Scaffold porosity is a critical factor in replicating the complex in vivo microenvironment, directly influencing cellular interactions, migration, nutrient transfer, vascularization, and the formation of functional tissues. For optimal tissue formation, scaffold design must account for various parameters, including material composition, morphology, mechanical properties, and cellular compatibility. This review highlights the importance of interconnected porosity and pore size, emphasizing their impact on cellular behavior and tissue formation across several tissue engineering domains, such as skin, bone, cardiovascular, and lung tissues. Specific pore size ranges enhance scaffold functionality for different tissues: small pores (∼1–2 µm) aid epidermal cell attachment in skin regeneration, moderate pores (∼2–12 µm) support dermal migration, and larger pores (∼40–100 µm) facilitate vascular structures. For bone tissue engineering, multi-layered scaffolds with smaller pores (50–100 µm) foster cell attachment, while larger pores (200–400 µm) enhance nutrient diffusion and angiogenesis. Cardiovascular and lung tissues benefit from moderate pore sizes (∼25–60 µm) to balance cell integration and nutrient diffusion. By addressing critical design challenges and optimizing pore size distributions, this review provides insights into scaffold innovations, ultimately advancing tissue regeneration strategies.

The collagenous capsule formed around an implant will ultimately determine the nature of its in vivo fate. To provide a better understanding of how surface modifications can alter the collagen orientation and composition in the fibrotic capsule, we used second harmonic generation (SHG) microscopy to evaluate collagen organization and structure generated in mice subcutaneously injected with chemically functionalized polystyrene particles. SHG is sensitive to the orientation of a molecule, making it a powerful tool for measuring the alignment of collagen fibers. Additionally, SHG arises from the second order susceptibility of the interrogated molecule in response to the electric field. Variation in these tensor components distinguishes different molecular sources of SHG, providing collagen type specificity. Here, we demonstrated the ability of SHG to differentiate collagen type I and type III quantitatively and used this method to examine fibrous capsules of implanted polystyrene particles. Data presented in this work shows a wide range of collagen fiber orientations and collagen compositions in response to surface functionalized polystyrene particles. Dimethylamino functionalized particles were able to form a thin collagenous matrix resembling healthy skin. These findings have the potential to improve the fundamental understanding of how material properties influence collagen organization and composition quantitatively.

We present a low-cost, handheld plastic optical fiber (POF) sensor for hydrogen sulfide (H₂S) detection integrated onto a smartphone. The sensor uses smartphone flashlight as a source and camera as a pixel-based intensity detector. The POF is interconnected to the smartphone with a 3-D-printed connector on both source/detector sides. The sensing mechanism is embedded in the fiber link, making the system an all-fiber smartphone architecture. A mobile application handles data acquisition on the Android operative system. The sensor is functionalized for H₂S detection through silver deposition on the POF outer surface. Experiments demonstrate the feasibility of the sensor system as the presence of H₂S is successfully measured through an increase of optical losses through the POF link. This cost-effective, scalable, and compact sensor is promising for application in environmental sensing.

Bone fractures are widespread, especially in the elderly population and people involved in extensive physical activity (e.g., sportsmen, military personnel, and heavy load physical labor force), and their impact is pervasive. From an individual’s perspective, a fracture negatively affects the physical and mental health, whereas complicated cases such as hip fractures increase can lead to the permanent disability and increased the risk of death. Direct and indirect costs of the fracture care can be high. According to the report on Osteoporosis in the European Union, in 2010 care expenditures of the healthcare systems for the fragility fractures were €37 billion.¹