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Wathudura P, Wamsley M, Wang A, Chen K, Nawalage S, Wang H, Zou S, Zhang D. Effects of Cascading Optical Processes: Part II: Impacts on Experimental Quantification of Sample Absorption and Scattering Properties. Anal Chem 2023; 95:4461-4469. [PMID: 36787490 DOI: 10.1021/acs.analchem.2c05055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
In Part I of the three companion articles, we reported the effects of light scattering on experimental quantification of scattering extinction, intensity, and depolarization in solutions that contain only scatterers with no significant absorption and photoluminescence activities. The present work (Part II) studies the effects of light scattering and absorption on a series of optical spectroscopic measurements done on samples that contain both absorbers and scatterers, but not emitters. The experimental UV-vis spectrum is the sum of the sample absorption and scattering extinction spectra. However, the upper limit of the experimental Beer's-law-abiding extinction can be limited prematurely by the interference of forward scattered light. Light absorption reduces not only the sample scattering intensity but also the scattering depolarization. The impact of scattering on sample light absorption is complicated, depending on whether the absorption of scattered light is taken into consideration. Scattering reduces light absorption along the optical path length from the excitation source to the UV-vis detector. However, the absorption of the scattered light can be adequate to compensate the reduced light absorption along such optical path, making the impacts of light scattering on the sample total light absorption negligibly small (<10%). The latter finding constitutes a critical validation of the integrating-sphere-assisted resonance synchronous spectroscopic method for experimental quantification of absorption and scattering contribution to the sample UV-vis extinction spectra. The techniques and general guidelines provided in this work should help improve the reliability of optical spectroscopic characterization of nanoscale or larger materials, many of which are simultaneous absorbers and scatterers. The insights from this work are foundational for Part III of this series of work, which is on the cascading optical processes on spectroscopic measurements of fluorescent samples.
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Affiliation(s)
- Pathum Wathudura
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39759, United States
| | - Max Wamsley
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39759, United States
| | - Ankai Wang
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Kexun Chen
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Samadhi Nawalage
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39759, United States
| | - Hui Wang
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Shengli Zou
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Dongmao Zhang
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39759, United States
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Nawalage S, Wathudura P, Wang A, Wamsley M, Zou S, Zhang D. Effects of Cascading Optical Processes: Part I: Impacts on Quantification of Sample Scattering Extinction, Intensity, and Depolarization. Anal Chem 2023; 95:1899-1907. [PMID: 36598877 DOI: 10.1021/acs.analchem.2c03917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Light scattering is a universal matter property that is especially prominent in nanoscale or larger materials. However, the effects of scattering-based cascading optical processes on experimental quantification of sample absorption, scattering, and emission intensities, as well as scattering and emission depolarization, have not been adequately addressed. Using a series of polystyrene nanoparticles (PSNPs) of different sizes as model analytes, we present a computational and experimental study on the effects of cascading light scattering on experimental quantification of NP scattering activities (scattering cross-section or molar coefficient), intensity, and depolarization. Part II and Part III of this series of companion articles explore the effects of cascading optical processes on sample absorption and fluorescence measurements, respectively. A general theoretical model is developed on how forward scattered light complicates the general applicability of Beer's law to the experimental UV-vis spectrum of scattering samples. The correlation between the scattering intensity and PSNP concentration is highly complicated with no robust linearity even when the scatterers' concentration is very low. Such complexity arises from the combination of concentration-dependence of light scattering depolarization and the scattering inner filter effects (IFEs). Scattering depolarization increases with the PSNP scattering extinction (thereby, its concentration) but can never reach unity (isotropic) due to the polarization dependence of the scattering IFE. The insights from this study are important for understanding the strengths and limitations of various scattering-based techniques for material characterization including nanoparticle quantification. They are also foundational for quantitative mechanistic understanding on the effects of light scattering on sample absorption and fluorescence measurements.
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Affiliation(s)
- Samadhi Nawalage
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Pathum Wathudura
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Ankai Wang
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Max Wamsley
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Shengli Zou
- Department of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Dongmao Zhang
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
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Wu Z, Yang H, Pan S, Liu H, Hu X. Fluorescence-Scattering Dual-Signal Response of Carbon Dots@ZIF-90 for Phosphate Ratiometric Detection. ACS Sens 2020; 5:2211-2220. [PMID: 32602336 DOI: 10.1021/acssensors.0c00853] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ratiometric fluorescence has drawn extensive attention owing to its self-calibration property. However, it is difficult to obtain appropriate fluorescent materials that can be excited under one excitation and possess well-resolved signals simultaneously. In this work, with the optical properties of the fluorescence of carbon dots (CDs) and the second-order scattering (SOS) of ZIF-90 (zeolitic imidazole frameworks-90) nanoparticles, the synthesized CDs@ZIF-90 can be applied to phosphate (PO43-) ratiometric detection. The fluorescence of CDs is greatly suppressed through encapsulating CDs into ZIF-90. Nevertheless, the SOS is quite obvious due to the high scattering intensity of large size ZIF-90. The competitive coordination between PO43- and the metal node of ZIF-90 decomposes CDs@ZIF-90, leading to the restoration of fluorescence and the diminution of SOS. On the basis of the PO43--induced ZIF-90 decomposition and CD release, a novel method for PO43- ratiometric detection is developed through the dual-signal response of the fluorescence scattering. Under the optimal condition, the method shows a linear range from 1.0 to 50.0 μmol L-1 with a detection limit of 0.23 μmol L-1. Furthermore, the probes are employed to assess PO43- in practical aqueous samples successfully. Compared with the traditional approach, which only records fluorescence signals, the method reported here provides a new strategy to design ratiometric sensors by fluorescence and scattering.
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Affiliation(s)
- Zhihao Wu
- College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Huan Yang
- College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Shuang Pan
- College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
| | - Hui Liu
- College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China
| | - Xiaoli Hu
- College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
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Wu Z, Nan D, Yang H, Pan S, Liu H, Hu X. A ratiometric fluorescence-scattered light strategy based on MoS2 quantum dots/CoOOH nanoflakes system for ascorbic acid detection. Anal Chim Acta 2019; 1091:59-68. [DOI: 10.1016/j.aca.2019.09.054] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/18/2019] [Accepted: 09/21/2019] [Indexed: 12/11/2022]
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