P- and N-type InAs nanocrystals with innately controlled semiconductor polarity.

InAs semiconductor nanocrystals (NCs) exhibit intriguing electrical/optoelectronic properties suitable for next-generation electronic devices. Although there is a need for both n- and p-type semiconductors in such devices, InAs NCs typically exhibit only n-type characteristics. Here, we report InAs NCs with controlled semiconductor polarity. Both p- and n-type InAs NCs can be achieved from the same indium chloride and aminoarsine precursors but by using two different reducing agents, diethylzinc for p-type and diisobutylaluminum hydride for n-type NCs, respectively. This is the first instance of semiconductor polarity control achieved at the synthesis level for InAs NCs and the entire semiconductor nanocrystal systems. Comparable field-effective mobilities for holes (3.3 × 10-3 cm2/V·s) and electrons (3.9 × 10-3 cm2/V·s) are achieved from the respective NC films. The mobility values allow the successful fabrication of complementary logic circuits, including NOT, NOR, and NAND comprising photopatterned p- and n-channels based on InAs NCs.

Enhanced recellularization by using albumin coating with roller bottle cell culture.

Introduction: The decellularization and recellularization is a promising approach for tissue engineering and regenerative medicine. However, the decellularization process depletes important components like glycosaminoglycans (GAGs), affecting cell attachment and causing immunogenicity. Studies have explored various surface modification strategies to enhance recellularization. Methods: To optimize the decellularization method, we employed whole kidney perfusion and slice kidney immersion/agitation techniques. The decellularized extracellular matrix (dECM) was then analyzed using hematoxylin and eosin (H&E) staining, scanning electron microscope (SEM), and DNA quantification. To enhance cell proliferation efficiency, albumin coating and rotating culture were applied. Also, we evaluated in vitro blood clot formation on the albumin-coated dECM by immersing it in blood. Results: After decellularization, the unique structures of the kidney were preserved whether cellular components were removed. Subsequently, we utilized albumin coating and rotating culture for recellularization, and observed that albumin-coated dECM not only promoted high cell proliferation rates but also prevented blood clot formation. Conclusion: The albumin-coated dECM promoted cell proliferation and reduced blood clot formation in vitro. Also, dynamic culture condition using rotating culture allowed for improved cellular penetration into the dECM, leading to a conductive environment for enhanced tissue infiltration. This new approach suggests that the combined utilization of albumin coating and rotating culture conditions can improve the efficiency of recellularization.

Safety assessment of a three-dimensional-printed autologous omentum patch: An application on the kidneys as a new treatment approach.

Recently, the field of regenerative medicine has made great strides in the development of new treatments for various organ dysfunctions. One of the most promising new approaches is the use of three-dimensional (3D) printing and autologous tissues. In this study, we evaluated the safety of a 3D-printed autologous omentum patch to kidneys using large animals. A total of seven micropigs underwent transplantation of the 3D-printed autologous omentum patch. Twelve weeks after transplantation, the safety was evaluated by measuring body weight, blood, and the renal resistive index. In addition, biopsy samples were histologically analyzed. The results showed no surgical complications, renal functional hematological changes, or inflammatory responses. Therefore, this study provides important insights into direct therapy to kidneys with a 3D-printed patch made of autologous tissue. Furthermore, it has the potential for the development of new therapies for various organ dysfunction.

Three-Dimensional Bio-Printed Autologous Omentum Patch Ameliorates Unilateral Ureteral Obstruction-Induced Renal Fibrosis.

