Categorizing interaction modes of antimicrobial peptides with extracellular vesicles: Disruption, membrane trespassing, and clearance of the protein corona.

Host antimicrobial peptides (AMPs) and extracellular vesicles (EVs) are known to play important roles as part of the immune system, from antimicrobial actions to immune regulation. Recent results also demonstrate that EVs could serve as carriers for AMPs. Related, it was shown that some AMPs can remove the protein corona (PC), the externally adsorbed layer of proteins, from EVs which can be exploited for subtractive proteomics strategies. The interaction of these compounds is thus interesting for multiple reasons from better insight to natural processes to direct applications in EV-based bioengineering. However, we have only limited information on the various ways these species may interact with each other. To reach a broader overview, here we selected twenty-six AMPs, including cell-penetrating peptides (CPPs), and investigated their interactions with red blood cell-derived vesicles (REVs). For this, we employed a complex lipid biophysics including linearly polarized light spectroscopy, flow cytometry, nanoparticle tracking analysis, electron microscopy and also zeta-potential measurements. This enabled the categorization of these peptides into distinct groups. At specific low concentrations, peptides such as LL-37 and lasioglossin-III were effective in PC elimination with minimal disruption of the membrane. In contrast, AMPs like KLA, bradykinin, histatin-5, and most of the tested CPPs (e.g. octa-arginine, penetratin, and buforin II), demonstrate cell-penetrating mechanisms as they could sustain large peptide concentrations with minimal membrane damage. The systematic overview presented here shows the potential mechanism of how AMPs and EVs could interact in vivo, and also how certain peptides may be employed to manipulate EVs for specific applications.

Recent advances in the analytical methods for quantitative determination of antioxidants in food matrices.

Antioxidants are crucial in reducing oxidative stress and enhancing health, necessitating precise quantification in food matrices. Advanced techniques such as biosensors and nanosensors offer high sensitivity and specificity, enabling real-time monitoring and accurate antioxidant quantification in complex food systems. These technologies herald a new era in food analysis, improving food quality and safety through sophisticated detection methods. Their application facilitates comprehensive antioxidant profiling, driving innovation in food technology to meet the rising demand for nutritional optimization and food integrity. These are complemented by electrochemical techniques, spectroscopy, and chromatography. Electrochemical methods provide rapid response times, spectroscopy offers versatile chemical composition analysis, and chromatography excels in precise separation and quantification. Collectively, these methodologies establish a comprehensive framework for food analysis, essential for improving food quality, safety, and nutritional value. Future research should aim to refine these analytical methods, promising significant advancements in food and nutritional science.

Multispectral bioactivity studies of N-terminal fatty acid modified antimicrobial peptide Andricin B.

A series of Andricin B derivatives were designed and synthesized using fatty acid modification at N-terminus of the antimicrobial peptides. The hydrophobicity of Andricin B was altered through fatty acid modification, and the bioactivity was investigated. The interaction between Andricin B and its derivatives with DNA was measured using multi-spectroscopy. Spectroscopic analysis revealed that Andricin B and its derivatives can interact with ct-DNA and G-quadruplexes DNA, and the interaction related with the length of fatty acid chain. Antimicrobial activity tests showed a significant increase using peptides with 8-10 carbons fatty acid chain. C10-Andricin B exhibited the highest antimicrobial activity, with up to a 16-fold enhancement compared to the original peptide Andricin B. Meanwhile, the protease hydrolysis stability test showed that fatty acid modification improved the stability of Andricin B against protease. Scanning electron microscopy results distinctly showed that C8-Andricin B could rupture the cell wall of bacteria. All results indicated that fatty acid modification peptides are an effective strategy for enhancing activity and stability of antimicrobial peptides. This research provides valuable insights for further research on antimicrobial peptides.

Synthesis, optical properties, DNA, ß-cyclodextrin interactions, and antioxidant evaluation of novel isoxazolidine derivative (ISoXD2): A multispectral and computational analysis.

