A review of air filtration technologies for sustainable and healthy building ventilation

Urbanization increased population density in cities and consequently leads to severe indoor air pollution. As a result of these trends, the issue of sustainable and healthy indoor environment has received increasing attention. Various air filtration techniques have been adopted to optimize indoor air quality. Air filtration technique can remove air pollutants and effectively alleviate the deterioration of indoor air quality. This paper presents a comprehensive review on the synergistic effect of different air purification technologies, air filtration theory, materials and standards. It evaluated different air filtration technologies by considering factors such as air quality improvement, filtering performance, energy and economic behaviour, thermal comfort and acoustic impact. Current research development of air filtration technologies along with their advantages, limitations and challenges are discussed. This paper aims to drive the future of air filtration technology research and development in achieving sustainable and healthy building ventilation

The Role of HIF-1α in Bone Regeneration: A New Direction and Challenge in Bone Tissue Engineering

The process of repairing significant bone defects requires the recruitment of a considerable number of cells for osteogenesis-related activities, which implies the consumption of a substantial amount of oxygen and nutrients. Therefore, the limited supply of nutrients and oxygen at the defect site is a vital constraint that affects the regenerative effect, which is closely related to the degree of a well-established vascular network. Hypoxia-inducible factor (HIF-1α), which is an essential transcription factor activated in hypoxic environments, plays a vital role in vascular network construction. HIF-1α, which plays a central role in regulating cartilage and bone formation, induces vascular invasion and differentiation of osteoprogenitor cells to promote and maintain extracellular matrix production by mediating the adaptive response of cells to changes in oxygen levels. However, the application of HIF-1α in bone tissue engineering is still controversial. As such, clarifying the function of HIF-1α in regulating the bone regeneration process is one of the urgent issues that need to be addressed. This review provides insight into the mechanisms of HIF-1α action in bone regeneration and related recent advances. It also describes current strategies for applying hypoxia induction and hypoxia mimicry in bone tissue engineering, providing theoretical support for the use of HIF-1α in establishing a novel and feasible bone repair strategy in clinical settings

A Comprehensive Review on Silk Fibroin as a Persuasive Biomaterial for Bone Tissue Engineering

Bone tissue engineering (BTE) utilizes a special mix of scaffolds, cells, and bioactive factors to regulate the microenvironment of bone regeneration and form a three-dimensional bone simulation structure to regenerate bone tissue. Silk fibroin (SF) is perhaps the most encouraging material for BTE given its tunable mechanical properties, controllable biodegradability, and excellent biocompatibility. Numerous studies have confirmed the significance of SF for stimulating bone formation. In this review, we start by introducing the structure and characteristics of SF. After that, the immunological mechanism of SF for osteogenesis is summarized, and various forms of SF biomaterials and the latest development prospects of SF in BTE are emphatically introduced. Biomaterials based on SF have great potential in bone tissue engineering, and this review will serve as a resource for future design and research

Strontium-Incorporated Carbon Nitride Nanosheets Modulate Intracellular Tension for Reinforced Bone Regeneration

Strontium-containing agents have been demonstrated to elicit both bone anabolic and antiosteoporotic effects, showing great potential for the treatment of bone loss. However, an increased incidence of strontium-induced side effects restricts their clinical applications. Herein, oxidized carbon nitride nanosheets (CN) are delicately used to incorporate Sr2+ for the first time to achieve high osteogenic efficacy. The lamellar structure and enriched nitrogen species of CN provide them with a high surface area-to-volume ratio and abundant anchoring sites for Sr2+ incorporation. Importantly, Sr2+-incorporated CN (CNS) could synergistically promote osteoblast differentiation and bone regeneration at a single, very low Sr2+ dose. Mechanically, CNS could activate the FAK/RhoA signaling pathway to modulate the intracellular tension that stimulates osteoblasts differentiation. The present study will provide a new paradigm to enhance the efficacy of osteogenic metal ions by using lamellar nanocarriers