Influence of Gelatin Source and Bloom Number on Gelatin Methacryloyl Hydrogels Mechanical and Biological Properties for Muscle Regeneration

Approximately half of an adult human’s body weight is made up of muscles. Thus, restoring the functionality and aesthetics of lost muscle tissue is critical. The body is usually able to repair minor muscle injuries. However, when volumetric muscle loss occurs due to tumour extraction, for instance, the body will form fibrous tissue instead. Gelatin methacryloyl (GelMA) hydrogels have been applied for drug delivery, tissue adhesive, and various tissue engineering applications due to their tuneable mechanical properties. Here, we have synthesised GelMA from different gelatin sources (i.e., porcine, bovine, and fish) with varying bloom numbers, which refers to the gel strength, and investigated for the influence of the source of gelatin and the bloom number on biological activities and mechanical properties. The results indicated that the source of the gelatin and variable bloom numbers have an impact on GelMA hydrogel properties. Furthermore, our findings established that the bovine-derived gelatin methacryloyl (B-GelMA) has better mechanical properties than the other varieties composed of porcine and fish with 60 kPa, 40 kPa, and 10 kPa in bovine, porcine, and fish, respectively. Additionally, it showed a noticeably greater swelling ratio (SR) ~1100% and a reduced rate of degradation, improving the stability of hydrogels and giving cells adequate time to divide and proliferate to compensate for muscle loss. Furthermore, the bloom number of gelatin was also proven to influence the mechanical properties of GelMA. Interestingly, although GelMA made of fish had the lowest mechanical strength and gel stability, it demonstrated excellent biological properties. Overall, the results emphasise the importance of gelatin source and bloom number, allowing GelMA hydrogels to have a wide range of mechanical and excellent biological properties and making them suitable for various muscle tissue regeneration applications

Nickel Release and the Viability of Streptococcus mutans Corresponding to Low Risk of Dental Caries in Artificial Saliva Containing Orthodontic Appliances: In Vitro Study

Objective: The aims of this study were to determine the effect of different levels of Streptococcus mutans that correspond to a low risk of dental caries on nickel release and to determine the viability of S. mutans.Methods: Simulated fixed orthodontic appliances composed of copper nickel titanium, nickel titanium, or stainless steel were immersed in Klimek artificial saliva for 10 days with or without S. mutans inoculation on day 7. Same levels of S. mutans cultures (4 × 104 cfu/mL) were inoculated into the artificial saliva without orthodontic appliances. Nickel release was detected by inductively coupled plasma mass spectrometry. The archwire surface was analyzed by atomic force microscopy and scanning electron microscopy.Results: The density of S. mutans significantly increased in the artificial saliva without orthodontic appliances (P < .05). Appliances with nickel titanium alloys showed higher nickel release in the artificial saliva with or without S. mutans than those with copper nickel titanium or stainless steel archwires (P < .05). However, S. mutans increased nickel release only in orthodontic appliances with stainless steel archwires (P < .05). Although atomic force microscopy showed that the surface of as-received stainless steel archwires was smoother than that of nickel titanium or nickel titanium archwires, S. mutans increased the surface roughness of only the SS archwires. S. mutans adhered to all archwire types.Conclusion: While corrosion or corrosion-related processes may have decreased the growth capacity of S. mutans, reciprocally, S. mutans influenced corrosion. Rough surfaces can also promote corrosion; therefore, the surface roughness of metal alloy orthodontic appliances should be evaluated to determine their corrosion behavior

Selenium- and/or copper-substituted hydroxyapatite: A bioceramic substrate for biomedical applications

Atomic substitution or doping of a bioceramic material hydroxyapatite (HA) with specific ions is an appealing approach for improving its biocompatibility and activity, as well as imparting antibacterial properties. In this study, selenium- and/or copper-substituted hydroxyapatite powders were synthesized by an aqueous precipitation method and using the freeze-drying technique. The molar concentrations of constituents were calculated based on the proposed mechanism whereby selenium (Se4+) ions partially substitute phosphorus (P5+) sites, and copper (Cu2+) ions partially substitute (Ca2+) sites in the HA lattice. Dried precipitated samples were characterized using Inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FTIR) and Field-emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDX). Accordingly, substitution of Se4+ and/or Cu2+ ions took place in the crystal lattice of HA without the formation of any impurities. The presence of sulphur (S2-) ions in the hydroxyapatite was detected by ICP-OES in all samples with copper substituted in the lattice. The cytotoxicity of the powders on osteoblastic (MC3T3-E1) cells was evaluated in vitro. Selenium substituted hydroxyapatite (SeHA), at the concentration (200 μg/mL), demonstrated higher populations of the live cells than that of control (cells without powders), suggesting that selenium may stimulate the proliferation of these cells. In addition, the copper substituted hydroxyapatite (CuHA) and the selenium and copper substituted hydroxyapatite (SeCuHA) at the concentrations (200 and 300 μg/mL) and (200 μg/mL), respectively demonstrated better results than the unsubstituted HA. Antimicrobial activity was assessed using a well-diffusion method against Streptococcus mutans and Candida albicans, and superior results has obtained with SeCuHA samples. Presented findings imply that selenium and/or copper substituted modified hydroxyapatite nanoparticles, may be an attractive antimicrobial and cytocompatible substrate to be considered for use in a range of translational applications