Recent advances in the field of tissue engineering and regenerative medicine have contributed to the repair of damaged tissues and organs. Renal dysfunctions such as chronic kidney disease (CKD) are considered intractable owing to its cellular heterogeneity. In addition, the absence of definitive treatment options other than dialysis or kidney transplantation in advanced CKD. In this study, we investigated therapeutic effects of a three-dimensional (3D) bio-printed omentum patch as treatment source. Because omentum contains a lot of biological sources for immune regulation and tissue regeneration, it has been used in clinic for >100 years. By using autologous tissue as a bio-ink, the patch could minimize the immune response. The mechanically micronized omentum without any additives became small enough to print, but the original components could be preserved. Then, the 3D printed omentum patch was transplanted under renal subcapsular layer in unilateral ureteral obstruction (UUO) rat model. After 14 days of patch transplantation, the kidneys were analyzed through bulk RNA sequencing and histopathological staining. From the results, decreased tubular injury was observed in the omentum patch group. In addition, the omentum patch significantly altered biological process of gene ontology such as fibrosis-related gene and growth factors. RNA sequencing confirmed the antifibrotic effect by inhibiting fibrosis-inducing mechanisms within PI3K-AKT and JAK-STAT pathways. In conclusion, the omentum patch showed the effect of antitubular injury and antifibrosis on UUO kidneys. In particular, the omentum patch is expected to protect the organ from further degeneration and loss of function by inhibiting the progression of fibrosis. The omentum patch can be a novel therapeutic option for renal dysfunction. Impact statement Many studies and clinical trials are being conducted to develop new treatments for kidney disease. However, there are no newly developed renal replacement therapies. In this study, we developed a new treatment that can ameliorate renal interstitial fibrosis using three-dimensional (3D) bio-printed autologous omentum patch. The 3D printer enables precise patch printing, and the bio-ink made of autologous tissue minimizes the immune response after transplantation. The whole kidneys were analyzed by RNA sequencing and histopathological staining 14 days after transplantation. From the results, the omentum patch had the effect of relieving tubular injury in the injured state. Also, the omentum patch significantly altered biological process of gene ontology. In particular, genes related to fibrosis were observed to be downregulated by the omentum patch. RNA sequencing confirmed that the antifibrotic effect was owing to inducing mechanisms of PI3K-AKT and JAK-STAT pathways. The findings reported in this study represent a significant advancement in the application of 3D bio-printer to damaged organ treatments, especially fibrosis-related diseases.

Nondestructive Photopatterning of Heavy-Metal-Free Quantum Dots.

Electroluminescence from quantum dots (QDs) is a suitable photon source for futuristic displays offering hyper-realistic images with free-form factors. Accordingly, a nondestructive and scalable process capable of rendering multicolored QD patterns on a scale of several micrometers needs to be established. Here, nondestructive direct photopatterning for heavy-metal-free QDs is reported using branched light-driven ligand crosslinkers (LiXers) containing multiple azide units. The branched LiXers effectively interlock QD films via photo-crosslinking native aliphatic QD surface ligands without compromising the intrinsic optoelectronic properties of QDs. Using branched LiXers with six sterically engineered azide units, RGB QD patterns are achieved on the micrometer scale. The photo-crosslinking process does not affect the photoluminescence and electroluminescence characteristics of QDs and extends the device lifetime. This nondestructive method can be readily adapted to industrial processes and make an immediate impact on display technologies, as it uses widely available photolithography facilities and high-quality heavy-metal-free QDs with aliphatic ligands.

Direct patterning of colloidal quantum dots with adaptable dual-ligand surface.

Colloidal quantum dots (QDs) stand at the forefront of a variety of photonic applications given their narrow spectral bandwidth and near-unity luminescence efficiency. However, integrating luminescent QD films into photonic devices without compromising their optical or transport characteristics remains challenging. Here we devise a dual-ligand passivation system comprising photocrosslinkable ligands and dispersing ligands to enable QDs to be universally compatible with solution-based patterning techniques. The successful control over the structure of both ligands allows the direct patterning of dual-ligand QDs on various substrates using commercialized photolithography (i-line) or inkjet printing systems at a resolution up to 15,000 pixels per inch without compromising the optical properties of the QDs or the optoelectronic performance of the device. We demonstrate the capabilities of our approach for QD-LED applications. Our approach offers a versatile way of creating various structures of luminescent QDs in a cost-effective and non-destructive manner, and could be implemented in nearly all commercial photonics applications where QDs are used.

Stoichiometric Doping of Highly Coupled Cu2-xS Nanocrystal Assemblies.

