Simultaneous Crosslinking Research Articles

Structure-Property Relationships of Shape Memory, Semicrystalline Polymers Fabricated by In Situ Polymerization and Crosslinking of Octadecyl Acrylate/Polybutadiene Blends.

The current work presents the study of a semicrystalline, shape memory polymer synthesized by simultaneous free radical polymerization and crosslinking in a blend of polybutadiene (PB) and octadecyl acrylate. Blending elastomers and phase change materials provide a modular method for new smart materials, such as shape memory polymers. In this system, grafted, side-chain crystalline poly(octadecyl acrylate) (PODA) fixes a programmed shape in the shape memory cycle, while crosslinked polybutadiene drives shape recovery. This work focuses on improving material parameters important for shape memory (crystallinity, gel fraction, melting temperature) by tuning the processing and formulation parameters (amount of crosslinker and PB weight fraction). The result is a shape memory PB-PODA copolymer that can be fabricated by melt processing and programmed without cooling below ambient temperature. It is found that good shape memory (i.e., high shape fixity and recovery) is obtained at a low PB weight fraction where a percolating PODA crystal network is formed at room temperature. The optimized sample shows excellent shape memory properties (fixity > 99%, recovery = 96%). It is shown that it is possible to mold this material into complex 3D shapes or topography with potential use in anticounterfeiting and antitampering applications.

Simultaneous One-Pot Interpenetrating Network Formation to Expand 3D Processing Capabilities.

The incorporation of a secondary network into traditional single-network hydrogels can enhance mechanical properties, such as toughness and loading to failure. These features are important for many applications, including as biomedical materials; however, the processing of interpenetrating polymer network (IPN) hydrogels is often limited by their multistep fabrication procedures. Here, a one-pot scheme for the synthesis of biopolymer IPN hydrogels mediated by the simultaneous crosslinking of two independent networks with light, namely: i) free-radical crosslinking of methacrylate-modified hyaluronic acid (HA) to form the primary network and ii) thiol-ene crosslinking of norbornene-modified HA with thiolated guest-host assemblies of adamantane and β-cyclodextrin to form the secondary network, is reported. The mechanical properties of the IPN hydrogels are tuned by changing the network composition, with high water content (≈94%) hydrogels exhibiting excellent work of fracture, tensile strength, and low hysteresis. As proof-of-concept, the IPN hydrogels are implemented as low-viscosity Digital Light Processing resins to fabricate complex structures that recover shape upon loading, as well as in microfluidic devices to form deformable microparticles. Further, the IPNs are cytocompatible with cell adhesion dependent on the inclusion of adhesive peptides. Overall, the enhanced processing of these IPN hydrogels will expand their utility across applications.

Сравнительная оценка результатов комбинированного применения различных методов лечения: кросслинкинга роговицы, имплантации интрастромальных роговичных колец-сегментов и трансэпителиальной топографической фоторефрактивной кератэктомии при лечении кератоконуса

Purpose. Comparative evaluation of the results of combined use of corneal cross-linking (CXL) and implantation of intrastromal corneal ring segments (ICRS) followed by transepithelial topographic photorefractive keratectomy (ТE-topoPRK) in the treatment of keratoconus. Material and methods. The study had been conducted at the National Centre of Ophthalmology named after acad. Zarifa Aliyeva. Within the frames of the first stage of the study during 2016–2019 years: 48 patients (48 eyes) have been operated only with using CXL (first group); 48 patients (48 eyes) – with using only ICRS (second group); and 48 patients (48 eyes) – with using of combination of CXL and ICRS (ICRS first, then CXL after 24 hours) for treatment of keratoconus of II–III stages due to Amsler M. classification. After 8 months, all patients (144 eyes) underwent the second stage of treatment using ТE-topoPRK. Results. Visual acuity and corneal status 8 months later after CXL, ICRS and the combination of CXL with ICRS generally changed significantly, which confirms the achievement of the expected effect. Comparing the studied parameters after the operation in the groups of patients operated on by the CXL, ICRS methods and their combination, a significant difference was revealed only in the value of NCVA (0.22±0.04, 0.46±0.03 и 0.52±0.04; р<0.05). Conclusion. The combined two-stage (with the interval of 8 months) treatment of keratoconus by implantation of intrastromal corneal rings with simultaneous corneal crosslinking followed by topographic photorefractive keratectomy is more effective than the use of these operations without combinations. Key words: crosslinking, corneal segments, keratoconus, topographic photorefractive keratectomy

Topography versus non-topography-guided photorefractive keratectomy with corneal cross-linking variations in keratoconus.

