Over the decades, researchers have strived to synthesize and modify nature-inspired biomaterials, with the primary aim to address the challenges of designing functional biomaterials for regenerative medicine and tissue engineering....

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The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p < 0.01) in cells per scaffold mass vs. AD constructs. Collagen was ∼31% greater (p < 0.01) on FDAD compared to AD scaffolds not evident in microscopy of microsphere surfaces. Alternatively, AD scaffolds demonstrated a superior threefold increase in compressive strength over FDAD (12 vs. 4 MPa) with minimal degradation. Inclusion of FD spheres within the FDAD scaffolds allowed increased cellular activity through improved seeding, proliferation, and extracellular matrix production (as collagen), although mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.

Hemorrhage is the leading cause of trauma-related deaths, in hospital and pre-hospital settings. Hemostasis is a complex mechanism that involves a cascade of clotting factors and proteins that result in the formation of a strong clot. In certain surgical and emergency situations, hemostatic agents are needed to achieve faster blood coagulation to prevent the patient from experiencing a severe hemorrhagic shock. Therefore, it is critical to consider appropriate materials and designs for hemostatic agents. Many materials have been fabricated as hemostatic agents, including synthetic and naturally derived polymers. However, compared to synthetic polymers, natural polymers or biopolymers, which include polysaccharides and polypeptides, have greater biocompatibility, biodegradability, and processibility. Thus, in this review, we focus on biopolymer-based hemostatic agents of different forms, such as powder, particles, sponges, and hydrogels. Finally, we discuss biopolymer-based hemostats currently in clinical trials and offer insight into next-generation hemostats for clinical translation.

Chitosan (CTS) is biocompatible, biodegradable, and can be formed into 3D porous structures for bone tissue engineering applications. Although studies have reported on the effects of molecular weight (MW) on CTS physicochemical properties, studies evaluating CTS biological property relationships often do not account for MW that confounds interpretation of study results. The aim of this study was to evaluate the effect of MW on CTS physicochemical and biological properties. CTS materials were treated for 6, 18, and 30 min by microwave irradiation to decrease MW without affecting deacetylation (DDA). Materials were evaluated for crystallinity using X-ray diffraction, thermal degradation using differential scanning calorimetry, water content, swelling ratio, and in vitro compatibility using Saos-2. Results showed that microwave treatments did not affect DDA but decreased MW and swelling ratio by 45.78% and 36.75%, respectively, after 30 min of microwave treatment. Microwave-treated CTS showed reduced or no crystalline peaks. Initial increase in exothermic peak temperatures with short (6 min) microwave treatment times were followed by a decrease with longer (18 and 30 min) treatment times. Cell growth over 7 days on samples was proportional to MW with the number of cells being 62% higher on CTS with the highest MW (3.71 ± 0.25 × 10(5) g/mol) when compared with the lower MW CTS (2.38 ± 0.12 × 10(5) g/mol). These results demonstrate the importance of MW of CTS to both its physicochemical characteristics and biological properties, providing researchers with another tool for the modulation and optimization of CTS for different biomedical applications.

Microphysiological systems (MPSs), also known as organ-on-a-chip models, aim to recapitulate the functional components of human tissues or organs in vitro. Over the last decade, with the advances in biomaterials,...

refers to a multicellular unit in the brain including cells of the cerebral vasculature and brain parenchyma. [2] As part of the NVU, the blood-brain barrier (BBB) acts as a physiological barrier at the interface between peripheral blood circulation and the central nervous system (CNS). The BBB is indispensable for the proper CNS function and regulation of CNS homeostasis; it controls the transport of substances between the CNS and the blood via various transport mechanisms. [3] The BBB also protects the brain from neurotoxic plasma components, certain chemicals, and pathogens. Functional and structural changes of the BBB are implicated in several neurological diseases and disorders, which have severely impacted individuals worldwide. For example, there are currently estimated to be about 5.7 million people living with Alzheimer's disease (AD), and the number is projected to reach 13.8 million by 2050. [4] Stroke is the second leading cause of death and the third most common cause of disability. [5] Glioblastoma multiforme (GBM), which accounts for almost 50% of all brain tumors (i.e., glioma), is relatively rare with a global incidence rate of 3.19 per 100 000 people; however, it has a devastatingly poor prognosis with a typical survival rate of 14-15 months rendering it a critical public health problem. [6] The human brain and central nervous system (CNS) present unique challenges in drug development for neurological diseases. One major obstacle is the blood-brain barrier (BBB), which hampers the effective delivery of therapeutic molecules into the brain while protecting it from blood-born neurotoxic substances and maintaining CNS homeostasis. For BBB research, traditional in vitro models rely upon Petri dishes or Transwell systems. However, these static models lack essential microenvironmental factors such as shear stress and proper cell-cell interactions. To this end, organ-on-a-chip (OoC) technology has emerged as a new in vitro modeling approach to better recapitulate the highly dynamic in vivo human brain microenvironment socalled the neural vascular unit (NVU). Such BBB-on-a-chip models have made substantial progress over the last decade, and concurrently there has been increasing interest in modeling various neurological diseases such as Alzheimer's disease and Parkinson's disease using OoC technology. In addition, with recent advances in other scientific technologies, several new opportunities to improve the BBB-on-a-chip platform via multidisciplinary approaches are available. In this review, an overview of the NVU and OoC technology is provided, recent progress and applications of BBB-on-a-chip for personalized medicine and drug discovery are discussed, and current challenges and future directions are delineated.The ORCID identification number(s) for the author(s) of this article can be found under

Hemorrhage is the leading cause of death following battlefield injuries. Although several hemostats are commercially available, they do not meet all the necessary requirements to stop bleeding in combat injuries....