Freeze-drying Procedure Research Articles

Cu-MOF loaded chitosan based freeze-dried highly porous dressings with anti-biofilm and pro-angiogenic activities accelerated Pseudomonas aeruginosa infected wounds healing in rats

Metal–organic frameworks (MOFs)-based therapy opens a new area for antibiotic-drug free infections treatment. In the present study, chitosan membranes (CS) loaded with two concentrations of copper-MOF 10 mg/20 ml (Cu-MOF10/CS) & 20 mg/20 ml (Cu-MOF20/CS) were prepared by a simple lyophilization procedure. FTIR spectra of Cu-MOF10/CS and Cu-MOF20/CS dressings confirmed absence of any undesirable chemical changes after loading Cu-MOF. The SEM images of the synthesized materials (CS, Cu-MOF10/CS & Cu-MOF20/CS) showed interconnected porous structures. Cytocompatibility of the materials was confirmed by fibroblasts cells culturing and the materials were hemocompatible, with blood clotting index <5 %. Cu-MOF20/CS showed comparatively higher effective antibacterial activity against the tested strains; E. coli (149.2 %), P. aeruginosa (165 %) S. aureus (117.8 %) and MRSA (142 %) as compared to Amikacin, CS and Cu-MOF10/CS membranes. Similarly, Cu-MOF20/CS dressing significantly eradicated the biofilms; P. aeruginosa (37 %) and MRSA (52 %) respectively. In full thickness infected wound rat model, on day 23, Cu-MOF10/CS and Cu-MOF20/CS promoted wound healing up to 87.7 % and 82 % respectively. H&E staining of wounded tissues treated with Cu-MOF10/CS & Cu-MOF20/CS demonstrated enhanced neovascularization and re-epithelization along-with reduced inflammation, while trichrome staining exhibited increased collagen deposition. Overall, this study declares Cu-MOFs loaded chitosan dressings a multifunctional platform for the healing of infected wounds.

Fabrication of MOF-rGO aerogels to enhance electromagnetic wave absorption by adjusting the morphology and structure of MOFs by electron transfer

Graphene and its derivatives have become the star materials in the field of electromagnetic wave (EMW) absorption, and have been widely studied because of their unique structure and excellent properties. However, the high electrical conductivity of graphene-based material leads to poor impedance matching performances, so it often needs to be annealed at high temperatures, which is a intricate procedure and cause the waste of energy. Herein, we develop a convenient strategy to synthesize metal organic framework-reduced graphene oxide (MOF-rGO) aerogels through facile hydrothermal and freeze drying procedure. Firstly, the excessive electrons on graphene can be transferred to MOF, in this way, no annealing is needed. Secondly, the morphology and structure of MOF can be regulated electronically to endow the material with rich heterojunction interfaces and enhance its interfacial polarization. Thirdly, the synthesized aerogels satisfy the requirements of thin thickness, low density and light weight. The fabricated Ni-MOF-rGO and FeNi-MOF-rGO aerogels exhibit remarkable EMW absorption performances with strong reflection loss (RL) and broad effective absorption band (EAB) at the thickness of 2.4 (−47.8 dB and 7.84 GHz) and 2.9 mm (−48.3 dB and 8.32 GHz) whereas the filling contents are just 5 %. Moreover, the attenuation capacity of the fabricated aerogels are verified through the radar-section simulation and the interfacial polarization loss are confirmed by the COMSOL analogue simulation. In a word, this work provides a new afflatus and inspiration for the design of graphene-based EMW absorption materials.