A Sustainable, Green-Processed, Ag-Nanoparticle-Incorporated Eggshell-Derived Biomaterial for Wound-Healing Applications

The eggshell membrane (ESM) is a natural biomaterial with unique physical and mechanical properties that make it a promising candidate for wound-healing applications. However, the ESM’s inherent properties can be enhanced through incorporation of silver nanoparticles (AgNPs), which have been shown to have antimicrobial properties. In this study, commercially produced AgNPs and green-processed AgNPs were incorporated into ESM and evaluated for their physical, biological, and antimicrobial properties for potential dermal application. The ESM was extracted using various techniques, and then treated with either commercially produced AgNPs (Sigma-Aldrich, Poole, UK) or green-synthesized AgNPs (Metalchemy, London, UK) to produce AgNPs-ESM samples. The physical characteristics of the samples were evaluated using scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and the biological properties were assessed through in vitro studies using human dermal fibroblasts (HDFs) and BJ cells. The SEM analysis of the AgNPs-ESM samples showed localization of AgNPs on the ESM surface, and that the ESM maintained its structural integrity following AgNP incorporation. The FTIR confirmed loading of AgNPs to ESM samples. The biological studies showed that the 5 μg/mL AgNPs-ESM samples were highly biocompatible with both HDFs and BJ cells, and had good viability and proliferation rates. Additionally, the AgNPs-ESM samples demonstrated pro-angiogenic properties in the CAM assay, indicating their potential for promoting new blood vessel growth. Assessment of the antimicrobial activity of the enhanced AgNPs/ESMs was validated using the International Standard ISO 16869:2008 methodology and exploited Cladosporium, which is one of the most commonly identified fungi in wounds, as the test microorganism (≥5 × 106 cells/mL). The AgNPs-ESM samples displayed promising antimicrobial efficacy as evidenced by the measured zone of inhibition. Notably, the green-synthesized AgNPs demonstrated greater zones of inhibition (~17 times larger) compared to commercially available AgNPs (Sigma-Aldrich). Although both types of AgNP exhibited long-term stability, the Metalchemy-modified samples demonstrated a slightly stronger inhibitory effect. Overall, the AgNPs-ESM samples developed in this study exhibited desirable physical, biological, and antimicrobial properties for potential dermal wound-dressing applications. The use of green-processed AgNPs in the fabrication of the AgNPs-ESM samples highlights the potential for sustainable and environmentally friendly wound-healing therapies. Further research is required to assess the long-term biocompatibility and effectiveness of these biomaterials in vivo

Inclusion of calcium phosphate does not further improve in vitro and in vivo osteogenesis in a novel, highly biocompatible, mechanically stable and 3D printable polymer

At a time of unpredictable challenges for health, one trend is certain: there is an exceedingly high demand for functional implants, particularly bone grafts. This has encouraged the emergence of bone tissue engineering substitutes as an alternative method to conventional bone grafts. However, the current approaches in the field face several limitations that have prevented the ultimate translation into clinical settings. As a result, many attempts have been made to fabricate synthetic bone implants that can offer suitable biological and mechanical properties.Light curable methacrylate-based polymers have ideal properties for bone repair. These materials are also suitable for 3D printing which can be applicable for restoration of both function and aesthetics. The main objective of this research was to investigate the role of calcium phosphate (CaP) incorporation in a mechanically stable, biologically functional and 3D printable polymer for the reconstruction of complex craniofacial defects. The experimental work initially involved the synthesis of (((((((((((3R,3aR,6S,6aR)- hexahydrofuro[3,2-b]furan-3,6-diyl)bis(oxy))bis(ethane-2,1- 48 diyl))bis(oxy))bis(carbonyl))bis(azanediyl))bis(3,3,5-trimethylcyclohexane-5,1- 49 diyl))bis(azanediyl))bis(carbonyl))bis(oxy))bis(ethane-2,1-diyl) bis(2-methylacrylate) referred to as CSMA and fabrication of composite discs via a Digital Light Printing (DLP) method. The flow behaviour of the polymer as a function of CaP addition, surface remineralisation potential, in vitro cell culture, using MC3T3 and Adipose-Derived Mesenchymal Stem Cells (ADSCs) and ex ovo angiogenic response was assessed. Finally, in vivo studies were carried out to investigate neo-bone formation at 4- and 8-weeks post-implantation. Quantitative micro-CT and histological evaluation did not show a higher rate of bone formation in CaP filled CSMA composites compared to CSMA itself. Therefore, such polymeric systems hold promising features by allowing more flexibility in designing a 3D printed scaffold targeted at the reconstruction of maxillofacial defects