ISoXD2 are well explored among versatile and outstanding class of pharmacophores for the preparation and discovery of drugs. Herein, the electronic absorption and emission spectra of ISoXD2 were investigated in three different solvents. The observed transition was attributed to π-π* with charge transfer character. Changes in the excited state and shift of the absorption and emission peaks to longer wavelengths are observed as a result of increasing solvent polarity, due to the interactions between the ISoXD2 molecule and the solvent molecules surrounding it. Changing the solvent confirms its solvatochromic effect. UV-vis and fluorescence analysis revealed that ISoXD2 binds to deoxyribonucleic acid (DNA) by intercalation mode, with a stoichiometric ratio of 1:1.5. Moreover, the fluorescence intensity of DNA bound to ethidium bromide (EB) in the presence of ISoXD2 was investigated. From this analysis, the Stern-Volmer quenching constant (Ksv), quenching rate constant (kq), binding constant (Kb) and binding sites number (n) were found to be 5.654 × 103 M-1, 2.827 × 1011 M-1 s-1, 3.81 × 104 M-1 and 1.225, respectively. The interaction between ISoXD2 and ß-CD was investigated through absorption spectra analysis. Kb for this interaction was determined to be 4.9 × 104 M-1. The free radical-scavenging ability of the prepared ISoXD2, examined by DPPH and ABTS assays have shown a good antioxidant activity. Furthermore, modeling study was conducted to explore their plausible binding mechanism with ISoXD2 and to support the experimental results.

Mechanism understanding of PIKfyve inhibitor YM201636 with human serum albumin: Insights from molecular modeling and multiple spectroscopic techniques.

YM201636 is the potent PIKfyve inhibitor that is being actively investigated for liver cancer efficacy. In this study, computer simulations and experiments were conducted to investigate the interaction mechanism between YM201636 and the transport protein HSA. Results indicated that YM201636 is stably bound between the subdomains IIA and IIIA of HSA, supported by site marker displacement experiments. YM201636 quenched the endogenous fluorescence of HSA by static quenching since a decrease in quenching constants was observed from 7.74 to 2.39 × 104 M-1. UV-vis and time-resolved fluorescence spectroscopy confirmed the YM201636-HSA complex formation and this binding followed a static mechanism. Thermodynamic parameters ΔG, ΔH, and ΔS obtained negative values suggesting the binding was a spontaneous process driven by Van der Waals interactions and hydrogen binding. Binding constants ranged between 5.71 and 0.33 × 104 M-1, which demonstrated a moderately strong affinity of YM201636 to HSA. CD, synchronous, and 3D fluorescence spectroscopy revealed that YM201636 showed a slight change in secondary structure. The increase of Kapp and a decrease of PSH with YM201636 addition showed that YM201636 changed the surface hydrophobicity of HSA. The research provides reasonable models helping us further understand the transportation and distribution of YM201636 when it absorbs into the blood circulatory system.

A review of biophysical strategies to investigate protein-ligand binding: What have we employed?

The protein-ligand binding frequently occurs in living organisms and plays a crucial role in the execution of the functions of proteins and drugs. It is also an indispensable part of drug discovery and screening. While the methods for investigating protein-ligand binding are diverse, each has its own objectives, strengths, and limitations, which all influence the choice of method. Many studies concentrate on one or a few specific methods, suggesting that comprehensive summaries are lacking. Therefore in this review, these methods are comprehensively summarized and are discussed in detail: prediction and simulation methods, thermal and thermodynamic methods, spectroscopic methods, methods of determining three-dimensional structures of the complex, mass spectrometry-based methods and others. It is also important to integrate these methods based on the specific objectives of the research. With the aim of advancing pharmaceutical research, this review seeks to deepen the understanding of the protein-ligand binding process.

Observation of oxygenated intermediates in functional mimics of aminophenol dioxygenase.

Aminophenol dioxygenases (APDO) are mononuclear nonheme iron enzymes that utilize dioxygen (O2) to catalyze the conversion of o-aminophenols to 2-picolinic acid derivatives in metabolic pathways. This study describes the synthesis and O2 reactivity of two synthetic models of substrate-bound APDO: [FeII(TpMe2)(tBu2APH)] (1) and [FeII(TpMe2)(tBuAPH)] (2), where TpMe2 = hydrotris(3,5-dimethylpyrazole-1-yl)borate, tBu2APH = 4,6-di-tert-butyl-2-aminophenolate, and tBuAPH2 = 4-tert-butyl-2-aminophenolate. Both Fe(II) complexes behave as functional APDO mimics, as exposure to O2 results in oxidative CC bond cleavage of the o-aminophenolate ligand. The ring-cleaved products undergo spontaneous cyclization to give substituted 2-picolinic acids, as verified by 1H NMR spectroscopy, mass spectrometry, and X-ray crystallography. Reaction of the APDO models with O2 at low temperature reveals multiple intermediates, which were probed with UV-vis absorption, electron paramagnetic resonance (EPR), Mössbauer (MB), and resonance Raman (rRaman) spectroscopies. The most stable intermediate at -70 °C in THF exhibits multiple isotopically-sensitive features in rRaman samples prepared with 16O2 and 18O2, confirming incorporation of O2-derived atom(s) into its molecular structure. Insights into the geometric structures, electronic properties, and spectroscopic features of the observed intermediates were obtained from density functional theory (DFT) calculations. Although functional APDO models have been previously reported, this is the first time that an oxygenated ligand-based radical has been detected and spectroscopically characterized in the ring-cleaving mechanism of a relevant synthetic system.

