Exploiting biomaterial approaches to manufacture an artificial trabecular meshwork: A progress report

Glaucoma is the second leading cause of irreversible blindness worldwide. Glaucoma is a progressive optic neuropathy in which permanent loss of peripheral vision results from neurodegeneration in the optic nerve head. The trabecular meshwork is responsible for regulating intraocular pressure, which to date, is the only modifiable risk factor associated with the development of glaucoma. Lowering intraocular pressure reduces glaucoma progression and current surgical approaches for glaucoma attempt to reduce outflow resistance through the trabecular meshwork. Many surgical approaches use minimally invasive glaucoma surgeries (MIGS) to control glaucoma. In this progress report, biomaterials currently employed to treat glaucoma, such as MIGS, and the issues associated with them are described. The report also discusses innovative biofabrication approaches that aim to revolutionise glaucoma treatment through tissue engineering and regenerative medicine (TERM). At present, there are very few applications targeted towards TM engineering in vivo, with a great proportion of these biomaterial structures being developed for in vitro model use. This is a consequence of the many anatomical and physiological attributes that must be considered when designing a TERM device for microscopic tissues, such as the trabecular meshwork. Ongoing advancements in TERM research from multi-disciplinary teams should lead to the development of a state-of-the-art device to restore trabecular meshwork function and provide a bio-engineering solution to improve patient outcomes

Effect of Polymer Demixed Nanotopographies on Bacterial Adhesion and Biofilm Formation

As the current global threat of antimicrobial resistance (AMR) persists, developing alternatives to antibiotics that are less susceptible to resistance is becoming an urgent necessity. Recent advances in biomaterials have allowed for the development and fabrication of materials with discrete surface nanotopographies that can deter bacteria from adhering to their surface. Using binary polymer blends of polystyrene (PS), poly(methyl methacrylate) (PMMA) and polycaprolactone (PCL) and varying their relative concentrations, PS/PCL, PS/PMMA and PCL/PMMA polymer demixed thin films were developed with nanoisland, nanoribbon and nanopit topographies. In the PS/PCL system, PS segregates to the air-polymer interface, with the lower solubility PCL preferring the substrate-polymer interface. In the PS/PMMA and PCL/PMMA systems, PMMA prefers the air-polymer interface due to its greater solubility and lower surface energy. The anti-adhesion efficacy of the demixed films were tested against Pseudomonas aeruginosa (PA14). PS/PCL and PCL/PMMA demixed films showed a significant reduction in cell counts adhered on their surfaces compared to pure polymer control films, while no reduction was observed in the counts adhered on PS/PMMA demixed films. While the specific morphology did not affect the adhesion, a relationship between bacterial cell and topographical surface feature size was apparent. If the surface feature was smaller than the cell, then an anti-adhesion effect was observed; if the surface feature was larger than the cell, then the bacteria preferred to adhere. View Full-Tex

Microcapsules Prepared via Pickering Emulsion Polymerization for Multifunctional Coatings

Micro/nanocontainer-based self-healing coatings have achieved enormous interest in scientific community during the last decade. However, the search for multifunctional micro/nanocontainers still has research challenge, especially for the micro/nanocontainers with dual functionality (both anticorrosion and antimicrobial). Here, a novel type of microcapsules with antimicrobial shell and anticorrosion core was prepared by the Pickering emulsion polymerization technique. Dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (QC18) and linseed oil were encapsulated as the antimicrobial and the anticorrosion agents, respectively. The results of local electrochemical impedance spectroscopy (LEIS) at 10 Hz demonstrated corrosion suppression in the scratched area of coatings doped with multifunctional microcapsules. Additionally, the QC18modified microcapsules exhibited high antibacterial performance, showing over 90 % antimicrobial efficacy against gram-positive bacteria. This type of dual-functional coating might guide future design of micro/nanocontainer-based self-healing paint formulations

Surface Modification of Medically Relevent Polymers using Atmospheric Pressure Plasma Processing

The nature of a biomaterial surface will influence interactions that will occur thereon. specifically, the chemical composition and topography will dictate the availability of sites of reactivity thereby determining the interfacial response. At the biological level, it is this surface mediated response that indicates the biocompatibility of the material. Hence, understanding and controlling the causative elements of the interfacial response will allow for the engineering of specific cell-biomaterial interactions.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The Role of Enamel Proteins in Protecting Mature Human Enamel Against Acidic Environments: A Double Layer Force Spectroscopy Study