Protective effects of different lyoprotectants on survival of clinical bacterial isolates in a hospital biobank

Nowadays the significant role of biobanks in medical, diagnostic, industrial, and environmental research is well known. Bacterial biobanks could be used as a good resource for designing new treatments, biomedical and industrial researches, and laboratory diagnostics. To have a collection of bacteria from clinical samples and maintain their long-term viability, their preservation needs appropriate protective agents, like cryoprotectants and lyoprotectants. In this study, we collected and characterized Gram-negative and Gram-positive bacteria carrying important antibiotic resistance markers from different clinical samples of hospitalized children. Sucrose (10%), skimmed milk (10%), skimmed milk plus sodium glutamate (10% + 1%), and bovine serum albumin (BSA, 10%) were used as lyoprotectants during the freeze-drying procedure. The survival rate of the lyophilized samples was calculated by dilution plating and measuring the colony forming unit (CFU) after 3 months of storage. The culture analysis results indicated that 25 of the 27 studied bacterial genera (Dilutions 10−3 to 10−6), including Shigella, Methicillin-resistant S. aureus, Acinetobacter spp., Escherichia spp., Pseudomonas spp., Klebsiella spp., Enterococcus spp., were recovered in cultured fractions from all preservation conditions, while 2 genera were only detected in a single preservation condition (2/27, 7.4%). Based on the results, sucrose (10%) and skimmed milk (10%) presented the most protective features. The survival rates varied significantly according to types of the bacteria. Collectively, our results showed a diversity in the recovery of different bacterial genera after lyophilization. While statistically no significant difference was detected among the studied protective agents, sucrose (10%) and skimmed milk (10%) exhibited more effective lyoprotective properties for both Gram-positive and Gram-negative bacteria among the clinical isolates in our study.

Correlative single-cell hard X-ray computed tomography and X-ray fluorescence imaging

X-ray computed tomography (XCT) and X-ray fluorescence (XRF) imaging are two non-invasive imaging techniques to study cellular structures and chemical element distributions, respectively. However, correlative X-ray computed tomography and fluorescence imaging for the same cell have yet to be routinely realized due to challenges in sample preparation and X-ray radiation damage. Here we report an integrated experimental and computational workflow for achieving correlative multi-modality X-ray imaging of a single cell. The method consists of the preparation of radiation-resistant single-cell samples using live-cell imaging-assisted chemical fixation and freeze-drying procedures, targeting and labeling cells for correlative XCT and XRF measurement, and computational reconstruction of the correlative and multi-modality images. With XCT, cellular structures including the overall structure and intracellular organelles are visualized, while XRF imaging reveals the distribution of multiple chemical elements within the same cell. Our correlative method demonstrates the feasibility and broad applicability of using X-rays to understand cellular structures and the roles of chemical elements and related proteins in signaling and other biological processes.

Inhibition of Osteoclasts in Multiple Myeloma by Reactive Oxygen Species Responsive Alendronate Liposomes

In recent years, nanomedicine delivery systems have shown unique advantages in treating various diseases, especially for tumor diseases. Our study synthesized reactive oxygen species (ROS) responsive phospholipid DSPE-TK-PEG2000 and constructed ROS responsive liposomes loaded with alendronate using thin-film hydration method. Dynamic light scattering (DLS) showed that the liposomes had good nanoparticle size and polydispersity index (PDI), negative zeta potential and transmission electron microscope (TEM) also showed that the liposomes had a spherical appearance and nanoscale size. In vitro release experiments confirmed their ROS responsive release ability. Through lyophilization procedure and resconstituted the liposomes, and placing at room temperature for 8 days, we found no significant changes in the appearance and DLS of the material, proving that alendronate liposomes are relatively stable. Bone marrow derived macrophages (BMMs) cytotoxicity experiments have shown that alendronate liposomes did not exhibit cytotoxicity at concentrations below 10−5 M. Meanwhile, Western blotting suggested that drug loaded liposomes could inhibit osteoclast associated proteins. The above studies indicated the potential of ROS responsive alendronate liposomes in inhibiting osteoclasts in multiple myeloma.

Enhanced Solubility and Dissolution Rate of Aceclofenac using Freeze Drying Technique

The purpose of this investigation was to determine whether lyophilization or freeze-drying Aceclofenac could improve the solubility of the medicine, making it more easily dissolved into tablets. The drug aceclofenac is classified as a biopharmaceutical classification system (BCS) class II medicine. The lyophilization process was facilitated by the addition of SLS as an adjuvant, which has the potential to enhance the dissolving rate. Aceclofenac was swiftly released from fast-dissolving tablets by including an appropriate ratio of PVP K-30. Aceclofenac from a lyophilized sample dissolved at a much faster pace than plain aceclofenac in-vitro. The amount of polymer had an effect on the dissolving rate. The dissolving efficiency of the drug and polymer is enhanced at a 1:2 ratio. Therefore, aceclofenac can be effectively dissolved using the lyophilization procedure.