Therapeutic Application of an Ag-Nanoparticle-PNIPAAm-Modified Eggshell Membrane Construct for Dermal Regeneration and Reconstruction

Current therapeutic treatments for the repair and/or replacement of damaged skin following disease or traumatic injury is severely limited. The chicken eggshell membrane (ESM) is a unique material: its innate physical and mechanical characteristics offer optimal barrier properties and, as a naturally derived extract, it demonstrates inherent biocompatibility/biodegradability. To further enhance its therapeutic and clinical potential, the ESM can be modified with the thermo-responsive polymer, poly(N-isopropylacrylAmide) (PNIPAAm) as well as the incorporation of (drug-loaded) silver nanoparticles (AgNP); essentially, by a simple change in temperature, the release and delivery of the NP can be targeted and controlled. In this study, ESM samples were isolated using a decellularization protocol, and the physical and mechanical characteristics were profiled using SEM, FT-IR, DSC and DMA. PNIPAAm was successfully grafted to the ESM via amidation reactions and confirmed using FT-IR, which demonstrated the distinctive peaks associated with Amide A (3275 cm−1), Amide B (2970 cm−1), Amide I (1630 cm−1), Amide II (1535 cm−1), CH2, CH3 groups, and Amide III (1250 cm−1) peaks. Confirmation of the incorporation of AgNP onto the stratified membrane was confirmed visually with SEM, qualitatively using FT-IR and also via changes in absorbance at 380 nm using UV-Vis spectrophotometry during a controlled release study for 72 h. The biocompatibility and cytotoxicity of the novel constructs were assessed using human dermal fibroblast (HDFa) and mouse dermal fibroblast (L929) cells and standard cell culture assays. Metabolic activity assessment (i.e., MTS assay), LDH-release profiles and Live/Dead staining demonstrated good attachment and spreading to the samples, and high cell viability following 3 days of culture. Interestingly, longer-term viability (&gt;5 days), the ESM-PNIPAAm and ESM-PNIPAAm (AgNP) samples showed a greater and sustained cell viability profile. In summary, the modified and enhanced ESM constructs were successfully prepared and characterized in terms of their physical and mechanical profiles. AgNP were successfully loaded into the construct and demonstrated a desirable release profile dependent on temperature modulation. Fibroblasts cultured on the extracted ESM samples and ESM-PNIPAAm demonstrated high biocompatibility in terms of high cell attachment, spreading, viability and proliferation rates. As such, this work summarizes the development of an enhanced ESM-based construct which may be exploited as a clinical/therapeutic wound dressing as well as a possible application as a novel biomaterial scaffold for drug development

Hydrogel – Phosphate Glass Fibre Constructs For Neural Tissue Engineering Applications

Neural injuries, particularly spinal cord injuries, are considered critical global health priorities due to causing severe loss of function and disabilities that could last a lifetime. Besides restricted regeneration capacity of the axons in the central nervous system, following an injury with damaged integrity of axons, there are also other inhibitory factors like inflammation and the glial scar that restrict recovery. Although no valid therapies have been found effective for functional recovery; tissue engineering applications offer promising approaches to support axonal regeneration after such debilitating incidents. Utilising hydrogels as tissue constructs for the targeted injury sites can serve multifunctional purposes, from cell therapies to scaffolding to bridging the disconnected nerve stumps and carrying drugs and other bioactive molecules to mitigate local challenges. Current tissue engineering approaches are limited in CNS, because of either complexity of developed constructs or focusing on just nerves and continuity of axons so a tissue engineered construct that is while offering simple design also is presenting favourable outcomes for functional neural recovery is required. Thus, the development of a GelMA hydrogel-based, biocompatible, and biodegradable construct containing phosphate-based glass fibres (PGFs) within its physical form was investigated in this thesis aiming to provide a favourable environment to cells and provide directionality to axons with aligned glial cell growth. It has been hypothesised that having PGFs in the GelMA hydrogel platform can provide a physical cue for directional growth of glial cells, and GelMA can provide a supportive and permissive environment while offering its ability to serve as a cell and drug carrier. Two PGFs formulations with different metal oxides, Fe+3 and Ti+2, were assessed within GelMA, and their extensive physicochemical and mechanical characterisations were conducted with further n vitro and in vivo biocompatibility analyses. Moreover, in vitro 3D cell culture assessments were carried out with primary astrocytes to investigate the potential of GelMA-PGFs constructs to ameliorate glial scar formation and inflammation indirectly via upregulation of GFAP and IL6 after LPS induced reactivity in addition to the exploration of lithium introduction via loading into GelMA hydrogel have also investigated. The outputs of this thesis provide comprehensive characterisations of PGFs and GelMA hydrogels for utilisation in neural tissue engineering. Glial cells have shown significantly enhanced directional growth into GelMA-PGFs scaffolds than GelMA only hydrogel. Furthermore, while the presence of PGFs(Fe) in GelMA has led more decreasing GFAP expression levels, lithium has provided a protective effect to mitigate the early expression of IL6 with LPS induced reactive primary astrocytes

