Assessing the suitability of fused deposition modeling to produce acrylic removable denture bases Khalid K. Alanazi, Duncan Wood, Joanna Shepherd, Christopher W. Stokes, Ilida Ortega Asencio Clinical and Experimental Dental Research, 2024 ObjectiveTo study the feasibility of using poly methyl methacrylate (PMMA) filament and fused deposition modeling (FDM) to manufacture denture bases via the development of a study that considers both conventional and additive‐based manufacturing techniques.Materials and MethodsFive sample groups were compared: heat and cold cured acrylic resins, CAD/CAM milled PMMA, 3D‐printed PMMA (via FDM), and 3D‐printed methacrylate resin (via stereolithography, SLA). All groups were subjected to mechanical testing (flexural strength, impact strength, and hardness), water sorption and solubility tests, a tooth bonding test, microbiological assessment, and accuracy of fit measurements. The performance of sample groups was referred to ISO 20795‐1 and ISO/TS 19736. The data was analyzed using one‐way ANOVA.ResultsSamples manufactured using FDM performed within ISO specifications for mechanical testing, water sorption, and solubility tests. However, the FDM group failed to achieve the ISO requirements for the tooth bonding test. FDM samples presented a rough surface finish which could ultimately encourage an undesirable high level of microbial adhesion. For accuracy of fit, FDM samples showed a lower degree of accuracy than existing materials.ConclusionsAlthough FDM samples were a cost‐effective option and were able to be quickly manufactured in a reproducible manner, the results demonstrated that current recommended testing regimes for conventionally manufactured denture‐based polymers are not directly applicable to additive‐manufactured denture base polymers. Therefore, new standards should be developed to ensure the correct implementation of additive manufacturing techniques within denture‐based fabrication workflow.
Fabrication and characterisation of random and aligned electrospun scaffolds to investigate hypothalamic stem/progenitor cell behaviour Selina Beal, Iain Stewart, Paul Hatton, Marysia Placzek, Ilida Ortega Engineered Regeneration, 2024 Tanycytes are stem/progenitor cells that reside in the hypothalamus of the adult vertebrate brain. Tanycytes can be cultured as free-floating neurospheres in vitro but tend to spontaneously differentiate over time. Here we asked whether morphological cues provided by engineered polymer scaffolds can modify spontaneous differentiation. Tanycyte-derived neurospheres were cultured on electrospun scaffolds, prepared with either random or aligned fiber morphologies. Cells dispersed widely on the scaffolds, and - on aligned scaffolds - were highly organized, orientated parallel to the fibers. Immunocytochemical analysis showed that cells cultured on aligned scaffolds showed significantly greater expression of the neural stem/progenitor cell marker, NrCAM and reduced expression of differentiated cell markers in comparison to those cultured on random scaffolds. Together this shows that tanycytes respond to local engineered cues, and that a morphologically constrained environment can better maintain tanycytes as stem cells. The aligned scaffold culture system provides a powerful tool to better investigate this novel stem/progenitor cell population.
Enhanced Antibacterial Ability of Electrospun PCL Scaffolds Incorporating ZnO Nanowires Jingjing Tian, Thomas E. Paterson, Jingjia Zhang, Yingxing Li, Han Ouyang, Ilida Ortega Asencio, Paul V. Hatton, Yu Zhao, Zhou Li International Journal of Molecular Sciences, 2023 The infection of implanted biomaterial scaffolds presents a major challenge. Existing therapeutic solutions, such as antibiotic treatment and silver nanoparticle-containing scaffolds are becoming increasingly impractical because of the growth of antibiotic resistance and the toxicity of silver nanoparticles. We present here a novel concept to overcome these limitations, an electrospun polycaprolactone (PCL) scaffold functionalised with zinc oxide nanowires (ZnO NWs). This study assessed the antibacterial capabilities and biocompatibility of PCL/ZnO scaffolds. The fabricated scaffolds were characterised by SEM and EDX, which showed that the ZnO NWs were successfully incorporated and distributed in the electrospun PCL scaffolds. The antibacterial properties were investigated by co-culturing PCL/ZnO scaffolds with Staphylococcus aureus. Bacterial colonisation was reduced to 51.3% compared to a PCL-only scaffold. The biocompatibility of the PCL/ZnO scaffolds was assessed by culturing them with HaCaT cells. The PCL scaffolds exhibited no changes in cell metabolic activity with the addition of the ZnO nanowires. The antibacterial and biocompatibility properties make PCL/ZnO a good choice for implanted scaffolds, and this work lays a foundation for ZnO NWs-infused PCL scaffolds in the potential clinical application of tissue engineering.
