Selective recognition of ammonia and aliphatic amines by C-N fused phenazine derivative: A hydrogel based smartphone assisted 'opto-electronic nose' for food spoilage evaluation with potent anti-counterfeiting activity and a potential prostate cancer biomarker sensor

Abstract

In real day scenario, it is an urge to provide a single solution of multiple problems. In this regard, herein rapid, selective and highly efficient chromo-fluorogenic detection of ammonia/aliphatic amines over aromatic amines has been investigated by means of a novel "opto-electronic nose", CN-2, synthesized in a single-step via multiple inter/intramolecular C-N fusion reactions. The in-situ generated mono-protonated CN-2 can selectively detect primary to secondary to even tertiary aliphatic amines over aromatic amines within ∼40 S with extremely low detection threshold values of 27.2 ppb, 0.7 ppm, 5.4 ppm, 1.7 ppm from UV-Vis and 42.5 ppb, 1.61 ppm, 5.5 ppm, 6.14 ppm from fluorescence spectral data for NH₃, hydrazine (primary amine), diethanolamine (secondary amine) and triethylamine (tertiary amine) respectively with the hypsochromic shift in the UV-Vis spectra along with fluorescence attenuation via target-specific deprotonation. The colorimetric signal can also be examined by Smartphone APP, which is well correlated with spectrophotometric outcomes. Interestingly, due to presence of a unique protonated antenna centre CN-2 with anti-oxidant activity can also detect aliphatic biogenic amines, like putrescine, spermidine, which are frequently released from spoiled food. Therefore, it may be exploited as smart food-spoilage indicator in real-time. Again, the aliphatic biogenic amines recognition capability from human urine made it as a potential prostate cancer biomarker sensor for clinical use, which alleviates the need of biopsies. CN-2 could also be employed towards one-to-two decoder logic-circuitry formulation to monitor the ammonia levels. Moreover, CN-2-functionalized hydrogel-membrane based portable, handy prototype could be utilized for easy on-site recognition of amine vapour. Reversible sensing behaviour in presence of HCl enables CN-2 to exhibit anti-counterfeiting activity. To the best of our knowledge, this is the first all-in-one phenazine-based Smartphone-assisted chromo-fluorogenic-chemosensor, which would be of enormous interest in food-packaging industry, information technology as well as in early-stage-cancer diagnosis.

Keywords: Ammonia/aliphatic amines detection; Anti-counterfeiting activity; C-N fusion; Food spoilage indicator; Hydrogel-based prototype; Smartphone application.