Time-resolved Fluorescence Spectroscopy Research Articles

Humic fractions from Amazon soils: Lifetime study and humification process by fluorescence spectroscopy

The Amazon Forest is an important and primordial ecosystem, as it controls the dynamics of soil organic matter (SOM) and is considered one of the crucial carbon reservoirs in the world. Based on that, this study evaluated the molecular properties of humic (HA) and fulvic (FA) acid from Amazon soil, with and without Cu(II) ions, by Time-Resolved Laser Fluorescence Spectroscopy (TRLFS) and Fluorescence Spectroscopy (FS). Fluorescence excitation-emission matrix (EEM) was obtained by FS, and EEM spectra were treated by canonical polyadic/parallel factor analysis (EEM-CP/PARAFAC). The results showed that the humification index (A465nm) determined by FS is directly dependent on fluorophores’ CII/CI ratio in these soils with depth (r = 0.89), especially for HA samples in deep horizons, which demonstrated that the CII consists more complex and humified structure of the SOM. The lifetime decay showed the presence of static quenching in the humic fractions. From the lifetime data provided by TRLFS and the different correlations with carbon content and A465nm, it can be suggested that the fluorescence suppression modifies the molecular properties of the humic fractions with the addition of Cu(II) ions, such as altering the mobility and availability of the metal in the complexation reactions in these Amazonian Spodosols, mainly for the fulvic fraction.

Modulated photophysical properties and sequestration of potent anti-acetylcholinesterase active coumarinyl dyes in human serum albumin

Multi-pronged spectroscopic techniques were employed to provide quantitative inputs on the modulated photophysics of nine coumarinyl derivatives in an array of solvents. Significant solvatochromic effect on the spectral behavior of the investigated systems was quantified using multiparametric regression analysis along with Density Functional Theory (DFT) calculations. The optical properties of the compounds were seen to be contingent on solvent polarity/polarizability and hydrogen bonding to varying degrees. Assessment of in-vitro anti-acetylcholinesterase (AChE) activity of the investigated systems indicates their efficacy to be even better than FDA approved drug donepezil to treat Alzheimer's disease (AD) and shed novel insights into the biomedical applications of coumarinyl compounds. Interestingly, the AChE inhibition capacity of these compounds showed significant diminution in presence of human serum albumin (HSA), the principal transport protein in blood serum and therefore, reinstated its ability to modulate the therapeutic efficacies of potential drugs. The observed results were validated by quantifying the interaction of the investigated systems with HSA and also investigated through steady state and time-resolved fluorescence spectroscopy along with several other bio-analytical tools. A combination of static and dynamic mechanisms was responsible for the quenching of intrinsic protein fluorescence due to the strong sequestration ability of these coumarin derivatives into the protein binding domain. The observed results emphasized on the need of screening the pharmacological effectiveness of proposed drugs in biologically relevant media rather than in pure buffer.

Intramolecular H-type dimer and excimer formation in dibenzoylmethanatoboron difluoride dyads connected via diphenylsiloxane linkers

A series of new dibenzoylmethanatoboron difluoride (DBMBF2) and methoxy-substituted DBMBF2 dyads linked via flexible diphenylsiloxane linkers of various length have been synthesized and characterized. The structure and optical properties of these compounds were studied by X-ray single-crystal measurements, electron absorption, and steady-state and time-resolved fluorescence spectroscopy. In the dyads under study, which are in an equilibrium between the open and folded conformations, the formation of intramolecular H-dimers in the ground state are observed. For the dyads in dilute solutions in various solvents, both monomer and excimer (through intramolecular excimer formation) emissions are observed at room temperature. The effect of solvent polarity and linker length on the formation of intramolecular excimers has been studied. The contribution of excimers into the total fluorescence spectrum decreases with increasing the solvent polarity, and the length of the siloxane linker. The studied dyads in hexane and cyclohexane solutions have CIE chromaticity coordinates very close to the white color point. The mechanofluorochromic properties of the synthesized dyads were studied.

Quenching of Protein Fluorescence by Fullerenol C60(OH)36 Nanoparticles.

