scholarly journals Optimization of Collagen Chemical Crosslinking to Restore Biocompatibility of Tissue-Engineered Scaffolds

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 832
Author(s):  
Mohammad Mirazul Islam ◽  
Dina B. AbuSamra ◽  
Alexandru Chivu ◽  
Pablo Argüeso ◽  
Claes H. Dohlman ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Crosslinking Agent ◽  
Collagen Scaffold ◽  
Human Monocyte ◽  
Subsequent Treatment ◽  
Sodium Metabisulfite ◽  
Corneal Tissue ◽  
Dependent Manner ◽  
Collagen Scaffolds ◽  
Enzymatic Stability

Collagen scaffolds, one of the most used biomaterials in corneal tissue engineering, are frequently crosslinked to improve mechanical properties, enzyme tolerance, and thermal stability. Crosslinkers such as 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) are compatible with tissues but provide low crosslinking density and reduced mechanical properties. Conversely, crosslinkers such as glutaraldehyde (GTA) can generate mechanically more robust scaffolds; however, they can also induce greater toxicity. Herein, we evaluated the effectivity of double-crosslinking with both EDC and GTA together with the capability of sodium metabisulfite (SM) and sodium borohydride (SB) to neutralize the toxicity and restore biocompatibility after crosslinking. The EDC-crosslinked collagen scaffolds were treated with different concentrations of GTA. To neutralize the free unreacted aldehyde groups, scaffolds were treated with SM or SB. The chemistry involved in these reactions together with the mechanical and functional properties of the collagen scaffolds was evaluated. The viability of the cells grown on the scaffolds was studied using different corneal cell types. The effect of each type of scaffold treatment on human monocyte differentiation was evaluated. One-way ANOVA was used for statistical analysis. The addition of GTA as a double-crosslinking agent significantly improved the mechanical properties and enzymatic stability of the EDC crosslinked collagen scaffold. GTA decreased cell biocompatibility but this effect was reversed by treatment with SB or SM. These agents did not affect the mechanical properties, enzymatic stability, or transparency of the double-crosslinked scaffold. Contact of monocytes with the different scaffolds did not trigger their differentiation into activated macrophages. Our results demonstrate that GTA improves the mechanical properties of EDC crosslinked scaffolds in a dose-dependent manner, and that subsequent treatment with SB or SM partially restores biocompatibility. This novel manufacturing approach would facilitate the translation of collagen-based artificial corneas to the clinical setting.

Modifying the Properties of Collagen Scaffolds with Microfluidics

2005 ◽  
Vol 897 ◽  
Author(s):  
David I Shreiber ◽  
Harini G Sundararaghavan ◽  
Minjung Song ◽  
Vikram Munikoti ◽  
Kathryn E Uhrich
Keyword(s):  
Mechanical Properties ◽  
Cell Adhesion ◽  
Cellular Response ◽  
Type I Collagen ◽  
Crosslinking Agent ◽  
Force Balance ◽  
Adherent Cell ◽  
Type I ◽  
Spinal Cord Regeneration ◽  
Collagen Scaffolds

AbstractIt is now well accepted that the mechanical properties and cell adhesion profile of 2D and 3D extracellular matrix molecules combine to dictate cellular fate processes, such as differentiation, migration, proliferation, and apoptosis, through a process generally known as 'mechanotransduction', or the conversion of mechanical signals into a cellular response. The stiffness and adhesion density combine to affect the force balance that exists between an adherent cell and the surrounding substrate. We have established BioMEMS, microfluidic technology to alter the mechanical properties and cell adhesion profile of collagen scaffolds. Using soft lithography, we fabricate elastomeric networks that serve as conduits for the controlled mixing of type I collagen solutions. Our technology enables us to generate reproducible, controlled homogeneous and inhomogeneous microenvironments for 3D cell culture, assays of cell behavior in 3D, and the development of bioartificial tissue equivalents for regenerative and reparative therapies. The adhesivity of collagen is modulated by covalently grafting peptides (such as RGD) or proteins (such as albumin) to soluble collagen molecules with 1- ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC), a hetero-bifunctional coupling agent. EDC activates the carboxylic group of collagen and forms an amine bond with the grafting molecule. The grafted collagen self-assembles into a fibrillar gel at physiological temperature and pH with no measurable changes in rheological properties compared to controls. A solution of peptide-grafted collagen is then mixed in microfluidic networks with unaltered collagen to form controlled gradients or other patterns of the two solutions, which immobilize upon self-assembly. Separately or in the same network, the mechanical properties of the collagen gel can be altered regionally by the microfluidic delivery a solution of a cell-tolerated crosslinking agent. We use genipin, which has the unique property of generating crosslinks that autofluoresce. The intensity of the fluorescence correlates with the degree of crosslinking (and thus the mechanical properties) enabling us to monitor and measure changes in mechanical properties dynamically and non-invasively. Lastly, though it requires constant delivery or recirculation, the same networks can be used to impose gradients of soluble factors, such as growth factors and cytokines. Thus, we have developed a platform to examine the response of cells to simultaneous chemotactic, haptotactic, and durotactic gradients in a 3D environment. We are employing this technology to examine the response of neural cells to gradients of biomaterial properties to optimize cues for spinal cord regeneration.