To compare the visual results of non-topography-guided and topography-guided photorefractive keratectomy (PRK) applying sequential and simultaneous corneal cross-linking (CXL) treatment for keratoconus. Interventional and comparative prospective study. Sixty-nine eyes (36 patients) suffering from keratoconus (stages 1 Amsler-Krumeich classification) were divided into four groups: sequential topography-guided photorefractive keratectomy with CXL, simultaneous topography-guided photorefractive keratectomy with CXL, simultaneous non-topography guided photorefractive keratectomy with CXL, and sequential non-topography guided photorefractive keratectomy with CXL. The main outcome measures were pre- and postoperative uncorrected distance visual acuity (UDVA), best corrected distance visual acuity (CDVA), manifest refraction, contrast sensitivity, and keratometry. All analyzed visual, contrast sensitivity, and refractive parameters showed a significant improvement in the four groups (all P<0.05). A noticeable improvement was seen in keratometry in all the groups, and a remarkable difference was observed between topography-guided groups in comparison to non-topography-guided groups (P<0.05). Interestingly, the improvement in all parameters showed a degree of stability to the end of the follow-up. The treatment priorities in all four groups are safety, efficacy, and predictability in the correction of the sphero-cylindrical errors in mild and moderate keratoconus. No significant differences among groups in the recorded objective outcomes were found.

Piperazine-functionalized porous anion exchange membranes for efficient acid recovery by diffusion dialysis

Diffusion dialysis employing anion exchange membranes (AEMs) as an energy-efficient and environmentally-friendly technology is highly desirable for acid recovery from acidic wastewater. Herein, porous AEMs with high acid permeability were tailored via a simple one-step route, in which porous chloromethyl polyethersulfone (CMPES) membrane substrate was modified by 1,4-dimethylpiperazine (DMP) to achieve simultaneous crosslinking and quaternization. The prepared piperazine-functionalized AEMs were characterized by morphology, ion exchange capacity, water uptake, water contact angle, stabilities and diffusion dialysis performance. Specifically, the optimal AEM (i.e., DPES-3h) applied in acid recovery from the simulated HCl (1.0 mol L−1)/FeCl2 (0.2 mol L−1) mixed solution at 25 °C possessed a proton dialysis coefficient (UH+) of 43.2 × 10−3 m h−1 and an acid/salt separation factor (S) of 29.6, remarkably outperforming the previously reported state-of-the-art AEMs. Furthermore, the DPES-3h AEM showed excellent thermal stability and acid resistance, suggesting considerable durability for long-term application. These results indicated that our piperazine-functionalized porous AEMs appear to be promising for acid recovery from the acidic waste streams via diffusion dialysis.

Homologous flexible multi-cationic cross-linkers modified poly(aryl ether sulfone) anion exchange membranes for fuel cell applications

Issues of unsatisfactory ionic conductivity and chemical stability should be solved for anion exchange membranes (AEMs) in practical fuel cell applications. A series of flexible spacers, homologous multi-cationic cross-linkers with different lengths, were designed and synthesized from 1,4-diazabicyclo(2.2.2)octane (DABCO) and 1,6-dibromohexane, and subsequently used to fabricate a series of flexible multi-cationic cross-linked poly(aryl ether sulfone) (CQPAES) AEMs. The CQPAES membranes fabricated by simultaneous cross-linking and membrane formation are tough and pliable. The length and number of cations of the cross-linkers show noticeable effects on the comprehensive membrane performance. The CQPAES membranes display more distinct nano-phase separation morphology and well-developed ion transfer channels due to the higher mobility and hydrophilicity of the flexible long-chain multi-cationic segments. As a result, the CQPAES membranes exhibit gradually increased water uptake and ionic conductivity with the increase of cross-linker length. Furthermore, DABCO and hexyl segments in the cross-linker greatly enhance the steric hindrance and electron cloud density of the quaternary ammonium groups, which inhibit the Hoffmann elimination reaction. Consequently, the CQPAES membranes display a significant improvement in alkali stability than conventional benzyl-substituted quaternary ammonium group type AEMs.

