Publications by authors named "Derrick Yong"

Hyperspectral imaging (HSI) provides additional information compared to regular color imaging, making it valuable in areas such as biomedicine, materials inspection and food safety. However, HSI is challenging because of the large amount of data and long measurement times involved. Compressed sensing (CS) approaches to HSI address this, albeit subject to tradeoffs between image reconstruction accuracy, time and generalizability to different types of scenes.

View Article and Find Full Text PDF

Human mesenchymal stromal cells (hMSCs) have demonstrated, in various preclinical settings, consistent ability in promoting tissue healing and improving outcomes in animal disease models. However, translation from the preclinical model into clinical practice has proven to be considerably more difficult. One key challenge being the inability to perform in situ assessment of the hMSCs in continuous culture, where the accumulation of the senescent cells impairs the culture's viability, differentiation potential and ultimately leads to reduced therapeutic efficacies.

View Article and Find Full Text PDF

With the development in tissue engineering, cell transplantation, and genetic technologies, living cells have become an important therapeutic tool in clinical medical care. For various cell-based technologies including cell therapy and cell-based sensors in addition to fundamental studies on single-cell biology, the cytoprotection of individual living cells is a prerequisite to extend cell storage life or deliver cells from one place to another, resisting various external stresses. Nature has evolved a biological defense mechanism to preserve their species under unfavorable conditions by forming a hard and protective armor.

View Article and Find Full Text PDF

Patient-specific therapies require that cells be manufactured in multiple batches of small volumes, making it a challenge for conventional modes of quality control. The added complexity of inherent variability (even within batches) necessitates constant monitoring to ensure comparable end products. Hence, it is critical that new non-destructive modalities of cell monitoring be developed.

View Article and Find Full Text PDF

Regardless of their tissue of origin, multipotent mesenchymal stromal cells (MSCs) are commonly expanded in vitro for several population doublings to achieve a sufficient number of cells for therapy. Prolonged MSC expansion has been shown to result in phenotypical, morphological and gene expression changes in MSCs, which ultimately lead to the state of senescence. The presence of senescent cells in therapeutic MSC batches is undesirable because it reduces their viability, differentiation potential and trophic capabilities.

View Article and Find Full Text PDF

The notion of lasing with biologics has recently been realized and has rapidly developed with the collective objective of creating lasers in vivo. One major limitation of achieving this is the requirement of exogenous dyes and fluorescent materials. We thus investigate for the first time the possibility of lasing unlabelled cells, using just cell-endogenous fluorophores - the source of cell autofluorescence.

View Article and Find Full Text PDF

In this study, we investigated the inactivation efficacy of endospore-forming bacteria, Bacillus pumilus, irradiated by low-energy X-rays of different beam qualities. The different low-energy X-rays studied had cut-off energies of 50, 100 and 150 keV. Bacillus pumilus spores (in biological indicator strips) were irradiated at step doses between 6.

View Article and Find Full Text PDF

We demonstrate the first in-fiber light-induced bioactive biotin-functionalization via photobleaching fluorophore-conjugated biotin. Photobleaching the fluorophores generated free radicals that bind to the albumin-passivated inner surface of pure silica photonic crystal fiber. The subsequent attachment of dye-conjugated streptavidin to the bound biotin qualified the photo-immobilization process and demonstrated a potential for the construction of in-fiber macromolecular assemblies or multiplexes.

View Article and Find Full Text PDF

We report a simplified model for the computation of light-fluorescence interactions within photonic crystal fibers (PCFs). It involved the plotting of ray trajectories confined by total internal reflection within a geometrically simplified PCF core. This was followed by the calculation of absorption and fluorescence emission at each point of reflection, which were subsequently summed and averaged over all the launched rays.

View Article and Find Full Text PDF