Search Results
Dehydroabietylamine-Based Cellulose Nanofibril Films: A New Class of Sustainable Biomaterials for Highly Efficient, Broad-Spectrum Antimicrobial Effects
The design of antimicrobial surfaces as integral parts of advanced biomaterials is nowadays a high research priority, as the accumulation of microorganisms on surfaces inflicts substantial costs on the health and industry sectors. At present, there is a growing interest in designing functional materials from polymers abundant in nature, such as cellulose, that combine sustainability with outstanding mechanical properties and economic production. There is also the need to find suitable replacements for antimicrobial silver-based agents due to environmental toxicity and spread of resistance to metal antimicrobials. Herein we report the unprecedented decoration of cellulose nanofibril (CNF) films with dehydroabietylamine 1 (CNF-CMC-1), to give an innovative contact-active surface active against Gram-positive and Gram-negative bacteria including the methicillin-resistant S. aureus MRSA14TK301, with low potential to spread resistance and good biocompatibility, all achieved with low surface coverage. CNF-CMC-1 was particularly effective against S. aureus ATCC12528, causing virtually complete reduction of the total cells from 10 5 colony forming units (CFU)/mL bacterial suspensions, after 24 h of contact. This gentle chemical modification of the surface of CNF fully retained the beneficial properties of the original film, including moisture buffering and strength, relevant in many potential applications. Our originally designed surface represents a new class of ecofriendly biomaterials that optimizes the performance of CNF by adding antimicrobial properties without the need for environmentally toxic silver. © Copyright 2019 American Chemical Society.
Microenvironments designed to support growth and function of neuronal cells
Strategies for neural tissue repair heavily depend on our ability to temporally reconstruct the natural cellular microenvironment of neural cells. Biomaterials play a fundamental role in this context, as they provide the mechanical support for cells to attach and migrate to the injury site, as well as fundamental signals for differentiation. This review describes how different cellular processes (attachment, proliferation, and (directional) migration and differentiation) have been supported by different material parameters, in vitro and in vivo. Although incipient guidelines for biomaterial design become visible, literature in the field remains rather phenomenological. As in other fields of tissue regeneration, progress will depend on more systematic studies on cell-materials response, better understanding on how cells behave and understand signals in their natural milieu from neurobiology studies, and the translation of this knowledge into engineered microenvironments for clinical use.
Biomineralization of Engineered Spider Silk Protein-Based Composite Materials for Bone Tissue Engineering
Materials based on biodegradable polyesters, such as poly(butylene terephthalate) (PBT) or poly(butylene terephthalate-co-poly(alkylene glycol) terephthalate) (PBTAT), have potential application as pro-regenerative scaffolds for bone tissue engineering. Herein, the preparation of films composed of PBT or PBTAT and an engineered spider silk protein, (eADF4(C16)), that displays multiple carboxylic acid moieties capable of binding calcium ions and facilitating their biomineralization with calcium carbonate or calcium phosphate is reported. Human mesenchymal stem cells cultured on films mineralized with calcium phosphate show enhanced levels of alkaline phosphatase activity suggesting that such composites have potential use for bone tissue engineering.
Optical biosensors based on silicon-on-insulator ring resonators: A review
Recent developments in optical biosensors based on integrated photonic devices are reviewed with a special emphasis on silicon-on-insulator ring resonators. The review is mainly devoted to the following aspects: (1) Principles of sensing mechanism, (2) sensor design, (3) biofunctionalization procedures for specific molecule detection and (4) system integration and measurement set-ups. The inherent challenges of implementing photonics-based biosensors to meet specific requirements of applications in medicine, food analysis, and environmental monitoring are discussed. © 2019 by the authors.
Effect of chemical solvents on the wetting behavior over time of femtosecond laser structured ti6al4v surfaces
The effect of chemical solvents on the wetting state of laser-structured surfaces over time is systematically examined in this paper. By using a 300-fs laser, nanostructures were generated on Ti6Al4V, subsequently cleaned in an ultrasonic bath with different solvents and stored in ambient air. The static contact angle showed significant differences for cleaning with various solvents, which, depending on the applied cleaning and time, amounted up to 100°. X-ray photoelectron spectroscopy analyses reveal that the cleaning of the laser-structured surfaces affects the surface chemistry and the aging behavior of the surfaces, even with highly volatile solvents. The effect of the chemical surface modification is particularly noticeable when using alcohols for cleaning, which, due to their OH groups, cause highly hydrophilic behavior of the surface after one day of storage. Over the course of 14 days, enrichment with organic groups from the atmosphere occurs on the surface, which leads to poorer wetting on almost every structured surface. In contrast, the cleaning in hexane leads to a fast saturation of the surface with long-chain carbon groups and thus to a time-independent hydrophobic behavior.
Nano-imaging confirms improved apatite precipitation for high phosphate/silicate ratio bioactive glasses
Bioactive glasses convert to a biomimetic apatite when in contact with physiological solutions; however, the number and type of phases precipitating depends on glass composition and reactivity. This process is typically followed by X-ray diffraction and infrared spectroscopy. Here, we visualise surface mineralisation in a series of sodium-free bioactive glasses, using transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDXS) and X-ray nano-computed tomography (nano-CT). In the glasses, the phosphate content was increased while adding stoichiometric amounts of calcium to maintain phosphate in an orthophosphate environment in the glass. Calcium fluoride was added to keep the melting temperature low. TEM brought to light the presence of phosphate clustering and nearly crystalline calcium fluoride environments in the glasses. A combination of analytical methods, including solid-state NMR, shows how with increasing phosphate content in the glass, precipitation of calcium fluoride during immersion is superseded by fluorapatite precipitation. Nano-CT gives insight into bioactive glass particle morphology after immersion, while TEM illustrates how compositional changes in the glass affect microstructure at a sub-micron to nanometre-level.