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The versatile nature of organic conjugated materials renders their flawless integration into a diverse family of optoelectronic devices with light-harvesting, photodetection, or light-emitting capabilities. Classes of materials that offer the possibilities of two or more distinct optoelectronic functions are particularly attractive as they enable smart applications while providing the benefits of the ease of fabrication using low-cost processes. Here, we develop a novel, multi-purpose conjugated small molecule by combining boron-azadipyrromethene (aza-BODIPY) as electron acceptor with triphenylamine (TPA) as end-capping donor units. The implemented donor–acceptor–donor (D–A–D) configuration, in the form of TPA-azaBODIPY-TPA, preserves ideal charge transfer characteristics with appropriate excitation energy levels, with the additional ability to be used as either a charge transporting interlayer or light-sensing semiconducting layer in optoelectronic devices. To demonstrate its versatility, we first show that TPA-azaBODIPY-TPA can act as an excellent hole transport layer in methylammonium lead triiodide (MAPbI3)-based perovskite solar cells with measured power conversion efficiencies exceeding 17%, outperforming control solar cells with PEDOT:PSS by nearly 60%. Furthermore, the optical bandgap of 1.49 eV is shown to provide significant photodetection in the wavelength range of up to 800 nm where TPA-azaBODIPY-TPA functions as donor in near-infrared organic photodetectors (OPDs) composed of fullerene derivatives. Overall, the established versatility of TPA-azaBODIPY-TPA, combined with its robust thermal stability as well as excellent solubility and processability, provides a new guide for developing highly efficient multi-purpose electronic materials for the next-generation of smart optoelectronic devices. Ministry of Education (MOE) National Research Foundation (NRF) Published version Lam Yeng Ming would like to thank the support of the Singapore Ministry of Education Academic Research Fund Tier 2 (Grant No. MOE2019-T2-1-085). Annalisa Bruno and Enkhtur thank the National Research Foundation for the financial support (Grant No. S18-1176-SCRP). Prashant Sonar is thankful to QUT for the financial support from the Australian Research Council (ARC) for the Future Fellowship (Grant No. FT130101337) and QUT core funding (Grant No. QUT/322120-0301/07). Ajay K. Pandey acknowledges support from Australia India Strategic Research Fund (Project AISRF53820).

In this work, we utilise the disulphide bond structure of insulin and a new benzothiazole Raman probe for the detection of human insulin using surface-enhanced Raman spectroscopy (SERS). The disulphide bond structure of the insulin was reduced to generate free sulfhydryl terminal groups. When reacted with benzothiazole-functionalised gold nanoparticles, the reduced protein desorbs the Raman probe and causes its Raman signal intensity to quench. Using this approach, insulin was quantified in the concentration range of 1 × 10-14 -1 × 10-8 M by SERS quenching. The limit of quantification of insulin by the SERS quenching method was found to be 1 × 10-14 M (0.01 pM or 58 pg/L), which satisfies the requirements for monitoring its blood concentration in patients. Because many proteins and peptides have disulphide bonds in their molecular structures, the new SERS quenching method has a strong potential for the rapid determination of ultralow concentrations of proteins in formulations and biological fluids.

Cyanide (CN−) is one of the most hazardous ions to humans and the environment. Therefore, sensitive, and selective sensors for CN− monitoring are highly required. A novel chemosensor based on naphthalene flanked diketopyrrolopyrrole dye (TBC-DPPN) is synthesized for the direct detection of CN− in water samples by naked eye and vibrational spectroscopy (UV–Vis and fluorescence). The electron deficient carbonyl group of the lactam ring of TBC-DPPN undergoes a nucleophilic attack by the CN− thus causing the yellow color of the dye turn to colorless, and fluorescence of the dye at 527 nm to turn-off. The mechanism of CN− sensing by the TBC-DPPN sensor is confirmed by spectral measurements and density functional theory (DFT) calculations. The TBC-DPPN sensor is utilized to determine the CN− by colorimetric and fluorescence methods in water down to 0.5 and 0.05 µm, respectively, which is well below the cut off limit of 1.9 µm that is recommended by the World Health Organization (WHO). Therefore, TBC-DPPN can act as dual channel sensor with high selectivity and sensitivity for the determination of CN− in water.

We have explored the potential of deep Raman spectroscopy, specifically surface enhanced spatially offset Raman spectroscopy (SESORS), for non-invasive detection from within animal tissue, by employing SERS-barcoded nanoparticle (NP) assemblies as the diagnostic agent. This concept has been experimentally verified in a clinic-relevant backscattered Raman system with an excitation line of 785 nm under ex vivo conditions. We have shown that our SORS system, with a fixed offset of 2-3 mm, offered sensitive probing of injected QTH-barcoded NP assemblies through animal tissue containing both protein and lipid. In comparison to that of non-aggregated SERS-barcoded gold NPs, we have demonstrated that the tailored SERS-barcoded aggregated NP assemblies have significantly higher detection sensitivity. We report that these NP assemblies can be readily detected at depths of 7-8 mm from within animal proteinaceous tissue with high signal-to-noise (S/N) ratio. In addition they could also be detected from beneath 1-2 mm of animal tissue with high lipid content, which generally poses a challenge due to high absorption of lipids in the near-infrared region. We have also shown that the signal intensity and S/N ratio at a particular depth is a function of the SERS tag concentration used and that our SORS system has a QTH detection limit of 10-6 M. Higher detection depths may possibly be obtained with optimization of the NP assemblies, along with improvements in the instrumentation. Such NP assemblies offer prospects for in vivo, non-invasive detection of tumours along with scope for incorporation of drugs and their targeted and controlled release at tumour sites. These diagnostic agents combined with drug delivery systems could serve as a “theranostic agent”, an integration of diagnostics and therapeutics into a single platform.

Time‐resolved Raman spectroscopy, spatially offset Raman spectroscopy and time‐resolved spatially offset Raman spectroscopy (TR‐SORS) have proven their capability for the non‐invasive profiling of deep layers of a sample. Recent studies have indicated that TR‐SORS exhibits an enhanced selectivity toward the deep layers of a sample. However, the enhanced depth profiling efficiency of TR‐SORS, in comparison with time‐resolved Raman spectroscopy and spatially offset Raman spectroscopy, is yet to be assessed and explained in accordance to the synergistic effects of spatial and temporal resolutions. This study provides a critical investigation of the depth profiling efficiency of the three deep Raman techniques. The study compares the efficiency of the various deep Raman spectroscopy techniques for the stand‐off detection of explosive precursors hidden in highly fluorescing packaging. The study explains for the first time the synergistic effects of spatial and temporal resolutions in the deep Raman techniques and their impact on the acquired spectral data. Copyright © 2013 John Wiley & Sons, Ltd.

Current concerns regarding terrorism and international crime highlight the need for new techniques for detecting unknown and hazardous substances. A novel Raman spectroscopy-based technique, spatially offset Raman spectroscopy (SORS), was recently devised for non-invasively probing the contents of diffusely scattering and opaque containers. Here, we demonstrate a modified portable SORS sensor for detecting concealed substances in-field under different background lighting conditions. Samples including explosive precursors, drugs and an organophosphate insecticide (chemical warfare agent surrogate) were concealed inside diffusely scattering packaging including plastic, paper and cloth. Measurements were carried out under incandescent and fluorescent light as well as under daylight to assess the suitability of the probe for different real-life conditions. In each case, it was possible to identify the substances against their reference Raman spectra in less than one minute. The developed sensor has potential for rapid detection of concealed hazardous substances in airports, mail distribution centers and customs checkpoints.