Engineered hydrogels for brain tumor culture and therapy

Brain tumors’severity ranges from benign to highly aggressive and invasive.Bioengineering tools can assist in understanding the pathophysiology of these tumors from outside the body and facilitate development of suitable antitumoral treatments.Here,we first describe the physiology and cellular composition of brain tumors.Then,we discuss the development of threedimensional tissue models utilizing brain tumor cells.In particular,we highlight the role of hydrogels in providing a biomimetic support for the cells to grow into defined structures.Microscale technologies,such as electrospinning and bioprinting,and advanced cellular models aim to mimic the extracellular matrix and natural cellular localization in engineered tumor tissues.Lastly,we review current applications and prospects of hydrogels for therapeutic purposes,such as drug delivery and co-administration with other therapies.Through further development,hydrogels can serve as a reliable option for in vitro modeling and treatment of brain tumors for translational medicine.

A perspective on 3D bioprinting in tissue regeneration

IntroductionA rapidly increasing need for organ transplantation and short list of donated organs have led to the development of new materials and technologies for organ manufacturing. Although some simple organs, such as skin and cartilage, have been successfully fabricated and commercialized, it is still difficult to make tissues and organs with high complexity. Engineered tissues have other biomedical applications, such as drug screening models and bio-actuators. Threedimensional （3D） bioprinting has become a great tool to fabricate tissue constructs on demand for transplantation and other biomedical applications.

Glucose-responsive oral insulin delivery for postprandial glycemic regulation

Controlling postprandial glucose levels for diabetic patients is critical to achieve the tight glycemic control that decreases the risk for developing long-term micro- and macrovascular complications.Herein,we report a glucose-responsive oral insulin delivery system based on Fc receptor (FcRn)-targeted liposomes with glucose-sensitive hyaluronic acid (HA) shell for postprandial glycemic regulation.After oral administration,the HA shell can quickly detach in the presence of increasing intestinal glucose concentration due to the competitive binding of glucose with the phenylboronic acid groups conjugated with HA.The exposed Fc groups on the surface of liposomes then facilitate enhanced intestinal absorption in an FcRn-mediated transport pathway.In vivo studies on chemically-induced type 1 diabetic mice show this oral glucose-responsive delivery approach can effectively reduce postprandial blood glucose excursions.This work is the first demonstration of an oral insulin delivery system directly triggered by increasing postprandial glucose concentrations in the intestine to provide an on-demand insulin release with ease of administration.

Advances of injectable hydrogel-based scaffolds for cartilage regeneration

Articular cartilage is an important load-bearing tissue distributed on the surface of diarthrodial joints.Due to its avascular,aneural and non-lymphatic features,cartilage has limited self-regenerative properties.To date,the utilization of biomaterials to aid in cartilage regeneration,especially through the use of injectable scaffolds,has attracted considerable attention.Various materials,therapeutics and fabrication approaches have emerged with a focus on manipulating the cartilage microenvironment to induce the formation of cartilaginous structures that have similar properties to the native tissues.In particular,the design and fabrication of injectable hydrogel-based scaffolds have advanced in recent years with the aim of enhancing its therapeutic efficacy and improving its ease of administration.This review summarizes recent progress in these efforts,including the structural improvement of scaffolds,network cross-linking techniques and strategies for controlled release,which present new opportunities for the development of injectable scaffolds for cartilage regeneration.

Shape-controlled synthesis of liquid metal nanodroplets for photothermal therapy

The capping agents for liquid metal (LM) nanodroplets in aqueous solutions are restricted to thiol-containing and positively-charged molecules or macromolecules.However,both thiolate-metal complex and electrostatic interaction are liable to detachment upon strong mechanical forces such as sonication,leading to limited stability and applications.To address this,we utilized ultrasmall water soluble melanin nanoparticles (MNPs) as the capping agent,which exhibited strong metal binding capability with the oxide layer of gallium based LMs and resulted in enhanced stability.Interestingly,shape-controlled synthesis of LM nanodroplets can be achieved by the incorporation of MNPs.Various EGaln nanostructures including nanorice,nanosphere and nanorod were obtained by simply tuning the feed ratio,sonication time,and suspension temperature.Among these shapes,EGaln nanorice has the best photothermal conversion efficiency,which could be leveraged for photothermal therapy.

Cargo-encapsulated cells for drug delivery

Synthetic micro-/nanoparticle(MNP)carriers,either organic or inorganic ones,have advanced considerably in recent years for drug delivery with the aim of enhancing drug solubility/stability,reducing systemic toxicity and increasing dosing at pathological sites(Chen and Liang,2018;Xiang et al.,2018).Specially,the properties of MNPs,such as size,morphology,or surface groups,can be easily modulated to maximize their potency in delivering drugs to the targeted areas(Ran and Xue,2018).Nevertheless,till now,only a handful of MNPs have been approved by the US Food and Drug Administration for clinical application.Although numerous proof-of-concept studies of MNPs in animal models are in progress or are being clinically evaluated,synthetic MNPs are still struggling to reach the clinical expectations.

Mesoporous silica rods with cone shaped pores modulate inflammation and deliver BMP-2 for bone regeneration

Biomaterials with suitable osteoimmunomodulation properties and ability to deliver osteoinductive biomolecules,such as bone morphogenetic proteins,are desired for bone regeneration.Herein,we report the development of mesoporous silica rods with large cone-shaped pores(MSR-CP)to load and deliver large protein drugs.It is noted that those cone-shaped pores on the surface modulated the immune response and reduced the pro-inflammatory reaction of stimulated macrophage.Furthermore,bone morphogenetic proteins 2(BMP-2)loaded MSR-CP facilitated osteogenic differentiation and promoted osteogenesis of bone marrow stromal cells.In vivo tests confirmed BMP-2 loaded MSR-CP improved the bone regeneration performance.This study provides a potential strategy for the design of drug delivery systems for bone regeneration.

Smart scaffolds in tissue regeneration

Recent advances in biofabrication technologies and chemical synthesis approaches have enabled the fabrication of smart scaffolds that aim to mimic the dynamic nature of the native extracellular matrix.These scaffolds have paved the way for tissue regeneration in a dynamic and controllablemanner.

The inaugural Nano Research Young Innovators （NR45） Award in nanobiotechnology

It is our great pleasure to announce awardees of the inaugural 2018 Nano Research Young Innovators （NR45） in nanobiotechnology. Congratulations to all of the 45 outstanding young investigators under 45! They were selected through a competitive process by an award committee from our editorial board. Nano Research is launching the NR45 Award program to young researchers in various fields of nanoscience and nanotechnology, in recognition to their distinguished accomplishments and/or potential to make substantial contributions to their fields. The aim of Nano Research NR45 is to recognize the outstanding contributions of young scientists and together with the Nano Research Symposium integrated in the annual US-SINO Nano Forum provide a platform for communication, discussions and collaborations between scientists inter- nationally. For this inaugural year.

Therapeutic potential of adipose tissue

Adipose tissue is a highly specialized connective tissue that typically contributes to 10%-29%of body weight in an adult[1].Fat cells,including white adipocytes responsible for lipid storage and brown and beige adipocyte responsible for thermogenesis,play important roles in systemic lipid metabolism and energy supply.