A Comprehensive Study for Determination of Free Fatty Acids in Selected Biological Materials: A Review.

The quality of oil is highly dependent on its free fatty acid (FFA) content, especially due to increased restrictions on renewable fuels. As a result, there has been a growing interest in free fatty acid determination methods over the last few decades. While various standard methods are currently available, such as the American Oil Chemists Society (AOCS), International Union of Pure and Applied Chemistry (IUPAC), and Japan Oil Chemists' Society (JOCS), to obtain accurate results, there is a pressing need to investigate a fast, accurate, feasible, and eco-friendly methodology for determining FFA in biological materials. This is owing to inadequate characteristics of the methods, such as solvent consumption and reproducibility, among others. This study aims to investigate FFA determination methods to identify suitable approaches and introduce a fresh perspective.

Discovery of a Biocontrol Strain Trichaptum laricinum: Its Metabolites and Antifungal Activity against Pathogenic Fungus Colletotrichum anthrisci.

Finding safe and environmentally friendly fungicides is one of the important strategies in modern pesticide research and development. In this work, the antipathogenic effects of the fungus Trichaptum laricinum against the anthracnose pathogen Colletotrichum anthrisci were studied. The EtOAc extract of T. laricinum showed remarkable antifungal activity against C. anthrisci with an inhibition rate of 50% at 256 µg/mL. Bioguided isolation of the cultural broth of T. laricinum produced four new drimane sesquiterpenes, trichalarins A-D (1-4), and six other metabolites (5-10). Their structures were established by extensive spectroscopic methods, quantum chemical calculations, and single-crystal X-ray diffraction. All compounds exhibited antifungal activity against C. anthrisci with minimum inhibitory concentrations (MICs) of 8-64 µg/mL in vitro. Further in vivo assay suggested that compounds 2, 6, and 9 could significantly inhibit C. anthrisci growth in avocado fruit with inhibition rates close to 80% at the concentration of 256 µg/mL, while compounds 2 and 6 had an inhibition rate over 90% at the concentration of 512 µg/mL. The EtOAc extract of T. laricinum had no inhibitory effect on Pinus massoniana seed germination and growth at the concentration of 2 mg/mL, showing good environmental friendliness. Thus, the fungus T. laricinum could be considered as an ideal biocontrol strain, and its metabolites provided a diverse material basis for the antibiotic agents.

Insight into the interaction and binding mechanism of a natural nonnutritive sweetener mogroside V with soybean protein isolates based on multi-spectroscopic techniques and computational simulations.

As a natural low-calorie sweetener, Mogroside V (Mog-V) has gradually become one of the alternatives to sucrose with superior health attributes. However, Mog-V will bring unpleasant aftertastes when exceeding a threshold concentration. To investigate the possibility of soy protein isolates (SPIs), namely ß-conglycinin (7S), and glycinin (11S) as flavor-improving agents of Mog-V, the binding mechanism between Mog-V and SPIs was explored through multi-spectroscopy, particle size, zeta potential, and computational simulation. The results of the multi-spectroscopic experiments indicated that Mog-V enhanced the fluorescence of 7S/11S protein in a static mode. The binding affinity of 7S-Mog-V was greater compared with 11S-Mog-V. Particle size and zeta potential analysis revealed that the interaction could promote aggregation of 7S/11S protein with different stability. Furthermore, computational simulations further confirmed that Mog-V could interact with the 7S/11S protein in different ways. This research provides a theoretical foundation for the development and application of SPI to improve the flavor of Mog-V, opening a new avenue for further expanding the market demand for Mog-V.

In vitro studies of hemoglobin's affinity for the Vitamin B9 and control of its stability character.