Guided Tissue and Bone Regeneration Membranes: A Review of Biomaterials and Techniques for Periodontal Treatments Ali Alqahtani, Robert Moorehead, Ilida Ortega Asencio Polymers, 2023 This comprehensive review provides an in-depth analysis of the use of biomaterials in the processes of guided tissue and bone regeneration, and their indispensable role in dental therapeutic interventions. These interventions serve the critical function of restoring both structural integrity and functionality to the dentition that has been lost or damaged. The basis for this review is laid through the exploration of various relevant scientific databases such as Scopus, PubMed, Web of science and MEDLINE. From a meticulous selection, relevant literature was chosen. This review commences by examining the different types of membranes used in guided bone regeneration procedures and the spectrum of biomaterials employed in these operations. It then explores the manufacturing technologies for the scaffold, delving into their significant impact on tissue and bone regenerations. At the core of this review is the method of guided bone regeneration, which is a crucial technique for counteracting bone loss induced by tooth extraction or periodontal disease. The discussion advances by underscoring the latest innovations and strategies in the field of tissue regeneration. One key observation is the critical role that membranes play in guided reconstruction; they serve as a barrier, preventing the entry of non-ossifying cells, thereby promoting the successful growth and regeneration of bone and tissue. By reviewing the existing literature on biomaterials, membranes, and scaffold manufacturing technologies, this paper illustrates the vast potential for innovation and growth within the field of dental therapeutic interventions, particularly in guided tissue and bone regeneration.
Reduced Fibroblast Activation on Electrospun Polycaprolactone Scaffolds Joe P. Woodley, Daniel W. Lambert, Ilida Ortega Asencio Bioengineering, 2023 In vivo, quiescent fibroblasts reside in three-dimensional connective tissues and are activated in response to tissue injury before proliferating rapidly and becoming migratory and contractile myofibroblasts. When deregulated, chronic activation drives fibrotic disease. Fibroblasts cultured on stiff 2D surfaces display a partially activated phenotype, whilst many 3D environments limit fibroblast activation. Cell mechanotransduction, spreading, polarity, and integrin expression are controlled by material mechanical properties and micro-architecture. Between 3D culture systems, these features are highly variable, and the challenge of controlling individual properties without altering others has led to an inconsistent picture of fibroblast behaviour. Electrospinning offers greater control of mechanical properties and microarchitecture making it a valuable model to study fibroblast activation behaviour in vitro. Here, we present a comprehensive characterisation of the activation traits of human oral fibroblasts grown on a microfibrous scaffold composed of electrospun polycaprolactone. After over 7 days in the culture, we observed a reduction in proliferation rates compared to cells cultured in 2D, with low KI67 expression and no evidence of cellular senescence. A-SMA mRNA levels fell, and the expression of ECM protein-coding genes also decreased. Electrospun fibrous scaffolds, therefore, represent a tuneable platform to investigate the mechanisms of fibroblast activation and their roles in fibrotic disease.
Hydrophobicity of the biofunctionalized scaffolds for bone tissue engineering application in Dentistry Ridhayani Hatta, Beatriz JC. Monteiro, Ílida O. Asencio Journal of Dentomaxillofacial Science, 2023 Objective: This study aimed to characterize the hydrophobicity of the functionalized scaffolds for bone tissue engineering applications in Dentistry. Materials and Methods: This experimental study was conducted in the Tissue Engineering Laboratory of The University of Sheffield. The scaffolds were polycaprolactone (PCL) and functionalized using heparin, divided into five groups of prepared electrospun scaffolds. i.e., 1) Fully coated heparin, 2) Random drops of heparin, 3) Organized drops of heparin, 4) Stamping-micropockets with heparin, 5) PCL scaffold only (Control). Hydrophobicity was characterized by measuring the contact angle of distilled water drops on the scaffolds. One-way ANOVA was used as a data analysis test, with p<0.05. Result: The mean contact angle of each group was 63.33, 63.83, 63.33, 73.00, and 64.58, respectively. There was no group of scaffolds categorized as hydrophobics and no statistically significant difference among and within groups. Conclusion: The functionalized scaffolds were mostly un-hydrophobic, being a deliberation of their biocompatibility and role in bone tissue engineering application in dentistry.