Keratin içeren bakteriyel selüloz tabanlı yeni bir kompozit biyomalzeme üretimi, karakterizasyonu ve biyoyapay deri geliştirilmesinde kullanım potansiyelinin araştırılması

In this thesis, a new natural biocomposite production has been done by combining bacterial cellulose (BC) produced by Acetobacter xylinum with keratin protein isolated from human hair. Two different composite production approaches have been used named as in situ production and post modification. Both two methods have yielded successful results for production of BC based nanocomposite-containing keratin. Keratin isolation from human hair has been performed with Shindai method. BC modifications have been made using 1, 2, 3 % w/v keratin for in situ production and 0,1 ml/cm2 keratin (3,66 mg/ml) for post modification. A new biocomposite materials have been investigated for surface properties, appearence, elemental analysis, chemical bond structure, cytotoxicity and endotoxicity. Human skin fibroblast and keratinocyte cells coculture interaction have been investigated by using in vitro animal cell culture techniques for the assessment of application potential of the new BC/keratin composites as bioartificial skin. Combining of BC with keratin have been provided a new composite biomaterial production which could have high potential for bioartificial skin by supporting skin cells.Bu tezde Acetobacter xylinum tarafından üretilen bakteriyel selüloz (BS), insan keratin proteini ile birleştirilerek yeni bir doğal kompozit biyomalzeme üretimi gerçekleştirilmiştir. Çalışmada üretimle eş zamanlı (in situ) ve üretim sonrasında (post) olmak üzere iki farklı yaklaşım kullanılarak BS tabanlı keratin içeren yeni bir nanokompozit malzeme üretilmiştir. Atık insan saçından keratin izolasyonu Shindai yöntemi ile gerçekleştirilmiştir. BS'ye in situ olarak %1, 2, 3 w/v, üretim sonrası (post) 0,1 ml/cm2 keratin çözeltisi (3,66 mg/ml) kullanılarak modifikasyonlar uygulanmıştır. Üretimler sonrası %3 keratin ile in situ BS/keratin kompoziti ve post modifiye BS/keratin kompozitlerinin SEM, EDX, FTIR, XRD, sitotoksisite ve endotoksisite analizleri ile ileri karakterizasyon çalışmaları gerçekleştirilmiştir. Üretilen yeni BS/keratin kompozitinin biyoyapay deri geliştirmede kullanım potansiyelinin araştırılması amacıyla in vitro hayvan hücre kültürü teknikleri ile insan deri fibroblast ve keratinosit hücreleri ile olan ko-kültür etkileşimlerine bakılmıştır. BS'nin keratin ile birleştirilmesi deri hücreleri ile etkileşimi destekleyici özellikte, biyoyapay deri malzemesi geliştirmede yüksek potansiyele sahip olabilecek yeni bir kompozit biyomalzeme üretimi ile sonuçlandırılmıştır

(SANAT OLARAK BİYOMÜHENDİSLİK)

Biyomühendislik alanı multidisipliner mühendislik alanlarının birlikteliğinin yanı sıra hızla büyüyen bir alandır. 7. Biyomühendislik Kongresi organizasyon komitesi doğası gereği interdisipliner bir yapısı olan biyomühendisliğefarklı ve yenilikçi bir bakışı hedefledi. Sanat olarak biyomühendislik sergisi, "Biyotasarım- Toplumsal Avantaj için Doğanın Çözümleri" başlığı ile düzenlenen Bec 2015'in üç sergisinden biri olup bu yazıda farklı katılımcıların açılımları sunulmaktadır.Bioengineering is a rapidly growing area that is commonly defined as a highly multidisciplinary engineering field. The organising committee of the 7. International Bioengineering Congress decided to add a different and innovative perspective to our understanding of the multidisciplinary nature of bioengineering. "Bioengineering As Art" contest is one of the three exhibitions of the congress Bec2015, was conducted with the theme of "biodesign - solutions of nature for societal challenges", has attracted much interest from participants and delegates and also presented in that paper