Nanoscale Horizons最新文献

This article highlights the recent work of Biju, Takano et al. (Nanoscale Horiz., 2024, 9, 1128–1136, https://doi.org/10.1039/D4NH00134F) on using a unique bio-catalytic nanoparticle shaping method for preparing mesoscopic particles.

This study explores the phase-controlled growth of few-layered 2H-MoTe₂, 1T′-MoTe₂, and 2H-/1T′-MoTe₂ heterostructures and their impacts on metal contact properties. Cold-wall chemical vapor deposition (CW-CVD) with varying growth rates of MoO_x and reaction temperatures with Te vapors enabled the growth of continuous thin films of either 1T′-MoTe₂ or 2H-MoTe₂ phases on two-inch sapphire substrates. This methodology facilitates the meticulous optimization of chemical vapor deposition (CVD) parameters, enabling the realization of phase-controlled growth of few-layered MoTe₂ thin films and their subsequent heterostructures. The study further investigates the influence of a 1T′-MoTe₂ intermediate layer on the electrical properties of metal contacts on few-layered 2H-MoTe₂. Bi-layer Ti/Al contacts directly deposited on 2H-MoTe₂ exhibited Schottky behavior, indicating inefficient carrier transport. However, introducing a few-layered 1T′-MoTe₂ intermediate layer between the metal and 2H-MoTe₂ layers improved the contact characteristics significantly. The resulting Al/Ti/1T′-MoTe₂/2H-MoTe₂ contact scheme demonstrates Ohmic behavior with a specific contact resistance of around 1.7 × 10⁻⁴ Ω cm². This substantial improvement is attributed to the high carrier concentration of the 1T′-MoTe₂ intermediate layer which could be attributed tentatively to the increased tunneling events across the van der Waals gap and enhancing carrier transport between the metal and 2H-MoTe₂.

Sonodynamic therapy (SDT) is gaining popularity in cancer treatment due to its superior controllability and high tissue permeability. Nonetheless, the efficacy of SDT is severely diminished by the transient generation of limited reactive oxygen species (ROS). Herein, we introduce an acid-activated nanosonosensitizer, CaO₂@PCN, by the controllable coating of porphyrinic metal–organic frameworks (PCN-224) on CaO₂ to induce cascaded oxidative stress in tumors. The PCN-224 doping can generate ROS during SDT to induce intracellular oxidative stress and abnormal calcium channels. Meanwhile, the ultrasound also promotes extracellular calcium influx. In addition, CaO₂@PCN sequentially degrades in the tumor cell lysosomes, releasing Ca²⁺ and H₂O₂ to induce further abnormal calcium channels and elevate the levels of Ca²⁺. Insufficient catalase (CAT) in tumor cells promotes intracellular calcium overload, which can induce persistent ROS generation and mitochondrial dysfunction through ion interference therapy (IIT). More importantly, PCN-224 also protects CaO₂ against significant degradation under neutral conditions. Hence, the well-designed CaO₂@PCN produces synergistic SDT/IIT effects and persistent ROS against cancer. More notably, the acidity-responsive biodegradability endows CaO₂@PCN with excellent biosafety and promising clinical potential.

Immune profiling provides insights into the functioning of the immune system, including the distribution, abundance, and activity of immune cells. This understanding is essential for deciphering how the immune system responds to pathogens, vaccines, tumors, and other stimuli. Analyzing diverse immune cell types facilitates the development of personalized medicine approaches by characterizing individual variations in immune responses. With detailed immune profiles, clinicians can tailor treatment strategies to the specific immune status and needs of each patient, maximizing therapeutic efficacy while minimizing adverse effects. In this review, we discuss the evolution of immune profiling, from interrogating bulk cell samples in solution to evaluating the spatially-rich molecular profiles across intact preserved tissue sections. We also review various multiplexed imaging platforms recently developed, based on immunofluorescence and imaging mass spectrometry, and their impact on the field of immune profiling. Identifying and localizing various immune cell types across a patient's sample has already provided important insights into understanding disease progression, the development of novel targeted therapies, and predicting treatment response. We also offer a new perspective by highlighting the unprecedented potential of nanoparticles (NPs) that can open new horizons in immune profiling. NPs are known to provide enhanced detection sensitivity, targeting specificity, biocompatibility, stability, multimodal imaging features, and multiplexing capabilities. Therefore, we summarize the recent developments and advantages of NPs, which can contribute to advancing our understanding of immune function to facilitate precision medicine. Overall, NPs have the potential to offer a versatile and robust approach to profile the immune system with improved efficiency and multiplexed imaging power.