Understanding Fibroblast Behavior in 3D Biomaterials Joe P. Woodley, Daniel W. Lambert, Ilida Ortega Asencio Tissue Engineering Part B Reviews, 2022 Traditional monolayer culture fails to fully recapitulate the in vivo environment of connective tissue cells such as the fibroblast. When cultured on stiff two-dimensional plastic, fibroblasts become highly proliferative forming broad lamellipodia and stress fibres. Conversely, in different 3D culture systems fibroblasts have displayed a diverse array of features; from an 'activated' phenotype like that observed in 2D cultures and by myofibroblasts, to a quiescent state that likely better represents in vivo fibroblasts at rest. Today, a plethora of microfabrication techniques have made 3D culture commonplace, for both tissue engineering purposes and in the study of basic biological interactions. However, establishing the in vivo mimetic credentials of different biomimetic materials is not always straightforward, particularly in the context of fibroblast responses. Fibroblast behaviour is governed by the complex interplay of biological features such as integrin binding sites, material mechanical properties which influence cellular mechanotransduction and microarchitectural features like pore and fibre size as well as chemical cues. Furthermore, fibroblasts are a heterogeneous group of cells with specific phenotypic traits dependent on their tissue of origin. These features have made understanding the influence of biomaterials on fibroblast behaviour a challenging task. Here we present a review of the strategies used to investigate fibroblast behaviour with a focus on the material properties that influence fibroblast activation, a process which becomes pathological in fibrotic diseases and certain cancers.
The Use of Cerium Compounds as Antimicrobials for Biomedical Applications Emilia Barker, Joanna Shepherd, Ilida Ortega Asencio Molecules, 2022 Cerium and its derivatives have been used as remedies for wounds since the early 20th century. Cerium nitrate has attracted most attention in the treatment of deep burns, followed later by reports of its antimicrobial properties. Its ability to mimic and replace calcium is presumed to be a major mechanism of its beneficial action. However, despite some encouraging results, the overall data are somewhat confusing with seemingly the same compounds yielding opposing results. Despite this, cerium nitrate is currently used in wound treatment in combination with silver sulfadiazine as Flammacérium. Cerium oxide, especially in nanoparticle form (Nanoceria), has lately captured much interest due to its antibacterial properties mediated via oxidative stress, leading to an increase of published reports. The properties of Nanoceria depend on the synthesis method, their shape and size. Recently, the green synthesis route has gained a lot of interest as an alternative environmentally friendly method, resulting in production of effective antimicrobial and antifungal nanoparticles. Unfortunately, as is the case with antibiotics, emerging bacterial resistance against cerium-derived nanoparticles is a growing concern, especially in the case of bacterial biofilm. However, diverse strategies resulting from better understanding of the biology of cerium are promising. The aim of this paper is to present the progress to date in the use of cerium compounds as antimicrobials in clinical applications (in particular wound healing) and to provide an overview of the mechanisms of action of cerium at both the cellular and molecular level.
Demonstrating the Potential of Using Bio-Based Sustainable Polyester Blends for Bone Tissue Engineering Applications David H. Ramos-Rodriguez, Samand Pashneh-Tala, Amanpreet Kaur Bains, Robert D. Moorehead, Nikolaos Kassos, Adrian L. Kelly, Thomas E. Paterson, C. Amnael Orozco-Diaz, Andrew A. Gill, Ilida Ortega Asencio Bioengineering, 2022 Healthcare applications are known to have a considerable environmental impact and the use of bio-based polymers has emerged as a powerful approach to reduce the carbon footprint in the sector. This research aims to explore the suitability of using a new sustainable polyester blend (Floreon™) as a scaffold directed to aid in musculoskeletal applications. Musculoskeletal problems arise from a wide range of diseases and injuries related to bones and joints. Specifically, bone injuries may result from trauma, cancer, or long-term infections and they are currently considered a major global problem in both developed and developing countries. In this work we have manufactured a series of 3D-printed constructs from a novel biopolymer blend using fused deposition modelling (FDM), and we have modified these materials using a bioceramic (wollastonite, 15% w/w). We have evaluated their performance in vitro using human dermal fibroblasts and rat mesenchymal stromal cells. The new sustainable blend is biocompatible, showing no differences in cell metabolic activity when compared to PLA controls for periods 1–18 days. FloreonTM blend has proven to be a promising material to be used in bone tissue regeneration as it shows an impact strength in the same range of that shown by native bone (just under 10 kJ/m2) and supports an improvement in osteogenic activity when modified with wollastonite.
An 'off-the shelf' synthetic membrane to simplify regeneration of damaged corneas Farshid Sefat, Ilida Ortega, Robert McKean, Pallavi Deshpande, Charanya Ramachandran, Christopher J Hill, Svetomir B Tzokov, Frederik Claeyssens, Virender S Sangwan, Anthony J Ryan, Sheila MacNeil Middle East Conference on Biomedical Engineering Mecbme, 2014
Development of a microfabricated outer ring for corneal repair European Cells and Materials, 2011
Microstructuring of photocurable biomaterials with applications in neuronal repair European Cells and Materials, 2011
Direct laser writing of polylactide 3D scaffolds V. Melissinaki, A.A. Gill, I. Ortega, M. Vamvakaki, A. Ranella, C. Fotakis, M. Farsari, F. Claeyssens 2011 Conference on Lasers and Electro Optics Europe and 12th European Quantum Electronics Conference CLEO Europe Eqec 2011, 2011