Hybrid In Situ Reinforcement of EPDM Rubber Compounds Based on Phenolic Novolac Resin and Ionic Coagent

For the design of stretchable and flexible high-performing materials, the reinforcement of elastomeric grades plays a crucial role. State-of-the-art fillers such as carbon black benefit from a high reinforcement but often negatively affect the processing and mixing properties of rubber compounds. To overcome this drawback, the synergistic properties of hybrid in situ filler systems are studied for EPDM compounds comprising a phenol novolac resin and ionic coagents such as zinc (meth)acrylates (ZD(M)A. With the help of a combined novolac/ZD(M)A system, the compounds could be tailored in a unique way towards higher toughness and enhanced cross-link density. Further, the fracture surface of the EPDM–novolac compounds was analyzed by scanning electron microscopy, revealing a significant change of the morphology from rough and disordered to smooth and homogenous for samples with coagents. In addition, the results clearly showed that the introduction of ionic coagents is able to compensate shares of carbon black filler in the EPDM compound. The toughening of samples with zinc (meth)acrylates is attributed to the synergistic formation of an interpenetrating polymer-filler network by simultaneous covalent and ionic cross-linking.

Recovery of Model Pharmaceutical Compounds from Water and Organic Solutions with Alginate-Based Composite Membranes.

In this work, we combined the non-solvent induced phase separation (NIPS) and further cross-linking by cations towards the preparation of nanofiltration membranes based on sodium alginate, a biodegradable, natural polymer. Acetone, ethanol, toluene, and hexane were used as non-solvents, and cations of calcium, silver, and aluminum—for polymer cross-linking, respectively. Results showed the precipitation strength of non-solvent played a noticeable role in the membrane’s performance; for instance, the toluene permeability changed by four orders of magnitude with the decrease of precipitation strength of the non-solvent: acetone (Ptoluene = 0.1 kg∙m−2∙h−1∙bar−1) < ethanol (3 kg∙m−2∙h−1∙bar−1) < hexane (41 kg∙m−2∙h−1∙bar−1) < toluene (415 kg∙m−2∙h−1∙bar−1). It was shown that simultaneous precipitation and crosslinking in aqueous solutions AlCl3 or AgNO3 must be used in the preparation of alginate membranes for the highly selective recovery of pharmaceutical compounds from organic media. These membranes show rejection R = 90–93% of substances with MW = 626 g/mol and ethanol permeability PEtOH = 1.5–2.5 kg∙m−2∙h−1∙bar−1. For the highly selective recovery of pharmaceutical compounds from water, the method of obtaining membranes must be changed. Precipitation in toluene and then crosslinking in aqueous solutions of AlCl3 or AgNO3 must be used sequentially instead of simultaneous precipitation and crosslinking in aqueous solutions of the same inorganic salts. The permeability of such membranes varied from 0.44 to 7.8 kg∙m−2∙h−1∙bar−1 depending on the crosslinking cation in the alginate. The rejection of model substances with MW 350 and 626 g/mol were on the level of 99%. Alginate membranes can be used to solve separation problems in the pharmaceutical field, for example, to isolate antibiotics from their extractants and remove the same antibiotics from aqueous pharmaceutical waste to prevent their accumulation in the environment and the emergence of resistant genes and bacteria.

Scheimpflug imaging of the anterior segment following simultaneous cross-linking with topography-guided custom ablation treatment for keratoconus.

To report alterations in the anterior segment following accelerated corneal collagen cross-linking and topo-guided customized ablation treatment with the Nidek vision excimer laser system (Nidek Co., Ltd., Gamagori, Japan) in a single procedure. We reviewed the medical records of patients who underwent cross-linking for progressive keratoconus. We divided patients into four groups based on the treatment protocol. Eyes were evaluated regarding uncorrected distance visual acuity, corrected distance visual acuity, keratometry (maximum [Kmax], equivalent keratometry readings, Ksteep and Kflat parameters), corneal elevations (anterior and posterior), the anterior radius of curvature, the posterior radius of curvature, anterior chamber volume, anterior chamber depth, anterior chamber angle and the pachymeter of the thinnest locale of the cornea before the surgery and at 1, 3, 6, and 12 months after the procedure. We included 259 eyes of 227 patients with progressive keratoconus who underwent treatment. The mean respective baseline uncorrected distance visual acuity and corrected distance visual acuity were: 0.68 ± 0.45 and 0.34 ± 0.40 in Group 1; 0.82 ± 0.44 and 0.33 ± 0.23 in Group 2; 0.61 ± 0.36 and 0.21 ± 0.17 in Group 3; and 0.65 ± 0.38 and 0.23 ± 0.18 in Group 4; logMAR did not show significant difference among the groups (p=0.14 and p=0.06, respectively). Visual improvements were better in the combined surgery groups. Mean Kmax in Groups 1, 2, 3, and 4 were 57.24 ± 7.51, 59.26 ± 6.94, 53.73 ± 4.60, and 54.31 ± 4.25 diopter (D), respectively. Group 1 demonstrated increased Kmax for 6 months. Maximum flattening by 3.38 ± 2.35 D 1 year after surgery was observed in Group 4 (p<0.05). Decreased anterior chamber angle, anterior chamber depth, and anterior chamber volume were similar, indicating the stability of the anterior chamber. Visual and anatomical improvement is better, with improved stability of the anterior segment, in combined surgery groups compared with cross-linking alone.