The effect of the interaction between fullerenol C60(OH)36 (FUL) and alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae and human serum albumin (HSA) was studied by absorption spectroscopy, fluorescence spectroscopy, and time-resolved fluorescence spectroscopy. As shown in the study, the fluorescence intensities of ADH and HSA at excitation wavelengths λex = 280 nm (Trp, Tyr) and λex = 295 nm (Trp) are decreased with the increase in the FUL concentration. The results of time-resolved measurements indicate that both quenching mechanisms, dynamic and static, are present. The binding constant Kb and the number of binding sites were obtained for HSA and ADH. Thus, the results indicated the formation of FUL complexes and proteins. However, the binding of FUL to HSA is much stronger than that of ADH. The transfer of energy from the protein to FUL was also proved.

Luminescent Carbon Dots from Wet Olive Pomace: Structural Insights, Photophysical Properties and Cytotoxicity.

Carbon nanomaterials endowed with significant luminescence have been synthesized for the first time from an abundant, highly localized waste, the wet pomace (WP), a semi-solid by-product of industrial olive oil production. Synthetic efforts were undertaken to outshine the photoluminescence (PL) of carbon nanoparticles through a systematic search of the best reaction conditions to convert the waste biomass, mainly consisting in holocellulose, lignin and proteins, into carbon dots (CDs) by hydrothermal carbonization processes. Blue-emitting CDs with high fluorescence quantum yields were obtained. Using a comprehensive set of spectroscopic tools (FTIR, Raman, XPS, and 1H/13C NMR) in combination with steady-state and time-resolved fluorescence spectroscopy, a rational depiction of WP-CDs structures and their PL properties was reached. WP-CDs show the up-conversion of PL capabilities and negligible cytotoxicity against two mammalian cell lines (L929 and HeLa). Both properties are excellent indicators for their prospective application in biological imaging, biosensing, and dynamic therapies driven by light.

L-valine functionalized nitrogen doped non-graphitic carbon dots as a photoluminescent probe for detection of tetracycline

Here we present l-valine functionalized non-graphitic carbon dots (denoted as N-CDvaline) as a photoluminescent (PL) probe for highly sensitive and selective detection of tetracycline antibiotic. The probe, synthesized by heating of ethylene glycol with l-valine at 170 °C for 10 min, exhibited bright bluish photoluminescence at λemission = 445 nm by exciting at λexcitation = 370 nm with 11.4% photoluminescence quantum yield. The higher resolution transmission electron micrograph, selected area electron diffraction, Fourier transformed infrared spectroscopy and X-ray photoelectron spectroscopy of N-CDvaline suggested highly ordered arrangement of linear transverse chains of oligomers of ethylene glycol and l-valine, attributable to self-assembly. Under optimized conditions, the probe exhibited linear PL quenching by tetracycline in the concentration range between 0.25 and 5.00 μM and satisfied the Stern-Volmer equation, with a detection limit of 0.054 μM. This method is highly selective towards tetracycline detection against host of interfering agents e.g., some common cations, anions and other classes of antibiotics. The PL quenching mechanism is attributed to ground state complex formation between the probe and tetracycline, corroborated by time resolved fluorescence spectroscopy studies and due to inner filter effect (IFE) owing to strong spectral overlap between UV–vis absorption spectrum of tetracycline with excitation and emission spectra of N-CDvaline. The scope for using this method for detection of tetracycline in real samples e.g., river water and milk is successfully demonstrated by spike analysis.

Silica/Proteoliposomal Nanocomposite as a Potential Platform for Ion Channel Studies.

The nanostructuration of solid matrices with lipid nanoparticles containing membrane proteins is a promising tool for the development of high-throughput screening devices. Here, sol-gel silica-derived nanocomposites loaded with liposome-reconstituted KcsA, a prokaryotic potassium channel, have been synthesized. The conformational and functional stability of these lipid nanoparticles before and after sol-gel immobilization have been characterized by using dynamic light scattering, and steady-state and time-resolved fluorescence spectroscopy methods. The lipid-reconstituted KcsA channel entrapped in the sol-gel matrix retained the conformational and stability changes induced by the presence of blocking or permeant cations in the buffer (associated with the conformation of the selectivity filter) or by a drop in the pH (associated with the opening of the activation gate of the protein). Hence, these results indicate that this novel device has the potential to be used as a screening platform to test new modulating drugs of potassium channels.

