Injectable Materials Research Articles

Properties and Applications of Copper(I) Thiocyanate Hole‐Transport Interlayers Processed from Different Solvents

AbstractCopper(I) thiocyanate (CuSCN) is an effective interlayer material for hole injection and transport in organic electronic devices but its solution processing has conventionally utilized undesirable di‐n‐alkyl sulfide solvents such as diethyl‐ (DES) and dipropyl‐sulfide (DPS). Herein, this paper reports on the use of N,N‐dimethylformamide (DMF) and 1‐methyl‐2‐pyrrolidinone (NMP) as alternative solvents for CuSCN interlayers and performs a detailed comparison of the resulting properties relative to films processed from DES and DPS and two other recent alternatives, dimethyl sulfoxide (DMSO) and ammonium hydroxide. The surface roughness, polymorphism, and surface chemistry of the resulting CuSCN layers are reported. The interlayer surface energy and ionization potential that are key to the overlying semiconductor microstructure and interfacial energy barrier, and hence to charge transport and injection, are also discussed. Finally, systematic device tests using well‐known organic semiconductors in light‐emitting diode, solar cell and field‐effect transistor structures demonstrate the overall suitability of DMSO and DMF as solvents for CuSCN interlayer deposition to achieve better device performance. This study broadens the applicability of CuSCN as a highly efficient hole injection/transport material for organic semiconductor devices by expanding the documented range of suitable CuSCN solvents.

Dynamic Molding: Additive manufacturing in partially ordered system

Additive manufacturing (AM) is now identified as a powerful bundle of fabrication techniques. Limitations were identified to be mostly related to the availability of reformulated materials compatible with existing AM technologies. What if we were able to dynamically generate sacrificial molds with unlimited architectures and material composition? We have developed such a process, called Dynamic Molding in partially ordered powder system and demonstrated its capacity to produce highly complex objects with 100 µm resolution, without any building plate or support structures. The Dynamic Molding compatible materials were shown to be almost infinite, from low to high viscosity, from thermoplastic to elastomers. This process enables to build unexpected composite objects made up of injection material and powder grains inherited from the dynamic mold. This feature opens the path to a complete new field of research and applications. • A new additive manufacturing method was developed which fill the gap between 3D printing and molding. • The new technique was named Dynamic Molding Deposition. • The method was shown to be free-form and capable of handling a large range of material viscosity. • The technique was shown to permit the production of unexpected composite objects with interesting mechanical properties.

Characteristics of Biopolymer Guar Gum Solution Injection for Eco-Friendly Ground Reinforcement

Recently, research on the use of biopolymers for environmentally friendly soil improvement has been actively conducted. Biopolymer soil treatment has various effects, such as the enhancement of soil strength, reduction of hydraulic conductivity, and enhancement of vegetation. In this study, the flow and injection characteristics of guar gum solutions were analyzed to develop biopolymer-based injection materials. Viscosity measurements and micromodel experiments were conducted to analyze the flow and injection properties. Viscosity measurements indicated that the guar gum solution showed a tendency of shear-thinning, in which the viscosity decreased as the shear rate increased. By applying the Power-law, the consistency index tended to increase as the concentration of aqueous guar gum solution increased. However, no clear trend was observed for the behavior index. As a result of the micromodel experiment, the pore saturation tended to increase as the volumetric flow rate and concentration of the guar gum solution increased. This is because of an increase in the injection pressure and apparent viscosity. When applied to an actual field, the required injection pressure varies depending on the ground conditions. Therefore, the results of this study will be used as fundamental data for determining the concentration of aqueous guar gum solution suitable for ground conditions.

Preparation and characterization of injectable gelatin/alginate/chondroitin sulfate/α-calcium sulfate hemihydrate composite paste for bone repair application.