In vivo Evaluation of a Collagen Scaffold Preconditioned with Adipose-derived Mesenchymal Stem Cells Used for Bone Regeneration A histological study

2018 ◽  
Vol 55 (4) ◽  
pp. 691-695
Author(s):  
Tudor Sorin Pop ◽  
Anca Maria Pop ◽  
Alina Dia Trambitas Miron ◽  
Klara Brinzaniuc ◽  
Simona Gurzu ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Bone Regeneration ◽  
Histological Study ◽  
Collagen Scaffold ◽  
Bone Defects ◽  
Collagen Scaffolds ◽  
In Vivo Evaluation ◽  
Calvarial Bone ◽  
Bone Apposition

The use of collagen scaffolds and stem cells for obtaining a tissue-engineering complex has been an important concept in promoting repair and regeneration of the bone tissue. Such units represent important steps in the development of an ideal scaffold-cell complex that would sustain new bone apposition. The aim of our study was to perform a histologic evaluation of the healing of critical-sized bone defects, using a biologic collagen scaffold with adipose-derived mesenchymal stem cells, in comparison to negative controls created in the adjacent bone. We used 16 Wistar rats and according to the study design 2 calvarial bone defects were created in each animal, one was filled with collagen seeded with adipose-derived stem cells and the other one was considered negative control. During the following month, at weekly intervals, the animals were euthanized and the specimens from bone defects were histologically evaluated. The results showed that these scaffolds were highly biocompatible as only moderate inflammation no rejection reactions were observed. Furthermore, the first signs of osseous healing appeared after two weeks accompanied by angiogenesis. Collagen scaffolds seeded with adipose-derived mesenchymal stem cells can be considered a promising treatment option in bone regeneration of large defects.

scholarly journals Coatings with recycled polyvinyl butyral on polyester and polyamide mono- and multifilament yarns

2021 ◽  
Author(s):  
Rike Brendgen ◽  
Carsten Graßmann ◽  
Thomas Grethe ◽  
Boris Mahltig ◽  
Anne Schwarz-Pfeiffer
Keyword(s):  
Mechanical Properties ◽  
Chemical Resistance ◽  
Crosslinking Agent ◽  
Polyvinyl Butyral ◽  
Polymer Dispersion ◽  
Safety Glass ◽  
Enhanced Properties ◽  
Multifilament Yarns ◽  
Textile Coating ◽  
Recycled Material

AbstractPolyvinyl butyral is used in safety glass interlayers, mainly in car windshields. Legislative regulations require a recycling of cars after their lifetime and therefore also their safety glass. This causes the availability of recycled polyvinyl butyrate (r-PVB) originated from safety glass interlayers. Due to deteriorated optical properties, such as the transparency, and unknown amounts of plasticizers, it is challenging to reuse the recycled material in new windshields. Therefore, it is of particular interest to find new fields of application for r-PVB, such as the usage as a textile coating. In this research, r-PVB was investigated as a material for yarn coating. Polyester and polyamide mono- and multifilament yarns were coated continuously with solely a polymer dispersion and with mixtures of crosslinking agent and polymer dispersion. Crosslinked r-PVB coatings showed enhanced properties toward abrasion and chemical resistance. Coatings without the crosslinking agent showed a diminished abrasion resistance and could be washed off with ethanol. Mechanical properties of the monofilaments were influenced by the r-PVB coating in general. However, varying concentrations of the crosslinking agent did not affect the mechanical properties.

scholarly journals Rheometer Evidences for the Co-Curing Effect of a Bismaleimide in Conjunction with the Accelerated Sulfur on Natural Rubber/Chloroprene Rubber Blends