Synthesis and photophysical investigations of pyridine-pyrazolate bound boron(III) diaryl complexes

This study presents the design and synthetic pathway of unsymmetric ligands based on pyridine-pyrazolate scaffold with Donor–Acceptor (D–A) molecular arrays and their boron complexes to achieve a large Stokes shift. Intermolecular charge transfer (ICT) triggered by the uneven molecular charge distribution from electronically dense pyrazolate (donor) part of the ligands to electron-deficient boron centre (acceptor) resulted in a mega Stokes shift up to 263 nm for selected compounds while retaining the characteristic quantum efficiency and chemical stability. The photophysical properties of derivatization of pyrazolate group in the pyridine-pyrazolate scaffold of diaryl boron complexes were explored based on UV–Visible, steady-state and time-resolved fluorescence spectroscopy. An interesting dual emission along with quenching behaviour was also observed for 2-(6-methoxynaphthelene) 5-(2-pyridyl) pyrazolate boron complex (P5) due to the formation of a twisted intermolecular charge transfer (TICT) state from a locally excited (LE) state rendering it a potential candidate for sensing applications based on H-Bond quenching. In addition, the extended excited state lifetime of the reported compounds compared to classical boron-dipyrromethene (BODIPY) makes them suitable as potential probes for analytical applications requiring a longer excited state lifetime.

Tri-mode optical biopsy probe with fluorescence endomicroscopy, Raman spectroscopy, and time-resolved fluorescence spectroscopy.

We present an endoscopic probe that combines three distinct optical fibre technologies including: A high-resolution imaging fibre for optical endomicroscopy, a multimode fibre for time-resolved fluorescence spectroscopy, and a hollow-core fibre with multimode signal collection cores for Raman spectroscopy. The three fibers are all enclosed within a 1.2 mm diameter clinical grade catheter with a 1.4 mm end cap. To demonstrate the probe's flexibility we provide data acquired with it in loops of radii down to 2 cm. We then use the probe in an anatomically accurate model of adult human airways, showing that it can be navigated to any part of the distal lung using a commercial bronchoscope. Finally, we present data acquired from fresh ex vivo human lung tissue. Our experiments show that this minimally invasive probe can deliver real-time optical biopsies from within the distal lung - simultaneously acquiring co-located high-resolution endomicroscopy and biochemical spectra.

Study of Albumin Oxidation in COVID-19 Pneumonia Patients: Possible Mechanisms and Consequences.

Oxidative stress induced by neutrophils and hypoxia in COVID-19 pneumonia leads to albumin modification. This may result in elevated levels of advanced oxidation protein products (AOPPs) and advanced lipoxidation end-products (ALEs) that trigger oxidative bursts of neutrophils and thus participate in cytokine storms, accelerating endothelial lung cell injury, leading to respiratory distress. In this study, sixty-six hospitalized COVID-19 patients with respiratory symptoms were studied. AOPPs-HSA was produced in vitro by treating human serum albumin (HSA) with chloramine T. The interaction of malondialdehyde with HSA was studied using time-resolved fluorescence spectroscopy. The findings revealed a significantly elevated level of AOPPs in COVID-19 pneumonia patients on admission to the hospital and one week later as long as they were in the acute phase of infection when compared with values recorded for the same patients 6- and 12-months post-infection. Significant negative correlations of albumin and positive correlations of AOPPs with, e.g., procalcitonin, D-dimers, lactate dehydrogenase, aspartate transaminase, and radiological scores of computed tomography (HRCT), were observed. The AOPPs/albumin ratio was found to be strongly correlated with D-dimers. We suggest that oxidized albumin could be involved in COVID-19 pathophysiology. Some possible clinical consequences of the modification of albumin are also discussed.

The Mortality Risk and Pulmonary Fibrosis Investigated by Time-Resolved Fluorescence Spectroscopy from Plasma in COVID-19 Patients.

