Small Methods最新文献

Exothermic photopolymerization releases heat into the sample environment. Using NaYF₄:Yb³⁺/Er³⁺ upconversion nanoparticle (UCNP) photoluminescence and a colinear lithography and thermometry laser configuration, we monitor thermal signatures in the focal spot during femtosecond direct laser writing in real time. A statistical short-pass filtering is introduced to reduce the standard error in temperature calibration compared to conventional Gaussian deconvolution. Thermometry performance of our set-up achieved a relative sensitivity of 0.89-1.58% K^-1 and a measurement uncertainty of 0.2-0.4 K for 2 Hz sample rates. With this, the effect of scan speed, laser power, and photoinitiator concentration on accompanying local heating could be followed. Nonlinearities and thermal runaway effects with transient temperature spikes above 120-140°C demonstrate the need for a stringent reduction of the thermal burden when writing aqueous bioinks for biomedical applications. Physiological conditions were maintained only for fast 20 µm/s scan speeds, which limited temperature quenches to not exceed physiological temperatures. This paves the way to improve process control and to optimize for laser-assisted bioprinting and other related technologies.

Multi-Atom catalysts (MACs) have emerged as a pioneering domain in heterogeneous catalysis, distinguished by their exceptional intrinsic characteristics. These catalysts not only preserve the atomic dispersion and superior atomic utilization efficiency characteristic of single-atom catalysts, but also address their inherent limitations through enhanced metal loading capacity. Crucially, the interatomic synergy within the cluster facilitates the formation of more intricate and adaptable active sites, thereby potentially elevating catalytic performance and expanding reaction scope to more complex chemical processes. This comprehensive review systematically examines three fundamental aspects: (1) The architectural diversity of atom cluster catalysts; (2) Advanced strategies for electronic structure modulation, encompassing atomic interface engineering, coordination environment optimization, and substrate-mediated regulation; (3) Synergistic mechanisms that transcend conventional linear scaling relationships and enable precise control over critical catalytic parameters. We further consolidate contemporary synthesis methodologies and cutting-edge characterization techniques specifically tailored for these catalytic systems. Particular emphasis is placed on their transformative applications across electrocatalytic, photocatalytic, and thermocatalytic domains. The work concludes by outlining persistent challenges and future research directions in catalyst design principles, mechanistic elucidation through advanced characterizations, and practical implementation strategies. This systematic analysis provides theoretical guidance and methodological references for developing next-generation high-performance catalysts.

Organ-on-a-chip (OoC) technology is a powerful tool for creating physiologically relevant microscale models applicable to biomedical studies. Despite the advances in OoC technology, its fabrication method still primarily relies on soft lithography, which has a long design-to-prototype cycle that creates a bottleneck in the acceleration of OoC innovation. To increase the agility of the OoC fabrication process, a system is developed to fabricate OoC using a digital photomask aligned with a microchamber. The approach uses a pre-defined microfluidic chamber customized by xurography and microfluidic channels photopatterned by a digital photomask. The versatility of the approach offered previously unattainable features in the fabrication of OoC, including non-reticular height profiles of the OoC architecture, and real-time modification of channel designs to trap suspension culture (e.g., spheroids). In summary, this work highlights a versatile system to fabricate OoC by direct photopatterning that can accommodate various OoC design requirements of microenvironments of specific organ tissues. It is anticipated that the system can facilitate the rapid fabrication of OoC, potentially supporting advancements in OoC design innovation, which can potentially increase the adoption of the OoC technology for therapeutic screening and elucidation of disease mechanisms in the scientific community.