In this study, a group of injectable composite pastes with a novel formulation consisting of two inorganic components: α-calcium sulfate hemihydrate (α-CSH, P/L = 1.8-2.1g/ml) and calcium-deficient hydroxyapatite (CDHA, P/L = 0.1g/ml) nanoparticles; and three biopolymers: gelatin (2, 4wt. %), alginate (1, 1.5wt. %), and chondroitin sulfate (0.5wt. %) were carefully prepared and thoroughly characterized with commensurate characterizations. The composite sample composed of gelatin (2wt. %), alginate (1.5wt. %), chondroitin sulfate (0.5wt. %), and also CDHA nanoparticles and α-CSH with P/L ratios of 0.1 and 2.1g/ml, respectively, exhibited optimal properties in terms of injectability, anti-washout performance, and rheological characteristics. After 14days of immersion of the chosen sample in the simulated body fluid medium, a dense layer of apatite was formed on the surface of the composite paste. The cellular in vitro tests, such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT), alkaline phosphatase assay, 4',6-diamidino-2-phenylindole staining, and cellular attachment, revealed the desirable response of MG-63 cells to the composite paste. The chondroitin sulfate significantly improved the injectability, anti-washout performance, and cellular response of the samples. Considering the promising features of the composite paste prepared in this research work, it could be considered as an alternative injectable bioactive material for bone repair applications.[Formula: see text].

SmartWater based synergistic technologies for enhanced oil recovery

Enhanced oil recovery (EOR) technologies based on chemicals and solvents require significant volume of source injection materials, and have limited applicability in difficult environments and harsh reservoir conditions. Synergizing injection water compositions in terms of salinity and ionic content (SmartWater) with existing recovery methods can become a game changer to overcome these limitations.The main objective is to explore the synergistic effects of SmartWater as a potential optimization avenue for achieving more efficient and economic EOR applications. To achieve this objective, a range of multiscale experimental data from macro- to core-scale were analyzed to demonstrate and quantify the benefits of water chemistry synergies with different recovery methods. The multiscale experimental data analyzed comprised of polymer rheology, contact angles, core floods, foam stability and rheology, besides evaluating the zeta potential results obtained from surface complexation modeling (SCM).The dilute concentrations of polymer ranging from 250 to 500 ppm in SmartWater increased the injection water viscosities by 2 to 4 times to provide better mobility control for light oil recovery. The tailored water chemistry reduced the polymer consumption requirements by one-third (from 3000 ppm to 2000 ppm) and increased the oil recovery by 5–7% in polymer flooding processes used for viscous oil recovery. Synergizing water chemistry with surfactant-polymer flooding resulted in an incremental oil recovery of about 4% besides lowering the surfactant and polymer concentrations by 50% (from 2000 ppm to 1000 ppm). SmartWater has also been found to synergistically combine with carbonated waterflooding to increase the CO2 dissolved volumes by 25–30% for effectively lowering the pH and develop favorable wettability alterations towards water-wet conditions. The tailored water chemistry increased the foam stabilities by resulting in 2–3 times higher foam half-lifes in addition to raising the foam apparent viscosities by 1.5 times. SmartWater foams also increased the pressure drops in porous media by 50% to confirm higher foam apparent viscosities and more resistance to gas flow.The benefits of different SmartWater based synergistic EOR technologies demonstrated in this study can be significant. They can deliver higher oil recoveries in addition to lowering the volume requirements of different EOR agents such as chemicals and gas. These findings will have a practical impact to result in more practical, efficient and economical EOR projects in the field.

Injectable recombinant human collagen-derived material with high cell adhesion activity limits adverse remodelling and improves pelvic floor function in pelvic floor dysfunction rats

Female pelvic floor dysfunction (FPFD) is a life-changing condition that severely affects women's physical and mental health. Despite the effectiveness of current treatments for FPFD, there is a high rate of short-term recurrence. Here, we introduced an injectable recombinant human collagen (rhCOL)-derived material with high cell adhesion activity to achieve pelvic floor repair and extracellular matrix (ECM) assembly. In our study, rhCOL promoted human uterosacral ligament fibroblast (HULF) adhesion, migration, and collagen I and III expression and regulated the metabolism of HULFs in vitro. Subsequently, we established a rat model of FPFD. Then, rhCOL, including rhCOLI and rhCOLIII, was perivaginally injected into FPFD rats, resulting in a significant increase in abdominal urine leak point pressure (LPP) and maximum tensile strength compared to the FPFD model group. Better organization of the lamina propria and muscularis in FPFD rats was observed after 14 days of rhCOL treatment. Meanwhile, the expression of collagen I, collagen III, and TIMP1 was upregulated, and MMP2 was downregulated. Furthermore, rhCOL promoted HULF adhesion, migration, and ECM synthesis by upregulating the focal adhesion kinase (FAK)/RhoA/ROCK signalling pathway in vitro and in vivo. These findings suggest that the perivaginal injection of rhCOL is a promising treatment for FPFD with potential for future clinical use.