Positive effect of lyophilization on the stability of halohydrin dehalogenase

In this study, a lyophilization protocol was established for storable and ready-to-use halohydrin dehalogenase (HHDH) from Agrobacterium radiobacter AD1 (HheC), as a model enzyme. HheC showed high activity preservation after the lyophilization procedure, even in the absence of lyoprotectants. Freeze-dried HheC exhibited higher residual activity compared to the liquid form when stored at 50 °C. Among tested additives the formulation with glycine was found to be the best choice regarding the mechanical strength of the lyophilized pellets. Besides, the results revealed significant stability of dry HheC exposed to MTBE, toluene, and 2-MeTHF. However, no activity of the lyophilized HheC was observed in the dehalogenation of 1,3-dichloro-2-propanol (1,3-DCP) in non-aqueous organic media. This study showed that the lyophilization method provides a convenient way for long-term storage of HHDH enzymes and could have an impact on their wider application in the research and industrial biotechnology.

Bifunctional TiCo electrocatalysts based on N-doped graphene cryogels for the oxygen evolution and reduction reactions

Three-dimensional N-doped graphene cryogels (NGC) modified with Ti and Co nanoparticles are investigated as bifunctional oxygen electrocatalysts for potential application in unitized regenerative fuel cells (URFCs). These composites have been successfully produced via a combined solvothermal, freeze-drying, and thermal treatment procedure. Crystallographic structure, surface properties, and morphology are analyzed to study the influence of each metal and the bimetallic combination in forming active sites for oxygen reduction (ORR) and oxygen evolution (OER) reactions. The intrinsic catalytic activity of the composites was determined by rotating disk electrode and further assessed in a gas diffusion electrode to test them in more realistic conditions for URFCs in 6 M KOH. Results revealed the remarkable bifunctional activity of Co/NGC and bimetallic TiCo/NGC composites. The synergistic effect of the metallic cobalt and surface atomic composition of Co3O4 distributed on the N-doped graphene cryogel in Co/NGC is responsible for the high bifunctional performance. Moreover, the partial substitution of cobalt for a less critical raw material, such as titanium, allows the electrocatalyst to maintain great bifunctional activity and stability. The nitrogen doping of the graphene cryogel structure can influence the anatase/rutile titania ratio that forms during pyrolysis. As a result, defects, oxygen vacancies, and Ti3+ species are formed, which, when combined with Co nanoparticles, contribute to the outstanding performance and stability of the TiCo/NGC composite. The excellent performance of N-doped graphene cryogel-based electrocatalysts in GDE conditions indicates their potential use in electrochemical processes, which involve gas-phase reactions.

Preparation of Polyurethane–Urea Fibers with Controlled Surface Morphology via Gel State

It is widely known that skin irritation can be induced by interactions between polymer fibers constituting clothing and the skin, leading to skin inflammation and unfavorable dermatological reactions. Thus, significant endeavors have been directed toward ameliorating this phenomenon. This study engineered synthetic fibers with reduced potential for skin irritation. This was achieved via a strategy inspired by the inherent smoothness of silk fibers, which exhibit minimal friction and irritation against the skin. This investigation focused on urethane fibers, a class of synthetic fibers frequently used in textile applications. Hydrogel cross-linked polyurethane–urea fibers were subjected to controlled swelling in different hydrophilic mixed-solvent environments. Subsequent freeze-drying procedures were employed to yield fibers with diverse surface morphologies and encompassing features such as elevations and creases. The correlation between the compositions of the solvent mixtures used and the resulting surface morphologies of the fibers was rigorously assessed through polarized light and scanning electron microscopies. Additionally, the interplay between the degree of swelling and the tensile strength of the fabricated fibers was comprehensively analyzed. Consequently, the methodological combination of swelling and freeze-drying endowed the polyurethane–urea fibers with various surface profiles. Future studies will delve into the intricate connection between fiber surface characteristics and their potential to induce skin irritation. It is envisaged that such investigations will substantially contribute to the refinement of textile fibers designed for enhanced compatibility with the skin.

