1
|
Wathudura P, McEachin J, Zhang D. Insights into Spectral Distortion and Nonlinearity in UV-Vis and Fluorescence Spectroscopy of Molecular Fluorophore Solutions: Effects of Cascading Optical Processes (Part IV). Anal Chem 2024; 96:13542-13550. [PMID: 39101903 DOI: 10.1021/acs.analchem.4c02173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/06/2024]
Abstract
Reproducibility and linearity are crucial benchmarks for any measurement technology. However, UV-vis and fluorescence spectral distortion and nonlinearity are prevalent, even in seemingly simple fluorescent solutions that comprise only one dissolved molecular fluorophore, without exogenous absorbing or scattering species. In this report, we introduce an analytical model for the quantification of fluorescence interference on UV-vis measurements and a conceptual model for mechanistically understanding the impacts of higher-order cascading optical processes on fluorescence measurements. The experimental UV-vis transmittance can be dominated by interfering fluorescence, even for fluorophore solutions with theoretical absorbance values far below the instrument's linear dynamic range (LDR). Absorption-inner-filter-effect (aIFE) correction drastically improves the fluorescence LDR. However, the efficacy of aIFE correction hinges on two competing factors that strongly depend on the fluorophore's optical properties: the degree of fluorescence interference in UV-vis and the significance of secondary or higher-order emission triggered by fluorophore absorption of emitted photons. Our research sheds light on the remarkable complexity of cascading optical processes that can occur even in the simplest fluorescent solutions. It emphasizes the necessity of critically evaluating optical spectroscopic measurements of fluorescent solutions to improve the reliability of analyzing and interpreting optical spectra. Moreover, it lays the groundwork for future development of methods capable of handling challenging samples that exceed the capabilities of the current tools.
Collapse
Affiliation(s)
- Pathum Wathudura
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Joshua McEachin
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| | - Dongmao Zhang
- Department of Chemistry, Mississippi State University, Mississippi State, Mississippi 39762, United States
| |
Collapse
|
2
|
Tongkanarak K, Loupiac C, Neiers F, Chambin O, Srichana T. Evaluating the biomolecular interaction between delamanid/formulations and human serum albumin by fluorescence, CD spectroscopy and SPR: Effects on protein conformation, kinetic and thermodynamic parameters. Colloids Surf B Biointerfaces 2024; 239:113964. [PMID: 38761495 DOI: 10.1016/j.colsurfb.2024.113964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/27/2024] [Accepted: 05/10/2024] [Indexed: 05/20/2024]
Abstract
Delamanid is an anti-tuberculosis drug used for the treatment of drug-resistant tuberculosis. Since delamanid has a high protein bound potential, even patients with low albumin levels should experience high and rapid delamanid clearance. However, the interaction between delamanid and albumin should be better controlled to optimize drug efficacy. This study was designed to evaluate the binding characteristics of delamanid to human serum albumin (HSA) using various methods: fluorescence spectroscopy, circular dichroism (CD), surface plasmon resonance (SPR), and molecular docking simulation. The fluorescence emission band without any shift indicated the interaction was not affected by the polarity of the fluorophore microenvironment. The reduction of fluorescence intensity at 344 nm was proportional to the increment of delamanid concentration as a fluorescence quencher. UV-absorbance measurement at the maximum wavelength (λmax, 280 nm) was evaluated using inner filter effect correction. The HSA conformation change was explained by the intermolecular energy transfer between delamanid and HSA during complex formation. The study, which was conducted at temperatures of 298 K, 303 K, and 310 K, revealed a static quenching mechanism that correlated with a decreased of bimolecular quenching rate constant (kq) and binding constant (Ka) at increased temperatures. The Ka was 1.75-3.16 × 104 M-1 with a specific binding site with stoichiometry 1:1. The negative enthalpy change, negative entropy change, and negative Gibbs free energy change demonstrated an exothermic-spontaneous reaction while van der Waals forces and hydrogen bonds played a vital role in the binding. The molecular displacement approach and molecular docking confirmed that the binding occurred mainly in subdomain IIA, which is a hydrophobic pocket of HSA, with a theoretical binding free energy of -9.33 kcal/mol. SPR exhibited a real time negative sensorgram that resulted from deviation of the reflex angle due to ligand delamanid-HSA complex forming. The binding occurred spontaneously after delamanid was presented to the HSA surface. The SPR mathematical fitting model revealed that the association rate constant (kon) was 2.62 × 108 s-1M-1 and the dissociation rate constant (koff) was 5.65 × 10-3 s-1. The complexes were performed with an association constant (KA) of 4.64 × 1010 M-1 and the dissociation constant (KD) of 2.15 × 10-11 M. The binding constant indicated high binding affinity and high stability of the complex in an equilibrium. Modified CD spectra revealed that conformation of the HSA structure was altered by the presence of delamanid during preparation of the proliposomes that led to the reduction of secondary structure stabilization. This was indicated by the percentage decrease of α-helix. These findings are beneficial to understanding delamanid-HSA binding characteristics as well as the drug administration regimen.