MRI imaging versus histologic volumetric estimation of residual injection laryngoplasty material.

ObjectivesTo examine the degree of agreement between MRI and histologically generated volumetric measurements of residual injection laryngoplasty material.MethodsFollowing left recurrent laryngeal nerve transection, rabbit vocal cords were injected with jellyfish collagen, Cymetra®, or Restylane®. Laryngeal tissue was harvested 4 or 12 weeks post injection followed by MRI imaging and histologic cross‐sectioning. Two raters estimated the volume of remaining injection material in specimens within MRI and histologic axial cross sections. Wilcoxon signed rank tests were employed to detect gross differences between inter‐rater measurements and between imaging modalities across time. Agreement between rater measurements and imaging (histology and MRI) was assessed using intra‐class correlation coefficients.ResultsData was available from 16 rabbits sacrificed at 4 weeks (n = 8) and 12 weeks (n = 8). Inter‐rater testing of MRI imaging revealed no significant differences (p > .05) between rater measurements across time points, and excellent agreement (0.93; 95% confidence interval 0.80–0.98) while histologically estimated volumes demonstrated a significant difference at 4 weeks (p < .05) and overall good agreement (0.89; 95% confidence interval 0.59–0.97). Comparison of MRI and histologically estimated volume measurements revealed significant differences at the 4‐week time point (p < .05) but not at 12 weeks (p > .05). Overall, there is only moderate agreement between MRI and histology estimates (0.72; 95% confidence interval 0.22–0.90).ConclusionsMRI imaging demonstrates good reliability and similar estimates of volume to histologically estimated measurements of residual injection laryngoplasty material at time points clinically relevant for future injection laryngoplasty experiments.Level of EvidenceNA.

A Review of Bone Cements as Injectable Materials for Treatment of Bone-Related Diseases: Current Status and Future Developments

Increasing the average age of the population as well as sports injuries, bone-related diseases, such as osteoporosis, rupture or damage to cartilage and bone tissues, and bone fractures, has dramatically increased the need for repair and joint replacement surgeries. Biocompatible materials that are used as prosthetic stabilizers and bone fillers in orthopedic surgery are known as injectable bone cement (IBCs). Available clinical IBCs, such as polymethyl methacrylate and calcium phosphate cement are the most important of these materials. This paper presents the most popular substances for medical use. Although this replacement procedure reduces the pain and restores joint function, it is associated with several drawbacks that limit its efficiency and effectiveness, and sometimes patients should undergo revision surgeries. Recently, the development of the next generation of IBCs, which are bioactive and degradable with good mechanical properties, is of great interest. For the long-term clinical performance in cement arthroplasty, the next generation of bone cement with far greater mechanical and biological properties than acrylic bone cement on the market is required. As a result, new approaches and formulas have been developed using various techniques from different disciplines. This study summarizes the challenges, developments, and recommendations for the future. For this purpose, various literature from databases, such as ScienceDirect, SpringerLink, PubMed, and so on were consulted from 2000 to 2020.

Combination of mesenchymal stem cells and bioactive molecules in hydrogels for osteoarthritis treatment

Osteoarthritis (OA) is a chronic and inflammatory disease with no effective regenerative treatments to date. The therapeutic potential of mesenchymal stem cells (MSCs) remains to be fully explored. Intra-articular injection of these cells promotes cartilage protection and regeneration by paracrine signaling and differentiation into chondrocytes. However, joints display a harsh avascular environment for these cells upon injection. This phenomenon prompted researchers to develop suitable injectable materials or systems for MSCs to enhance their function and survival. Among them, hydrogels can absorb a large amount of water and maintain their 3D structure but also allow incorporation of bioactive agents or small molecules in their matrix that maximize the action of MSCs. These materials possess advantageous cartilage-like features such as collagen or hyaluronic acid moieties that interact with MSC receptors, thereby promoting cell adhesion. This review provides an up-to-date overview of the progress and opportunities of MSCs entrapped into hydrogels, combined with bioactive/small molecules to improve the therapeutic effects in OA treatment.