A comparison of adsorption capacity of several synthesis methods of cellulose-based absorbent towards Pb(II) removal: Optimization with response surface methodology

The effects of various synthesis methods of a novel biodegradable magnetically recyclable cellulose-based adsorbent (a magnetized modified silica aerogel) on Pb(II) removal efficiency were studied. QSM (quince seed mucilage) was modified via hydrothermal and ultrasonic modes. Oven-drying and freeze-drying procedures were then used to obtain the final adsorbents. The adsorbents were named A1 to A4 and B1 to B4, depending on the synthesis and drying techniques. XRD, FTIR, BET, and SEM are characterization techniques for identifying the adsorbents. Average crystallite sizes of 15.5, 8.3, 10.9, and 2.7 nm were obtained for A1, A2, A3, and A4 samples (Scherrer formula). SEM image confirmed a Sticky bullets-like morphology. The pHpzc values of 3.4, 6.0, and 4.1 were also determined for Fe-silica aerogel, Fe-QSM, and Fe-silica aerogel-QSM samples. The highest adsorption efficiency of the A2 adsorbent towards Pb(II) cations was followed via the experimental design by the RSM (response surface methodology) approach. ANOVA results showed model F value 185 (>F0.05, 14, 15 = 2.42) and LOF F-value of 0.3831 (<F0.05, 10, 5 = 4.74) at a 95 % confidence interval. The center point run conditions were catalyst dose: 7 g/L, pH: 3.2; CPb: 11 mg/L, and contact time: 55 min, while the optimal run conditions were adsorbent dose: 1.0 g/L; pH: 2.6; CPb: 7 mg/L; and contact time: 80 min with about 94 % Pb(II) removal efficiency. The adsorption mechanism was studied, and correlation coefficient (R2) values of Langmuir (0.9814), Freundlich (0.9328), Temkin (0.8898), and Redlich-Peterson (0.9977). They have recommended that the adsorption process fit best with the Langmuir and Redlich-Peterson models. A kinetic study revealed that adsorption was well described by pseudo-second-order kinetics. The thermodynamic studies showed a spontaneous and endothermic adsorption process.

Stability of Monoclonal Antibodies as Solid Formulation for Auto-Injectors: A Pilot Study.

Drug adherence is a significant medical issue, often responsible for sub-optimal outcomes during the treatment of chronic diseases such as rheumatoid or psoriatic arthritis. Monoclonal antibodies (which are exclusively given parenterally) have been proven to be an effective treatment in these cases. The use of auto-injectors is an effective strategy to improve drug adherence in parenteral treatments since these pen-like devices offer less discomfort and increased user-friendliness over conventional syringe-based delivery. This study aims to investigate the feasibility of including a monoclonal antibody as a solid formulation inside an auto-injector pen. Specifically, the objective was to evaluate the drug stability after a concentration (to reduce the amount of solvent and space needed) and freeze-drying procedure. A preliminary screening of excipients to improve stability was also performed. The nano-DSC results showed that mannitol improved the stability of the concentrated, freeze-dried antibody in comparison to its counterpart without it. However, a small instability of the CH2 domain was still found for mannitol samples, which will warrant further investigation. The present results serve as a stepping stone towards advancing future drug delivery systems that will ultimately improve the patient experience and associated drug adherence.