3D printing of tough hydrogels based on metal coordination with a two-step crosslinking strategy.

We demonstrate the self-supporting 3D printing of complex hydrogel structures based on simultaneous crosslinking reactions while printing. The printing strategy is based on the Schiff base reaction and metal coordination with a two-step crosslinking process. The printing ink was first prepared by dispersing oxidized sodium alginate (OSA) and adipic dihydrazide (ADH) in poly(acrylamide-co-acrylic acid) (P(AAm-co-AAc)) polymer solutions, and was mixed and printed into 3D structures with an extrusion-based coaxial printing platform. Because of the rapid chemical crosslinking reaction between the aldehyde group in OSA and the hydrazide group in ADH, the printed structures can be solidified quickly, and are further crosslinked by forming carboxyl-Fe3+ coordination complexes to enhance their mechanical properties. The dynamic time-sweep rheological properties of the gel composed of different proportions of OSA and ADH were systematically investigated for the characteristic gelation time, and compression tests were carried out to measure the mechanical properties of the gel composed of OSA and ADH. Combining the gelation time and mechanical properties of the gel, the weight ratio of OSA and ADH was selected as 1 : 0.44 for an optimized setting in the subsequent printing. To evaluate the printability of inks, the material formula and printing parameters were systematically varied. The ink exhibited a wide printing range, self-supporting properties, and good printability. Tensile tests of the printed single fiber crosslinked by Fe3+ show that its strength and toughness are tunable. Complex 3D structures such as pyramids, cylinders, and noses were constructed to demonstrate the printability of the ink. This printing method provides a facile approach for tough hydrogel fabrication without changing the rheological properties of the ink or sacrificing the ultimate mechanical properties of the printed materials.

Prophylactic corneal crosslinking in myopic small-incision lenticule extraction - Long-term visual and refractive outcomes.

Purpose:To analyze the efficacy, safety, predictability, and stability in myopic and astigmatic small-incision lenticule extraction (SMILE) with simultaneous prophylactic corneal crosslinking (CXL) in thin corneas.Methods:A total of 48 eyes from 24 patients who underwent myopic and astigmatism SMILE with simultaneous prophylactic CXL were included in this retrospective study. All patients had a 24-month follow-up. A femtosecond laser was performed with VisuMax (Carl Zeiss Meditec). CXL treatment was applied when the predicted stromal thickness was less than 330 μm.Results:The patients’ mean age was 31.58 ± 6.23 years. The previous mean spherical equivalent was − 6.85 ± 1.80 (−9.75 to − 2.00) D. The postoperative mean spherical equivalent was − 0.50 ± 0.26 (−1.00 to + 0.25) D; 60% of the eyes had 20/20 or better; 19% lost one line; 58% were within ± 0.50 D; and 8.3% of the eyes changed 0.50 D or more between 3 and 24 months.Conclusion:Prophylactic CXL with simultaneous SMILE for myopia and astigmatism femtosecond laser surgery technique appears to be partially effective, safe, predictable, and stable after 24 months of follow-up.

Removal of Metal Ions in Phosphoric Acid by Electro-Electrodialysis with Cross-Linked Anion-Exchange Membranes.

