Shantanu Pradhan

The vital role of structurally and functionally stable vasculature in engineered tissues is well-established in regenerative medicine. Large-volume, natural, and synthetic tissue constructs require a high degree of perfusion and nutrient diffusion to meet the physiological demands of the encapsulated cells. Additionally, cancer tissue models fabricated using various scaffolds and matrices also need to incorporate tumor-mimetic abnormal vasculature to study the influence of angiogenesis on tumor growth, progression, and anti-cancer drug delivery. In this chapter, prominent hydrogel-based matrices that have been developed for vascular tissue engineering as well as modeling of the tumor vasculature and angiogenesis are discussed. Various microenvironmental considerations (including biophysical and biochemical characteristics of the matrix) required for emulating vascular regeneration as well as tumor angiogenesis are described. A wide range of hydrogel-based models (including natural, synthetic and hybrid materials) and associated biofabrication strategies (spanning molecular design to macroscale materials processing) for creating vascularized scaffolds are elaborated. Overall, this chapter provides an overview to the reader on creation of engineered scaffolds for implementation in tissue vascularization and repair and in disease models for future applications in drug testing.

The vascular system is integral for maintaining organ-specific functions and homeostasis. Dysregulation in vascular architecture and function can lead to various chronic or acute disorders. Investigation of the role of the vascular system in health and disease has been accelerated through the development of tissue-engineered constructs and microphysiological on-chip platforms. These in vitro systems permit studies of biochemical regulation of vascular networks and parenchymal tissue and provide mechanistic insights into the biophysical and hemodynamic forces acting in organ-specific niches. Detailed understanding of these forces and the mechanotransductory pathways involved is necessary to develop preventative and therapeutic strategies targeting the vascular system. This review describes vascular structure and function, the role of hemodynamic forces in maintaining vascular homeostasis, and measurement approaches for cell and tissue level mechanical properties influencing vascular phenomena. State-of-the-art techniques for fabricating in vitro microvascular systems, with varying degrees of biological and engineering complexity, are summarized. Finally, the role of vascular mechanobiology in organ-specific niches and pathophysiological states, and efforts to recapitulate these events using in vitro microphysiological systems, are explored. It is hoped that this review will help readers appreciate the important, but understudied, role of vascular-parenchymal mechanotransduction in health and disease toward developing mechanotherapeutics for treatment strategies.

Targeted intracellular delivery of biomolecules and therapeutic cargo enables the controlled manipulation of cellular processes. Laser-based optoporation has emerged as a versatile, non-invasive technique that employs light-based transient physical disruption of the cell membrane and achieves high transfection efficiency with low cell damage. Testing of the delivery efficiency of optoporation-based techniques has been conducted on single cells in monolayers, but its applicability in three-dimensional (3D) cell clusters/spheroids has not been explored. Cancer cells grown as 3D tumor spheroids are widely used in anti-cancer drug screening and can be potentially employed for testing delivery efficiency. Towards this goal, we demonstrated the optoporation-based high-Throughput intracellular delivery of a model fluorescent cargo (propidium iodide, PI) within 3D SiHa human cervical cancer spheroids. To enable this technique, nano-spiked core-shell gold-coated polystyrene nanoparticles (ns-AuNPs) with a high surface-To-volume ratio were fabricated. ns-AuNPs exhibited high electric field enhancement and highly localized heating at an excitation wavelength of 680 nm. ns-AuNPs were co-incubated with cancer cells within hanging droplets to enable the rapid aggregation and assembly of spheroids. Nanosecond pulsed-laser excitation at the optimized values of laser fluence (45 mJ cm-2), pulse frequency (10 Hz), laser exposure time (30 s), and ns-AuNP concentration (5 × 1010 particles per ml) resulted in the successful delivery of PI dye into cancer cells. This technique ensured high delivery efficiency (89.6 2.8%) while maintaining high cellular viability (97.4 0.4%), thereby validating the applicability of this technique for intracellular delivery. The optoporation-based strategy can enable high-Throughput single cell manipulation, is scalable towards larger 3D tissue constructs, and may provide translational benefits for the delivery of anti-cancer therapeutics to tumors. This journal is

Milk adulteration is a major challenge faced by the dairy sector. Starch is a common milk adulterant with negative impact on consumer health. The major shortfalls in the present methods for detection and quantification of starch in milk are the higher limit of detection (LOD) and the need for additional chemical reagents. Hence, developing a chemical-free method with lower LOD for starch in milk is urgently required, especially in low- and middle-income countries. We propose a sessile drop evaporation-based approach to detect starch adulteration in milk. The influence of starch adulteration on the evaporative deposition patterns is studied using light microscopy as a function of dilution level (10–50%, v/v), starch type (potato and tapioca starches) and starch concentration (0.005–0.2%, w/v). The dried deposit patterns formed after drying drops of pristine and adulterated milk at 60 °C are dictated by the competing effects of outward capillary flow and inward Marangoni flows. Confocal Raman spectroscopy indicated the presence of fatty acids and other lipophilic constituents at the center, a combination of proteins and lipophilic constituents at the edge, and starch in regions close to the coffee stain, i.e., at the edge of the dried deposits. Higher level of water addition and lower level of starch adulteration resulted in the formation of coffee ring deposits with larger width. Surface profilometry indicated a decrease in the height of coffee-ring with increase in the concentration of both water and starch. The width and maximum height of edge deposits thus measured are proposed as the parameters to quantify starch concentration in milk. The proposed approach is effective in detecting starch concentration as low as 0.005% (w/v), as well as identifying the starch type, thereby facilitating facile, rapid, chemical-free, and in situ detection of starch adulteration in milk.