Freeze-drying of few microliters of antibody formulations to implement 384-wells homogeneous instant assays

Enzyme-linked immunosorbent assay protocols have traditionally complex workflows with several intensive wash steps. Analytical tools with both shorter time-to-result and hands-on-time using smaller sample and assays reagents volumes are now investigated. In this context, fluorescence resonance energy transfer (FRET)-based assays are emerging as one of the most promising analytical tools in high-throughput screening (HTS). These immunoassays allow fast quantification of antigens at the nano-gram level in a final assay volume of only a few μL. We used a homogeneous time-resolved FRET (called HTRF) assay to develop a freeze-dried screening and ready-to-use format with only one rehydration step called “instant assay”.To assure optimal performance of the developed homogeneous instant assay, we investigated the critical quality attributes by studying the functionality and stability of the critical reagents and fluorophores. The cyclic adenosine 3′-5′-monophosphate (cAMP) was selected as the antigen target. We tested various formulations (with different buffers, sugars, bulking reagents, surfactants and co-solvants) combined with a slow freezing and the use of an aluminium plate holder during the freeze-drying of few microliter of bioreagents.The optimized freeze-drying procedure permits to preserve more than 70% of Ab recognition properties. The developed off-the-shelf homogeneous FRET immunoassay allows direct and fast quantification of cAMP at a nanogram level.

Synthesis of waterborne polyurethane aerogels-like materials via freeze-drying: an innovative approach

Waterborne polyurethane (WBPUR) aerogels using acetone method and freeze-drying procedure have been successfully synthesized. The morphology, chemical structure, and thermal and mechanical properties of obtained aerogels were analysed by means of scanning electron microscopy, Fourier-transform infrared spectroscopy, contact angle, thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical analysis. In addition, the influence of the solids content in the hydrogel (2–15 wt.%), obtained by varying the amount of water added in the suspension, on the density and thermal conductivity was evaluated. Obtained results demonstrated that the properties of aerogels strongly depend on the solids content assayed in the parent solution. As the solids content in the WBPUR aerogels increases, the density and thermal conductivity for materials with 2.5 and 10% solids content follow an upward trend, while their elasticity decreases. Materials with solids content below 2.5% and above 10% have not demonstrated adequate processability due to their high deformity and hardness, respectively. The drying methodology (freeze-drying) can be profitably used to prepare aerogels-like materials in a cost-effective way.Graphical abstractIllustration of the alternative preparation process of WBPUR aerogels and its potential industrial application.

Different amount of carboxyl-aldehyde fractionated nanofibril cellulose and main characteristics of chitosan, gelatin, alginate added composites

In this research, two different types of nanofibrillated celluloses (NFCs) having different amounts of aldehyde and carboxyl groups were mixed with chitosan (CH), gelatin (GL), and alginate (AL) with different mixing ratios to produce biocomposite aerogels. There was no related study in the literature about producing aerogels with the addition of NC and mentioning biopolymers in addition to the effect of carboxyl and aldehyde fraction of the main matrix NC on composite properties. For this purpose, the main aim of this study was to investigate how carboxyl and aldehyde groups affect the basic characteristics of NFC-biopolymer based materials addition to efficiency of biopolymer amount in main matrix. Even after preparing homogenous NC-biopolymer compositions at 1 % concentration with varied proportions (75 %–25 %, 50 %–50 %, 25 %–75 %, 100 %), aerogels were still made using the fundamentally easy lyophilization procedure. Porosity values for NC-Chitosan (NC/CH) based aerogels range from 97.85 to 99.84 %, whereas those made from NC-Gelatin (NC/GL) and NC-Alginate (NC-AL) have values of 99.2–99.8 % and 98.47 to 99.7 %, respectively. In addition, densities were determined in the range of 0.01 g/cm3 for both NC-CH and NC-GL composites, but higher values were obtained in ranged between 0.01 and 0.03 g/cm3 for NC-AL samples. The crystallinity index values showed a decreasing trend with the addition of biopolymers into NC composition. SEM images showed that all materials have a porous micro structure with different size pores and homogenous surface topography. As a result of the specified tests, these materials can be used in many different industrial applications, such as dust collectors, liquid adsorbers, specific material for packaging and medical materials.

