Micro and nanocarriers Micro and nanoscale technologies Oral drug delivery Tissue models Oral administration is a pillar of the pharmaceutical industry and yet it remains challenging to administer hydrophilic therapeutics by the oral route. Smart and controlled oral drug delivery could bypass the physiological barriers that limit the oral delivery of these therapeutics. Micro-and nanoscale technologies, with an unprecedented ability to create, control, and measure micro-or nanoenvironments, have found tremendous applications in biology and medicine. In particular, significant advances have been made in using these technologies for oral drug delivery. In this review, we briefly describe biological barriers to oral drug delivery and micro and nanoscale fabrication technologies. Micro and nanoscale drug carriers fabricated using these technologies, including bioadhesives, microparticles, micropatches, and nanoparticles, are described. Other applications of micro and nanoscale technologies are discussed, including fabrication of devices and tissue engineering models to precisely control or assess oral drug delivery in vivo and in vitro, respectively. Strategies to advance translation of micro and nanotechnologies into clinical trials for oral drug delivery are mentioned. Finally, challenges and future prospects on further integration of micro and nanoscale technologies with oral drug delivery systems are highlighted.

Droplet-based microfluidic systems have been employed to manipulate discrete fluid volumes with immiscible phases. Creating the fluid droplets at microscale has led to a paradigm shift in mixing, sorting, encapsulation, sensing, and designing high throughput devices for biomedical applications. Droplet microfluidics has opened many opportunities in microparticle synthesis, molecular detection, diagnostics, drug delivery, and cell biology. In the present review, we first introduce standard methods for droplet generation (i.e., passive and active methods) and discuss the latest examples of emulsification and particle synthesis approaches enabled by microfluidic platforms. Then, the applications of droplet-based microfluidics in different biomedical applications are detailed. Finally, a general overview of the latest trends along with the perspectives and future potentials in the field are provided.

The exceptional chemical and physical properties of graphene oxide (GO) make it an attractive nanomaterial for biomedical applications, particularly in drug delivery. In this work we synthesized a novel, GO-based nanocarrier for the delivery of docetaxel (DTX), a potent hydrophobic chemotherapy drug. The GO was functionalized with transferrin (Tf)-poly(allylamine hydrochloride) (PAH), which provided targeted and specific accumulation to extracellular Tf receptors and stabilized GO in physiological solutions. Tf was conjugated to PAH via amide covalent linkages, and Tf-PAH coated the surface of DTX-loaded GO through electrostatic interactions. The morphology and structure of the resulting nanostructure, along with its surface modifications, were verified by use of Fourier transform infrared (FT-IR) and UV-vis spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM). DTX was loaded at a relatively high loading capacity of 37% and released in a pH-dependent and sustained manner under physiological conditions. The targeting efficiency and cytotoxicity of this drug delivery system were evaluated on MCF-7 breast cancer cells. Improved efficacy of targeted DTX-loaded nanocarrier was observed compared to nontargeted carrier and free DTX, especially at high drug concentrations. The Tf-PAH-functionalized GO nanocarrier is a promising candidate for targeted delivery and controlled release of DTX.

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Tissue reconstruction requires the utilization of multiple biomaterials and cell types to replicate the delicate and complex structure of native tissues. Various three-dimensional (3D) bioprinting techniques have been developed to fabricate customized tissue structures; however, there are still significant challenges, such as vascularization, mechanical stability of printed constructs, and fabrication of gradient structures to be addressed for the creation of biomimetic and complex tissue constructs. One approach to address these challenges is to develop multimaterial 3D bioprinting techniques that can integrate various types of biomaterials and bioprinting capabilities towards the fabrication of more complex structures. Notable examples include multi-nozzle, coaxial, and microfluidics-assisted multimaterial 3D bioprinting techniques. More advanced multimaterial 3D printing techniques are emerging, and new areas in this niche technology are rapidly evolving. In this review, we briefly introduce the basics of individual 3D bioprinting techniques and then discuss the multimaterial 3D printing techniques that can be developed based on combination of these techniques for the engineering of complex and biomimetic tissue constructs. We also discuss the perspectives and future directions to develop state-of-the-art multimaterial 3D bioprinting techniques for engineering tissues and organs.

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Graphene quantum dots (GQDs) have been emerging as next‐generation bioimaging agents because of their intrinsic strong fluorescence, photostability, aqueous stability, biocompatibility, and facile synthesis. In this work, GQDs are encapsulated in ferritin protein nanocages to develop multi‐functional nanoplatforms toward multi‐modal imaging and cancer therapy. Encapsulation of ultra‐small GQDs is expected to reduce their quick excretion from the body and increase their bioimaging efficiency. To expand the functionality of protein nanocages as multi‐modal imaging nanoprobes capable of both fluorescence and magnetic resonance imaging (MRI), GQDs and iron are encapsulated inside the core of AfFtn‐AA (an engineered ferritin nanocage derived from the archaeon Archaeoglobus fulgidus). The co‐encapsulation is achieved through an iron‐mediated, self‐assembly of ferritin dimers resulting in the formation of GQD–iron complex in the ferritin nanocages ((GQDs/Fe)AA). The (GQDs/Fe)AA shows high relaxivities in MRI and pH‐sensitive fluorescence with strong fluorescence at low pH values and on MDA‐MB‐231 cells. As an imaging agent and a drug nanocarrier, (GQDs/Fe)AA exhibits negligible cytotoxicity on the cells and a high loading capacity (35%) of doxorubicin. Taken together, the (GQDs/Fe)AA shows promising applications in cancer diagnosis and therapy as a pH‐responsive fluorophore, MRI agent, and drug nanocarrier.

A critical review of healthy and diseased in vitro models of the vascular system and in particular for atherosclerosis, aneurysm, and thrombosis.