A method of rapidly pointing out the risk of developing persistent pulmonary fibrosis from a sample of blood is extraordinarily needed for diagnosis, prediction of death, and post-infection prognosis assessment. Collagen scar formation has been found to play an important role in the lung remodeling following SARS-CoV-2 infection. For this reason, the concentration of collagen degradation products in plasma may reflect the process of lung remodeling and determine the extent of fibrosis. According to our previously published results of an in vitro study, an increase in the concentration of type III collagen degradation products in plasma resulted in a decrease in the fluorescence lifetime of plasma at a wavelength of 450 nm. The aim of this study was to use time-resolved fluorescence spectroscopy to assess pulmonary fibrosis, and to find out if the lifetime of plasma fluorescence is shortened in patients with COVID-19. The presented study is thus far the only one to explore the fluorescence lifetime of plasma in patients with COVID-19 and pulmonary fibrosis. The time-resolved spectrometer Life Spec II with the sub-nanosecond pulsed 360 nm EPLED® diode was used in order to measure the fluorescence lifetime of plasma. The survival analysis showed that COVID-19 mortality was associated with a decreased mean fluorescence lifetime of plasma. The AUC of mean fluorescence lifetime in predicting death was 0.853 (95% CI 0.735–0.972, p < 0.001) with a cut-off value of 7 ns, and with 62% sensitivity and 100% specificity. We observed a significant decrease in the mean fluorescence lifetime in COVID-19 non-survivors (p < 0.001), in bacterial pneumonia patients without COVID-19 (p < 0.001), and in patients diagnosed with idiopathic pulmonary fibrosis (p < 0.001), relative to healthy subjects. Furthermore, these results suggest that the development of pulmonary fibrosis may be a real and serious problem in former COVID-19 patients in the future. A reduction in the mean fluorescence lifetime of plasma was observed in many patients 6 months after discharge. On the basis of these data, it can be concluded that a decrease in the mean fluorescence lifetime of plasma at 450 nm may be a risk factor for mortality, and probably also for pulmonary fibrosis in hospitalized COVID-19 patients.

Combining batch experiments and spectroscopy for realistic surface complexation modelling of the sorption of americium, curium, and europium onto muscovite

For a safe enclosure of contaminants, for instance in deep geological repositories of radioactive waste, any processes retarding metal migration are of paramount importance. This study focusses on the sorption of trivalent actinides (Am, Cm) and lanthanides (Eu) to the surface of muscovite, a mica and main component of most crystalline rocks (granites, granodiorites). Batch sorption experiments quantified the retention regarding parameters like pH (varied between 3 and 9), metal concentration (from 0.5 µM Cm to 10 µM Eu), or solid-to-liquid ratio (0.13 and 5.25 g·L−1). In addition, time-resolved laser fluorescence spectroscopy (TRLFS) using the actinide Cm(III) identified two distinct inner-sphere surface species. Combining both approaches allowed the development of a robust surface complexation model and the determination of stability constants of the spectroscopically identified species of (S-OH)2M3+ (logKo −8.89), (S-O)2M+ (logKo −4.11), and (S-O)2MOH (logKo −10.6), with all values extrapolated to infinite dilution. The inclusion of these stability constants into thermodynamic databases will improve the prognostic accuracy of lanthanide and actinide transport through groundwater channels in soils and crystalline rock systems.

Fluorescence interactions of a novel chalcone derivative with membrane model systems and human serum albumin

A novel chalcone derivative (4-(5-(pyridin-2-yl)-4,5-dihydro-1H-pyrazol-3-yl) phenol (PDP) was synthesized, characterized and investigated for its potential as a fluorescent probe. The structure of the synthesized molecule was determined by FTIR, 1H NMR, 13C NMR and LC-MS/MS. The interactions of PDP with fluorescent dyes in aqueous SDS environment and HSA were studied by using fluorescence resonance energy transfer (FRET) technique and steady-state and time-resolved fluorescence spectroscopy techniques. In addition, the cytotoxic effects of PDP against various cell lines (MCF -7, HT −29, and 3 T3-L1) as well as their corresponding healthy cell lines were tested by MTT assay and visualization of FRET efficiency of PDP in vitro was monitored by confocal microscopy. MTT assay showed that PDP has no significant cytotoxic effect on HT −29 cancer cells and moderate cytotoxicity on MCF -7 and 3 T3-L1 cells even at a concentration of 250 μM. Combining confocal microscopes with the FRET technique showed that PDP significantly stained the cytoplasm of MCF -7 cell lines. These results suggest that PDP could be used in fluorescence microscopy for cell staining.

