Study of the interaction between tosufloxacin tosylate and bovine serum albumin by multi-spectroscopic methods

The interaction of tosufloxacin tosylate (TSFX) and bovine serum albumin (BSA) was studied by fluorescence spectroscopy, UV–vis spectroscopy and FT-IR spectroscopy. The results indicated that the intrinsic fluorescence of BSA was quenched by TSFX through a static quenching mechanism, and the effective binding constants (K_a) were obtained by means of the modified Stern–Volmer equation. Thermodynamic parameters showed that electrostatic interaction was mostly responsible for the binding of TSFX to BSA. The binding distance (r) between TSFX and Trp-212 was determined to be 3.90 nm according to Föster non-radiative energy transfer theory. BSA had a single class of binding site at Sudlow' site I in subdomain IIA for TSFX. The effects of TSFX on the conformation of BSA were analyzed by synchronous fluorescence spectra and three-dimensional fluorescence spectra, and the results exhibited that the hydrophobicity of tryptophan microenvironment was decreased. In FT-IR spectra, Fourier self-deconvolution, secondary derivative and the curve-fitting process were carried out to obtain the components of BSA secondary structure at 298 K and 310 K. The full basic data indicated that the presence of TSFX resulted in α-helix and β-sheet changing into β-turn and random, which displayed that TSFX induced the unfolding of the polypeptides of BSA.     

Study on the conjugation mechanism of colistin sulfate with bovine serum albumin and effect of the metal ions on the reaction

Colistin sulfate (CS) can quench the fluorescence of bovine serum albumin (BSA) in an aqueous solution at pH 7.40. The static fluorescence-quenching process between BSA and CS was confirmed and the binding constant, the number of binding sites and thermodynamic data for the interaction between BSA and CS were also obtained. Results showed that the order of magnitude of binding constant (K_a) was 10⁴, and the number of binding site (n) in the binary system was approximately equal to 1; electrostatic force played an important role on the conjugation reaction between BSA and CS. On the basis of the Förster theory of the resonance energy transfer, the binding distance (r) between CS and BSA was less than 7 nm. Comparing the quenching of protein fluorescence excited at 280 nm and 295 nm and from the site marker replacement experiments, it was shown that the primary CS binding site was located in the sub-domain IIA (site I) of BSA. Synchronous fluorescence spectra clearly revealed that the binding of CS with BSA can induce conformation changes in BSA. In addition, the effects of common metal ions on the binding constants of CS–BSA complex were also discussed. It was shown that, except Cu²⁺, the high metal ion concentrations improved the CS efficacy.     

Spectroscopic studies on the interaction of bovine serum albumin with ginkgolic acid: Binding characteristics and structural analysis

The interaction between ginkgolic acid (GA, C15:0) and bovine serum albumin (BSA) is investigated by several spectroscopic methodologies. At first, the binding characteristics of GA and BSA are determined by fluorescence emission spectra. It is showed that GA quenches the fluorescence of BSA and the static quenching constant K_LB is 11.7891×10⁴ L mol^?1 s^?1 at 297 K. GA and BSA form a 1:1 complex with a binding constant of 9.12×10⁵ L mol^?1. GA binds to the Sudlow's drug binding site II in BSA, and the binding distance between them is calculated as 1.63 nm based on the Förster theory. The thermodynamic parameters indicate that the interaction between BSA and GA is driven mainly by hydrophobic forces. On the other hand, structural analysis indicates that GA binding results in an increased hydrophobicity around the tryptophan residues of BSA as revealed by the synchronous fluorescence spectra, and a decrease in α-helix as revealed by the far-UV CD spectra. In addition, ANS, UV–vis and RLS experiments confirmed that GA binding causes a certain structural changes in BSA. These findings provide the binding information between BSA and GA, and may be helpful for pharmacokinetics and the design of dosage forms of GA.     

Spectroscopic study of interaction of styrylcyanine dye Sbt and its derivatives with bovine serum albumin

The spectral-fluorescent characteristics of styrylcyanine dye Sbt ((E)-2-(4-(dimethylamino) styryl)-3-methylbenzo[d]thiazol-3-ium iodide) and homodimers, dyes conjugated with two chromophores in aqueous solutions without and in the presence of bovine serum albumin (BSA), are studied. It is established that in the presence of BSA for dyes Dbt-5 and Dbt-10, an increase of the absorptivity, a slight broadening and the emergence of new band on the short wavelength range with λ_max=410 nm is observed; also hypsochromic shift of the absorption and fluorescence at 30 nm and 7 nm, respectively for the dye D-183 is observed. The intensity of the fluorescence emission fundamental band in all the studied dyes in the presence of BSA increases by 3.5 to 55 times. The binding constant (K) and number of binding sites (N) of studied dyes with BSA are determined. The dependence of the binding constants with BSA from the dipole moment of dye molecules is identified, which shows that in addition to the electrostatic attraction forces between molecules of styrylcyanine dyes with BSA, hydrophobic interactions are essential. It is shown that the aggregation of dye affects the processes of interaction of the dyes with the BSA.     

