Composite track-etched membranes (CTeMs) emerged as a versatile and high-performance class of materials, combining the precise pore structures of traditional track-etched membranes (TeMs) with the enhanced functionalities of integrated nanomaterials. This review provides a comprehensive overview of the synthesis, functionalization, and applications of CTeMs. By incorporating functional phases such as metal nanoparticles and conductive nanostructures, CTeMs exhibit improved performance in various domains. In environmental remediation, CTeMs effectively capture and decompose pollutants, offering both separation and detoxification. In sensor technology, they have the potential to provide high sensitivity and selectivity, essential for accurate detection in medical and environmental applications. For energy storage, CTeMs may be promising in enhancing ion transport, flexibility, and mechanical stability, addressing key issues in battery and supercapacitor performance. Biomedical applications may benefit from the versality of CTeMs, potentially supporting advanced drug delivery systems and tissue engineering scaffolds. Despite their numerous advantages, challenges remain in the fabrication and scalability of CTeMs, requiring sophisticated techniques and meticulous optimization. Future research directions include the development of cost-effective production methods and the exploration of new materials to further enhance the capabilities of CTeMs. This review underscores the transformative potential of CTeMs across various applications and highlights the need for continued innovation to fully realize their benefits.

Track-etched membranes (TeMs) have emerged as a promising class of nanostructured materials for the development of advanced sensing platforms. Owing to their highly uniform pore architecture, controllable dimensions, and versatile surface chemistry, TeMs can be used to create highly sensitive, selective, and robust sensors. This review provides a comprehensive overview of recent advances in the use of TeMs for sensor development, with a particular emphasis on functionalization strategies and application domains. The review discusses stimuli-responsive TeMs in detail which are capable of dynamic switching in response to environmental triggers such as pH, temperature, light, or redox. Functional nanochannels engineered through various modifications, such as polymer grafting or metal-organic frameworks incorporation, exhibit unique ionic transport behaviors suitable for real-time detection and biomimetic sensing. TeMs have also shown considerable potential in the detection of toxic metal ions, where tailored chemical groups and hybrid interfaces enable sub-ppb sensitivity in complex matrices. Furthermore, their capacity to host biomolecules like DNA probes, antibodies, or enzymes opens avenues for biosensing applications, including clinical diagnostics, virus detection, and neurotransmitter detecting. Additionally, their integration into wearable devices highlights their potential for flexible, real-time health monitoring. Challenges related to large-scale manufacturing, long-term stability, and standardization remain and are addressed in this review. Looking forward, TeMs have potential to bridge the gap between lab-scale innovation and practical sensor technologies, offering solutions for environmental, biomedical, and industrial applications.

This study investigates the catalytic properties of mono- and bimetallic composite track-etched membranes (CTeMs) fabricated using a galvanic replacement strategy. Two bimetallic architectures, Ag/Cu@PET and Cu/Ag@PET, were synthesized by sequentially depositing copper and silver onto poly(ethylene terephthalate) (PET) templates. X-ray diffraction analysis revealed that doping Cu@PET with silver nanoparticles formed a substitutional solid solution (Ag₉₇Cu₃), which increased crystallinity by >45 % compared to monometallic Cu@PET. In contrast, doping Ag@PET with copper produced a two-layer tubular structure with phase-separated copper co-deposited along silver microtubes. The catalytic performance was evaluated through the pseudo-first-order reduction of potassium ferricyanide (PFC) by sodium borohydride. The Cu/Ag@PET composite with separate phases demonstrated superior activity, achieving 94.3 % PFC reduction within 40 minutes, significantly exceeding the performance of monometallic Ag@PET and Cu@PET. Kinetic analysis indicated that the rate constant and activation energy strongly depended on membrane structure and silver doping time in case of formation of substitutional solid solution phase. A minimum doping duration of 20 minutes was required for performance enhancement, with 30-minute Ag/Cu@PET samples reducing activation energy from 62.35 kJ/mol to 32.67 kJ/mol. These findings highlight the critical role of metal deposition order and structural configuration in optimizing catalytic activity, demonstrating the efficacy of galvanic replacement for designing high-performance, multi-metallic membrane catalysts.

Biodegradable gel-polymer electrolytes (GPEs) represent a promising alternative to liquid electrolytes and synthetic separators in solid-state supercapacitors for wearable electronics, biomedical devices, and autonomous sensors. They offer enhanced safety, prevent electrolyte leakage, increase device flexibility, and reduce environmental impact. This review systematizes current approaches to the development of biodegradable GPEs based on chitosan, alginate, gelatin, cellulose and its derivatives, starch, lignin, polylactic acid, and other polymers. Methods of modification (crosslinking, functionalization, compositing, incorporation of nanofillers) and mechanisms of ion transport in gel matrices are considered. Particular attention is paid to the influence of the electrolyte on ionic conductivity, equivalent series resistance (ESR), operating voltage, and cyclic stability. The main limitations of biodegradable GPEs and prospects for the development of “green solid-state energy storage devices are discussed.