No abstract

The technology of organ-on-a-chip tries to mimic the complexity of native tissues in vitro.Important progress has been made recently in using this technology to study the gut with and without microbiota. These in vitro models can serve as an alternative to animal models for studying physiology, pathology, and pharmacology. While these models have greater physiological relevance compared to two-dimensional (2D) cell systems in vitro, endocrine and immunological functions in gut-on-a-chip models are still poorly represented. Furthermore, the construction of complex models, in which different cell types and structures interact, remains a challenge. Generally, gut-on-chip models have the potential to advance our understanding of the basic interactions found within the gut and lay the foundation for future applications in understanding pathophysiology, developing drugs, and personalizing medical treatments.

Skeletal muscle tissue engineering aims to fabricate tissue constructs to replace or restore diseased or injured skeletal muscle tissues in the body. Several biomaterials and microscale technologies have been used in muscle tissue engineering. However, it is still challenging to mimic the function and structure of the native muscle tissues. Three-dimensional (3D) bioprinting is a powerful tool to mimic the hierarchical structure of native tissues. Here, 3D bioprinting was used to fabricate tissue constructs using gelatin methacryloyl (GelMA)-alginate bioinks. Mechanical and rheological properties of GelMA-alginate hydrogels were characterized. C2C12 myoblasts at the density 8 × 106 cells/mL were used as the cell model. The effects of alginate concentration (0, 6, and 8% (w/v)) and crosslinking mechanism (UV crosslinking or ionic crosslinking with UV crosslinking) on printability, cell viability, proliferation, and differentiation of bioinks were studied. The results showed that 10% (w/v) GelMA-8% (w/v) alginate crosslinked using UV light and 0.1 M CaCl2 provided the optimum niche to induce muscle tissue formation compared to other hydrogel compositions. Furthermore, metabolic activity of cells in GelMA bioinks was improved by addition of oxygen-generating particles to the bioinks. It is hoped that such bioprinted muscle tissues may find wide applications in drug screening and tissue regeneration.

Understanding complex cell–cell interactions and physiological microenvironments is critical for the development of new therapies for treating human diseases. Current animal models fail to accurately predict success of therapeutic compounds and clinical treatments. Advances in biomaterials, engineering, and additive manufacturing have led to the development of printed tissues, lab-on-chip devices, and, more recently, organ-on-chip systems. These technologies have promising applications for the fabrication of more physiologically representative human tissues and can be used for high-throughput testing of human cells and organoids. These organ-on-chip systems can be fabricated with integrated fluidics to allow for the precise control and manipulation of cellular microenvironments with multiple cell types. Further control over these cellular environments can be achieved with bioprinting, allowing for three-dimensional (3D) printing of multiple materials and cell types to provide precisely controlled structures manufactured in a one-step process. As cell behavior is highly dependent on the physical and chemical properties of the environment, the behavior of cells in two-dimensional and 3D culture systems varies drastically. Providing devices that can support long-term cell culture and controlled stimulation of 3D culture systems will have a profound impact on the study of physiological processes and disease, as well as the development of new therapies. This review highlights recent advances in organ-on-chip systems and 3D bioprinting techniques for the development of in vitro physiological models.

The ability to monitor diseases, therapies, and their effects on the body is a critical component of modern care and personalized medicine. Real time monitoring can be achieved by analyzing body fluids or by applying sensors on, or alternatively, inside the body. Implantable sensors, however, must be removed. Second removal procedures lead to further tissue damage, which can be a problem in tissues such as those of the central nervous system. The use of biodegradable sensors alleviates these problems since they do not require removal procedures. Recent advances in material science made it possible for all sensor components to be biodegradable. Small size and power of implants, and the limited selection of materials are the main constraints determining the capabilities of the biodegradable device. Thus, the design will be always a challenge exploring a trade-off among these parameters. Despite of the encouraging results illustrating that biodegradable sensors can be as accurate and reliable as commercially available nondegradable ones, biodegradable implantable sensors are still in their infancy. Significant advances made in this area are critically reviewed in this paper, and future prospects are highlighted.

No abstract

Smart contact lenses have emerged as novel wearable devices. Due to their multifunctional biosensing capabilities and highly integrated performance, they provide a great platform for the diagnosis of eye diseases and the delivery of drugs. Herein, a brief history of the development of contact lenses is given. Then, the state‐of‐the‐art design and fabrication of smart contact lenses for biomedical applications, including contact lens materials, fabrication technologies, and integration, are presented. Furthermore, biosensors implemented in contact lenses to measure lactic acid, glucose, intraocular pressure, and other key metabolites in tears are highlighted. Applications of smart contact lenses in drug delivery are also described. These unique features make smart contact lenses promising diagnostic and treatment devices. Challenges and future opportunities for further applications of smart contact lenses in biomedicine are also discussed.

The demand for biomaterials with properties that provide sustained release of substances with pharmacological interest is constant. One candidate for applications in this area is the Natural Rubber Latex (NRL) extracted from the rubber tree Hevea brasiliensis. Recent studies indicate the NRL as a matrix for sustained release, showing promising results for biomedical applications such as: can stimulate natural angiogenesis and is capable of adhering cells on its surface, promoting the replacement and regeneration of tissue. So, the NRL is an excellent candidate to propitiate the sustained release of peptides of pharmacological interest such as oxytocin, a hormonal peptide which has the function to promote uterine muscle contractions and reduce bleeding during childbirth, and stimulate the release of breast milk. Results demonstrated that 90 lg mL-1 (45 %) of the incorporated peptide in Natural Rubber Latex Biomedical (NRLb) functionalized membranes was released at 10 h in phosphate-buffered saline (PBS) solution. Swelling kinetics assay showed that the NRLb membranes are able to absorb over a period of 16 h up to 1.08 grams of water per grams of membrane. Scanning electron microscopy showed that the peptide was adsorbed on the surface and within NRLb membrane. Fourier transform infrared and Derivative Thermo-gravimetric analysis indicated that oxytocin did not interacted chemically with the membrane. Furthermore, hemolysis of erythrocytes, quantified spectrophotometrically using materials (Oxytocin, NRLb, and NRLb ? Oxytocin) showed no hemolytic effects up to 100 lg mL-1 (compounds and mixtures), indicating no detectable disturbance of the red blood cell membranes. Based on these results it was possible to conclude that the NRLb has shown effectiveness as a model in the release of peptides with pharmacological interest.