TY - CONF A1 - Prakash, Swayam T1 - Silane Functionalized Paper Test Strips for Rapid and Sensitive Faecal Pigments Detection towards On-site Water Quality Testing N2 - Introduction. W.H.O estimated that globally at least 2 billion people use drinking water sources contaminated with faeces and according to UNICEF, most of these faecal detection methods are expensive, time-consuming (18–24 h time to result), and, with few exceptions, not suited for on-site analysis. Hence, there is an urgent need for the development of analytical methods that allow to unequivocally test for drinking water quality directly on-site. Aims. Development of rapid and sensitive fluorescence based analytical methods for faecal pigments (FPs) detection towards on-site water quality testing. Methods. Silane functionalized glass fiber paper test strips were developed for the sensitive drop-&-detect analysis of FPs. Drop casting of water samples containing faecal pigment on specifically functionalized test strips allowed the sensitive detection of FPs with a smartphone coupled to a 3D printed optical setup. Results. A series of silanes were used to functionalize glass fiber paper and tune its hydrophobicity, exploiting the influence of matrix tailoring to enhance binding of the Zn salt used as co-reagent to urobilin for optimal fluorescence response. Combination of bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane with zinc chloride-impregnated test strips demonstrated optimum fluorescence response for sensitive (nano- and sub-nanomolar concentration) smartphone-based faecal pigments detection. The obtained fluorescence sensing results were validated with a benchtop fluorometer. Furthermore, the developed analytical method was successfully applied to the analysis of real water samples. Conclusions. The possibilities of matrix tailoring and co-reagent nature on the development of a rapid, sensitive, and embedded fluorescence-based on-site strip test are presented and discussed. This technique has potential application for faecal biomarker detection/primary screening for water quality in developing countries, where sophisticated instruments may not be available. T2 - 18th Conference of Methods and Applications in Fluorescence CY - Valencia, Spain DA - 08.09.2024 KW - Faecal contamination KW - Fluorescence KW - Metal complexes KW - Water analysis PY - 2024 AN - OPUS4-61479 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prakash, Swayam T1 - Fluorescence Spectroscopy as an Analytical Tool for Rapid and Sensitive Faecal Pigments Detection: From Fundamentals to Onsite Applications N2 - W.H.O estimated that globally at least 2 billion people use drinking water sources contaminated with faeces [1] and according to UNICEF, most of these faecal detection methods are expensive, time-consuming (18–24 h time to result),[2] and, with few exceptions, not suited for on-site analysis.[3] Hence, there is an urgent need for the development of analytical methods that allow to unequivocally test for drinking water quality directly on-site. Today, microbial detection methods primarily targeting E. coli, the major faecal indicator bacteria, are still the prevalent methods for detecting faecal contamination of drinking and recreational waters. As an alternative, Schlesinger proposed the detection of urobilin (UB), a metabolic degradation product of haemoglobin occurring in all mammals, as faecal indicator pigment (FIP) through enhancement of its weak fluorescence by complexation with Zn2+ in alcoholic media already 120 years ago.[4] However, the major limitation of this method is the only weak enhancement of the intrinsically very weak UB fluorescence in aqueous media, requiring either the use of organic solvents or very sensitive instrumentation to reach the relevant detection limits, hampering the method’s use outside of a laboratory environment.[3] In the present work, we addressed the shortcomings relying on interfacial and supramolecular chemistry as well as materials functionalization, transforming Schlesinger’s approach into a fluorometric ‘drop and detect’ assay using a smartphone coupled to a 3D-printed optical setup as a simple and portable device. A series of silanes were used to functionalize glass fibre paper and tune its hydrophobicity, exploiting the influence of matrix tailoring to enhance binding of the Zn salt used as co-reagent to UB for optimal fluorescence response. Combination of bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane and N-octyltrimethoxysilane with ZnCl2-impregnated test strips showed the best response for sensitive (nano- and sub-nanomolar concentration) smartphone-based FIP detection. The obtained fluorescence sensing results were validated with a benchtop fluorometer. Furthermore, the developed analytical method was successfully applied to the analysis of real water samples, allowing for the first time to test for faecal water contamination directly on site in a very short time of few minutes. T2 - Anakon 2025 CY - Leipzig, Germany DA - 10.03.2025 KW - Faecal contamination KW - Fluorescence KW - Metal complexes KW - Water analysis KW - Optical and chemical sensing PY - 2025 AN - OPUS4-62795 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Prakash, Swayam T1 - Photophysical Understanding of Urobilin and its Zinc Complexes for Water Quality Testing N2 - Faecal contaminants in water are considered serious threats for human health, due to the presence of viruses, bacteria and other harmful microorganisms.1 Urobilin (UB) is a well-known faecal pigment and can be used as a marker for faecal matter in water.2 UB is commonly present in the urine of all mammals as the catabolic end product of bilirubin degradation.2 As the only simple chemical approach to its detection, Schlesinger’s test is usually used to enhance the weak fluorescence of UB in alcoholic media by complexation with Zinc.2, 3 The major limitation of this method is the only weak enhancement of the intrinsically weak UB fluorescence in aqueous media.3 This work presents an approach to introduce different Zn salts for improved fluorescence response, where we found a clear dependence of the fluorescence yield of UB-Zn(II) complexes on the counterion of the salt in water. By employing a combination of fluorescence parameters like transition energy, fluorescence intensity, and fluorescence lifetime, a photophysical understanding of the structure and conformation of the UB-Zn(II) complexes responsible for the fluorescence enhancement in water could be gained. The possibilities of developing a sensitive analytical method based on the acquired understanding are also discussed. T2 - Central European Conference on Photochemistry CECP 2024 CY - Bad Hofgastein, Austria DA - 18.02.2024 KW - Water analysis KW - Faecal contamination KW - Metal complexes KW - Fluorescence PY - 2024 AN - OPUS4-59874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -