having different mode of anticancer action allows to develop systems for cancer therapy with enhanced efficacy. In vitro drug release experiments clearly exhibit the low leakage of drug under physiological conditions while ≈98% DOX and ≈96% curcumin is released after 136h under GSH reducing conditions. The cytotoxicity experiments against HCT116 cells demonstrate higher cytotoxicity of dual drug loaded CSSA NPs. In vivo biodistribution experiments with c57bl/6j mice confirms the retention of CSSA NPs in the colon area up to 24h exhibiting their potential for colorectal cancer therapy.

Determination of synthetic estrogens in milk by a novel hyper-crosslinked polymer SPME coupled with HPLC-MS

A novel hyper-crosslinked 2, 8, 14, 20-tetraphenyl calix [4] resorcinol arene polymer (HCP-TCRA) was synthesized by using an external crosslinking of 2, 8, 14, 20-Tetraphenyl calix [4] resorcinol arene (TCRA) as monomers and dimethoxymethane as crosslinker. The HCP-TCRA was explored as a SPME fiber coating material. A variety of physicochemical characterization demonstrated that the material has excellent chemical/thermal stability and strong hydrophobicity. The fiber demonstrated fantastic adsorptive property for three synthetic estrogens (diethylstilbestrol, hexestrol, ethinyloestradiol, abbreviated to SESs). In this work, an efficient HCP-TCRA fiber-based SPME method was developed to analyze SESs by coupling with HPLC-MS detection. Under the optimized SPME conditions, this method was shown a wide range of linearity (2.0–100.0 ng mL−1 for diethylstilbestrol, 1.0–100.0 ng mL−1 for hexestrol, and 30.0–480.0 ng mL−1 for ethinyloestradiol), low limits of detection (LODs, 0.5 ng mL−1 for DES 0.3 ng mL−1 for HEX, 10.0 ng mL−1 for EES) and fine reusability (more than 30 times). Finally, the proposed methods had been applied to the determination of SESs in milk samples with a simple pretreatment. At three different levels, relative recoveries presented between 86.7 and 106.4%. The method put up highly sensitive and budget-friendly in detection SESs, and has capacity in quality control of milk products.

Graphene Oxide-Chitosan Network on a Dialysis Cellulose Membrane for Efficient Removal of Organic Dyes.

Currently, water pollution is a significant health problem for both humans and animals due to large amounts of dye-containing wastewater. Thus, polymer composite membranes (PCMs) are considered as efficient adsorption/filtration membranes that can be utilized for removing organic dyes from contaminated water/wastewater. In this study, the goal is to explore the modification of the interfacial dialysis cellulose (DC) surface through molecular interactions of an active graphene oxide-chitosan (GO-CTS) composite hydrogel (GCCH) network without the use of an external cross-linker toward an effective dye removal ability using a simple casting process and a low-cost adsorption technique, resulting in the formation of a PCM, i.e., GO/CTS/DC membrane (GCD-mems). Concomitantly, the incorporation of the GCCH network (as an active hybrid network) and DC (as a supporting material) is considered as a promising approach toward a dye-removing PCM. As a result, the GCD-mems showed that cellulose robustly interacted via the chemical bonds of the GCCH network by maintaining the three-dimensional (3D) porous layer structures, and the functional surface of the membrane was enhanced toward specific groups for an effective dye removal approach. In addition, there is a significant improvement in dye removal performance after modification of the interfacial DC surface through molecular interactions of GCCH, i.e., high adsorption capacities of cationic and anionic dye molecules on the GCD-mems, compared to the relevant GO-based adsorbents. Also, the dye flux and rejection of the GCD-mems can simultaneously remove both methylene blue and Congo red. In the adsorption, it is appropriate with the pseudo-second-order and Langmuir models corresponding to chemical adsorption and monolayer approaches, as well as physical sieving through the 3D layers of porous channels of GCD-mems during the filtration process. Moreover, the structural stability and sustainability of the PCMs are enhanced during the recycling process, and the use of ethanol in the recycling process further simplifies the process and reduces the cost of the PCMs. Thus, the GCD-mems are encouraged as potential candidates that can be applied directly in the removal of dyes from the wastewater of textile industries or selective dialysis applications.

