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Among a promising photovoltaic technology for solar energy conversion, organic solar cells (OSCs) have been paid much attention, of which the power conversion efficiencies (PCEs) have rapidly surpassed over 20%, approaching the threshold for potential applications. However, the device stability of OSCs including storage stability, photostability and thermal stability, remains to be an enormous challenge when faced with practical applications. The major causes of device instability are rooted in the poor inherent properties of light‐harvesting materials, metastable morphology, interfacial reactions and highly sensitive to external stresses. To get rid of these flaws, a comprehensive review is provided about recent strategies and methods for improving the device stability from active layers, interfacial layers, device engineering and encapsulation techniques for high‐performance OSC devices. In the end, prospectives for the next stage development of high‐performance devices with satisfactory long‐term stability are afforded for the solar community. [ABSTRACT FROM AUTHOR]

Poisson's ratio in auxetic materials shifts from typically positive to negative, causing lateral expansion during axial tension. This scale‐independent characteristic, originating from tailored architectures, exhibits specific physical properties, including energy adsorption, shear resistance, and fracture resistance. These metamaterials demonstrate exotic mechanical properties with potential applications in several engineering fields, but biomedical applications seem to be one of the most relevant, with an increasing number of articles published in recent years, which present opportunities ranging from cellular repair to organ reconstruction with outstanding mechanical performance, mechanical conduction, and biological activity compared with traditional biomedical metamaterials. Therefore, focusing on understanding the potential of these structures and promoting theoretical and experimental investigations into the benefits of their unique mechanical properties is necessary for achieving high‐performance biomedical applications. Considering the demand for advanced biomaterial implants in surgical technology and the profound advancement of additive manufacturing technology that are particularly relevant to fabricating complex and customizable auxetic mechanical metamaterials, this review focuses on the fundamental geometric configuration and unique physical properties of negative Poisson's ratio materials, then categorizes and summarizes auxetic material applications across some surgical departments, revealing efficacy in joint surgery, spinal surgery, trauma surgery, and sports medicine contexts. Additionally, it emphasizes the substantial potential of auxetic materials as innovative biomedical solutions in orthopedics and demonstrates the significant potential for comprehensive surgical application in the future. [ABSTRACT FROM AUTHOR]

Photochemical internalization is an efficient strategy relying on photodynamic reactions to promote siRNA endosomal escape for the success of RNA‐interference gene regulation, which makes gene‐photodynamic combined therapy highly synergistic and efficient. However, it is still desired to explore capable carriers to improve the delivery efficiency of the immiscible siRNA and organic photosensitizers simultaneously. Herein, we employ a micellar nanostructure (PSNA) self‐assembled from polymer‐DNA molecular chimeras to fulfill this task. PSNA can plentifully load photosensitizers in its hydrophobic core simply by the nanoprecipitation method. Moreover, it can organize siRNA self‐assembly by the densely packed DNA shell, which leads to a higher loading capacity than the typical electrostatic condensation method. The experimental results prove that this PSNA carrier can greatly facilitate siRNA escape from the endosome/lysosome and enhance transfection. Accordingly, the PSNA‐administrated therapy exhibits a significantly improved anti‐tumor efficacy owing to the highly efficient co‐delivery capability. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR)‐II fluorescence imaging‐guided photothermal therapy (PTT) has attracted great research interest, and constructing donor‐acceptor (D‐A) electronic configurations has become an established approach to lower bandgap and realize NIR‐II emission. However, very few π‐conjugated phototheranostic agents can realize efficient NIR‐II guided PTT using a clinically safe laser power density, implying that sufficient photothermal performance is still desired. In addition to the continuously refreshed photothermal conversion efficiency levels, the strategies that focus on enhancing light absorptivity have been rarely discussed and endow a new direction for enhancing PTT. Herein, a dimerization π‐extension strategy is raised to synthesize π‐conjugated dimers with A‐D‐A monomers. We observe that the light absorptivity (ε) of the dimers is strengthened three times owing to the enhanced electronic coupling effect as a result of the π‐conjugation extension, thereby surpassing the 2‐fold increase in chromophore numbers from the monomer to dimers. Thanks to the enhancement in light absorption, the dimers could generate much more photothermal heat than the monomer in in vivo PTT treatments. Therefore, an efficient anti‐tumor outcome has been fulfilled by using dimers under a low laser power (0.3 W/cm2). Moreover, the dimers with extended π‐conjugation structures become more favorable to the radiative excited state decay, thus exhibiting a distinguishing improvement in NIR‐II imaging compared with monomer. Collectively, due to the improved light absorptivity, the dimers can gain superior NIR‐II fluorescence brightness and photothermal performance over the recently reported material, which goes beyond the monomer in double doses for in vivo applications. All these results prove that dimerization is an effective strategy for designing high‐performance phototheranostic materials. [ABSTRACT FROM AUTHOR]