Interactions between 4-(2-dimethylaminoethyloxy)-N-octadecyl-1,8-naphthalimide and serum albumins: Investigation by spectroscopic approach

A novel 4-(2-dimethylaminoethyloxy)-N-octadecyl-1,8-naphthalimide (DON) has been synthesized as a spectrofluorimetric probe for the determination of proteins. Photophysics of DON in different solvents has been delineated in this paper. Progressive redshift with polarity of solvents in emission and absorption spectra hints at intramolecular charge transfer. The interactions of DON with serum albumins (i.e., human serum albumin (HSA) and bovine serum albumin (BSA)) were studied by fluorescence and absorption spectroscopy. Fluorescence data revealed that the quenching of HSA/BSA by DON were static quenching and the DON–HSA/BSA complexes were formed. The binding constant (K_b) for HSA and was found to be 8.44×10^?4 and 60.26×10^?4 M^?1 and the number of binding sites (n) were 1.00 and 1.40, respectively. The thermodynamic parameters, ΔH and ΔS, for the DON–HSA system was calculated to be ?14.83 kJ mol^?1 and 23.61 J mol^?1 K^?1, indicating the hydrogen bonds and hydrophobic interactions were the dominant intermolecular force. ΔH and ΔS for the binding of DON with BSA was ?60.08 kJ mol^?1 and ?90.7441 mol^?1 K^?1, suggesting the hydrogen bonds and van der Waals force played the main role in the interaction. The results of displacement experiments showed that DON bound HSA/BSA occurred at the Trp-214 proximity, located in subdomain IIA of the serum albumin structure (the warfarin binding pocket). The effect of DON on the conformation of HSA was also analyzed by synchronous and three-dimensional fluorescence spectra. The fluorescence of DON could be quenched by HSA, based on which, a fluorometric method for the determination of microamount protein using DON in the medium of HCl?Tris buffer solution (pH=7.4) was developed. The linear range of the calibration curves was 0.1–10.0 μM for HSA, 0.1–11.2 μM for BSA and 0.2–9.7 μM for egg albumin (EA). The detection limit (3σ) for HSA was 1.12×10^?10 M, for BSA it was 0.92×10^?10 M and for EA it was 4.33×10^?10 M. The effect of metal cations on the fluorescence spectra of DON in ethanol was also investigated. The method has been applied to detect the total proteins in human serum samples and the results were in good agreement with those reported by the hospital.     

Spectroscopic study on the interaction of eugenol with salmon sperm DNA in vitro

Fluorescence spectra, absorption spectra, melting temperature, ionic strength effect, and viscosity experiments were described that characterize the interaction of eugenol with salmon sperm DNA in vitro. Eugenol was found to bind but weakly to DNA, with binding constants of 4.23×10³, 3.62×10³ and 2.47×10³ L mol^?1 at 18, 28 and 38 °C respectively. The Stern–Volmer plots at different temperatures suggested that the quenching type of fluorescence of eugenol by DNA was a static quenching. Both the relative viscosity and the melting temperature of DNA were increased by the addition of eugenol. The changes of ionic strength had no affect on the binding. In addition, the binding constant of eugenol with single stranded DNA (ssDNA) was larger than that of eugenol with double stranded DNA (dsDNA). These results revealed that the binding mode of eugenol to DNA was intercalative binding. The thermodynamic parameters ΔH, ΔG and ΔS were also obtained according to the Van't Hoff equations, which suggested that hydrogen bond or van der Waals force might play an important role in a binding of eugenol to DNA. Based on the theory of the Förster energy transference, the binding distance between DNA and eugenol was determined as 4.40 nm, indicating that the static fluorescence quenching of eugenol by DNA was also a non-radiation energy transfer process.     

Investigation on the interactions of silymarin to bovine serum albumin and lysozyme by fluorescence and absorbance

The interactions of silymarin with bovine serum albumin (BSA) and lysozyme (LYS) were investigated in physiological buffer (pH = 7.4) by fluorescence spectroscopy and UV–vis absorption spectroscopy. The mechanism study indicated that silymarin could strongly quench the intrinsic fluorescence of BSA and LYS through static quenching procedures. At 291 K, the values of the binding constant K_A were 4.20×10⁴ and 4.71×10⁴ L mol^?1 for silymarin–BSA and silymarin–LYS, respectively. Using thermodynamic equations, the conclusion that hydrophobic and electrostatic forces played an important role in stabilizing complex of silymarin–BSA or silymarin–LYS was obtained. The effects of Cu²⁺, Mg²⁺, Ca²⁺, Fe²⁺, and Fe³⁺ on the binding were also studied at 291 K. According to Förster’s nonradiative energy transfer theory, the distances r₀ between donor and acceptor were calculated to be 3.36 and 2.71 nm for silymarin–BSA and silymarin–LYS, respectively. Synchronous fluorescence spectra showed that the conformation of BSA and LYS were changed by silymarin.     