Supramolecular Hydrogel Based Post-Surgical Implant System for Hydrophobic Drug Delivery Against Glioma Recurrence.

PurposeThe brain, protected by the cranium externally and the blood–brain barrier (BBB) internally, poses challenges in chemotherapy of aggressive brain tumors. Maximal tumor resection followed by radiation and chemotherapy is the standard treatment protocol; however, a substantial number of patients suffer from recurrence. Systemic circulation of drugs causes myelodysplasia and other side effects. To address these caveats, we report facile synthesis of a polyester-based supramolecular hydrogel as a brain biocompatible implant for in situ delivery of hydrophobic drugs.MethodsPolycaprolactone-diol (PCL) was linked to polyethyleneglycol-diacid (PEG) via an ester bond. In silico modeling indicated micelle-based aggregation of PCL-PEG co-polymer to form a supramolecular hydrogel. Brain biocompatibility was checked in Sprague Dawley rat brain cortex with MRI, motor function test, and histology. Model hydrophobic drugs carmustine and curcumin entrapment propelled glioma cells into apoptosis-based death evaluated by in vitro cytotoxicity assays and Western blot. In vivo post-surgical xenograft glioma model was developed in NOD-SCID mice and evaluated for efficacy to restrict aggressive regrowth of tumors.Results20% (w/v) PCL-PEG forms a soft hydrogel that can cover the uneven and large surface area of a tumor resection cavity and maintain brain density. The PCL-PEG hydrogel was biocompatible, and well-tolerated upon implantation in rat brain cortex, for a study period of 12 weeks. We report for the first time the combination of carmustine and curcumin entrapped as model hydrophobic drugs, increasing their bioavailability and yielding synergistic apoptotic effect on glioma cells. Further in vivo study indicated PCL-PEG hydrogel with a dual cargo of carmustine and curcumin restricted aggressive regrowth post-resection significantly compared with control and animals with intravenous drug treatment.ConclusionPCL-PEG soft gel-based implant is malleable compared with rigid wafers used as implants, thus providing larger surface area contact. This stable, biocompatible, supramolecular gel without external crosslinking can find wide applications by interchanging formulation of various hydrophobic drugs to ensure and increase site-specific delivery, avoiding systemic circulation.

Hydroxyl-functionalized hypercrosslinked polymers with ultrafast adsorption rate as an efficient adsorbent for phenol removal

In the present study, the adsorptive potential of hypercrosslinked polymers (HCPs) was investigated for the removal of phenol from aqueous solutions. Herein, two HCPs were one-step synthesized by the Friedel-Crafts reaction using 4,4′-biphenyldiol (BPD) or hydroquinone (HQ) as the building unit and 1,4-bis(chloromethyl)benzene (DCX) as the external crosslinker. The results showed that the HCPs, derived from BPD and DCX (called as BPD-D), exhibited more excellent pore structures with the higher surface area of 697 m2 g−1 and the micropore volume of 0.23 cm3 g−1 and allowed for the extremely fast equilibrium adsorption of phenol, attributed to the hierarchical pore structure and the great hydrophilicity; meanwhile, the maximum adsorption capacity of BPD-D towards phenol was calculated to be 156.74 mg g−1. Moreover, the adsorption equilibrium and kinetic processes of BPD-D towards phenol were well described by the Freundlich model (R2 > 0.99) and the pseudo-second-order kinetic model (R2 > 0.9999) at 303 K. Moreover, negative changes in Gibbs free energy and enthalpy reflect that the adsorption of BPD-D for phenol is a spontaneous and exothermic process. In addition, adsorption performances were investigated under different conditions, e.g., the initial concentrations of phenol, the dosage of the BPD-D, the initial pH of phenol aqueous solution and recyclability. Our finding demonstrates that HCPs show potential application prospects in the removal of organic pollutants from wastewater.