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1510
Author(s):  
Marek Pöschl ◽  
Shibulal Gopi Sathi ◽  
Radek Stoček ◽  
Ondřej Kratina
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Crosslinking Agent ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ene Reactions ◽  
Rubber Blends ◽  
Diels Alder Reaction ◽  
Chloroprene Rubber

The rheometer curing curves of neat natural rubber (NR) and neat chloroprene rubber (CR) with maleide F (MF) exhibit considerable crosslinking torque at 180 °C. This indicates that MF can crosslink both these rubbers via Alder-ene reactions. Based on this knowledge, MF has been introduced as a co-crosslinking agent for a 50/50 blend of NR and CR in conjunction with accelerated sulfur. The delta (Δ) torque obtained from the curing curves of a blend with the addition of 1 phr MF was around 62% higher than those without MF. As the content of MF increased to 3 phr, the Δ torque was further raised to 236%. Moreover, the mechanical properties, particularly the tensile strength of the blend with the addition of 1 phr MF in conjunction with the accelerated sulfur, was around 201% higher than the blend without MF. The overall tensile properties of the blends cured with MF were almost retained even after ageing the samples at 70 °C for 72 h. This significant improvement in the curing torque and the tensile properties of the blends indicates that MF can co-crosslink between NR and CR via the Diels–Alder reaction.

Characterization of a Novel Collagen Scaffold for Corneal Tissue Engineering

2016 ◽  
Vol 22 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Jie Zhang ◽  
Aran M.G. Sisley ◽  
Alexander J. Anderson ◽  
Andrew J. Taberner ◽  
Charles N.J. McGhee ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Collagen Scaffold ◽  
Corneal Tissue

Effect of Silica and Hydroxyapatite Mineralization on the Mechanical Properties and the Biocompatibility of Nanocomposite Collagen Scaffolds

2011 ◽  
Vol 3 (11) ◽  
pp. 4323-4331 ◽  
Author(s):  
S. Heinemann ◽  
C. Heinemann ◽  
M. Jäger ◽  
J. Neunzehn ◽  
H. P. Wiesmann ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Collagen Scaffolds

Redox-Sensitive Ultrashort Peptide Hydrogel with Tunable Mechanical Properties for Anti-Tumor Drug Delivery

2020 ◽  
Vol 16 (11) ◽  
pp. 1588-1599
Author(s):  
Yiping Li ◽  
Ying Zhu ◽  
Shiyao Luo ◽  
Yue He ◽  
Zhewei Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Targeted Delivery ◽  
Subcutaneous Tissue ◽  
Drug Loading ◽  
Gelation Time ◽  
In Vivo Studies ◽  
Dependent Manner ◽  
The Cross ◽  
Hydrogel System

In this study, we report a new ultrashort peptide (LOC), which forms a redox-sensitive hydrogel after cross-linking with the mild oxidant H2 O2 and used it for tumor-targeted delivery of doxorubicin hydrochloride (DOX). LOC gelled within a few minutes in low-concentration H2 O2 solution. The concentration of H2 O2 significantly altered the gelation time and mechanical properties of the hydrogel. The in vitro micromorphology, secondary structure and rheology characterization of cross-linked hydrogels confirmed the sensitivity and injectability to reducing agent. The cross-linked hydrogel had a strong drug loading capacity, and the drug was released in a GSH concentration-dependent manner, following the Fick diffusion model. In addition, the cross-linked hydrogel showed no cytotoxicity to normal fibroblasts, and no damage to the subcutaneous tissue of mice was observed. In vitro cytotoxicity experiments showed that the DOX-hydrogel system exhibited good anti-cancer efficacy. In vivo studies using 4T1 tumor-bearing mice showed that the DOX-hydrogel system had a significant inhibitory effect on tumors. Therefore, the newly designed redox-sensitive hydrogel can effectively enhance the therapeutic efficacy of DOX and reduce toxicity, making it an attractive biological material.

scholarly journals Sintesis Hidrogel Pektin – Gelatin dengan Penambahan Ekstrak Kulit Buah Naga Sebagai Kandidat Pembalut Luka Bakar

2020 ◽  
Vol 4 (1) ◽  
pp. 53
Author(s):  
Fadhil Muhammad Tarmidzi ◽  
Inggit Kresna Maharsih ◽  
Tina Raihatul Jannah ◽  
Cici Sari Wahyuni
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Citric Acid ◽  
Wound Dressing ◽  
Wound Care ◽  
Crosslinking Agent ◽  
Wound Dressings ◽  
Esterification Reaction ◽  
Natural Polymers ◽  
Fruit Peel