Abstract 5183: Development of an aerosol-based immunotherapy for lung cancer

Abstract Lung cancer is one of the leading causes of cancer death and the second most cancer in the world. Compared to systematic administration, local delivery of therapeutic agents to the lung increases their accumulation in lung cancer cells and reduces the toxicity in other organs. We previously discovered an anti-PD-L1 peptide that can be potentially uses for lung cancer therapy. This project aims to develop an aerosolized formulation of the anti-PD-L1 peptide for the treatment of lung cancer. We hypothesize that the aerosolized peptide has higher accumulation in the lung compared to systematic formulations, leading to high therapeutic index with less side effects. We developed a spray freeze-drying procedure and optimized the formulation to prepare the peptide dry powders. The median mass aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of the aerosols were determined by an 8-stage Andersen Cascade Impactor. The morphology of the aerosols was studied using a scanning electron microscope (SEM). The stability of the aerosols in lung fluid was evaluated. Blocking assay suggested that the aerosolized formulation maintains the blocking efficiency of the peptide. Intratracheal administration of the peptide dry powder shows a high accumulation of the peptide in the lung. Citation Format: Yongren Li, Zhen Zhao, John Fetse, Reaid Hasan, Umar-Farouk Mamani, Yuhan Guo, Kun Cheng. Development of an aerosol-based immunotherapy for lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5183.

Universal Solid-Phase Seed-Mediated Synthesis of Monodisperse and Ultrasmall L10-PtM Intermetallic Nanocrystals

Intermetallic compounds have emerged as a class of promising electrocatalysts for fuel cells; however, it is still a great challenge to synthesize monodisperse and small intermetallic phases by an economical and scalable method. Herein, we demonstrate a generally applicable solid-phase seed-mediated diffusion strategy for controllable synthesis of ordered L10-PtM (M = Mn, Fe, Co, and Zn) nanoparticles, where the preprepared monodispersed Pt seeds are used as the growth sites. The freeze-drying procedure produces monodisperse metal precursors on Pt/C, and the subsequent annealing process in a H2/Ar atmosphere obtains highly dispersed and ultrasmall PtM intermetallic nanocrystals (∼3 nm) on carbon supports. More importantly, such a strategy is also applicable to the preparation of a high-loaded PtMn intermetallic catalyst (50 wt %). Taking PtMn/C catalysts as examples, we illustrate their synthetic details and formation mechanism of the desired ordered phases. This approach eliminates the need for energy-consuming filtering and washing procedures, which makes it very promising for large-scale production.

Fused heteroaromatic benzothiazoles functionalized nitrogen-doped graphene by non-covalent bonds for high-performance supercapacitors

Benzothiazole (Bz) molecules with excellent electrochemical stability and activity are favor of enhancing the capacitance performance of N-doped graphene (NG) by non-covalent functionalization. Herein, Bz molecules with different substituent groups (-ketone, -methoxy, -ketone and-methoxy) are used to functionalize NG nanosheets by a hydrothermal method and freeze-drying procedure. The surface chemistry and structure of as-prepared functionalized NG nanosheets are investigated through UV − vis, FTIR, SEM, AFM, XPS, TGA, XRD, Raman and BET. The electrochemical results of four functionalized NG nanosheets show that the substituent groups on Bz molecules have a great influence on their capacitive properties, among which the NG modified by the 6-methoxy benzothiazol-2-ketone (1-MhzNG) demonstrates the highest specific capacitance (420 F g−1 at 1 A g−1) and excellent cycle stability of 95.7 % after 10,000 cycles. In addition, the assembled supercapacitor based on the 1-MhzNG electrode delivers the highest energy density of 22.5 Wh kg−1 at 809 W kg−1. Our work provides a new idea to modify graphene with novel organic small molecules for high-performance SCs.

Freeze Drying of Polymer Nanoparticles and Liposomes Exploiting Different Saccharide-Based Approaches.

