1596 J. Indian Chem. Soc., Vol. 97, No. 9b, September 2020, pp. 1596-1603 Functionalization of silver nanoparticles with 1-naphthol-4-sulfonate for evaluation of ethylenediamine and diethylenetriamine Subanti Das, Shaktibrata Roy, Nishithendu Bikash Nandi, Shamim Ahmed Khan, Moumita Majumdar and Tarun Kumar Misra* Department of Chemistry, National Institute of Technology Agartala, Agartala-799 046, Tripura, India E- mail: tkmisra70@yahoo.com, tkmisra.chem@nita.ac.in Manuscript received online 30 June 2020, accepted 25 July 2020 Direct determination of polyamines (PAs) is an acute problem as PAs are not having any chromophoric or fluorophoric groups. Thus, a sensor is highly demanding to be developed for determining without derivatizing PAs from their aqueous solutions. In this context, functionalized metal nanoparticles (MNPs) having surface Plasmon resonance (SPR) band in the UV-Vis re- gion could be the ultimate choice. Citrate stabilized spherical silver nanoparticle (cit-SNPs, d = 6.3 nm,  = 1.23) were thus synthesized and functionalized with a photoacid, 1-naphthol-4-sulfonic (1Np4S) acid. The 1Np4S exhibits absorption maxima at 330 nm in water and pH > 7, which is the characteristic band of its anionic form. It shows two well defined excitation peaks (  ex ) at 280 nm and 370 nm and an emission peak (  em ) at 434 nm. Thus, 1Np4S is a fluorescent active species. In 1Np4S functionalized cit-SNPs, the fluorescent activity is ceased by the particles, because 1Np4S species get adsorbed onto the surface of cit-SNPs. The adsorption constant ( K ad ) was determined using quenching phenomenon occurring at excitation and emission wavelengths of 1Np4S which is very high ranging, 6.23×10 8 –16.47×10 8 M –1 , indicating very strong interaction of the photoacid, 1Np4S with the cit-SNPs. The 1Np4S functionalized cit-SNPs were then used as nanoprobe for evaluating polyamines: ethylenediamine (EDA) and diethylenetriamine (DETA), as mimic of biogenic amines (BGAs). The calibration curves of EDA and DETA are straight lines with concentration ranges, (5.9–52.1 mM) and (3.9–50.6 mM), respectively. The result indicates that the sensitivity of evaluating DETA is higher than that of EDA. Keywords: Silver nanoparticles, functionalization, adsorption constant, polyamines, fluorometric nanoprobe. Introduction Aliphatic polyamines are well known bioamines found in animals and plants and important analytical, medical, pesti- cides, dyestuffs and packaging reagents 1,2 . Generally, polyamines in low concentration are not considered toxic substances to individuals but of course in high concentra- tion. The point of concern is their secondary role. They are prone to form nitrosated derivatives in the presence of nitrite or act as precursors for other compounds forming carcino- genic nitrosamines 3–5 . They are the cause of histamine-tox- icity 6–9 as well. Moreover, ethylenediamine (EDA) and diethylenetriamine (DETA), the two simplest diamine and triamine, respectively are used as food additives or mono- mer in food packaging materials 2 . Their water solubility makes them environment contaminants. For example, EDA forms corrosive, toxic and irritating mist with the moisture in humid air, which may cause serious health damage 10 . EDA and DETA could be considered as mimic of biogenic diamines (putrescine (PUT), cadaverine (CAD)) and triamines (sper- midine (SPD)) (Scheme 1). Biogenic amines (BGAs) are in- voluntarily present in foods 11 and food products. They trig- ger many physiological and toxicological effects on human health 11–13 . Thus, the development of methodology for evalu- ation of polyamines (PAs) from water media is remained chal- lenging and demanding. Scheme 1. Molecular structures of EDA and DETA and mimicking bio- genic amines: putrescine (PUT), cadaverine (CAD), and spermidine (SPD).