The ongoing race of biomedical applications has given momentum to the development of graphene quantum dots (GQDs). GQDs are zero-dimensional fluorescent carbon-nanomaterials, with a pronounced quantum confinement effect, and abundant edge states and functional groups. Despite their potential applications, mass-scale synthesis of single crystalline graphene quantum dots (GQDs) with high quantum yields derived via a direct green synthesis approach from bio-wastes is a major challenge. Hitherto, green extract (i.e. sugarcane molasses) driven single crystalline sulphur-doped GQDs (S-GQDs) with a longer decay time, high quantum yield, and excellent biocompatibility have remained unexplored in the bioimaging arena. At the same time, this agro-industrial waste has value in terms of both products and byproducts i.e. zero waste generation resulting in reduced human footprint on the environment. For the first time, we present a facile, large-scale, one-step, economical, template- and catalyst-free synthesis of sustainable, highly crystalline S-GQDs via a hydrothermal route from second generation (2G) bio-wastes. Mechanistic insight into the formation of S-GQDs from their precursor was obtained using powder X-ray diffraction patterns (PXRD). S-GQDs directly obtained from bio-wastes without surface passivation showed the highest quantum yield (QY) ∼ 47% obtained to date. The wide and symmetric emission spectrum of these S-GQDs is instrumental for sensitive detection as labelling nanoprobes. Moreover, their non-toxic behavior, in vitro and in vivo, has a future in quick point-of-care screening and real-time bioimaging. Thus, the as-synthesized bio-waste derived S-GQDs accomplished the purpose of an advanced environmentally friendly and sustainable material which is non-toxic, viable, safe, and cheap. This unprecedented work advances the synthesis of high-quality S-GQDs from bio-waste, which provides a breakthrough in the bioimaging field.

Progress in understanding kidney disease mechanisms and the development of targeted therapeutics have been limited by the lack of functional in vitro models that can closely recapitulate human physiological responses. Organ Chip (or organ-on-a-chip) microfluidic devices provide unique opportunities to overcome some of these challenges given their ability to model the structure and function of tissues and organs in vitro. Previously established organ chip models typically consist of heterogenous cell populations sourced from multiple donors, limiting their applications in patient-specific disease modeling and personalized medicine. In this study, we engineered a personalized glomerulus chip system reconstituted from human induced pluripotent stem (iPS) cell-derived vascular endothelial cells (ECs) and podocytes from a single patient. Our stem cell-derived kidney glomerulus chip successfully mimics the structure and some essential functions of the glomerular filtration barrier. We further modeled glomerular injury in our tissue chips by administering a clinically relevant dose of the chemotherapy drug Adriamycin. The drug disrupts the structural integrity of the endothelium and the podocyte tissue layers, leading to significant albuminuria as observed in patients with glomerulopathies. We anticipate that the personalized glomerulus chip model established in this report could help advance future studies of kidney disease mechanisms and the discovery of personalized therapies. Given the remarkable ability of human iPS cells to differentiate into almost any cell type, this work also provides a blueprint for the establishment of more personalized organ chip and ‘body-on-a-chip’ models in the future.

The slings and arrows of two-dimensional (2D) graphene and one-dimensional (1D) carbon nanotubes embody a high risk-to-benefit ratio, which is challenging for their biocompatibility. Herein, we report for the first time the synthesis of hydrogel nanotubes (HNTs) with ice helices as exotic nanostructures via free radical-mediated aqueous copolymerization. Extensive embryonic 2D polymer nanosheets were produced after 10 h of reaction which buckled out-of-plane into HNTs, inspired by the ancient art of origami. Water drawn into the hydrophobic hollow conduit freezes spontaneously, acting as an epicenter for the genesis of an ice helix trapped in a kinetically stable arrangement with regular periodicity, extending rational synthesis into the nanoscale regime. In this seminal work, the mechanism for the formation of ice helices inside the HNTs was delineated with the aid of transmission electron microscopy (TEM), X-ray diffraction patterns (XRD) and Raman spectroscopy. Endowed with unique biocompatibility, these HNTs aided the rapid establishment of wound barrier properties with concomitant cell proliferation guided by a provisional matrix mimicking the extracellular matrix niche. The HNTs support a permissive milieu for vascular sufficiency with well-proliferated fibroblasts at the wound bed.

Podocytes derived from human induced pluripotent stem (hiPS) cells are enabling studies of kidney development and disease. However, many of these studies are carried out in traditional tissue culture plates that do not accurately recapitulate the molecular and mechanical features necessary for modeling tissue- and organ-level functionalities. Overcoming these limitations requires the design and application of tunable biomaterial scaffolds. Silk fibroin is an attractive biomaterial due to its biocompatibility and versatility, which include its ability to form hydrogels, sponge-like scaffolds, and electrospun fibers and membranes appropriate for tissue engineering and biomedical applications. In this study, we show that hiPS cells can be differentiated into post-mitotic kidney glomerular podocytes on electrospun silk fibroin membranes functionalized with laminin. The resulting podocytes remain viable and express high levels of podocyte-specific markers consistent with the mature cellular phenotype. The resulting podocytes were propagated for at least two weeks, enabling secondary cell-based applications and analyses. This study demonstrates for the first time that electrospun silk fibroin membrane can serve as a supportive biocompatible platform for human podocyte differentiation and propagation. We anticipate that the results of this study will pave the way for the use of electrospun membranes and other biomimetic scaffolds for kidney tissue engineering, including the development of co-culture systems and organs-on-chips microphysiological devices.