Small

Zhang, Qing; Chen, Dezhi; Liu, Xiaomeng; Deng, Zhewen; Li, Jiaqi; Zhu, Senqiang; Ma, Bo; Liu, Rui; Zhu, Hongjun

doi: 10.1002/smll.202403165pmid: 39246173

The development of small molecule photosensitizers based on iridium complex is limited by the mismatch between therapeutic effect and systemic toxicity, as well as the incomplete understanding of the molecular mechanism underlying cell death induction. Herein, a small molecule iridium complex IrC with high photocytotoxicity is synthesized, with half maximal inhibitory concentration as low as 91 nm, demonstrating excellent anti‐tumor, relief of splenomegaly, and negligible side effects. Starting from the factors of effective photosensitizers, the in‐depth theoretical analysis on photon absorption efficiency, energy transfer level matching, and properties of the triplet excited state of IrC is conducted. This also elucidates the feasibility of generating the high singlet oxygen quantum yield. In addition, the death mechanism induced by IrC is focused, innovatively utilizing GPX4‐overexpression and GPX4‐knockout cells via CRISPR/Cas9 technique to comprehensively verify ferroptosis and its further molecular mechanism. The generation of ROS mediated by IrC, along with the direct inhibition of GPX4 and glutathione, synergistically increased cellular oxidative stress and the level of lipid peroxidation. This study provides an effective approach for small molecule complexes to induce GPX4‐dependent ferroptosis at low‐dose photodynamic therapy.

Ghosh, Souvik; Dhiman, Megha; Chauhan, Samrat; Roy, Partha; Lahiri, Debrupa

doi: 10.1002/smll.202410735pmid: 40079164

Peripheral nerve injuries (PNIs) often lead to semi or complete loss of motor, sensory and autonomic functions. Although autografts are still the best option for PNI repair, their use is restricted due to the morbidity and availability of donor nerves. Because electrospun scaffolds may replicate the structure of native extracellular matrix (ECM), they provide a viable alternative. The present study represents a dual‐functional scaffold that combines the neuroprotective and antioxidant capabilities of Bacopa monnieri extract with the mechanical and electrical characteristics of polycaprolactone (PCL)‐collagen fibers reinforced with multi‐walled carbon nanotubes (MWCNTs). The anisotropic alignment of MWCNTs enhances conductivity of the scaffold and provides directional cues for growth of the axons, while secondary metabolites of Bacopa monnieri, such as bacosides, promote neuronal survival and mitigate oxidative stress. In vitro, the scaffold lowers oxidative stress while promoting adhesion, proliferation, and differentiation of the neural cells. Utilizing an in vivo model of sciatic nerve crush damage, nerve regeneration is evaluated and improvements in axonal development, myelination, and recovery of motor‐sensory function are seen. This biofortified scaffold offers a sustainable substitute for traditional growth factors and pharmaceutical drugs by exploiting the synergistic effects of electrical conductivity and plant‐based bioactivity to promote peripheral nerve regeneration.

Yin, Xue; Chen, Jia; Li, Xin; He, Qifang; Zhang, Junping; Shu, Yang; Wang, Jianhua; Chen, Banglin; Qiu, Hongdeng

doi: 10.1002/smll.202500066pmid: 40095341

In this work, a novel 1D metal‐mediated hydrogen‐bonded framework with rich phenyl groups is first synthesized employing Co2+ and dibenzoylmethane (DBM) as precursors, which are named HOF‐Co‐DBM and exhibit exceptional thermal stability, excellent chemical durability, and super hydrophobicity. These distinctive properties can be attributed to the high density, robust Co─O coordination bonds, and the presence of strong hydrogen bonds (O─H─O─C) characterized by short bond distances, which contribute to its close‐packed structure. Additionally, the benzene rings flanking the framework further enhance its hydrophobicity. The HOF‐Co‐DBM is subsequently integrated into a polyurethane (PU) sponge, resulting in exceptional oil removal performance. This study demonstrates the potential for preparing ultra‐stable and superhydrophobic hydrogen‐bonded organic framework materials with a wide range of applications.