Supramolecular Reinforcement of Polymer–Nanoparticle Hydrogels for Modular Materials Design

AbstractMoldable hydrogels are increasingly used as injectable or extrudable materials in biomedical and industrial applications owing to their ability to flow under applied stress (shear‐thin) and reform a stable network (self‐heal). Nanoscale components can be added to dynamic polymer networks to modify their mechanical properties and broaden the scope of applications. Viscoelastic polymer–nanoparticle (PNP) hydrogels comprise a versatile and tunable class of dynamic nanocomposite materials that form via reversible interactions between polymer chains and nanoparticles. However, PNP hydrogel formation is restricted to specific interactions between select polymers and nanoparticles, resulting in a limited range of mechanical properties and constraining their utility. Here, a facile strategy to reinforce PNP hydrogels through the simple addition of α‐cyclodextrin (αCD) to the formulation is introduced. The formation of polypseudorotoxanes between αCD and the hydrogel components resulted in a drastic enhancement of the mechanical properties. Furthermore, supramolecular reinforcement of CD–PNP hydrogels enabled decoupling of the mechanical properties and material functionality. This allows for modular exchange of structural components from a library of functional polymers and nanoparticles. αCD supramolecular binding motifs are leveraged to form CD–PNP hydrogels with biopolymers for high‐fidelity 3D (bio)printing and drug delivery as well as with inorganic NPs to engineer magnetic or conductive materials.

Metal oxide charge transfer complex for effective energy band tailoring in multilayer optoelectronics

Metal oxides are intensively used for multilayered optoelectronic devices such as organic light-emitting diodes (OLEDs). Many approaches have been explored to improve device performance by engineering electrical properties. However, conventional methods cannot enable both energy level manipulation and conductivity enhancement for achieving optimum energy band configurations. Here, we introduce a metal oxide charge transfer complex (NiO:MoO3-complex), which is composed of few-nm-size MoO3 domains embedded in NiO matrices, as a highly tunable carrier injection material. Charge transfer at the finely dispersed interfaces of NiO and MoO3 throughout the entire film enables effective energy level modulation over a wide work function range of 4.47 – 6.34 eV along with enhanced electrical conductivity. The high performance of NiO:MoO3-complex is confirmed by achieving 189% improved current efficiency compared to that of MoO3-based green OLEDs and also an external quantum efficiency of 17% when applied to blue OLEDs, which is superior to 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile-based conventional devices.

Anti-Vascular Endothelial Growth Factor Drug Conbercept-Loaded Peptide Hydrogel Reduced Angiogenesis in the Neovascular Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) accounts for 8.7% of the global blindness and neovascular form of AMD (nAMD) occupies a large proportion of severe visual loss and legal blindness caused by AMD with a relatively low incidence rate. Choroidal neovascularization (CNV) is overwhelmingly responsible for the occurrence of nAMD as bleeding and fluid leakage followed by abnormal formation of blood vessels could directly lead to loss of central vision so that reduce the choroidal angiogenesis is an ideal treatment method of nAMD. VEGF is an important cytokine which promote the signaling pathway of angiogenesis and the abnormal expression of VEGF is verified in great many CNV cases. Several anti-VEGF drugs have been widely used in clinical treatments such as ranibizumab, bevacizumab and aflibercept. Conbercept, as an originally developed drug in China, has attracted great attention. For the purpose of better treatment efficacy, our group designed a short chain peptide (Sequence: DDIIIRH-NH₂, M.W.880.99) for controlled drug release to remedy the drawback of the short half-time period. The peptide could self-assembled into a stable 'hydrogel under pH 7.4 condition and the 3D structure was clearly observed in TEM study. Rheological study exhibited its great injectability so that the hydrogel was a material for intravitreal injection. Statistics exhibited that the hydrogel could release approximately 50% of total conbercept. The In vitro experiments showed that either dose-dependent or the time-dependent incubation with peptide would not decrease the cell viability of HREC, revealing that the peptide was biocompatible. The most important is that co-incubation with HREC obviously reduced the HREC proliferation and tube formation induced by VEGF, ensuring its potential for the treatment efficacy of nAMD.

Evaluation of injectable nucleus augmentation materials for the treatment of intervertebral disc degeneration.