Speciation and spatial distribution of Eu(III) in fungal mycelium

Europium, as an easy-to-study analog of the trivalent actinides, is of particular importance for studying the behavior of lanthanides and actinides in the environment. Since different soil organisms can influence the migration behavior of these elements, a detailed knowledge of these interaction mechanisms is important. The aim of this study was to investigate the interaction of mycelia of selected wood-inhabiting (S. commune, P. ostreatus, L. tigrinus) and soil-inhabiting fungi (L. naucinus) with Eu(III). In addition to determining the Eu(III) complexes in the sorption solution, the formed Eu(III) fungal species were characterized using scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, chemical microscopy in combination with the time-resolved laser-induced fluorescence spectroscopy. Our data show that S. commune exhibited significantly higher Eu(III) binding capacity in comparison to the other fungi. Depending on fungal strain, the metal was immobilized on the cell surface, in the cell membranes, and within the membranes of various organelles, or in the cytoplasm in some cases. During the bioassociation process two different Eu(III) fungal species were formed in all investigated fungal strain. The phosphate groups of organic ligands were identified as being important functional groups to bind Eu(III) and thus immobilize the metal in the fungal matrix. The information obtained contributes to a better understanding of the role of fungi in migration, removal or retention mechanisms of rare earth elements and trivalent actinides in the environment.

One- and two-exciton states of pair centers of Kramers Nd3+ions in Nd-doped CaF2 and SrF2 crystals, and their possible use as qubits

Using two-color excitation with narrow laser lines of 0.2 cm−1 and time-resolved site-selective fluorescence spectroscopy, we measured the fluorescence excitation spectra of the one-exciton 4G5/2(1) x 4I9/2(1) state monitored in the near IR, and the two-exciton 4G5/2(1) x 4G5/2(1) state monitored in the near UV of the pair M centers in the Nd3+ doped CaF2 and SrF2 crystals at 6.5 K. We observed the splitting of the one-exciton state of the order of 2–3 cm−1 depending on the type of crystal matrix. A significant inhomogeneous splitting ∼1.5 cm−1 of the spectral lines of the one-exciton state of the pair M centers in the Nd3+: SrF2 crystals was found. The measured single spectral line of the two-exciton state of the pair M centers in these crystals has in one-photon scale the linewidth of ∼0.8 cm−1, which is mainly determined by inhomogeneous broadening.

Synthesis, optical and electrochemical properties of (D-π)2-type and (D-π)2Ph-type fluorescent dyes.

The (D–π)2-type fluorescent dye OTT-2 with two (diphenylamino)carbazole-thiophene units as D (electron-donating group)–π (π-conjugated bridge) moiety and the (D–π)2Ph-type fluorescent dye OTK-2 with the two D–π moieties connected through a phenyl ring were derived by oxidative homocoupling of a stannyl D–π unit and Stille coupling of a stannyl D–π unit with 1,3-diiodobenzene, respectively. Their optical and electrochemical properties were investigated by photoabsorption and fluorescence spectroscopy, time-resolved fluorescence spectroscopy, cyclic voltammetry (CV) and molecular orbital (MO) calculations. In toluene the photoabsorption and fluorescence maximum wavelengths (λmax,abs and λmax,fl) of OTT-2 appear in a longer wavelength region than those of OTK-2. The fluorescence quantum yield (Φfl) of OTT-2 is 0.41, which is higher than that (Φfl = 0.36) of OTK-2. In the solid state OTT-2 shows relatively intense fluorescence properties (Φfl-solid = 0.24 nm), compared with OTK-2 (Φfl-solid = 0.15 nm). CV results demonstrated that OTT-2 and OTK-2 exhibit a reversible oxidation wave. Based on photoabsorption, fluorescence spectroscopy and CV for the two dyes, it was found that the lowest unoccupied molecular orbital (LUMO) energy level of OTT-2 is lower than that of OTK-2, but OTT-2 and OTK-2 have comparable highest occupied molecular orbital (HOMO) energy levels. Consequently, this work reveals that compared to the (D–π)2Ph-type structure, the (D–π)2-type structure exhibits not only a bathochromic shift of the photoabsorption band, but also intense fluorescence emission both in solution and the solid state.

