Akhtar Hussain Malik

Volatile organic compounds (VOCs) are crucial components in many daily-use products, yet they pose a significant threat to public health and the environment, even in minute amounts, due to their high toxicity. Therefore, it is crucial to develop a reliable method that could track these hazardous vapours with high sensitivity and selectivity. Among various techniques, fluorescence-based detection strategies have demonstrated great efficiency in both qualitative and quantitative monitoring of VOCs in real-time. These methods are attractive due to their low cost and portability, making them suitable for on-site applications. This review explores the latest advancements in aggregation-induced emission (AIE)-based fluorescent probes tailored for VOC detection across diverse platforms, highlighting their selectivity, sensitivity, and real-world applications. The use of AIE events has been justified for the development of selective and sensitive sensors for VOC detection. Furthermore, the present work investigates the various sensing mechanisms involved in predicting the AIE nature of the fluorophores. Additionally, we discuss existing challenges and propose future directions for designing next-generation AIE-based VOC sensors with enhanced specificity, stability, and practical usability. Coupled with the latest advancements, AIE-based fluorescence sensing of VOCs could contribute to the structural design of future smart VOC sensors that are highly efficient and effective. Graphical abstract

Over the past decades, significant scientific and technological advancements have been made in the field of forensic science, particularly in the advancement of fingerprint technology. Latent fingerprints (LFPs) are considered to be the most crucial evidence found at crime scenes, necessitating extensive research efforts for their advancement. Conversely, conjugated polymers are extremely adaptable substances that are utilized in many domains like photonics, bio-imaging, optoelectronics, nanomedicine, and more. Conjugated polymers, especially conjugated polymer nanoparticles and polymer dots, exhibit remarkable photophysical and chemical features that contribute to their high resolution, enhanced selectivity, and heightened sensitivity in the development of LFPs. This provides a detailed overview of the production of LFPs utilizing conjugated polymers, as well as the imaging techniques employed for their visualization. Particular attention is given to conjugated polymer nanoparticles and polymer dots. In addition, the most often employed techniques for producing conjugated polymer-based nanoparticles have also been examined. Additionally, it encompasses the historical background of LFP identification and offers a valuable understanding of the diverse conventional approaches investigated for their advancement. This article offers a comprehensive examination of conjugated polymers as contrasting agents for imaging LFPs on different surfaces.

Solid-oxide fuel cells are efficient devices for the conversion of chemical to electrical energy and a typical solid-oxide fuel cell consists of a solid electrolyte, cathode, and anode. In the last few decades, researchers have been working extensively on materials development for different components of these devices. In this review article, we briefly discuss the requirements for different components and review prominent materials families explored by the scientific community. As the search for greener energy alternatives such as solid-oxide fuel cells have intensified manifold due to the climate change emergency, a substantial literature was produced on the materials development of these devices and, therefore, we believe a brief review article dedicated to the same will be valuable for the scientific community, particularly new young entrant researchers in the field.

This article provides a brief review of conjugated polymers and the various typical polymerization reactions exploited by the community to synthesise different conjugated polyelectrolytes with varied conjugated backbone systems. We further discuss with detailed emphasises the mechanism involved such as photo-induced electron transfer, resonance energy transfer, and intra-molecular charge transfer in the detection or sensing of various analytes. Owing to their excellent photo-physical properties, facile synthesis, ease of functionalization, good biocompatibility, optical stability, high quantum yield, and strong fluorescence emission. Conjugated polymers have been explored for wide applications such as chemical and biological sensors, drug delivery and drug screening, cancer therapeutics and imaging. As such we believe it will be a timely review article for the community.

This article provides an elaborate discussion of reports involving the development of latent fingerprints (LFPs) over the past decades with specific emphasis on the contribution of conjugated polymers (CPs) in the field of forensic science. CPs have been explored in the field of interdisciplinary sciences due to their widespread applications in the fields of imaging, chemical and biological sensors, electronic device, cancer therapeutics, etc. Even in the field of forensic sciences, these CP materials are in a continuous race with the existing technology and newer materials for the detection of fingerprint marks on various surfaces thus assisting in the unravelling of the precise identification of an individual suspect in modern criminology. Due to their excellent photophysical and chemical properties such as low toxicity, ease of functionalization, strong fluorescence emission, high quantum yield, and good optical stability, these CPs can lead to high resolution, and increased sensitivity and selectivity in the imaging of LFPs compared to those developed by traditional tedious methods. In this perspective, the challenges faced for LFP development and the role of various CPs including conjugated polyelectrolytes, polymer dots, and polymer nanoparticles are elaborately explained, thus, providing a systematic overview on techniques based on CPs as contrasting agents in the development of LFPs on various porous and nonporous substrates. There are various challenges pertaining to the development of LFPs on a multitude of surfaces which can be addressed by exploring materials with a suitable hydrophobic–hydrophilic balance and a receptor site for specific interactions with fingerprint components. The incorporation of this design principle has successfully led to the development of efficient platforms for rapid, onsite, intricate and unique LFP patterns on every kind of surface.

Considering the vital need to strengthen the national security emanating from chemical threats, a low-cost, portable ultra-sensitive electrical sensor for real-time monitoring of Diethylchlorophosphate (DCP) (nerve gas mimic) has been developed. The device consists of “simple to be fabricated” two-terminal resistor and an electronic combinational circuit for rapid onsite detection of lethal nerve gas vapors with high degree of accuracy in milliseconds. This device is a smart readout electronic model that detects ultra-trace DCP vapors by bright visual alerts from LED and loud alarm signal without the need for employing a sophisticated instrument. To obtain high sensitivity and discriminating response, a novel amine-functionalized Conjugated Polymer (CP) is designed as a sensory channel material for two-terminal sensor. The low powered Poly(3-(9,9-dioctyl-9H-fluoren-2-yl)benzene-1,2-diamine) (PFPDA) fabricated two-terminal electrical sensor is tested at ambient conditions, which shows excellent sensitivity towards nerve gas mimic DCP, with rapid response in 3 sec and very low limit of detection (LOD) of 5.88 ppb. The amine moiety of PFPDA CP plays a vital role in redox interaction between the semiconductor CP and organophosphates, which ultimately leads to the amplified current signal. The redox interactions occurring among the organophosphate analytes and the amine functional group on the PFPDA backbone provided insights into the mechanism of sensing which formed the basis of excellent sensitivity and discriminating ability of this sensor device. The newly designed PFPDA CP-based portable electrical sensor device demonstrates a key contribution in the field of portable electronics for defense safety and environmental monitoring applications.