Fabricating hypercrosslinked aromatic-rich starch urethane polymer with enhanced adsorption performance for separation of acetophenone and 1-phenylethanol

Starch-based urethane polymers hold great potential for adsorptive separation of acetophenone (AP) and 1-phenylethanol (PE), which coexist commonly in the petrochemical by-products. Yet, the overall adsorption performance was restricted due to the poor porosity of adsorbent. We herein applied external crosslinking strategy to fabricate hypercrosslinked aromatic-rich starch urethane polymer (HASUP) with large surface area. The structural evolution, including chemical state, porosity and morphology were observed through various characteristic techniques. The adsorption properties of AP and PE onto HASUP were investigated in both single and binary systems. Compared to its non-porous precursor, HASUP exhibited significantly higher overall adsorption capacity while maintaining the AP selectivity with varying compositions. The further static and dynamic adsorption assessments demonstrated that HASUP showed exceptional performance to separate AP and PE. And HASUP also exhibited excellent anti-interference ability and recyclability for selective adsorption of AP over PE. Furthermore, theoretical results indicated that the multiple interactions including hydrophobic, π-π, and hydrogen bonding interactions account for selective adsorption of AP. In combination with high surface area, this synergistic effect enhanced the adsorption strength, affording a high AP uptake for HASUP. This work may provide an insight for designing novel porous starch-based adsorbents with high performance. • Porous HASUP was fabricated by external crosslinking strategy. • The enhanced adsorption ability came from high porosity and introduced active sites. • HASUP showed excellent performance for separation of AP and PE. • The adsorption was mainly driven by π-π and hydrogen bonding interactions.

Facile fabrication of hypercrosslinked microporous polymer nanospheres for effective inhibition of triple negative breast cancer cells proliferation

Treatment failure is one of the main lethal causes of human triple negative breast cancer (TNBC) patients due to inefficient drug administration. The present study demonstrated the development of functional microporous organic polymers (MOPs) as a potential drug carrier and its controlled release. Due to the existence of abundant pores and high surface area, MOPs have promoted the high drug payloads, facilitating prolonged retention time and improved drug release. Herein, porous organic polymer has been fabricated via knitting strategy using the carbonyl bridged external crosslinker. Utilizing the imine chemistry, post-functionalization at the bridging carbon with the diamine resulted in the functional porous framework which had been further modified with single stranded DNA (ssDNA). Due to the conjugated structure, the designed material incorporates the strong blue fluorescence that assists in bio-imaging. In short, the inherent features of hypercrosslinked microporous polymers nanospheres (HMPNs) enabled the high encapsulation of Epirubicin (EPI) and its controlled release in TNBC cell lines (SUM-159 and MDA-MB-231) to inhibit cancer cells proliferation. We anticipate that the further development in functionalization of hypercrosslinked polymers may lead to a breakthrough in biomedical applications.

Bioprinting with bioactive alginate dialdehyde-gelatin (ADA-GEL) composite bioinks: Time-dependent in-situ crosslinking via addition of calcium-silicate particles tunes in vitro stability of 3D bioprinted constructs