The hole density of individual copper sulfide nanocrystals (Cu2-xS NCs) is determined from the stoichiometric mismatch (x) between copper and sulfide atoms. Consequently, the electronic properties of the material vary over a range of x. To exploit Cu2-xS NCs in devices, assemblies of NCs are typically required. Herein, we investigate the influence of x, referred to as the stoichiometric doping effect, on the structural, optical, electrical, and thermoelectric properties of electronically coupled Cu2-xS NC assemblies. The doping process is done by immersing the solid NC assemblies into a solution containing a Cu(I) complex for different durations (0-10 min). As Cu+ gradually occupied the copper-deficient sites of Cu2-xS NCs, x could be controlled from 0.9 to less than 0.1. Consequently, the near-infrared (NIR) absorbance of Cu2-xS NC assemblies changes systematically with x. With increasing x, electrical conductivity increased and the Seebeck coefficient decreased systematically, leading to the maximal thermoelectric power factor from a film of Cu2-xS NCs at an optimal doping condition yielding x = 0.1. The physical characteristics of the Cu2-xS NC assemblies investigated herein will provide guidelines for exploiting this emerging class of nanocrystal system based on doping.

Ionically Connected Floating Electrodes for Long-Distance (>1 mm) Coplanar-Gating Graphene Transistors.

Exploiting the long-range polarizability of an electrolyte based on ion migration, electric double-layer transistors (EDLTs) can be constructed in an unconventional configuration; here, the gate electrode is placed coplanarly with the device channel. In this paper, we demonstrate the influence of the distance factors of the electrolyte layer on the operation of EDLTs with a coplanar gate. As the promptness of the electric double-layer formation depends on the distance between the channel and the gate, the dynamic characteristics of a remote-gated transistor degrade with long distances. To suppress this degradation, we suggest using multiple coplanar floating gates bridged through ionic dielectric layers. Unlike remotely gated EDLTs that utilize a single extended electrolyte layer, the devices with multiple segmented electrolyte layers operate effectively even when they are gated from a distance longer than 1 mm.

Electrically Controllable Molecularization of Terahertz Meta-Atoms.

Active control of metamaterial properties is critical for advanced terahertz (THz) applications. However, the tunability of THz properties, such as the resonance frequency and phase of the wave, remains challenging. Here, a new device design is provided for extensively tuning the resonance properties of THz metamaterials. Unlike previous approaches, the design is intended to control the electrical interconnections between the metallic unit structures of metamaterials. This strategy is referred to as the molecularization of the meta-atoms and is accomplished by placing graphene bridges between the metallic unit structures whose conductivity is modulated by an electrolyte gating. Because of the scalable nature of the molecularization, the resonance frequency of the terahertz metamaterials can be tuned as a function of the number of meta-atoms constituting a unit metamolecule. At the same time, the voltage-controlled molecularization allows delicate control over the phase shift of the transmitted THz, without changing the high transmission of the materials significantly.

Nonvolatile Electric Double-Layer Transistor Memory Devices Embedded with Au Nanoparticles.

We present nonvolatile transistor memory devices that rely on the formation of electric double layer (EDL) at the semiconductor-electrolyte interface. The two critical functional components of the devices are the ion gel electrolyte and gold nanoparticles (NPs). The ion gel electrolyte contains ionic species for EDL formation that allow inducing charges in the semiconductor-electrolyte interface. The gold NPs inserted between the ion gel and the channel layer serve as trapping sites to the induced charges to store the electrical input signals. Two different types of gold NPs were used: one prepared using direct thermal evaporation and the other prepared using a colloidal process. The organic ligands attached onto the colloidal gold NPs prevented the escape of the trapped charges from the particles and thus enhanced the retention characteristics of the programmed/erased signals. The low-voltage-driven EDL formation resulted in a programmed/erased memory signal ratio larger than 103 from the nonvolatile indium-gallium-zinc oxide transistor memory devices at voltages below 10 V, which could be held for >105 s. The utility of the electrolytes to operate memory devices demonstrated herein should provide an alternative strategy to realize cheap, portable electronic devices powered with thin-film batteries.