Comparative study of two antipsychotic drugs binding to human serum albumin: By multispectroscopic and molecular docking methods

Psychiatric disorders are common diseases with a high prevalence. Currently, increasing focus on the treatment of psychiatric disorders has driven the development and investigation of antipsychotic drugs. In this paper, two classical antipsychotic drugs risperidone (RIP) and paliperidone (PIP) were selected as research subjects to explore their action mechanism with biological macromolecule human serum albumin (HSA). Combined UV spectroscopy and time-resolved fluorescence spectroscopy results showed that the quenching of HSA by RIP/PIP was a static process, and this result was further confirmed by temperature-dependent experiments, while hydrogen bonding, electrostatic forces and hydrophobic forces existed in the above process. Furthermore, synchronous fluorescence spectroscopy, three-dimensional fluorescence spectroscopy and circular dichroism (CD) spectroscopy experiments demonstrated the effect on HSA before and after the addition of RIP/PIP. Electrochemical experiments results determined that Ka of HSA and RIP/PIP system was 1.52 × 104 M−1–2.85 × 104 M−1. According to the competition experiments and molecular docking indicating RIP/PIP bound to site I of HSA. Finally, these results provided reliable information for the development of antipsychotic drugs.

Mechanistic Investigations into Amination of Unactivated Arenes via Cation Radical Accelerated Nucleophilic Aromatic Substitution.

A mechanistic investigation into the amination of electron-neutral and electron-rich arenes using organic photoredox catalysis is presented. Kinetic and computational data support rate-limiting nucleophilic addition into an arene cation radical using both azole and primary amine nucleophiles. This finding is consistent with both fluoride and alkoxide nucleofuges, supporting a unified mechanistic picture using cation radical accelerated nucleophilic aromatic substitution (CRA-SNAr). Electrochemistry and time-resolved fluorescence spectroscopy confirm the key role solvents play in enabling selective arene oxidation in the presence of amines. The synthetic limitations of xanthylium salts are elucidated via photophysical studies. An alternative catalyst scaffold with improved turnover numbers is presented.

Insight into mechanisms of creatinine optical sensing using fluorescein-gold complex

Creatinine level in biological fluids is a clinically relevant parameter to monitor vital functions and it is well assessed that measuring creatinine levels in the human body can be of great utility to evaluate renal, muscular, or thyroid dysfunctions. The accurate detection of creatinine levels may have a critical role in providing information on health status and represents a tool for the early diagnosis of severe pathologies. Among different methods for creatinine detection that have been introduced and that are evolving with increasing speed, fluorescence-based and colorimetric sensors represent one of the best alternatives, thanks to their affordability, sensitivity and easy readability. In this work, we demonstrate that the fluorescein-Au3+ complex provides a rapid, selective, and sensitive tool for the quantification of creatinine concentrations in ranges typical of sweat and urine. UV-visible absorption, diffuse reflectance spectroscopy, steady state and time resolved fluorescence spectroscopy were used to shed light on the molecular mechanisms involved in the changes of optical properties, which underlie the multiplexed sensor analytical reply. Interestingly, sensing can be performed in solution or on solid nylon support accessing different physiological concentrations from micromolar to millimolar range. As a proof-of-concept, the nylon-based platform was used to demonstrate its effectiveness in creatinine detection on a solid and flexible substrate, showing its analytical colorimetric properties as an easy and disposable creatinine point-of-care test.

Simulation-guided relationships and interaction characteristics of human CtBP1 in complex with protocatechualdehyde

• Quenching mechanism of PA to CtBP1 is static quenching with moderate affinity. • Hydrogen bond and van der Waals force are the main binding forces. • The amino acids of CtBP1, Try318, plays a key role in the interaction. • Binding induces conformational changes in CtBP1 after interaction. The mechanism of interaction of protocatechualdehyde (PA) to C-terminal-binding protein 1 (CtBP1) was studied in detail from a new perspective, and it was verified that PA was a potential inhibitor of CtBP1. Visual molecular recognition models were built based on molecular docking and molecular dynamics (MD) simulations, and it was shown that PA can bind to CtBP1 stably. The static quenching mechanism was confirmed by fluorescence spectroscopy and time-resolved fluorescence spectroscopy, indicating that the binding constant of the PA-CtBP1 system at a single binding site was approximately (5.291 ± 0.204) × 10 4 L/mol at 298 K . The thermodynamic parameters showed that the binding of PA to CtBP1 was mainly initiated by H-bond interactions and van der Waals forces. Circular dichroism (CD) and Fourier-Transform Infrared (FT-IR) spectroscopy manifested that the secondary structure of CtBP1 had slightly changed. This work clarified the research progress of the specific binding mechanism of PA and CtBP1 from the molecular level, which provided new insight into the pharmacological effects of PA.