There are numerous metallic impurities in wet phosphoric acid, which causes striking negative effects on industrial phosphoric acid production. In this study, the purification behavior of metallic impurities (Fe, Mg, Ca) from a wet phosphoric acid solution employing the electro-electrodialysis (EED) technology was investigated. The cross-linked polysulfone anion-exchange membranes (AEMs) for EED were prepared using N,N,N′,N′-tetramethyl-1,6-hexanediamine (TMHDA) to achieve simultaneous cross-linking and quaternization without any cross-linkers or catalysts. The performance of the resulting membranes can be determined using quaternization reagents. When the molar ratio of trimethylamine/TMHDA/chloromethylated polysulfone is 3:1:1, the cross-linked membrane CQAPSU-3-1 exhibits lower water swelling and membrane area resistance than the non-cross-linked membrane. The low membrane area resistance of CQAPSU-3-1 with long alkyl chains is obtained due to the hydrophilic–hydrophobic microphase separation structure formed by TMHDA. EED experiments with different initial phosphoric acid concentrations of 0.52 and 1.07 M were conducted to evaluate the phosphoric acid purification of different AEMs. The results show that the EED experiments were more suitable for the purification of wet phosphoric acid solution at low concentrations. It was found that the phosphoric acid concentration in the anode compartment could be increased from 0.52 to 1.04 M. Through optimization, with an initial acid concentration of 0.52 M, CQAPSU-3-1 exhibits an enhanced metallic impurity removal ratio of higher than 72.0%, the current efficiency of more than 90%, and energy consumption of 0.48 kWh/kg. Therefore, CQAPSU-3-1 exhibits much higher purification efficiency than other membranes at a low initial phosphoric acid concentration, suggesting its potential in phosphoric acid purification application.

New treatment algorithm for keratoconus and cataract: small-aperture IOL insertion with sequential topography-guided photorefractive keratectomy and simultaneous accelerated corneal crosslinking.

To describe a new treatment algorithm aimed at optimizing refractive outcomes for patients with keratoconus and cataract. Private practice in Sydney, Australia. Retrospective case series. This procedural approach involves cataract extraction with small-aperture intraocular lens (IOL) insertion, IC-8 IOL (AcuFocus, Inc.), followed by topography-guided photorefractive keratectomy (T-PRK) with simultaneous corneal crosslinking (CXL). Cataract surgery was performed with an initial 2.4 mm clear corneal incision enlarged to 3.5 mm to accommodate IC-8 IOL insertion. Once eyes demonstrated stable corneal tomography and refraction, T-PRK was performed using Schwind excimer laser (500 Hz) with the Vancouver custom topographical neutralization technique, aiming to achieve low myopia. CXL was performed immediately after T-PRK using Optolink hypotonic riboflavin with LIGHTLink-CXL (Lightmed) with 5.4 J total energy delivered at an 18 mw/cm2 irradiance. Outcomes of 4 eyes are reported with all achieving rigid gas-permeable (RGP) contact lens independence, improved corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), and regularization of corneal curvature with cone reduction. The mean CDVA improved from 0.43 preoperatively to 0.07 postoperatively (P = .00), and the mean UDVA improved from 0.81 preoperatively to 0.29 postoperatively (P = .04). Postoperative UNVA ranged from N.8 to N.12. This treatment algorithm demonstrates unique combination of existing corneal and cataract surgical procedures to achieve satisfactory refractive outcomes and RGP contact lens independence in patients with keratoconus and cataract.

Multilayered and heterogeneous hydrogel construct printing system with crosslinking aerosol

Microextrusion bioprinting has been used to recreate the complex architecture and composition of a physiological system through the quick and accurate handling of various biomaterials. However, existing techniques are limited in precisely fabricating complex constructs, including multilayers and heterogeneous patterns with distinct regions, because the extruded bioink spreads rapidly upon contact with the substrate and is partially mixed with subsequently printed bioinks. This issue leads to difficulties in accurately and stably constructing multi-material structures with clear interfaces for prolonged printing before gelation. To fabricate multilayered and heterogeneous constructs, a bioprinting system should be able to continuously extrude various biomaterials and simultaneously crosslink the extruded bioink to stabilize the printed construct. In this study, a multiple-bioink printing system was developed by integrating a multibarrel nozzle for extruding multiple bioinks with a nebulizer for simultaneous crosslinking. The crosslinking aerosol sprayed from the nebulizer was able to gelate the various hydrogel bioinks as they were extruded through the multibarrel nozzle. Such aerosol-based crosslinking improved printing resolution and stability. The developed bioprinting system showed the possibility of recapitulating the physiological complex architecture such as a cancer microenvironment with well-defined interfaces between regions of different mechanical properties and cellular compositions. Using the integrated bioprinting system, a multilayered and heterogeneous construct was printed with four bioinks, including three types of cells (breast cancer cells, stromal cells, and vascular endothelial cells). The printed biological model was characterized by analyzing cancer cell migration and vascular network formation. The developed multiple-bioink printing system is expected to be highly efficient in recapitulating complex tissues and their environments with compartmentalized regions.

