No abstract

Microfluidics is a flourishing field, enabling a wide range of biochemical and clinical applications such as cancer screening, micro-physiological system engineering, high-throughput drug testing, and point-of-care diagnostics. However, fabrication of microfluidic devices is often complicated, time consuming, and requires expensive equipment and sophisticated cleanroom facilities. Three-dimensional (3D) printing presents a promising alternative to traditional techniques such as lithography and PDMS-glass bonding, not only by enabling rapid design iterations in the development stage, but also by reducing the costs associated with institutional infrastructure, equipment installation, maintenance, and physical space. With the recent advancements in 3D printing technologies, highly complex microfluidic devices can be fabricated via single-step, rapid, and cost-effective protocols, making microfluidics more accessible to users. In this review, we discuss a broad range of approaches for the application of 3D printing technology to fabrication of micro-scale lab-on-a-chip devices.

No abstract

We provide a less conservative (compared with our previous results) lower bound on the horizon length for a stabilizing model predictive control algorithm where the terminal cost is not assumed to be a local control Lyapunov function. Our main additional assumption is that the value function is bounded by a linear function of a measure of the state uniformly in the horizon length.

No abstract

BackgroundThe latest generation of shoulder arthroplasty includes canal-sparing respectively stemless designs that have been developed to allow restoration of the glenohumeral center of rotation independently from the shaft, and to avoid stem-related complications. The stemless prosthesis design has also recently been introduced for use in reverse arthroplasty systems.MethodsWe systematically reviewed the literature for studies of currently available canal-sparing respectively stemless shoulder arthroplasty systems. From the identified series, we recorded the indications, outcome measures, and humeral-sided complications.ResultsWe identified 11 studies of canal-sparing respectively stemless anatomic shoulder arthroplasty implants, published between 2010 and 2016. These studies included 929 cases, and had a mean follow-up of 26 months (range, 6 to 72 months). The rates of humeral component-related complications ranged between 0 and 7.9 %. The studies reported only a few isolated cases of complications of the humeral component. Some arthroplasty systems are associated with radiological changes, but without any clinical relevance.ConclusionsAll of the published studies of canal-sparing respectively stemless shoulder arthroplasty reported promising clinical and radiological outcomes in short to midterm follow-up. Long-term studies are needed to demonstrate the long-term value of these kind of implants.

No abstract

Vascular grafts that can support total replacement and maintenance by the body of the injured vessel would improve outcomes of major surgical reconstructions. Building scaffolds using components of the native vessel can encourage biological recognition by native cells as well as mimic mechanical characteristics of the native vessel. Evidence is emerging that incorporating predetermined building-blocks into a tissue engineering scaffold may oversimplify the environment and ignore critical structures and binding sites essential to development at the implant. We propose the development of a 3D-printable and degradable hybrid scaffold by combining polyethylene glycol (PEG)acrylate and homogenized pericardium matrix (HPM) to achieve appropriate biological environment as well as structural support. It was hypothesized that incorporation of HPM into PEG hydrogels would affect modulus of the scaffold and that the modulus and biological component would reduce the inflammatory signals produced from arriving macrophages and nearby endothelial cells. HPM was found to provide a number of tissue specific structural proteins including collagen, fibronectin, and glycosaminoglycans. HPM and PEGacrylate formed a hybrid hydrogel with significantly distinct modulus depending on concentration of either component, which resulted in scaffolds with stiffness between 0.5 and 20 kPa. The formed hybrid hydrogel was confirmed through a reduction in primary amines post-cross-linking. Using these hybrid scaffolds, rat bone marrow derived macrophages developed an M2 phenotype in response to low amounts (0.03%, w/v) of HPM in culture but responded with inflammatory phenotypes to high concentrations (0.3%, w/v). When cultured together with endothelial cells, both M1 and M2 macrophages were detected, along with a combination of both inflammatory and healing cytokines. However, the expression of inflammatory cytokines TNFα and IL1β was significantly (p < 0.05) lower with hybrid hydrogels compared to single component PEG or HPM hydrogels. This reduction in inflammatory cytokines could impact the healing environment that persists at the implantation site. Finally, using this developed hybrid hydrogel, models of neonatal vasculature were manufactured using digital light projection (DLP) 3D printing. The structural control achieved with this novel biomaterial suggests a promising new tool in vascular graft development and research, with potential for complex structures for use in congenital heart defect reconstruction.