Collapse
Affiliation(s)
- Krittawan Tongkanarak
- Drug Delivery System Excellence Center, Department of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand
| | - Camille Loupiac
- Univ. Bourgogne Franche - Comté, L'Institut Agro, Université de Bourgogne, INRAE, UMR PAM 1517, Joint Unit Food Processing and Microbiology, Food and Wine Physico-Chemistry Unit, 1 esplanade Erasme, Dijon 21000, France
| | - Fabrice Neiers
- Flavour Perception: Molecular Mechanisms (Flavours), Université de Bourgogne, 7 bd Jeanne d'Arc, Dijon 21000, France
| | - Odile Chambin
- Univ. Bourgogne Franche - Comté, L'Institut Agro, Université de Bourgogne, INRAE, UMR PAM 1517, Joint Unit Food Processing and Microbiology, Food and Wine Physico-Chemistry Unit, 1 esplanade Erasme, Dijon 21000, France; Department of Pharmaceutical Technology, Faculty of Health Sciences, Université de Bourgogne, 7 bd Jeanne d'Arc, Dijon Cedex 21079, France
| | - Teerapol Srichana
- Drug Delivery System Excellence Center, Department of Pharmaceutical Technology, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand.
| |
Collapse
|
3
|
Wamsley M, Zou S, Zhang D. Advancing Evidence-Based Data Interpretation in UV-Vis and Fluorescence Analysis for Nanomaterials: An Analytical Chemistry Perspective. Anal Chem 2023; 95:17426-17437. [PMID: 37972233 DOI: 10.1021/acs.analchem.3c03490] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
UV-vis spectrophotometry and spectrofluorometry are indispensable tools in education, research, and industrial process controls with widespread applications in nanoscience encompassing diverse nanomaterials and fields. Nevertheless, the prevailing spectroscopic interpretations and analyses often exhibit ambiguity and errors, particularly evident in the nanoscience literature. This analytical chemistry Perspective focuses on fostering evidence-based data interpretation in experimental studies of materials' UV-vis absorption, scattering, and fluorescence properties. We begin by outlining common issues observed in UV-vis and fluorescence analysis. Subsequently, we provide a summary of recent advances in commercial UV-vis spectrophotometric and spectrofluorometric instruments, emphasizing their potential to enhance scientific rigor in UV-vis and fluorescence analysis. Furthermore, we propose potential avenues for future developments in spectroscopic instrumentation and measurement strategies, aiming to further augment the utility of optical spectroscopy in nano research for samples where optical complexity surpasses existing tools. Through a targeted focus on the critical issues related to UV-vis and fluorescence properties of nanomaterials, this Perspective can serve as a valuable resource for researchers, educators, and practitioners.
Collapse
Affiliation(s)
- Max Wamsley
- Department of Chemistry, Mississippi State University, Starkville, 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, Starkville, Mississippi 39762, United States
| |
Collapse
|
4
|
Wamsley M, Peng W, Tan W, Wathudura P, Cui X, Zou S, Zhang D. Total Luminescence Spectroscopy for Quantification of Temperature Effects on Photophysical Properties of Photoluminescent Materials. ACS MEASUREMENT SCIENCE AU 2023; 3:10-20. [PMID: 36817009 PMCID: PMC9936609 DOI: 10.1021/acsmeasuresciau.2c00047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 06/18/2023]
Abstract
Quantification of the temperature effects on the optical properties of photoluminescent (PL) materials is important for a fundamental understanding of both materials optical processes and rational PL materials design and applications. However, existing techniques for studying the temperature effects are limited in their information content. Reported herein is a temperature-dependent total photoluminescence (TPL) spectroscopy technique for probing the temperature dependence of materials optical properties. When used in combination with UV-vis measurements, this TPL method enables experimental quantification of temperature effects on fluorophore fluorescence intensity and quantum yield at any combination of excitation and detection wavelengths, including the fluorophore Stokes-shifted and anti-Stokes-shifted fluorescence. All model polyaromatic hydrocarbon (PAH) and xanthene fluorophores exhibited a strong excitation- and emission-wavelength dependence in their temperature effects. However, the heavy-atom effects used for explaining the strong temperature dependence of brominated anthracenes are not operative with xanthene fluorophores that have heavy atom substitutions. The insights from TPL measurements are important not only for enhancing the fundamental understandings of the materials photophysical properties but also for rational measurement design for applications where the temperature sensitivity of the fluorophore fluorescence is critical. An example application is demonstrated for developing a sensitive and robust ratiometric fluorescence thermometric method for in situ real-time monitoring of sample temperatures inside a fluorescence cuvette placed in a temperature-controlled sample holder.
Collapse
Affiliation(s)
- Max Wamsley
- Department
of Chemistry, Mississippi University, Mississippi State, Mississippi 39759, United States
| | - Weiyu Peng
- Department
of Chemistry, Mississippi University, Mississippi State, Mississippi 39759, United States
| | - Weinan Tan
- Department
of Chemistry, Mississippi University, Mississippi State, Mississippi 39759, United States
| | - Pathum Wathudura
- Department
of Chemistry, Mississippi University, Mississippi State, Mississippi 39759, United States
| | - Xin Cui
- Department
of Chemistry, Mississippi University, Mississippi State, Mississippi 39759, United States
| | - Shengli Zou
- Department
of Chemistry, University of Central Florida, Orlando, Florida 32816, United States
| | - Dongmao Zhang
- Department
of Chemistry, Mississippi University, Mississippi State, Mississippi 39759, United States
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|