The development of hydrogels suitable for biofabrication is essential to enable advanced approaches for tissue engineering and regenerative medicine. Applications in both hard and soft tissues require tailor-made bioinks to guide cellular behavior in a 3D matrix. In this study we aimed to enhance the stability and adjust the degradation behavior of alginate dialdehyde-gelatine (ADA-GEL) hydrogels using an in-situ crosslinking mechanism additionally to external crosslinking. To test this approach, we added 0.1 and 0.5% (w/v) bioactive inorganic fillers (BIF) based on sub-micrometric calcium-silicate particles to ADA-GEL hydrogels. Such BIF release bivalent Ca2+ ions which can internally crosslink alginate chains and tune the degradation of the hydrogel over 28 days of incubation. It was found that pure ADA-GEL dissolved quickly after the first day while the composite hydrogels remained stable exhibiting reduced degradation (20–50% of the initial weight). 3D (bio)printing of composite bioinks revealed improved printing accuracy, 3D shape fidelity as well as cell spreading throughout the entire matrix during 14 days of evaluation. Chemically, BIF did not seem to have an influence on ADA-GEL Schiff's base bonds and also the mechanical properties of the composite hydrogels were comparable to those of pure ADA-GEL with Young's moduli of about 4 kPa. Comprehensive rheology measurements were carried out to determine printing parameters and the influence of BIF on the bioprinting process. We conclude that the novel hydrogel composition based on ADA-GEL system incorporating calcium-silicate BIF exhibits tunable behavior in vitro up to at least 28 days of incubation leading to improved stability and time-dependent cell behavior in 3D bioprinted constructs.

Hypercrosslinked triazine-phloroglucinol hierarchical porous polymers for the effective removal of organic micropollutants

The development of practical and efficient adsorbents is of great significance to the wastewater treatment. Here, we demonstrated trisphloroglucinol substituted triazine (TPT) as an intriguing building block to construct hypercrosslinked polymers (HCPs) for the removal of organic micropollutants (OMPs) from water. HCP-TPTs (HCP-TPT-1 and HCP-TPT-2) were facilely obtained via Friedel-Crafts alkylation of TPT with external crosslinkers, and possessed hierarchical porous structure, high degree of functionality, and good hydrophilicity. The embedded TPT skeletons in the porous structure help in effective adsorption of various cationic and nonionic OMPs. The maximum adsorption of HCP-TPT-1 reached 2336 mg g−1 for the rhodamine B, 2239 mg g−1 for the crystal violet, 521 mg g−1 for the 1-naphthylamine, and 500 mg g−1 for the 2-naphthol. In addition, the pseudo-second-order rate of HCP-TPT-1 for rhodamine B is 9.341 g mg−1min−1, which is superior to those adsorbent materials reported so far. Furthermore, HCP-TPT-1 can be easily reused at least seven times without obvious decrease of adsorption efficiency, indicating its potential application in wastewater treatment.

Nanostructured Hypercrosslinked Porous Organic Polymers: Morphological Evolution and Rapid Separation of Polar Organic Micropollutants.

Nanostructured hypercrosslinked porous organic polymers have triggered immense research interest for a broad spectrum of applications ranging from catalysis to molecular separation. However, it still remains a challenge to tune their nanoscale morphology. Herein, we demonstrated a remarkable variation of morphologies of triptycene-based hypercrosslinked microporous polymers starting from irregular aggregates (FCTP) to rigid spheres (SCTP) to two-dimensional nanosheets (SKTP) from three distinct polymerization methodologies, Friedel-Crafts knitting using an external crosslinker, Scholl reaction, and solvent knitting, respectively. Further, the dramatic role of reaction temperatures, catalysts, and solvents resulting in well-defined morphologies was elucidated. Mechanistic investigations coupled with microscopic and computational studies revealed the evolution of 2D nanosheets of a highly porous solvent-knitted polymer (SKTP, 2385 m2 g-1), resulting from the sequential hierarchical self-assembly of nanospheres and nanoribbons. A structure-activity correlation of hypercrosslinked polymers and their sulfonated counterparts for the removal of toxic polar organic micropollutants from water was delineated based on the chemical functionalities, specific surface area, pore size distribution, dispersity, and nanoscale morphology. Furthermore, a sulfonated 2D sheet-like solvent-knitted polymer (SKTPS) exhibited rapid adsorption kinetics (within 30 s) for a large array of polar organic micropollutants, including plastic components, steroids, antibiotic drugs, herbicides, and pesticides with remarkable uptake capacity and excellent recyclability. The current study provides the impetus for designing morphology-controlled functionalized porous polymers for task-specific applications.