Single-atom catalysis is a subcategory of heterogeneous catalysis with well-defined active sites. Numerous endeavors have been devoted to developing single-atom catalysts for industrially applicable catalysis, including the hydrogen evolution reaction (HER). High-current-density electrolyzers have been pursued for single-atom catalysts to increase active-site density and enhance mass transfer. Here, we reasoned that a single-atom metal embedded in nitrogen assembly carbon (NAC) catalysts with high single-atom density, large surface area, and ordered mesoporosity, could fulfil an industrially applicable HER. Among several different single-atom catalysts, the HER overpotential with the best performing Co-NAC reached a current density of 200 mA cm⁻² at 310 mV, which is relevant to industrially applicable current density. Density functional theory (DFT) calculations suggested feasible hydrogen binding on single-atom Co resulted in the promising HER activity over Co-NAC. The best-performing Co-NAC showed robust performance under alkaline conditions at a current density of 50 mA cm⁻² for 20 h in an H-cell and at a current density of 150 mA cm⁻² for 100 h in a flow cell.

In the electrochemical CO₂ reduction reaction (CO₂RR), Cu alloy electrocatalysts can control the CO₂RR selectivity by modulating the intermediate binding energy. Here, we report the thermodynamic-based Cu–Sn bimetallic phase control in heterogeneous catalysts for selective CO₂ conversion. Starting from the thermodynamic understanding about Cu–Sn bimetallic compounds, we established the specific processing window for Cu–Sn bimetallic phase control. To modulate the Cu–Sn bimetallic phases, we controlled the oxygen partial pressure (pO₂) during the calcination of electrospun Cu and Sn ions-incorporated nanofibers (NFs). This resulted in the formation of CuO–SnO₂ NFs (full oxidation), Cu–SnO₂ NFs (selective reduction), Cu₃Sn/CNFs, Cu₄₁Sn₁₁/CNFs, and Cu₆Sn₅/CNFs (full reduction). In the CO₂RR, CuO–SnO₂ NFs exhibited formate (HCOO⁻) production and Cu–SnO₂ NFs showed carbon monoxide (CO) production with the faradaic efficiency (FE) of 65.3% at −0.99 V (vs. RHE) and 59.1% at −0.89 V (vs. RHE) respectively. Cu-rich Cu₄₁Sn₁₁/CNFs and Cu₃Sn/CNFs enhanced the methane (CH₄) production with the FE of 39.1% at −1.36 V (vs. RHE) and 34.7% at −1.50 V (vs. RHE). However, Sn-rich Cu₆Sn₅/CNFs produced HCOO⁻ with the FE of 58.6% at −2.31 V (vs. RHE). This study suggests the methodology for bimetallic catalyst design and steering the CO₂RR pathway by controlling the active sites of Cu–Sn alloys.

Influenza viral infection poses a severe risk to global public health. Considering the suboptimal protection provided by current influenza vaccines against circulating influenza A viruses, it is imperative to develop novel vaccine formulations to combat respiratory infections. Here, we report the development of an intranasally-administered, self-adjuvanted double-layered protein nanoparticle consisting of influenza nucleoprotein (NP) cores coated with hemagglutinin (HA) and a truncated form of bacterial flagellin (tFliC). Intranasal vaccination of these nanoparticles notably amplified both antigen-specific humoral and cellular immune responses in the systematic compartments. Elevated antigen-specific IgA and IgG levels in mucosal washes, along with increased lung-resident memory B cell populations, were observed in the respiratory system of the immunized mice. Furthermore, intranasal vaccination of tFliC-adjuvanted nanoparticles enhanced survival rates against homologous and heterologous H3N2 viral challenges. Intriguingly, mucosal slow delivery of the prime dose (by splitting the dose into 5 applications over 8 days) significantly enhanced germinal center reactions and effector T-cell populations in lung draining lymph nodes, therefore promoting the protective efficacy against heterologous influenza viral challenges compared to single-prime immunization. These findings highlight the potential of intranasal immunization with tFliC-adjuvanted protein nanoparticles to bolster mucosal and systemic immune responses, with a slow-delivery strategy offering a promising approach for combating influenza epidemics.