Deep NIR organic phototheranostic molecules generally have large π‐conjugation structures and show highly hydrophobic properties, thus, forming strong π–π stacking in the aqueous medium, which will affect the phototheranostic performance. Herein, an end‐group strategy is developed to lift the performance of NIR‐II emitting photosensitizers. Extensive characterizations reveal that the hydrogen‐bonding interactions of the hydroxyl end group can induce a more intense π–π electronic coupling than the chlorination‐mediated intermolecular forces. The results disclose that π–π stacking will lower fluorescence quantum yield but significantly benefit the photodynamic therapy (PDT) efficiency. Accordingly, an asymmetrically substituted derivative (BTIC‐δOH‐2Cl) is developed, which shows balanced phototheranostic properties with excellent PDT efficiency (14.6 folds of ICG) and high NIR‐II fluorescence yield (2.27%). It proves the validity of the end‐group strategy on controlling the π–π interactions and rational tuning the performance of NIR‐II organic phototheranostic agents. [ABSTRACT FROM AUTHOR]

NIR‐II fluorescence imaging–guided photothermal therapy (PTT) has been widely investigated due to its great application potential in tumor theranostics. PTT is an effective and non‐invasive tumor treatment method that can adapt to tumor hypoxia; nevertheless, simple and effective strategies are still desired to develop new materials with excellent PTT properties to meet clinical requirements. In this work, we developed a bromine‐substitution strategy to enhance the PTT of A‐D‐A'‐D‐A π‐conjugated molecules. The experimental results reveal that bromine substitution can notably enhance the absorptivity (ϵ) and photothermal conversion efficiency (PCE) of the π‐conjugated molecules, resulting in the brominated molecules generating two times more heat (ϵ808 nm×PCE) than their unsubstituted counterpart. We disclose that the enhanced photothermal properties of bromine‐substituted π‐conjugated molecules are a combined outcome of the heavy‐atom effect, enhanced ICT effect, and more intense bromine‐mediate intermolecular π–π stacking. Finally, the NIR‐II tumor imaging capability and efficient PTT tumor ablation of the brominated π‐conjugated materials demonstrate that bromine substitution is a promising strategy for developing future high‐performance NIR‐II imaging‐guided PTT agents. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is a non-invasive imaging technology to diagnose health conditions, showing the weakness of low sensitivity. Herein, we synthesize a contrast agent, SPIO@SiO2@MnO2, which shows decreased T1 and T2 contrast intensity in normal physiological conditions. In the acid environment of tumor or inflamed tissue, the manganese dioxide (MnO2) layer decomposes into magnetically active Mn2+ (T1-weighted), and the T1 and T2 signals are sequentially recovered. In addition, both constrast quenching-activation degrees of T1 and T2 images can be accurately regulated by the silicon dioxide (SiO2) intermediate layer between superparamagnetic iron oxide (SPIO) and MnO2. Through the "dual-contrast enhanced subtraction" imaging processing technique, the contrast sensitivity of this MRI contrast agent is enhanced to a 12.3-time difference between diseased and normal tissue. Consequently, SPIO@SiO2@MnO2 is successfully applied to trace the tiny liver metastases of approximately 0.5 mm and monitor tissue inflammation. Magnetic resonance imaging (MRI) is a well-established non-invasive medical imaging technology. Here, to improve the performance of the technique, the authors describe the design of a pH-responsive T1-T2 dual-modal MRI contrast agent, showing enhanced imaging sensitivity in preclinical cancer models. [ABSTRACT FROM AUTHOR]

The morphological transformation from microspheres to helical supramolecular nanofibers with controllable handedness is achieved by the introduction of molecular chirality based on amino acid derivatives (TDAP), and the chirality of the supramolecular architectures that are achieved is nullified through the coassembly of the equivalent TDAP enantiomers. The molecular detection of achiral melamine based on the R‐TDAP‐COOH supramolecular system is achieved by the appearance of helicity and inversion. [ABSTRACT FROM AUTHOR]