Novel preparation of amidoxime functionalized hyper-cross-linked polymeric adsorbent on the efficient adsorption of uranium in aqueous solution

Herein, a series of novel amidoxime-functionalized porous polymeric adsorbents using dimethoxymethane (FDA) as the external cross-linker and biphenyl and amidoxime-functionalized 1-(benzyloxy)-4-ethylbenzene (BP-AO) as the original monomers were synthesized in one-pot Friedel-Crafts alkylation reactions via a simple “knitting” synthetic strategy. The adsorbents were characterized by FT-IR, solid-state 13 C NMR/MAS spectrum, N 2 adsorption-desorption, etc. The adsorption mechanism was probed by XPS, which suggests that the η 2 complexation between uranium and amidoxime, and the polymers provide an approach to synthesize novel porous materials. The batch adsorption experiments showed that amidoxime hyper-crosslinked polymer-2 (HCPA-2) displays a uranium adsorption capacity of 27.7 mg/g at pH 6. The static adsorption action was more consistent with the Langmuir model and pseudo-second-order kinetics. Ionic competition experiments showed that K d (U(IV)) is as high as 695.94 mL/g and reusable with a removal rate up to 60% after 7 cycles when 0.1 M HNO 3 was used as a stripping agent, which verifies the practical application potential of the materials. • The HCPAs adsorbents with porous structure was synthesized via facile “knitting” strategy. • The HCPAs exhibited high selectivity and long service life. • The adsorption capacity was affected by the specific surface area and amidoxime group content. • The adsorption process was spontaneous and endothermic.

Design of adjustable hypercrosslinked poly(ionic liquid)s for highly efficient oil-water separation

• A series of novel HCPILs were constructed to separate different oil–water mixtures. • The hydrophilicity and hydrophobicity of HCPL can be adjusted by changing different auxiliary crosslinking agents. • The resulting HCPLs possessed high separation efficiency for oil–water mixtures. • The designed HCPLs are reusable and environmentally friendly. Considering the environmental problems caused by oily wastewater, how to realize oil-water separation has attracted extensive attention from researchers. Herein, a series of hypercrosslinked poly(ionic liquid)s (HCPILs) were fabricated by using dimethoxymethane as an external crosslinking agent combined with different auxiliary crosslinking agents to “weave” the ionic liquid of 1,3-dibenzylimidazolium chloride for oil-water separation. The hydrophilicity and hydrophobicity of HCPL can be adjusted by changing different auxiliary crosslinking agents. When using aniline as an auxiliary crosslinking agent, the resulting HCPIL-A2 with approximately 5500 L/m 2 ·h of water flux exhibits super hydrophilicity-oleophobicity, its static water contact angle and underwater oil contact angle are close to 0° and 132°, respectively. When using benzyl alcohol instead of aniline, the obtained HCPIL-B2 exhibits good lipophilicity and hydrophobicity. Its static water contact angle and underwater oil contact angle are close to 126° and 0°, respectively. And its oil fluxes of chloroform and carbon tetrachloride are approximately 7645 and 7241 L/m 2 ·h, respectively. However, when using toluene instead of aniline, the obtained HCPIL-C2 exhibits hydrophilicity-lipophilicity and can’t separate the oil-water mixtures. Moreover, HCPILs show permanent pore structure, good stability, and environmental friendliness due to their high degree of crosslinking are constructed. Their loose surface roughness can realize the separation of the oil-water mixture by gravity. Therefore, the designed new materials can selectively remove water or oil mixture. Efficient separation of crude oil and seawater mixture will provide new ideas for future environmental problems such as offshore oil spills.

Magnetic Nanoparticle-Embedded Ionic Microporous Polymer Composite as an Efficient Scavenger of Organic Micropollutants.