Herein, a self-supported carbon network is designed through the sole pyrolysis of Carica papaya seeds (biomass) without any activation agent, demonstrating their field emission and supercapacitor applications. The pyrolysis of seeds in an argon atmosphere leads to the formation of interconnected, rod-like structures. Furthermore, the hydrofluoric acid treatment not only removed impurities, but also resulted in the formation of CaF₂ nanocrystals with the addition of F-doping. From the field emission studies, the turn-on field values defined at an emission current density of ∼10 μA cm⁻² were found to be ∼2.16 and 1.21 V μm⁻¹ for the as-prepared carbon and F-doped carbon, respectively. Notably, F-doped carbon exhibits a high emission current density of ∼9.49 mA cm⁻² and has been drawn at an applied electric field of ∼2.29 V μm⁻¹. Supercapacitor studies were carried out to demonstrate the multi-functionality of the prepared materials. The F-doped carbon electrode material exhibits the highest specific capacitance of 234 F g⁻¹ at 0.5 A g⁻¹. To demonstrate the actual supercapacitor application, the HFC//HFC symmetric coin cell supercapacitor device was assembled. The overall multifunctional applicability of the fabricated hybrid structures provides a futuristic approach to field emission and energy storage applications.

Neuroelectronic prostheses are being developed for restoring vision at the retinal level in patients who have lost their sight due to photoreceptor loss. The core component of these devices is the electrode array, which enables interfacing with retinal neurons. Generating the perception of meaningful images requires high-density microelectrode arrays (MEAs) capable of precisely activating targeted retinal neurons. Achieving this precision necessitates the downscaling of electrodes to micrometer dimensions. However, miniaturization increases electrode impedance, which poses challenges by limiting the amount of current that can be delivered, thereby impairing the electrode's capability for effective neural modulation. Additionally, it elevates noise levels, reducing the signal quality of the recorded neural activity. This report focuses on evaluating reduced graphene oxide (rGO) based devices for interfacing with the retina, showcasing their potential in vision restoration. Our findings reveal low impedance and high charge injection limit for microscale rGO electrodes, confirming their suitability for developing next-generation high-density retinal devices. We successfully demonstrated bidirectional interfacing with cell cultures and explanted retinal tissue, enabling the identification and modulation of multiple cells' activity. Additionally, calcium imaging allowed real-time monitoring of retinal cell dynamics, demonstrating a significant reduction in activated areas with small-sized electrodes. Overall, this study lays the groundwork for developing advanced rGO-based MEAs for high-acuity visual prostheses.

Recently, tellurium (Te) has been proposed as a promising p-type material; however, even the state-of-the-art results couldn’t overcome the critical roadblocks for its practical applications, such as large I–V hysteresis and high off-state leakage current. We developed a novel Te atomic layer deposition (ALD) process combined with a TeO_x seed layer and Al₂O₃ passivation to detour the limitations of p-type Te semiconducting materials. Also, we have identified the origins of high hysteresis and off current using the 77 K operation study and passivation process optimization. As a result, a p-type Te field-effect transistor exhibits less than 23 mV hysteresis and a high field-effect mobility of 33 cm² V⁻¹ s⁻¹ after proper channel thickness modulation and passivation. Also, an ultralow off-current of approximately 1 × 10⁻¹⁴ A, high on/off ratios in the order of 10⁸, and a steep slope subthreshold swing of 79 mV dec⁻¹ could be achieved at 77 K. These enhancements strongly indicate that the previously reported high off-state current was originated from interfacial defects formed at the metal–Te contact interface. Although further studies concerning this interface are still necessary, the findings herein demonstrate that the major obstacles hindering the use of Te for ultrathin p-channel device applications can be eliminated by proper process optimization.