Aptamer‐Engineered Natural Killer Cells for Cell‐Specific Adaptive Immunotherapy

Natural killer (NK) cells are a key component of the innate immune system as they can attack cancer cells without prior sensitization. However, due to lack of cell‐specific receptors, NK cells are not innately able to perform targeted cancer immunotherapy. Aptamers are short single‐stranded oligonucleotides that specifically recognize their targets with high affinity in a similar manner to antibodies. To render NK cells with target‐specificity, synthetic CD30‐specific aptamers are anchored on cell surfaces to produce aptamer‐engineered NK cells (ApEn‐NK) without genetic alteration or cell damage. Under surface‐anchored aptamer guidance, ApEn‐NK specifically bind to CD30‐expressing lymphoma cells but do not react to off‐target cells. The resulting specific cell binding of ApEn‐NK triggers higher apoptosis/death rates of lymphoma cells compared to parental NK cells. Additionally, experiments with primary human NK cells demonstrate the potential of ApEn‐NK to specifically target and kill lymphoma cells, thus presenting a potential new approach for targeted immunotherapy by NK cells.     

Artificial Natural Killer Cells for Specific Tumor Inhibition and Renegade Macrophage Re‐Education

Natural killer (NK) cells can not only recognize and eliminate abnormal cells but also recruit and re‐educate immune cells to protect the host. However, the functions of NK cells are often limited in the immunosuppressive tumor microenvironment (TME). Here, artificial NK cells (designated as aNK) with minor limitations of TME for specific tumor killing and renegade macrophage re‐education are created. The red blood cell membrane (RBCM) cloaks perfluorohexane (PFC) and glucose oxidase (GOX) to construct the aNK. The aNK can directly kill tumor cells by exhausting glucose and generating hydrogen peroxide (H₂O₂). The generated H₂O₂ is also similar to cytokines and chemokines for recruiting immune cells and re‐educating survived macrophages to attack tumor cells. In addition, the oxygen‐carried PFC can strengthen the catalytic reaction of GOX and normalize the hypoxic TME. In vitro and in vivo experiments display that aNK with slight TME limitations exhibit efficient tumor inhibition and immune activation. The aNK will provide a new sight to treat tumor as the supplement of aggressive NK cells.     

Electric‐Field‐Assisted Growth of Functionalized Poly(3,4‐ethylenedioxythiophene) Nanowires for Label‐Free Protein Detection

The construction of functionalized poly(3,4‐ethylenedioxythiophene) (PEDOT) nanowire devices for label‐free protein detection is reported. Direct growth/assembly of PEDOT nanowires with carboxylic acid side‐chain functional groups (poly(EDOT‐COOH)) across the electrode junction is achieved by using an electric‐field‐assisted method. These functionalized PEDOT nanowire devices show typical depletion‐mode p‐type field‐effect transistor (FET) properties. Upon conjugation with a protein‐binding aptamer, the PEDOT nanowire FET devices are used for label‐free electronic detection of a target protein of interest. The binding of a positively charged protein causes a substantial decrease in current flow, attributed to the specific interaction between target protein molecules and aptamer‐conjugated polymer chains.     

Modulation of Mesenchymal Stem Cells Mechanosensing at Fluid Interfaces by Tailored Self‐Assembled Protein Monolayers

Mechanical cues of cellular microenvironments can modulate cell functions including cell spreading and differentiation. Most studies of cellular functions are performed using a solid substrate, and it is thought that cells cannot spread on fluid substrates because of rapid relaxation, which cannot resist against actomyosin‐based cell contractility. Here, the spreading and growth of anchorage‐dependent cells such as human mesenchymal stem cells at the liquid interface between a perfluorocarbon fluid and the culture medium are observed. It is demonstrated that a monomolecular protein nanosheet self‐assembled at a fluid interface is sufficiently rigid to support cell spreading without additional treatment. Fine tuning of the packing of these proteins at the liquid interface permits tailoring of the mechanics of the protein layer, ultimately allowing for the regulation of cell spreading. The greater stiffness of the protein nanosheets triggers cell spreading, adhesion growth, and yes‐associated protein nuclear translocation. Cell behavior at the fluid interface is explained within the framework of the molecular clutch model. In addition, the freestanding ultrathin protein nanosheets are extremely flexible, easily deformed, and perceived by cells as being much softer. The findings are expected to provide a new perspective for insights into cell–material interactions.     

Tuning Nanowires and Nanotubes for Efficient Fuel‐Cell Electrocatalysis

Developing new synthetic methods for the controlled synthesis of Pt‐based or non‐Pt nanocatalysts with low or no Pt loading to facilitate sluggish cathodic oxygen reduction reaction (ORR) and organics oxidation reactions is the key in the development of fuel‐cell technology. Various nanoparticles (NPs), with a range of size, shape, composition, and structure, have shown good potential to catalyze the sluggish cathodic and anodic reactions. In contrast to NPs, one‐dimensional (1D) nanomaterials such as nanowires (NWs), and nanotubes (NTs), exhibit additional advantages associated with their anisotropy, unique structure, and surface properties. The prominent characteristics of NWs and NTs include fewer lattice boundaries, a lower number of surface defect sites, and easier electron and mass transport for better electrocatalytic activity and lower vulnerability to dissolution, Ostwald ripening, and aggregation than Pt NPs for enhanced stability. An overview of recent advances in tuning 1D nanostructured Pt‐based, Pd‐based, or 1D metal‐free nanomaterials as advanced electrocatalysts is provided here, for boosting fuel‐cell reactions with high activity and stability, including the oxygen reduction reaction (ORR), methanol oxidation reaction (MOR), and ethanol oxidation reaction (EOR). After highlighting the different strategies developed so far for the synthesis of Pt‐based 1D nanomaterials with controlled size, shape, and composition, special emphasis is placed on the rational design of diverse NWs and NTs catalysts such as Pt‐based NWs or NTs, non‐Pt NTs, and carbon NTs with molecular engineering, etc. for enhancing the ORR, MOR, and EOR. Finally, some perspectives are highlighted on the development of more efficient fuel‐cell electrocatalysts featuring high stability, low cost, and enhanced performance, which are the key factors in accelerating the commercialization of fuel‐cell technology.     

Edge‐Epitaxial Growth of InSe Nanowires toward High‐Performance Photodetectors

Semiconducting nanowires offer many opportunities for electronic and optoelectronic device applications due to their unique geometries and physical properties. However, it is challenging to synthesize semiconducting nanowires directly on a SiO₂/Si substrate due to lattice mismatch. Here, a catalysis‐free approach is developed to achieve direct synthesis of long and straight InSe nanowires on SiO₂/Si substrates through edge‐homoepitaxial growth. Parallel InSe nanowires are achieved further on SiO₂/Si substrates through controlling growth conditions. The underlying growth mechanism is attributed to a selenium self‐driven vapor–liquid–solid process, which is distinct from the conventional metal‐catalytic vapor–liquid–solid method widely used for growing Si and III–V nanowires. Furthermore, it is demonstrated that the as‐grown InSe nanowire‐based visible light photodetector simultaneously possesses an extraordinary photoresponsivity of 271 A W^?1, ultrahigh detectivity of 1.57 × 10¹⁴ Jones, and a fast response speed of microsecond scale. The excellent performance of the photodetector indicates that as‐grown InSe nanowires are promising in future optoelectronic applications. More importantly, the proposed edge‐homoepitaxial approach may open up a novel avenue for direct synthesis of semiconducting nanowire arrays on SiO₂/Si substrates.