A cationic microporous composite polymer (120-TMA@Fe) bearing free exchangeable chloride anions alongside easy magnetic separation was crafted through post-polymerization structure modulation. The precursor polymer 120-Cl was synthesized via an "external cross-linking" strategy in a straightforward one-pot Friedel-Crafts reaction. Subsequently, a cationic network accommodating magnetic Fe3O4 nanoparticles, viz., 120-TMA@Fe was fabricated through chemical modifications. 120-TMA@Fe displayed excellent adsorption proficiency both in terms of rapid kinetics and maximum uptake capacity when screened for a wide range of organic micropollutants of various categories. Amongst the tested pollutants, including anionic dyes, aromatic models, plastic components, and pharmaceuticals, 120-TMA@Fe illustrated exceptional performance in removing all of these model pollutants with adsorption equilibrium reaching within only 5 min. The Langmuir adsorption isotherm model determined the theoretical maximum uptake capacity (qmax,e) of 120-TMA@Fe to be 357 mg g-1 for methyl orange dye, 555 mg g-1 for plasticizer bisphenol A, and 285 mg g-1 for antibiotic ibuprofen. Additionally, 120-TMA@Fe showed unaltered performance upon harsh chemical treatment as well as in complex real-world samples. The potency of 120-TMA@Fe was further supported by its outstanding regeneration performance up to 10 cycles.

Synergistic dual-functionalities of starch-grafted-styrene hydrophilic porous resin for efficiently removing bisphenols from wastewater

• The porous and hydrophilic SGS-HPR was fabricated via feasible two-step strategy. • SGS-HPR 7 showed great ability for bisphenols removal. • Both static and dynamic adsorption studies verified recyclability of SGS-HPR 7 . • The synergistic effect of the hydrogen bond and π-π interactions were studied theoretically. Highly efficient remediation of bisphenols (BPs) contaminated wastewater by adsorption is intriguing but remains challenging. Herein, we present a starch-grafted-styrene hydrophilic porous resin (SGS-HPR) showing excellent BPs adsorption capacity, through simple graft copolymerization and then external knitting strategy. The typical influencing factors of graft copolymerization and external crosslinking processes were investigated systematically. A series of characterization experiments verified the successful fabrication of SGS-HPR and manifested that the optimum product, SGS-HPR 7 , possesses a hierarchical porous structure with strong hydrophilicity. The abundant presence of starch chain in SGS-HPR 7 , not only increased the hydrophilicity but also enhanced the adsorption affinity, making SGS-HPR 7 exhibit remarkable removal ability toward BPs. The adsorption performance of SGS-HPR 7 was studied systematically in static mode. The results showed that SGS-HPR 7 can adsorb BPs quickly with a stable ability irrespective of the varying aqueous environments. Besides, the continuous adsorption and regeneration experiments were conducted using bisphenol A (BPA) as the model BPs. The adsorbed BPA can be efficiently desorbed by ethanol elution, and the regenerated SGS-HPR 7 showed great recyclability. Interestingly, SGS-HPR 7 also retained the superior adsorption capacity and marvelous regeneration ability in the continuous adsorption experiments. Further, according to theoretical calculation studies, the hydrogen-bonding and π-π stacking interactions involved mechanism was uncovered clearly. Collectively, this work provides a new convenient strategy to fabricate new highly hydrophilic bio-based adsorbent for BPs removal.