Vitamin B9, known as folic acid, and hemoglobin play an important biological role in the human body. This study was designed to investigate the nature of the complex through multispectroscopic methods at physiological conditions due to the lack of research on the binding interactions between folic acid and hemoglobin. Structural analysis showed that the interactions between the molecules are mainly hydrophobic with binding constant of 0.73 × 104 L/mol at 37 °C. The secondary structure of the protein was stable after the addition of folic acid with a 20-fold excess of ligand per mol protein. The stability effect of folic acid on hemoglobin was examined as a function of release of iron ions and determination of the level of phenanthroline-Fe2+ complex. The protective function of folic acid was observed at a concentration of 6.12 nmol/L, and the release of iron ions was lower than in the control probe.

Host-Guest Interaction Study of Olmesartan Medoxomil with ß-Cyclodextrin Derivatives.

Olmesartan medoxomil (OLM) is a selective angiotensin II receptor antagonist used in the treatment of hypertension. Its therapeutic potential is limited by its poor water solubility, leading to poor bioavailability. Encapsulation of the drug substance by two methylated cyclodextrins, namely randomly methylated ß-cyclodextrin (RM-ß-CD) and heptakis(2,3,6-tri-O-methyl)-ß-cyclodextrin (TM-ß-CD), was carried out to overcome the limitation related to OLM solubility, which, in turn, is expected to result in an improved biopharmaceutical profile. Supramolecular entities were evaluated by means of thermoanalytical techniques (TG-thermogravimetry; DTG-derivative thermogravimetry), spectroscopic methods including powder X-ray diffractometry (PXRD), universal-attenuated total reflectance Fourier-transform infrared (UATR-FTIR) and UV spectroscopy, saturation solubility studies, and by a theoretical approach using molecular modeling. The phase solubility method reveals an AL-type diagram for both inclusion complexes, indicating a stoichiometry ratio of 1:1. The values of the apparent stability constant indicate the higher stability of the host-guest system OLM/RM-ß-CD. The physicochemical properties of the binary systems are different from those of the parent compounds, emphasizing the formation of inclusion complexes between the drug and CDs when the kneading method was used. The molecular encapsulation of OLM in RM-ß-CD led to an increase in drug solubility, thus the supramolecular adduct can be the subject of further research to design a new pharmaceutical formulation containing OLM, with improved bioavailability.

Molecular interaction of antiviral drug penciclovir with DNA and HSA insights from experimental and docking studies.

One approach to accelerate the availability of new cancer drugs is to test drugs approved for other conditions as anticancer agents. During recent decades, penciclovir (PNV) has been frequently utilized as a potent antiviral drug, in particular against infections caused by herpes viruses. Many antivirals interact with DNA and change their expression level, so determining the binding mode is of great importance. In our laboratory, we have focused our attention to design improved drugs that target cellular DNA, to understand the mechanism of action at the molecular level, and also to investigate the effect of antiviral drugs as anticancer agents. The results of ct-DNA-PNV interactions at physiological pH using fluorescence spectroscopy, UV-visible absorption spectroscopy, and molecular modeling reveal this drug binds well to ct-DNA through groove binding. The circular dichroism measurements displayed that PNV caused a slight change in the DNA structure which affirmed that the binding of PNV with the DNA occurs through the groove mode. Besides, multi-spectroscopic and molecular docking were used to evaluate how PNV interacts with human serum albumin under physiological conditions. The findings of fluorescence quenching suggested that static quenching was involved in the spontaneous development of HSA-PNV complex through hydrophobic force. The docking simulation results validated the findings of spectroscopic techniques.Communicated by Ramaswamy H. Sarma.

Interaction of Cecropin A (1-7) Analogs with DNA Analyzed by Multi-spectroscopic Methods.

Cecropin A (1-7) is a cationic antimicrobial peptide which contain lots of basic amino acids. To understand the effect of basic amino acids on cecropin A (1-7), analogues CA2, CA3 and CA4 which have more arginine or lysine at the N-terminal or C-terminal were designed and synthesized. The interaction of cecropin A (1-7) and its analogs with DNA was studied using ultraviolet-visible spectroscopy, fluorescence spectroscopy and circular dichroism spectroscopy. Multispectral analysis showed that basic amino acids improved the interaction between the analogues and DNA. The interaction between CA4 and DNA is most pronounced. Fluorescence spectrum indicated that Ksv value of CA4 is 1.19 × 105  L mol-1 compared to original peptide cecropin A (1-7) of 3.73 × 104  L mol-1. The results of antimicrobial experiments with cecropin A (1-7) and its analogues showed that basic amino acids enhanced the antimicrobial effect of the analogues. The antimicrobial activity of CA4 against E. coli was eightfold higher than that of cecropin A (1-7). The importance of basic amino acid in peptides is revealed and provides useful information for subsequent studies of antimicrobial peptides.