Graphite carbon nitride has garnered significant research interest for photocatalytic pollutant degradation. However, the slow kinetics of the oxygen reduction reaction and the high recombination rate of photogenerated charges have hindered improvements in its performance. This paper synthesizes etched and crushed carbon nitride by introducing sulfonyl groups into it. Comprehensive experimental characterization and theoretical calculation show that the sulfonyl group optimizes the electronic structure of the catalyst and promotes the separation and migration of photogenerated charges. More importantly, the sulfonyl group is directly anchored at the hydrophobic interface, reducing the reaction energy barrier while promoting the photocatalytic self-Fenton efficiency. In addition, the modified catalyst achieved a maximum H₂O₂ yield of 1571.63 µmol g^-1 h^-1, with a high apparent quantum efficiency of 11.37% at 380nm and a solar-to-chemical energy conversion efficiency of 0.81%. Ciprofloxacin was degraded into non-toxic small molecules within 30 min, and the degradation kinetic efficiency was increased by 6.04 times. The photocatalytic performance has been significantly improved. This study provides a significant strategy for adjusting the structure of photocatalysts by introducing electron-withdrawing groups and directionally anchoring them at hydrophobic interface to enhance catalytic activity and also provides valuable insights for the design and development of highly efficient photocatalysts.

Fusion of extracellular vesicles (EVs) with liposomes can be used to alter the properties of EVs to enhance their drug delivery capabilities. However, metrics for assessing fusion are not well established. Fusion efficiency, the most frequently provided metric, is often characterized in bulk, clouding distribution of fusion across heterogeneous EV populations, and lacking assessment of more precise physical effects of fusion. Here we applied orthogonal single-particle techniques including nanoparticle-tracking analysis (NTA), resistive-pulse sensing (RPS), nanoscale flow cytometry, interferometric fluorescence imaging, and laser trapping Raman spectroscopy (LTRS), each with different limitations, to examine the effects of fusion. All techniques reduced particle number, while single-particle fluorescence analyses revealed substantial differences in fused-particle yield. Nanoscale flow cytometry and interferometric fluorescence imaging consistently identified freeze-thaw and sonication as producing the highest numbers of fused vesicles, with freeze-thaw generating the lowest proportion of non-fused EVs and liposomes. Interferometric fluorescence imaging further showed that fused vesicles retained native EV membrane proteins, but that fusion also reduced the abundance of these proteins, indicating membrane perturbation. We introduce here a multi-metric framework to evaluate fusion efficiency, purity, and physical alterations to vesicles, as a basis for comparing techniques and to support future optimization of engineered EV formulations.

The development of low-cost and high-performance noble-metal-free catalysts for the oxygen evolution reaction (OER) is central to advancing alkaline water electrolysis. This work introduces a novel "composition-thermal history" design strategy, synergistically combining controlled A-site Sr²⁺ doping with optimized high-temperature sintering (950°C) in Pr-based perovskite. The resulting Pr_0.75Sr_0.25Ni_0.7Co_0.3O₃ (PSNC-25) exhibits unprecedented nanostructuring and a maximized concentration of oxygen vacancies, unlocking efficient OER via lattice oxygen-mediated mechanism. Sr-induced lattice distortion drastically reduces oxygen vacancy formation energy from 2.06 to 1.14 eV, promoting facile lattice oxygen participation. Thermal engineering stabilizes high-valence Co⁴⁺/Ni³⁺ states and enhances M─O covalency. Electrochemically, PSNC-25 achieves exceptional activity in 1 M KOH: a low overpotential of 389 mV at 10 mA cm^-2 and a Tafel slope of 83 mV dec^-1, significantly surpassing undoped PrNi_0.7Co_0.3O₃ (η₁₀ ＞ 570 mV). It also exhibits robust durability, by > 120 h chronopotentiometry at 10 mA cm^-2 with only ∼45 mV potential drift. This work establishes a rational framework for activating LOM in cost-effective perovskites through dopant-induced electronic modulation and nano-structural control, advancing scalable green hydrogen production.