Characterisation of the electrostatic properties of dental enamel is important for understanding the interfacial processes that occur on a tooth surface and how these relate to the natural ability of our teeth to withstand chemical attack from the acids in many soft drinks. Whereas, the role of the mineral component of the tooth enamel in providing this resistance to acid erosion has been studied extensively, the influence of proteins that are also present within the structure is not well understood. In this paper, we report for the first time the use of double-layer force spectroscopy to directly measure electrostatic forces on as received and hydrazine-treated (deproteinated) enamel surfaces in solutions with different pH to determine how the enamel proteins influence acid erosion surface potential and surface charge of human dental enamel. The deproteination of the treated samples was confirmed by the loss of the amide bands (~1,300–1,700 cm(−1)) in the FTIR spectrum of the sample. The force characteristics observed were found to agree with the theory of electrical double layer interaction under the assumption of constant potential and allowed the surface charge per unit area to be determined for the two enamel surfaces. The values and, importantly, the sign of these adsorbed surface charges indicates that the protein content of dental enamel contributes significantly to the electrostatic double layer formation near the tooth surface and in doing so can buffer the apatite crystals against acid attack. Moreover, the electrostatic interactions within this layer are a driving factor for the mineral transfer from the tooth surface and the initial salivary pellicle formation

Melt electro-written scaffolds with box-architecture support orthogonally oriented collagen

Melt electro-writing (MEW) is a state-of-the-art technique that supports fabrication of 3D, precisely controlled and reproducible fiber structures. A standard MEW scaffold design is a box-structure, where a repeat layer of 90 boxes is produced from a single fiber. In 3D form (i.e. multiple layers), this structure has the potential to mimic orthogonal arrangements of collagen, as observed in the corneal stroma. In this study, we determined the response of human primary corneal stromal cells and their deposited fibrillar collagen (detected using a CNA35 probe) following six weeks in vitro culture on these box-structures made from poly(-caprolactone) (PCL). Comparison was also made to glass substrates (topography-free) and electrospun PCL fibers (aligned topography). Cell orientation and collagen deposition were non-uniform on glass substrates. Electrospun scaffolds supported an excellent parallel arrangement of cells and deposited collagen to the underlying architecture of aligned fibers, but there was no evidence of bidirectional collagen. In contrast, MEW scaffolds encouraged the formation of a dense, interconnected cellular network and deposited fibrillar collagen layers with a distinct orthogonal-arrangement. Collagen fibrils were particularly dominant through the middle layers of the MEW scaffolds' total thickness and closer examination revealed these fibrils to be concentrated within the pores' central regions. With the demand for donor corneas far exceeding the supply - leaving many with visual impairment - the application of MEW as a potential technique to recreate the corneal stroma with spontaneous, bidirectional collagen organization warrants further study. </p

Antimicrobial nitric oxide releasing contact lens gels for the treatment of microbial keratitis.

Microbial keratitis is a serious sight threatening infection affecting approximately two million individuals worldwide annually. Whilst antibiotic eye drops remain the gold standard treatment for these infections, the significant problems associated with eye drop drug delivery and the alarming rise in antimicrobial resistance has meant that there is an urgent need to develop alternative treatments. In this work, a nitric oxide releasing contact lens gel displaying broad spectrum antimicrobial activity against two of the most common causative pathogens of bacterial keratitis is described. The contact lens gel is comprised of poly-ɛ-lysine (pɛK) functionalised with nitric oxide (NO) releasing diazeniumdiolate moieties which enables the controlled and sustained release of bactericidal concentrations of NO at physiological pH over a period of 15 hrs. Diazeniumdiolate functionalisation was confirmed by Fourier transform infrared (FTIR) and UV Vis spectroscopy and the concentration of NO released from the gels was determined by chemiluminescence. The bactericidal efficacy of the gels against Pseudomonas aeruginosa and Staphylococcus aureus was ascertained and between 1 and 4 log reductions in bacterial populations were observed over 24 hrs. Additional cell cytotoxicity studies with human corneal epithelial cells (HCE-T) also demonstrated that the contact lens gels were not cytotoxic suggesting that the developed technology could be a viable alternative treatment for bacterial keratitis