Crosslinking of CD38 Receptors Triggers Apoptosis of Malignant B Cells.

Recently, we designed an inventive paradigm in nanomedicine—drug-free macromolecular therapeutics (DFMT). The ability of DFMT to induce apoptosis is based on biorecognition at cell surface, and crosslinking of receptors without the participation of low molecular weight drugs. The system is composed of two nanoconjugates: a bispecific engager, antibody or Fab’ fragment—morpholino oligonucleotide (MORF1) conjugate; the second nanoconjugate is a multivalent effector, human serum albumin (HSA) decorated with multiple copies of complementary MORF2. Here, we intend to demonstrate that DFMT is a platform that will be effective on other receptors than previously validated CD20. We appraised the impact of daratumumab (DARA)- and isatuximab (ISA)-based DFMT to crosslink CD38 receptors on CD38+ lymphoma (Raji, Daudi) and multiple myeloma cells (RPMI 8226, ANBL-6). The biological properties of DFMTs were determined by flow cytometry, confocal fluorescence microscopy, reactive oxygen species determination, lysosomal enlargement, homotypic cell adhesion, and the hybridization of nanoconjugates. The data revealed that the level of apoptosis induction correlated with CD38 expression, the nanoconjugates meet at the cell surface, mitochondrial signaling pathway is strongly involved, insertion of a flexible spacer in the structure of the macromolecular effector enhances apoptosis, and simultaneous crosslinking of CD38 and CD20 receptors increases apoptosis.

Diazo-Based Copolymers for the Wet Strength Improvement of Paper Based on Thermally Induced CH-Insertion Cross-Linking.

We present an alternative to commonly used, but from an environmental point of view, problematic wet strength agents, which are usually added to paper to prevent a loss of mechanical stability and finally disintegrate when they get into contact with water. To this end, diazoester-containing copolymers are generated, which are coated onto paper and by heating to 110-160 °C for short periods of time become activated and form carbene intermediates, which undergo a CH-insertion cross-linking reaction. The process leads to a simultaneous cross-linking of the polymer and its attachment to the cellulose substrate. The immobilization process of copolymers consisting of a hydrophilic matrix based on N,N-dimethylacrylamide and a diazoester-based comonomer to a cellulose model surface and to laboratory-engineered, fibrous paper substrates is investigated as a function of time, temperature, and cross-linker composition. The distribution of the polymer in the fiber network is studied using confocal fluorescence microscopy. Finally, the tensile properties of modified wet and dry eucalyptus sulfate papers are measured to demonstrate the strong effect of the thermally cross-linked copolymers on the wet strength of paper substrates. Initial experiments show that the tensile indices of the modified and wetted paper samples are up to 50 times higher compared to the values measured for unmodified samples. When dry and wet papers coated with the above-described wetting agents are compared, relative wet strengths of over 30% are observed.

PH/near-infrared light dual activated Ce6-doped silicon nanoparticles with tumor chemo-photodynamic synergistic therapy for improving efficiency of monotherapy

Currently, single chemotherapeutics or photosensitizers implemented in clinic present huge challenges in terms of unfavorable therapeutic efficacy, physiological instability and non-selective toxicity. In order to remedy the faultiness of insufficient efficiency of monotherapy, we herein synthesized an “all-in-one” targeting drug delivery system with multimodal therapy based on chemo-photodynamic synergistic therapy. Specifically, mesoporous silica nanorods were first synthesized through doping chlorin e6 (Ce6) in the sol–gel process, and then were used to load chemotherapy drug. After the amino groups and boronic acid groups were sequentially modified on the surface of nanoparticles, lactobionic acid (LA) was chosen as an intermediary to achieve simultaneous crosslinking of targeting agent LA and sealing agent sericin through pH responsive boronic ester linkage. The obtained ultimate nanocomposites possessed good biocompatibility, colloidal stability and hemocompatibility. Besides, in vitro endocytosis experiment performed with confocal laser scanning microscopy and flow cytometry testified the LA-mediated accurate tumor-specific targeting ability of synthesized nanocarriers. Moreover, a series of in vitro assays demonstrated that fabricated therapeutic nanoplatform could not only release loaded drugs in response to acidic environment to achieve chemotherapy, but also could generate singlet oxygen from photosensitizer Ce6 under external light stimulation to realize photodynamic therapy. Most interestingly, the combination therapy including photodynamic therapy and chemotherapy exhibited a synergistic effect against tumor cells in both in vivo and ex vivo experiments. Briefly, the drug delivery system reported here could attain effective chemo-photodynamic synergistic therapy to dispose of the insufficient lethality of monotherapy while guaranteeing the safety during in vivo application.