Electrospinning is a promising technique for fabricating air filtration materials. Nevertheless, significant challenges remain in precise fiber diameter control, efficiency-pressure drop balance, and achieving multifunctional air purification. In this study, an organic semiconductor material (PDINN) is first utilized to modulate the fiber diameters of PLA nanofiber membranes (PDINN@PLA) by electrospinning. Due to the relatively high conductivity of PDINN, the fiber diameters were reduced from 2 µm to 500 nm. Subsequently, PDINN@PLA was employed in combination with PLA to fabricate the bimodal micro-nanofiber membrane, named PLA-PDINN@PLA. Benefiting from the gradient distribution of fiber diameters, PLA-PDINN@PLA has filtration efficiency of more than 99.5% for PM_0.3, maintained low pressure drop at air flow rates of both 32 and 85 L/min. In addition to remarkable filtration performance, this membrane also demonstrates excellent antibacterial properties, achieving inhibition rates of 99.99% against both S. aureus and E. coli. Meanwhile, the membrane exhibits deodorization efficiencies of 99.99% and 82% for ammonia and acetic acid, respectively, which can be attributed to the amino groups in PDINN. Therefore, this work presents an innovative strategy that enables simultaneous control over fiber diameters and functionalization of fibrous membranes, offering a promising approach toward highly efficient multifunctional nanofiber-based air filters.

Exploring a nitrogen reduction reaction (NRR) technology utilizing single-atom electrocatalysts, our research aims to develop an environmentally benign and highly efficient approach for ammonia (NH₃) synthesis. A sulfur-doped single-atom bismuth-based nitride catalyst (S-BiNSPC) was synthesized via a molecular engineering strategy, and its structure and electrochemical NRR performance were thoroughly characterized. X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) analyses revealed that sulfur incorporation optimizes the electronic structure and local geometry of bismuth, significantly enhancing NRR activity. Experimental results demonstrated that S-BiNSPC exhibited excellent NRR performance in 0.1 m KOH electrolyte, achieving an ammonia yield of 77.71 µg.h^-1 mgcat^-1 and a Faraday efficiency (FE) of 37.03%. Density functional theory (DFT) calculations indicated that sulfur doping lowers the energy barrier for the initial hydrogenation step and optimizes the electronic structure for nitrogen activation. In a system where the NRR is coupled with the ethylene glycol oxidation reaction (EGOR), the reaction potential was reduced and the generation of high-value-added products was enabled. This research offers novel perspectives on the advancement of high-performance NRR catalysts and highlights their potential for practical implementation.

Precise control of light polarization at the nanoscale is critical for accessing chiral optical responses and manipulating spin-photon interactions in advanced materials. Yet, conventional scattering-type near-field probes predominantly generate out-of-plane linear polarization and offer little control over phase or polarization state. Here, we introduce a polarization-engineered near-field methodology based on a combined metallic tip and planar dipole nanoantenna system. Using full-wave electromagnetic simulations, we show that the tip acts as a vertically oriented plasmonic resonator, while the antenna supports an in-plane dipolar mode. By tuning the tip-antenna geometry and tip height, the two orthogonal field components attain comparable amplitudes and a controllable ∼90° phase offset, producing circularly polarized nano-light in the antenna gap. The proposed system effectively functions as a nanoscale quarter-wave plate, converting linearly polarized illumination into circularly polarized hotspots without external polarization optics. This method establishes an experimentally accessible route toward polarization-programmable near-field nanoscopy, enabling chiral spectroscopy, selective excitation of spin/valley degrees of freedom, and quantum optical investigations at the nanoscale.

The electronic band structures of semiconducting materials significantly influence the functionality of photoelectronic devices such as solar cells, light-emitting diodes, and sensors. The energy-resolved electrochemical impedance spectroscopy (ER-EIS) method presents an effective and efficient means of determining the density of states (DOS) function spanning the entire energy range from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), including the presence of tail states and deep defect states in the bandgap. This article reviews the nearly ten-year use of the ER-EIS method in semiconductor research from its introduction to the present. We detail the basic principles of this technique, highlighting both its advantages and limitations. Furthermore, we discuss the insights gained from applying ER-EIS to a diverse range of materials. Finally, we outline the directions and potential advancements that this method may bring to the field of materials science in the future.