Back pain affects a person's health and mobility as well as being associated with large health and social costs. Lower back pain is frequently caused by degeneration of the intervertebral disc. Current operative and non-operative treatments are often ineffective and expensive. Nucleus augmentation is designed to be a minimally invasive method of restoring the disc to its native healthy state by restoring the disc height, and mechanical and/or biological properties. The majority of the candidate materials for nucleus augmentation are injectable hydrogels. In this review, we examine the materials that are currently under investigation for nucleus augmentation, and compare their ability to meet the design requirements for this application. Specifically, the delivery of the material into the disc, the mechanical properties of the material and the biological compatibility are examined. Recommendations for future testing are also made.

Review on injection moulding optimization techniques and materials used

Review on injection moulding optimization techniques and materials used

Controlled vitamin D delivery with injectable hyaluronic acid-based hydrogel for restoration of tendinopathy

Tendinopathy is a term used to describe tendon disorders that are marked by pain and a loss of function. Recent studies demonstrated that inflammation plays an important role throughout the broad spectrum of tendinopathy. Conventional treatments such as steroid injections, analgesics, and physical modalities simply give pain relief and do not alter the disease progression without the tendon regeneration effect. Tenocytes are responsible for maintaining the tendon matrix and understanding how they function is essential to studying new treatments for tendinopathy. Our previous study showed the protective effects of vitamin D (Vit D) on damaged tenocytes. Besides its well-known effects on bone metabolism, the non-classical action of Vit D is the pleiotropic effects on modulating immune function. In the present study, we developed a Vit D delivery system with hyaluronic acid (HA), which is one of the major components of the extracellular matrix that has anti-inflammation and wound-healing properties. A novel Vit D delivery system with cross-linked HA hydrogel (Gel) and Tween 80 (T80), Vit D@Gel/T80, could be a new regeneration technique for the treatment of tendinopathy. Vit D@Gel/T80 reduced TNF-α induced damage to human tenocytes in vitro. In an animal study, the Vit D@Gel/T80 injected group demonstrated tendon restoration features. As a result, this Vit D@Gel/T80 system might be a local injection material in the treatment for tendinopathy.

Easily-injectable shear-thinning hydrogel provides long-lasting submucosal barrier for gastrointestinal endoscopic surgery

Submucosal injection material has shown protective effect against gastrointestinal injury during endoscopic surgery in clinic. However, the protective ability of existing submucosal injection material is strictly limited by their difficult injectability and short barrier time. Herein, we report a shear-thinning gellan gum hydrogel that simultaneously has easy injectability and long-lasting barrier function, together with good hemostatic property and biocompatibility. Shear-thinning property endows our gellan gum hydrogel with excellent endoscopic injection performance, and the injection pressure of our gellan gum hydrogel is much lower than that of the small molecule solution (50 wt% dextrose) when injected through the endoscopic needle. More importantly, our gellan gum hydrogel shows much stronger barrier retention ability than normal saline and sodium hyaluronate solution in the ex vivo and in vivo models. Furthermore, our epinephrine-containing gellan gum hydrogel has a satisfactory hemostatic effect in the mucosal lesion resection model of pig. These results indicate an appealing application prospect for gellan gum hydrogel utilizing as a submucosal injection material in endoscopic surgery.

A study to evaluate the efficacy and safety of intradermal and intralesional Purified Protein Derivative (PPD) for treatment of common warts in children

: Viral warts are common dermatological diseases with wide range of treatment modalities. Utilization of various vaccines and skin test antigens has broadened the horizon of available immunotherapeutic agents for the treatment of warts. In this study, we compared efficacy and safety of intradermal and intralesional purified protein derivative (PPD) for treating common warts in children.Toevaluate efficacy and safety of intradermal and intralesional PPD in treatment of common warts in children.: 180 children (aged 5-15 years) with common warts were randomly divided to receive intradermal (n=90) PPD 10 TU/0.1 ml at middle third of right forearm or intralesional PPD (n=90) 0.1 ml in the largest wart once in 2-weeks till there is complete clearance or maximum of five injections whichever is earlier. Patients were followed at 4 week after last injection for assessment of response, adverse effects, and recurrence of common warts.: Complete, partial clearance and no response in 51.2%, 45.3% and 2.3% children was observed in intradermal group as compared to 54.2%, 42.5% and 1.1% response in intralesional group respectively. Recurrence of warts was observed in 1.2% and 2.2% children in intradermal and intralesional group respectively. Pain was the most common adverse effect in both groups followed by erythema lasting for 2-3 days not warranting for discontinuation of treatment in any patient.: Overall 96.5% and 96.7% patients in both intradermal and intralesional group responded to treatment respectively. We conclude that immunotherapy with PPD appears safe, effective, and acceptable treatment modality for common warts in children. Although intralesional group showed slightly higher efficacy for warts (0.2%), intradermal PPD has advantage of less pain, high patient satisfaction, less spillage of injection material onto surroundings and better compliance over intralesional group and hence can be considered as valuable first line treatment in children in resource poor developing countries.

