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Microfluidic droplets formed in emulsions are used in a variety of analytical techniques and hold great potential for future scientific and commercial applications. Our experiments present a microdroplet generation and consistency monitoring system with laser optics excitation and detection. We also demonstrate the detection of cancer cells encapsulated within aqueous microdroplets in continuous oil phase flow. The custom setup analyzes each droplet with sub-millisecond signal resolution and single photon accuracy, and is compatible with process-monitoring methods. To demonstrate the consistency of microdroplet generation over time, we measure and examine the mean frequency of aqueous plug-shaped droplet (microplug) formation in oil phase, as well as the mean length and interval between consecutive droplets. Two-channel optical monitoring allows for the simultaneous and independent inspection of both microdroplet generation and identification of green fluorescent protein-labeled cancer cells within the droplets. A precise, quantitative approach as utilized in these experiments may be helpful in the development of microfluidic concepts that require exacting reproducibility and would benefit from automated consistency monitoring techniques.

Despite the constant expansion of the global alginate market and the emergence of a plethora of new brands to meet the rising demand, the literature remains insufficient for the selection and preparation of optimized microcapsules. In this study, the cell transplantation potentials of two commercial alginate brands (Sigma and FMC Biopolymers-PRONATAL) with different M/G ratios were compared in vitro. Different brands of alginates were crosslinked with increasing concentrations of calcium chloride (1.5%, 2%, and 3%w/v). Utilizing size/dimension measurements, compression, swelling, and degradation tests, scanning electron microscopy (SEM), and bright field (BF) imaging, the intrastructure of each experimental group was investigated. Moreover, the cell viability of HDF-encapsulated Ca-alginate microcapsules was evaluated. According to SEM and compression analysis, PROTANAL KF200 with a lower M/G ratio was found to be more rigid and robust. Due to the different proportions of MM and GG blocks, Sigma Ca-alginate microcapsules exhibited greater flexibility but lower hardness than PRONATAL KF200 microcapsules. However, there was no significant difference in cell viability between the alginate microcapsules. In future in vivo experiments, encouraging cell transplantation outcomes could be monitored by the choice of PROTANAL KF200 sodium alginate polymer for the microcapsule preparation.

We describe a strategy to construct three-dimensional (3D) containers with nanoporous walls by the self-assembly of lithographically patterned two-dimensional cruciforms with solder hinges. The first step involves fabricating two-dimensional (2D) cruciforms composed of six unlinked patterns: each pattern has an open window. The second step entails photolithographic patterning of solder hinges that connect the cruciform. The third step involves the deposition of polystyrene particles within the windows and the subsequent electrodeposition of metal in the voids between the polystyrene particles. Following the dissolution of the particles, the cruciforms are released from the substrate and heated above the melting point of the solder causing the cruciforms to spontaneously fold up into 3D cubic containers with nanoporous walls. We believe these 3D containers with nanoporous side walls are promising for molecular separations and cell-based therapies.

Alginate hydrogel fibers are receiving a great attention for tissue engineering applications. However, an important limitation of alginate is that it does not provide cell adhesion motifs. In this work, albumin was blended with alginate to improve the compatibility of alginate fibers with cells. Cell laden alginate/albumin fibers, potentially usable for skin regeneration, were obtained through a spinning process, by extruding an alginate/albumin solution containing cells into a calcium chloride solution. Cell laden pure alginate fibers were prepared for comparison. Plain alginate and alginate/albumin fibers were also produced. Morphological, mechanical and functional properties of the produced fibers were investigated. In addition, the ability of the fibers to release albumin and to support the viability and growth of A549 cells embedded into them was studied. Fibers with a uniform shape and an average diameter within the range 550–570$\mu$m were produced. The water content was $94.6\pm 0.4$% for alginate fibers, and $94.9\pm 0.3$% for alginate/albumin fibers. Stress–strain tests showed, up to a strain value of 20%, the same Young’s modulus for the produced fibers, regardless of the presence of albumin. Overall, obtained results demonstrated that morphology, size, hydrophilicity and mechanical properties were not affected by albumin. Albumin was gradually released over a period of 4 days, with a residual amount (13%) remaining into the fibers. Viability test was carried out on A549 cells, laden inside alginate and alginate/albumin fibers, to evaluate cell proliferation ability. A favorable effect of albumin on the loaded cells was evidenced by a faster kinetics of growth.