A facile synthesis of hyper-cross-linked polystyrene resins for phenol removal

Hyper-cross-linked polystyrene networks (HPNs) were obtained from macroporous slightly cross-linked polystyrene by using inexpensive and commercial dichloroalkanes as external cross-linkers via a two-step Friedel-Crafts reaction. In this reaction, AlCl 3 or FeCl 3 was used as catalyst, and the highest Brunauer-Emmett-Teller (BET) surface area ( S BET ) of the HPNs was amounted to 832.8 m 2 /g using a starting polymer with a S BET of 19.5 m 2 /g. The results showed that physical properties such as surface area and swelling behaviors of the HPNs could be regulated by varying the strut length and structure of cross-linkers. The sorption performance of the HPNs for phenol was greatly improved due to both adsorption on the surface and absorption in the matrix through framework swelling. The equilibrium adsorption capacity of phenol on HPN-DCM-DCE reached 24.5 mg/g and 170.0 mg/g at the equilibrium concentration of 2 mg/L and 200 mg/L, respectively. The equilibrium isotherm and sorption kinetic studies indicated that the sorption behaviors could be well fitted with Freundlich isotherm equation and the pseudo-second-order rate equation. • A facile synthetic strategy for preparing hyper-cross-linked polystyrene polymers with well-developed porous framework was proposed. • Inexpensive and commercial available multi-chloroalkanes, including DCM, TCM and DCE, were used as external cross-linkers. • Surface area and swelling behaviors of HPNs could be regulated by varying the strut length and structure of cross-linkers. • The resultant sample HPN-DCM-DCE exhibited a highly performance for phenols adsorption.

Injectable, Self-Healing, and Biocompatible N,O-Carboxymethyl Chitosan/Multialdehyde Guar Gum Hydrogels for Sustained Anticancer Drug Delivery.

Local delivery of anticancer agents via injectable hydrogels could be a promising method for achieving spatiotemporal control on drug release as well as minimizing the disadvantages related to the systemic mode of drug delivery. Keeping this in mind, we report the development of N,O-carboxymethyl chitosan (N,O-CMCS)-guar gum-based injectable hydrogels for the sustained delivery of anticancer drugs. The hydrogels were synthesized by chemical crosslinking of multialdehyde guar gum (MAGG) and N,O-CMCS through dynamic Schiff base linkages, without requiring any external crosslinker. Fabrication of injectable hydrogels, involving N,O-CMCS and MAGG via Schiff base crosslinking, is being reported for the first time. The hydrogels exhibited pH-responsive swelling behavior and good mechanical properties with a storage modulus of about 1625 Pa. Due to the reversible nature of Schiff base linkages, hydrogels displayed excellent self-healing and thixotropic properties. Doxorubicin (Dox), an anticancer agent, was loaded onto these hydrogels and its release studies were conducted at pH 7.4 (physiological) and pH 5.5 (tumoral). A sustained release of about 67.06% Dox was observed from the hydrogel after 5 days at pH 5.5 and about 32.13% at pH 7.4. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay on the human embryonic kidney cell line (HEK-293) and the hemolytic assay demonstrated the biocompatible nature of the hydrogels. The Dox-loaded hydrogel exhibited a significant killing effect against breast cancer cells (MCF-7) with a cytotoxicity of about 72.13%. All the data presented support the efficiency of the synthesized N,O-CMCS/MAGG hydrogel as a biomaterial that may find promising applications in anticancer drug delivery.

Synthesis and characterization of polyvinyl alcohol/water-hyacinth (Eichhornia crassipes) based hydrogel by applying gamma radiation

A simple Gamma radiation (Cobalt-60 γ-ray source) technique was employed for the preparation of hydrogel based on Polyvinyl Alcohol (PVA)/water-hyacinth (Eichhornia crassipes) (PW hydrogel) without using any external cross-linker. The structure of the synthesized hydrogels was characterized using Fourier Transform Infrared-Attenuated Total Reflection Spectroscopy (FTIR-ATR) and Scanning Electron Microscopy (SEM). The effects of different radiation doses, the concentration of water-hyacinth on the properties of the prepared hydrogel, such as gel fraction, swelling ratio, water uptake, and mechanical properties including the tensile strength (TS), percentage elongation at break (EB) and biodegradability were investigated. The hydrogels showed a porous and interconnected network and flexible structure. The presence of water-hyacinth significantly escalated the swelling capacity of PVA hydrogels from 97.9% to 136.24% along with acceptable tensile strength. And the degradation percentage of PW hydrogel was remarkably higher than the pure PVA hydrogel. Furthermore, the weight loss of PW hydrogel was 12.86%, whereas 3.19% was for pure PVA hydrogel. Hence, this novel hydrogel showed some favorable potentials to be applied in various fields, especially, adsorption to remove the dye and heavy metals.