Interaction studies of water-soluble Zn(II) complex with calf thymus DNA using biophysical and molecular docking methods".

The binding between a fluorescent water-soluble Zn(II) complex of {2-[N-(2-hydroxyethylammonioethyl) imino methyl] phenol} and calf thymus DNA (ct-DNA) was investigated using spectroscopic techniques. The complex was prepared and identified by FT-IR, and 1H NMR spectroscopies. The significant changes in the absorption and the circular dichroism spectra of ct-DNA in the presence of the Zn(II) complex implied the interaction between the Zn(II) complex and ct-DNA. Upon addition of ct-DNA, the fluorescence emission intensity of the Zn(II) complex was increased and indicated the interaction between the Zn(II) complex and ct-DNA was occurred. The binding constant values (Kb) resulted from fluorescence spectra clearly showed the Zn(II) complex affinity to ct-DNA. The fluorescence studies also approved the static enhancement mechanism in the Zn(II) complex-DNA complexation process. The thermodynamic profile exhibited the exothermic and spontaneous formation of ct-DNA-Zn(II) complex system via hydrogen bonds and van der Waals forces. The competitive fluorescence investigation by methylene blue (MB), and Hoechst 33258 demonstrated that the Zn(II) complex could replace the DNA-bound Hoechst and bind to the minor groove binding site in ct-DNA. The viscosity changes were negligible, representing the Zn(II) complex binding to DNA via the groove binding mode. Molecular docking simulation affirmed that the Zn(II) complex is located in the minor groove of ct-DNA near the DG12, DA17, DA18, and DG16 nucleobases.

Fluorescence Quenching and the Chamber of Nitroaromatics: A Dinaphthoylated Oxacalix[4]arene's (DNOC) Adventure Captured through Computational and Experimental Study.

This research presents the application of Dinaphthoylated Oxacalix[4]arene (DNOC) as a novel fluorescent receptor for the purpose of selectively detecting nitroaromatic compounds (NACs). The characterization of DNOC was conducted through the utilization of spectroscopic methods, including 1H-NMR, 13C-NMR, and ESI-MS. The receptor demonstrated significant selectivity in acetonitrile towards several nitroaromatic analytes, such as MNA, 2,4-DNT, 2,3-DNT, 1,3-DNB, 2,6-DNT, and 4-NT. This selectivity was validated by the measurement of emission spectra. The present study focuses on the examination of binding constants, employing Stern-Volmer analysis, as well as the determination of the lowest detection limit (3σ/Slope) and fluorescence quenching. These investigations aim to provide insights into the inclusion behavior of DNOC with each of the six analytes under fluorescence spectra investigation. Furthermore, the selectivity trend of the ligand DNOC for NAC detection is elucidated using Density Functional Theory (DFT) calculations conducted using the Gaussian 09 software. The examination of energy gaps existing between molecular orbitals, namely the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), provides a valuable understanding of electron-transfer processes and electronic interactions. Smaller energy gaps are indicative of heightened selectivity resulting from favorable electron-transfer processes, whereas bigger gaps suggest less selectivity attributable to weaker electronic contacts. This work integrates experimental and computational methodologies to provide a full understanding of the selective binding behavior of DNOC. As a result, DNOC emerges as a viable chemical sensor for detecting nitroaromatic explosives.

Application of metabolomics in diagnostics and differentiation of meningitis: A narrative review with a critical approach to the literature.