Bioprinted hASC-laden structures with cell-differentiation niches for muscle regeneration

The development of an in situ (or in vivo) bioprinting system could lead to surgical devices that can directly print cells/tissues on the damaged anatomical location. Such devices would require tissue-specific bioinks, a bioreactor system, and an appropriately designed multiple-axis machine system. In order to operationalize the concept of an in vivo bioprinting system, we used a modified printing system that enables direct printing on the desired anatomical location through the use of cell-laden structures that result in differentiation niches based on printing parameters such as stiffness of the bioink and topographical and biochemical cues. To show the feasibility of the in situ bioprinting system, we used collagen bioink laden with human adipose-derived stem cells (hASCs) and human umbilical vein endothelial cells (HUVECs) and assessed the myogenic and angiogenic differentiation under optimal printing conditions combined with a simultaneous crosslinking process. Furthermore, the cells-laden bioinks processed with the in situ printing showed outstanding myogenesis through the implantation in the temporalis muscle flap of rats. To extend the technology, two bioinks—a decellularized extracellular matrix derived from porcine tendon and collagen/β-TCP—were accommodated, and the fabricated cell-laden structures processed with the bioprinting system were well differentiated into the designed tenogenic or osteogenic linages without using any additional in vitro experiments. Based on these results, we believe that the modified bioprinting process offers several important keys for achieving in situ bioprinting and provides valuable insights into the current directions of 3D bioprinting.

Cross-linked Poly(Octadecyl Acrylate)/Polybutadiene Shape Memory Polymer Blends Prepared by Simultaneous Free Radical Cross-linking, Grafting and Polymerization of Octadecyl Acrylate/Polybutadiene Blends.

A semi-crystalline, shape memory polymer (SMP) is fabricated by free radical cross-linking, polymerization, and grafting in a blend of n-octadecyl acrylate and polybutadiene (PB). Poly(n-octadecyl acrylate) (PODA) is a side-chain crystalline polymer, which serves as the structure-fixing network counterbalancing the elastically deformed, cross-linked polymer network. At a constant 50/50 ratio of monomer and polymer the amount of free radical initiator, dicumyl peroxide (DCP) is varied from 1% to 5%w/w PB. From swelling measurements and calculation of the cross-link density it is determined that DCP produces greater than one cross-link per DCP molecule. It is found that lower cross-linking efficiency is favorable for higher shape fixity. This lower efficiency is found to produce a higher degree of crystallinity of the PODA in the 2-5% DCP samples, which is determined to be the main driver of higher shape fixity of the polymer. A SMP with >90% fixity and 100% recovery at uniaxial strains from 34-79% is achieved. This material should be useful for mold processing of shape memory articles. This approach provides a method to decouple the elastomeric and thermoplastic portions of a SMP to convert commodity elastomers into SMPs and tailor the shape memory response.

A Gel Polymer Electrolyte Reinforced Membrane for Lithium-Ion Batteries via the Simultaneous-Irradiation of the Electron Beam.

In this research, a series of innovative and stable cross-linked gel polymer reinforced membranes (GPRMs), were successfully prepared and investigated for application in lithium-ion batteries. Herein, a gel directly within the commercial polyethylene (PE) separator is supported via electron-beam simultaneous irradiation cross-linking of commercial liquid electrolyte and poly(ethylene glycol) methacrylate (PEGMA) oligomers. The physical and electrochemical properties of the GPRMs were characterized by SEM, TEM, mechanical durability, heating shrinkage, and ion conductivity, etc. The GPRMs demonstrated excellent mechanical durability and high ion conductivity compared with traditional PE membranes. Moreover, coin-typed cells were assembled and cycle performance was also studied compared with same-typed cells with commercial PE membrane and liquid electrolyte. As a result, the coin-typed cells using GPRMs also showed a relatively good efficiency on the 50th cycles at a high 1.0 C-rate. These GPRMs with excellent properties present a very promising material for utilization in high-performance lithium-ion batteries with improved safety and reliability.