Crack-Bridging Property Evaluation of Synthetic Polymerized Rubber Gel (SPRG) through Yield Stress Parameter Identification.

Yield stress parameter derivation was conducted by stress-strain curve analysis on four types of grout injection leakage repair materials (GILRM); acrylic, epoxy, urethane and SPRG grouts. Comparative stress-strain curve analysis results showed that while the yield stress point was clearly distinguishable, the strain ratio of SPRG reached up to 664% (13 mm) before material cohesive failure. A secondary experimental result comprised of three different common component ratios of SPRG was conducted to derive and propose an averaged yield stress curve graph, and the results of the yield stress point (180% strain ratio) were set as the basis for repeated stress-strain curve analysis of SPRGs of up to 15 mm displacement conditions. Results showed that SPRG yield stress point remained constant despite repeated cohesive failure, and the modulus of toughness was calculated to be on average 53.1, 180.7, and 271.4 N/mm2, respectively, for the SPRG types. The experimental results of this study demonstrated that it is possible to determine the property limits of conventional GILRM (acrylic, epoxy and urethane grout injection materials) based on yield stress. The study concludes with a proposal on potential application of GILRM toughness by finite element analysis method whereby strain of the material can be derived by hydrostatic pressure. Comparative analysis showed that the toughness of SPRG materials tested in this study are all able to withstand hydrostatic pressure range common to underground structures (0.2 N/mm2). It is expected that the evaluation method and model proposed in this study will be beneficial in assessing other GILRM materials based on their toughness values.

Bi-metal composite material for plastic injection molding tooling applications via fused filament fabrication process

Metal fused filament fabrication (FFF) technology uses metal powder filled plastic filaments, coupled with debinding and sintering operations, to produce metal parts. This study builds upon FFF technology, combining the technique with melt infiltration to create a structure that retains the surface hardness of tool steel while also benefiting from the thermal conductivity of copper. We observe excellent wettability of the copper to the steel, a complete filling of the as-sintered steel infill free volume, and diffusion of iron and chromium into copper. To demonstrate a practical use of the process, an injection mold with conformal channels is shaped using the technology. The bi-metal composite of steel and copper exhibited a thermal conductivity of 108 W/mK and a modulus of elasticity of 145 GPa in an as-manufactured condition.

Enhanced wound healing properties of guar gum/curcumin-stabilized silver nanoparticle hydrogels

Biocompatible materials that act as scaffolds for regenerative medicine are of enormous interest. Hydrogel-nanoparticle composites have great potential in this regard, however evaluations of their wound healing and safety in vivo in animal studies are scarce. Here we demonstrate that a guar gum/curcumin-stabilized silver nanoparticle hydrogel composite is an injectable material with exceptional wound healing and antibacterial properties. We show that the curcumin-bound silver nanoparticles themselves exhibit low cytotoxicity and enhance proliferation, migration, and collagen production in in vitro studies of human dermal fibroblasts. We then show that the hydrogel-nanoparticle composite promotes wound healing in in vivo studies on rats, accelerating wound closure by > 40% and reducing bacterial counts by 60% compared to commercial antibacterial gels. Histopathology indicates that the hydrogel composite enhances transition from the inflammation to proliferation stage of healing, promoting the formation of fibroblasts and new blood vessels, while target gene expression studies confirm that the accelerated tissue remodeling occurs along the normal pathways. As such these hydrogel composites show great promise as wound dressing materials with high antibacterial capacity.