Due to its high mortality rate associated with various life-threatening sequelae, meningitis poses a vital problem in contemporary medicine. Numerous algorithms, many of which were derived with the aid of artificial intelligence, were brought up in a strive for perfection in predicting the status of sepsis-related survival or exacerbation. This review aims to provide key insights on the contextual utilization of metabolomics. The aim of this the metabolomic approach set of methods can be used to investigate both bacterial and host metabolite sets from both the host and its microbes in several types of specimens - even in one's breath, mainly with use of two methods - Mass Spectrometry (MS) and Nuclear Magnetic Resonance (NMR). Metabolomics, and has been used to elucidate the mechanisms underlying disease development and metabolic identification changes in a wide range of metabolite contents, leading to improved methods of diagnosis, treatment, and prognosis of meningitis. Mass spectrometry (MS) and Nuclear Magnetic Resonance (NMR) are the main analytical platforms used in metabolomics. Its high sensitivity accounts for the usefulness of metabolomics in studies into meningitis, its sequelae, and concomitant comorbidities. Metabolomics approaches are a double-edged sword, due to not only their flexibility, but also - high complexity, as even minor changes in the multi-step methods can have a massive impact on the results. Information on the differential diagnosis of meningitis act as a background in presenting the merits and drawbacks of the use of metabolomics in context of meningeal infections.

Probing the Interaction between Isoflucypram Fungicides and Human Serum Albumin: Multiple Spectroscopic and Molecular Modeling Investigations.

To better understand the potential toxicity risks of isoflucypram in humans, The interaction between isoflucypram and HSA (human serum albumin) was studied through molecular docking, molecular dynamics simulations, ultraviolet-visible absorption, fluorescence, synchronous fluorescence, three-dimensional fluorescence, Fourier transform infrared spectroscopies, and circular dichroism spectroscopies. The interaction details were studied using the molecular docking method and molecular dynamics simulation method. The results revealed that the effect of isoflucypram on human serum albumin was mixed (static and dynamic) quenching. Additionally, we were able to obtain important information on the number of binding sites, binding constants, and binding distance. The interaction between isoflucypram and human serum albumin occurred mainly through hydrogen bonds and van der Waals forces. Spectroscopic results showed that isoflucypram caused conformational changes in HSA (human serum albumin), in which the α-helix was transformed into a ß-turn, ß-sheet, and random coil, causing the HSA structure to loosen. By providing new insights into the mechanism of binding between isoflucypram and human serum albumin, our study has important implications for assessing the potential toxicity risks associated with isoflucypram exposure.

Quantifying metal-binding specificity of CcNikZ-II from Clostridium carboxidivorans in the presence of competing metal ions.

Many proteins bind transition metal ions as cofactors to carry out their biological functions. Despite binding affinities for divalent transition metal ions being predominantly dictated by the Irving-Williams series for wild-type proteins, in vivo metal ion binding specificity is ensured by intracellular mechanisms that regulate free metal ion concentrations. However, a growing area of biotechnology research considers the use of metal-binding proteins in vitro to purify specific metal ions from wastewater, where specificity is dictated by the protein's metal binding affinities. A goal of metalloprotein engineering is to modulate these affinities to improve a protein's specificity towards a particular metal; however, the quantitative relationship between the affinities and the equilibrium metal-bound protein fractions depends on the underlying binding mechanisms. Here we demonstrate a high-throughput intrinsic tryptophan fluorescence quenching method to validate binding models in multi-metal solutions for CcNikZ-II, a nickel-binding protein from Clostridium carboxidivorans. Using our validated models, we quantify the relationship between binding affinity and specificity in different classes of metal-binding models for CcNikZ-II. We further illustrate the potential relevance of data-informed models to predicting engineering targets for improved specificity.

A Comparative Study of Nanobio Interaction of Zn-Doped CdTe Quantum Dots with Lactoferrin Using Different Spectroscopic Methods.

In this paper, glutathione (GSH)-coated Zn-doped CdTe quantum dots (QDs) with different particle sizes were synthesized using the "reflow method", and the interaction mechanism between the two QDs and lactoferrin (LF) was investigated systemically with different spectroscopic methods. The steady-state fluorescence spectra showed that the LF formed a tight complex with the two QDs through static bursting and that the electrostatic force was the main driving force between the two LF-QDs systems. The complex generation process was found to be spontaneous (ΔG < 0) and accompanied by exothermic and increasing degrees of freedom (ΔH < 0, ΔS > 0) by using the temperature-dependent fluorescence spectroscopy. The critical transfer distance (R0) and donor-acceptor distance (r) of the two LF-QDs systems were obtained based on the fluorescence resonance energy transfer theory. In addition, it was observed that the QDs changed the secondary and tertiary structures of LF, leading to an increase in the hydrophobicity of LF. Further, the nano-effect of orange QDs on LF is much larger than that of green QDs. The above results provide a basis for metal-doped QDs with LF in safe nano-bio applications.