Biodegradable nanocarriers represent promising tools for controlled drug delivery. However, one major drawback related to their use is the long-term stability, which is largely influenced by the presence of water in the formulations, so to solve this problem, freeze-drying with cryoprotectants has been proposed. In the present study, the influence of the freeze-drying procedure on the storage stability of poly(lactide-co-glycolide) (PLGA) nanoparticles and liposomes was evaluated. In particular, conventional cryoprotectants were added to PLGA nanoparticle and liposome formulations in various conditions. Additionally, hyaluronic acid (HA), known for its ability to target the CD44 receptor, was assessed as a cryoprotective excipient: it was added to the nanocarriers as either a free molecule or conjugated to a phospholipid to increase the interaction with the polymer or lipid matrix while exposing HA on the nanocarrier surface. The formulations were resuspended and characterized for size, polydispersity index, zeta potential and morphology. It was demonstrated that only the highest percentages of cryoprotectants allowed the resuspension of stable nanocarriers. Moreover, unlike free HA, HA-phospholipid conjugates were able to maintain the particle mean size after the reconstitution of lyophilized nanoparticles and liposomes. This study paves the way for the use of HA-phospholipids to achieve, at the same time, nanocarrier cryoprotection and active targeting.

Development and characterisation of 3D collagen-gelatin based scaffolds for breast cancer research

While 2D culture presents a useful tool for cancer research, it fails to replicate the tumor microenvironment as it lacks proper three-dimensional cell-cell/cell-matrix interactions, often resulting in exaggerated responses to therapeutic agents. 3D models that aim to overcome the issues associated with 2D culture research offer a new frontier for cancer research with cell growth, morphology and genetic properties that more closely match in vivo cancers. Herein, we aim to develop a collagen-based scaffold that supports the attachment and proliferation of breast cancer (BC) cells as a 3D culture model. Scaffolds were produced on a repeatable basis using a freeze-drying procedure. The constructs were highly porous (>99%) with homogenous pore sizes (150–300 μm) and an interconnected structure. The application of 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDAC) crosslinking resulted in scaffolds with elastic moduli in the range of 1–2 kPa, mimicking cancerous breast tissue stiffness. Furthermore, the incorporation of gelatin into the scaffolds enabled the porosity, pore size and mechanical properties to be tailored, resulting in scaffolds with stiffness values that accurately replicate the stiffness of human BC extracellular matrix (ECM) (1.3–1.7 kPa). Scaffolds displayed high in vitro stability with 90% of mass remaining after 14 days of culture. The scaffolds were shown to be highly biocompatible, and capable of supporting the attachment, infiltration and proliferation of MCF7 breast cancer (BC) cells over +14 days. These results confirm the suitability of these scaffolds as culture models for BC cells. These collagen-based scaffolds offer significant potential for the exploration of aspects of BC, such as gene expression profiles and patterns, and for the assessment of the efficacy of therapeutic agents in treating BC.

Co-axial fibrous scaffolds integrating with carbon fiber promote cardiac tissue regeneration post myocardial infarction

Myocardium is an excitable tissue with electrical conductivity and mechanical strength. In this work, carbon fibers (CFs) and co-axial fibrous mesh were integrated which combined the high modulus and excellent electrical conductivity of CFs and the fibrous and porous structures of the electrospun fibers. The scaffold was fabricated by simply integrating coaxial electrospun fibers and carbon fibers through a freeze-drying procedure. It was shown that the integration of carbon fibers have the conductivity and Young's modulus of the fibrous mesh increased significantly, meanwhile, upregulated the expression of CX43, α-actinin, RhoA of the neonatal rat primary cardiomyocytes and primary human umbilical vein endothelial cells (HUVECs), and promoted the secretion of VEGF of HUVECs. Moreover, the cardiomyocytes grown on the scaffolds increased the ability of HUVECs migration. When implanted to the injury area post myocardial infraction, the scaffolds were able to effectively enhance the tissue regeneration and new vessel formation, which rescued the heart dysfunction induced by the myocardial infraction, evidenced by the results of echocardiography and histochemical analysis. In conclusion, the composite scaffolds could promote the myocardium regeneration and function's recovery by enhancing cardiomyocytes maturation and angiogenesis and establishing the crosstalk between the cardiomyocytes and the vascular endothelial cells.