Study of the impact on occupational health of the use of polyaziridine in leather finishing compared with a new epoxy acrylic self-crosslinking polymer

The leather industry needs innovative products to meet the continued demands of the global market. To achieve a good performance in the finishing operation, crosslinking of the polymers used in this leather production stage is necessary. These crosslinkers are irritating and harmful. This study is based on the synthesis of functionalized acryl polymers with epoxy groups to improve the properties of the leather finishing to avoid the use of external crosslinkers, and consequently; harmful products for health and the environment will not be necessary. Likewise, the affectation in the health of workers exposed to crosslinker has been investigated when the leather finish is carried out. To do this research, a clinical analysis has been carried out prior authorization of the workers. The study demonstrates a good performance finishing avoiding the use of crosslinkers. In addition, it has been determined that molecular fragments of the decomposition of polyaziridine are present in the urine of one of the employees. Although the human metabolism may metabolize these polyaziridine fragments being non detectable in the urine samples, a positive result was obtained in the analysis by GC-MSD of the urine, and therefore; it could affect the health of this employee.

Preparation of hyper-cross-linked hydroxylated polystyrene for adsorptive removal of methylene blue.

A series of hydroxylated polystyrene (PS-OH) resins were prepared from macroporous poly(styrene-co-divinylbenzene) by nitration, reductive amination, diazotation and hydrolysis in sequence, and then a series of hyper-cross-linked hydroxylated polystyrene (HCPS-OH) resins were successfully prepared from the PS-OH resins by the Friedel–Crafts post-cross-linking using dichloromethane as an external cross-linker. Benefiting from the synthetic protocol, the HCPS-OH resins showed better adsorption performance for methylene blue in aqueous solution as compared with the corresponding PS-OH resins. HCPS-OH-4, one of the fabricated HCPS-OH resins which had the hydroxyl content of 5.0 mmol g−1 and BET specific surface area of 69.0 m2 g−1, showed the highest adsorption capacity and selectivity for methylene blue. Higher temperature, higher pH, and higher ionic strength were beneficial to adsorption of methylene blue from aqueous solution. HCPS-OH-4 could be regenerated by treatment with 1.0 M HCl methanol solution and deionized water sequentially. Moreover, HCPS-OH-4 retained good adsorption performance for methylene blue even after 5 cycles of adsorption and regeneration, which implied that it was a good candidate for adsorptive removal of methylene blue dye in waste water.

Preparation of itaconic acid bio-based cross-linkers for hydrogels

Itaconic acid (IA) is a bio-based unsaturated monomer, which has been limitedly used in free-radical polymerization due to low reactivity of its carbon-carbon double bond and lack of tendency toward homo-polymerization. In the present work, IA was modified with glyceryl methacrylate (GMA) or epichlorohydrin (ECH) to synthesize two new IA-based materials, i.e., IA-GMA and IA-ECH, respectively. After the characterization of the crosslinkers by 1H NMR and FTIR, IA-GMA containing two methacrylate groups in the structure was used as an internal crosslinker for the preparation of a superabsorbent polymer (SAP). The obtained IA-GMA crosslinked SAP showed a high water absorbency under load (AUL) up to 23.9 g/g compared to commercial SAPs (14–18 g/g), so it can be a potential crosslinker for SAP preparation without a requirement of the surface treatment process as a time and energy-consuming process. Moreover, the application of IA-ECH, possessing hydroxyl or epoxy functionalities as an internal and surface crosslinker in the synthesis of SAPs was investigated. The unique ion structure of IA-ECH as an external crosslinker resulted in improvement in gel strength, as well as AUL up to 30.7 g/g. The SAPs crosslinked by IA-ECH as internal crosslinker presented a high water absorbency (Qw) and saline absorbency (Qs).