Gao, Yanjing; Shirinichi, Farbod; Hansrisuk, Audrey; Zhu, Runyao; Xian, Sijie; Lieberman, Marya; Webber, Matthew J.; Wang, Yichun

doi: 10.1002/smll.202407702pmid: 39707651

Synthetic opioids, especially fentanyl and its analogs, have created an epidemic of abuse and significantly increased overdose deaths in the United States. Current detection methods have drawbacks in their sensitivity, scalability, and portability that limit field‐based application to promote public health and safety. The need to detect trace amounts of fentanyl in complex mixtures with other drugs or interferents, and the continued emergence of new fentanyl analogs, further complicates detection. Accordingly, there is an urgent need to develop convenient, rapid, and reliable sensors for fentanyl detection. In this study, a sensor is prepared based on competitive displacement of a fluorescent dye from the cavity of a supramolecular macrocycle, with subsequent fluorescence quenching from graphene quantum dots. This approach can detect and quantify small quantities of fentanyl along with 58 fentanyl analogs, including highly potent variants like carfentanil that are of increasing concern. Detection of these agents is possible even at 0.01 mol% in the presence of common interferents. This simple, rapid, reliable, sensitive, and cost‐effective approach couples supramolecular capture with graphene quantum dot nanomaterial quenchers to create a tool with the potential to advance public health and safety in the context of field‐based detection of drugs in the fentanyl class.

Nguyen, Tran Thien An; Tran, Khoa Dang; Tran, Duy Thanh; Sidra, Saleem; Kim, Do Hwan; Kim, Nam Hoon; Lee, Joong Hee

doi: 10.1002/smll.202412435pmid: 40109132

To reach sustainable and robust green hydrogen energy production, the development of effective and long‐lasting electrocatalysts for hydrogen and oxygen evolution reactions (HER and OER) during overall electrochemical water splitting is a critical requirement. In this study, a novel hierarchical nanosheet‐based hollow heterostructure of CoxSy‐CoO integrated with active iridium clusters (IrCs‐CoxSy‐CoO) is prepared by a straightforward chemical synthesis approach. The heterostructure offers extensive tunnels, and abundant mesopores, and features a high‐density active site at the interfaces, thus greatly improving the overall catalytic performance through the promotion of synergistic effects. The IrCs‐CoxSy‐CoO catalyst demonstrates low overpotentials of 97 mV for HER and 243 mV for OER at 10 mA cm−2, showcasing remarkable stability and efficiency. The two‐electrode cell test demonstrates reliable current response of 10 mA cm−2 at voltage of 1.497 and 1.58 V at temperature of 75 and 25 °C, respectively. Furthermore, the IrCs‐CoxSy‐CoO catalyst exhibits enhanced durability and performance when compared to the Pt/C(−)//RuO2(+). In practical application, significant current of 0.5/1.0 A cm−2 at 1.8/1.97 V has been achieved in an anion exchange membrane electrolyzer stack, while maintaining high efficiency (68%) and exceptional stability (over 500 h), underscoring the promising potential for sustainable H2 energy production.

Zhu, Jing; Jin, Yuxin; Wu, Yunyun; Mo, Dong; Zhang, Tingting; Xiang, Lunli; Cai, Kaiyong; Zhang, Jixi

doi: 10.1002/smll.202411336pmid: 40059567

The dynamic process in tumor ablation requires both the generation of reactive oxygen species (ROS) to elicit immunogenic cell death (ICD) and the subsequent reduction of ROS levels to maintain the stimulatory activity of signaling proteins and recover T cells’ immune function. Inspired by the regulation mechanism of redox homeostasis in myeloid‐derived suppressor cells and the high‐selectivity in alcohols/aldehydes conversions of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and Fe(III) synergistic catalysis, photoenzymatic modulators with contradictory but synergistic functions are developed for adaptive photo‐immunotherapy of cancer. In particular, poly(caffeic acid) (PCA) nanospheres are synthesized by highly efficient oxidative polymerization of CA. The obtained π‐conjugated structures have an extended absorbance in the near‐infrared (NIR) region, narrow band energy (0.86 eV), and low exciton binding energy (43.56 meV) that lead to polymerization‐enhanced type I photosensitization and photostability. Meanwhile, abundant semiquinone radicals existing in PCA bestow them with superior antioxidant function. Under NIR irradiation, the elevated superoxide radical yields (3.5‐fold compared with CA) and heat stress elicit robust ICD. When irradiation ceases, active species downregulation and the infiltration of T lymphocytes increase by 2.7‐fold compared with conventional photosensitizers. As envisaged, this work demonstrates a novel tactic to remodel redox and immune homeostasis for effective inhibition of tumor growth and metastasis.