Teknik pembalutan luka saat ini menerapkan metode perawatan luka modern dengan cara mempertahankan isolasi lingkungan luka dalam keadaan tertutup dan lembab. Ada beberapa jenis pembalut luka yang telah dikembangkan, salah satunya hidrogel. Hidrogel merupakan pembalut luka berbentuk lembaran yang memiliki kemampuan menyerap cairan luka dan memiliki stabilitas yang baik pada pH asam sehingga dapat digunakan untuk pengobatan luka bakar. Dalam penelitian ini, hidrogel dibuat menggunakan polimer alami seperti pektin dan gelatin. Kedua bahan tersebut dikombinasikan menggunakan metode ikatan silang dengan penambahan asam sitrat sebagai agen pengikat silang. Penambahan asam sitrat memberikan pengaruh terhadap karakteristik material hidrogel yang dihasilkan, sehingga diperlukan jumlah yang tepat agar didapatkan hidrogel dengan properti material yang baik. Hidrogel juga ditambahkan zat aktif berupa flavonoid pada ekstrak kulit buah naga agar dapat digunakan sebagai pembalut luka untuk menyembuhkan luka bakar. Dari hasil penelitian, hidrogel dengan konsentrasi asam sitrat 4% (Hidrogel CA 4%) menghasilkan nilai swelling, tensile strength, dan elongation tertinggi sebesar 890%, 0,05 Mpa, dan 200%. Hasil properti mekanik dari Hidrogel CA 4% ini dibuktikan dengan uji FTIR yang telah dilakukan, yaitu munculnya gugus karbonil C=O sebagai hasil reaksi esterifikasi yang terjadi antara polimer dengan asam sitrat di daerah serapan 1733,9 cm-1.Wound dressing technique currently applies modern wound care methods by maintaining the environmental isolation of the wound in a closed and moist state. There are several types of wound dressing that have been developed, one of them is hydrogel. Hydrogel is sheet-shaped wound dressings which have the ability to absorb exudate and have good stability acidic pH that can be used for the treatment of burns. In this study, hydrogel were made using natural polymers such as pectin and gelatin. The two polymers were combined using crosslinking method with the addition of citric acid as a crosslinking agent. The addition of citric acid has affect on the characteristics of the hydrogel material produced, therefore the right amount is needed to obtain a hydrogel with good mechanical properties. Hydrogel also added by an active substance in the form of flavonoids from dragon fruit peel extract that can be used as a wound dressing to cure burns. This study resulting hydrogel with a concentration of 4% citric acid (Hydrogel CA 4%) produced highest value of swelling, tensile strength, and elongation are 890%, 0.05 Mpa, and 200%, repectively. The mechanical properties of Hydrogel CA 4% was proved by FTIR test that had been carried out, namely the presence of C=O carbonyl group as a result of the esterification reaction that occurred between the polymers and citric acid in the absorption area of 1733.9 cm-1.

scholarly journals Autologous Tenocyte Implantation (ATI) and the Use of Collagen Scaffolds: a Case Report of a Novel Surgical Treatment for Gluteal Tendon Repair

2021 ◽  
pp. 194
Author(s):  
◽  
◽  
◽  
◽  
Keyword(s):  
Platelet Rich Plasma ◽  
Tendon Repair ◽  
Tendon Healing ◽  
Collagen Scaffold ◽  
Gluteus Medius ◽  
Normal Function ◽  
Collagen Scaffolds ◽  
Mri Findings ◽  
Level Of Evidence ◽  
Mri Scans

Background: Ortho-biological therapies such as platelet-rich plasma and autologous tenocyte implantation injections are hypothesized to introduce cellular mediators such as growth factors into tendons, promoting natural healing. Methods: This case introduces a 63-year-old female with an extensive history of lateral hip pain and treatment refractory tendinopathy with tearing. She underwent open surgery to repair the gluteus medius tendon, using supplementary autologous tenocyte implantation (ATI) in conjunction with a Celgro (Orthocell, Perth, Australia) collagen scaffold. Level of evidence: 4 Results: She had normal function in the hip at 12 months. MRI scans post-operatively at 12 months showed a marked reduction in inflammation, an intact tendon and a reduction in atrophic changes in the muscle belly. Conclusion: Surgical repair of a large degenerate tear of the gluteus medius tendon, augmented with autologous tenocyte implantation in a collagen scaffold led to an excellent patient outcome and MRI findings demonstrated tendon healing with improved tendon structure and reduced inflammation.

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