Weiß, Lennart J. K.; Nikić, Marta; Simmel, Friedrich C.; Wolfrum, Bernhard

doi: 10.1002/smll.202410306pmid: 40079073

This study uses single‐impact experiments to explore how the nanoparticles’ surface chemistry influences their redox activity. 20 and 40 nm‐sized silver nanoparticles are functionalized with alkanethiol ligands of various chain lengths (n = 3, 6, 8, and 11) and moieties (carboxyl ─COOH / hydroxyl ─OH), and the critical role of the particle shell is systematically examined. Short COOH‐terminated ligands enable efficient charge transfer, resulting in higher impact rates and fast, high‐amplitude transients. Even elevated potentials fail to overcome tunneling barriers for ligand lengths of n ≥ 6 and risk oxidizing the electrode, forming an insulating layer. Electrostatic interactions play a key role in governing reaction dynamics. In general, particles with a COOH‐group exhibit higher impact rates and current amplitudes in KCl than those with an OH‐group. This effect is more pronounced for 40 nm‐sized particles; although, they rarely oxidize completely. The influence of electrolyte composition—concentration, pH, and a biologically relevant electrolyte—reveals that its impact on the redox activity can be as critical as that of the particle shell, with both determining particle adsorption and electron tunneling. These findings provide insights into the complex interdependencies at the electrode–particle–electrolyte interface, aiding the design of custom redox‐active (silver) nanoparticles for ultrasensitive electrochemical sensing.

Kumar, Manish; Singh, Sugandha; Samanta, Debabrata; Kar, Kamal K.; Ghorai, Manas K.

doi: 10.1002/smll.202500502pmid: 40059498

At present time the ever‐increasing demand for clean energy can only be met by renewable and green energy sources. One of the alternatives is the easy production and supply of hydrogen as an energy source. As an attempt to provide an alternate strategy for hydrogen production from easily available sources under mild conditions, novel metal‐free conjugated porous organic polymers (POPs) named tris(4‐aminophenyl)amine‐OMe (TPA‐OMe) and tris(4‐aminophenyl)amine‐NO2 (TPA‐NO2) which act as electrocatalysts for electrocatalytic hydrogen production and exhibit excellent hydrogen evolution reaction (HER) activity with the overpotential (η10) of 353 and 430 mV, respectively, at the current density of 10 mA cm−2 and low Tafel slope, are judiciously designed and synthesized. The electrocatalytic stability of the catalysts is excellent in the acidic electrolyte (0.5 m H2SO4) up to the 500th cycle, and a reduction of overpotential has also been observed. In chronoamperometry analysis, the current density remains constant up to 12 h which shows the excellent durability of the catalysts. The successful studies for the production of hydrogen gas and the catalytic activities of the aforementioned electrocatalysts (TPA‐OMe, TPA‐NO2) are reported.

Zhang, Yanlin; Yin, Hongting; Yao, Shun; Li, Siyu; Zhou, Keqi; Liu, Ruiping

doi: 10.1002/smll.202412398pmid: 40051251

Lithium metal batteries (LMBs) suffer from severe lithium dendrite growth and side reactions in conventional carbonate electrolytes, which are characterized by low coulombic efficiency and poor cycling stability, and electrolyte engineering is an effective method for increasing the reversibility of lithium anodes. Herein, the solubility of lithium nitrate (LiNO3), which is almost insoluble in carbonate electrolyte, is improved by adding zinc trifluoroacetate (Zn(TFA)2), and a competitive solvation structure is constructed, forming an anion‐enriched Li+ solvation structure, which is conducive to the formation of stable SEI and effectively inhibits adverse side reactions. The lithium metal anode exhibits uniform lithium deposition and extended cycle life, with high reversibility over plating/stripping for 640 h. Furthermore, the Li||LFP full cell with the upgraded carbonate electrolyte can operate steadily for over 300 cycles at 1 C, and the compatibility of the lithium anode with the high‐voltage NCM811 cathode are also significantly improved. This work provides a feasible strategy for dependable interfacial chemistry of lithium metal anodes.

Lee, Jeewon; Kim, Heebae; Jeon, Young Pyo; Jin, Huding; Cho, Jinil; Pyo, Seonmi; Yun, Heejun; Min, Byeongyun; Han, Juyeon; Yoo, Jeeyoung; Kim, Youn Sang

doi: 10.1002/smll.202412799pmid: 40059468