Investigation of three flavonoids binding to bovine serum albumin using molecular fluorescence technique

The three flavonoids including naringenin, hesperetin and apigenin binding to bovine serum albumin (BSA) at pH 7.4 was studied by fluorescence quenching, synchronous fluorescence and UV–vis absorption spectroscopic techniques. The results obtained revealed that naringenin, hesperetin and apigenin strongly quenched the intrinsic fluorescence of BSA. The Stern–Volmer curves suggested that these quenching processes were all static quenching processes. At 291 K, the value and the order of the binding constant were K_{A (naringenin)}=4.08×10⁴<K_{A (hesperetin)}=5.40×10⁴≈K_{A (apigenin)}=5.32×10⁴ L mol^?1. The main binding force between the flavonoid and BSA was hydrophobic and electrostatic force. According to the Förster theory of non-radiation energy transfer, the binding distances (r₀) were obtained as 3.36, 3.47 and 3.30 nm for naringenin–BSA, hesperetin–BSA and apigenin–BSA, respectively. The effect of some common ions such as Fe³⁺, Cu²⁺, Mg²⁺, Mn²⁺, Zn²⁺ and Ca²⁺ on the binding was also studied in detail. The competition binding was also performed. The apparent binding constant (K′_A) obtained suggested that one flavonoid had an obvious effect on the binding of another flavonoid to protein when they coexisted in BSA solution.     

Studies on the interaction between scopoletin and two serum albumins by spectroscopic methods

The interactions of scopoletin to bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated by spectroscopic methods. The fluorescence tests indicated that the formation mechanism of scopoletin–BSA/HSA complexes belonged to the static quenching. The displacement experiments suggested that scopoletin primarily bound to tryptophan residues of BSA/HSA within site I (subdomain IIA). The binding distance of scopoletin to BSA/HSA was 2.38/2.34 nm. The thermodynamic parameters (ΔG, ΔH and ΔS) calculated on the basis of different temperatures revealed that the binding of BSA–scopoletin was mainly depended on van der Waals interaction and hydrogen bond, and yet the binding of HSA–scopoletin was strongly relied on the hydrophobic interaction and electrostatic interaction. The results of synchronous fluorescence, 3D fluorescence, UV–vis absorption, and FT-IR spectra showed that the conformations of BSA and HSA altered with the addition of scopoletin. In addition, the effects of some common ions on the binding constants of scopoletin to proteins were also investigated.     

Sequestration of some biogenic amines and poly(allyl)amine by high molecular weight polycarboxylic ligands in aqueous solution

The interactions of two high molecular weight polycarboxylic ligands [polyacrylic-co-maleic, MW = 70 kDa, and poly(methyl vinyl ether-co-maleic acid), MW = 15 kDa] with some polyamines [1,4-diaminobutane (or putrescine), histamine and poly(allyl)amine, MW = 15 kDa] were studied, at t = 25 °C and at low ionic strength (I = 0.015 mol L^? 1) by potentiometric measurements. For all investigated systems, the formation of (am)(L)H_i species was found (am = amine, L = polycarboxylic ligand, i = 1…4); the stability of polyammonium–polycarboxylate complexes is fairly high and the formation percentage of most species reaches ～ 90% in the experimental conditions (mmolar concentration of reactants). The dependence on temperature and ionic strength of the stability of polyamine–polycarboxylate species was studied using some semiempirical equations and enthalpy data for the protonation of both components. The sequestering ability of polyelectrolytes towards amines was modeled by a sigmoid Boltzman type equation and was defined by calculating the parameter pL₅₀ (the total ligand concentration, as ? log C_L, able to bind 50% of cation); this parameter gives an objective representation of this ability. The dependence of pL₅₀ on pH, ionic strength and temperature was studied too.     

Interaction between fullerene-wheeled nanocar and gold substrate: A DFT study

Since the successful synthesis of nanocar and its surprising movement on the gold surface, several theoretical investigations have been devoted to explain the interaction properties as well as its movement mechanism on the substrate. All of them failed, however, to gain a clear theoretical insight into the respected challenges because of the weak computational methods implemented for this complex system including heavy metal atoms and giant size of the whole system. In this work, we have investigated the adsorption of fullerene-wheeled nanocar onto a Au (1 1 1) substrate using the comprehensive first-principles density functional theory (DFT) simulations. The binding energy between the nanocar and Au (1 1 1) surface was determined to be −9.43 eV (−217.45 kcal/mol). The net charge transfer from the nanocar to the gold substrate was calculated to be about 9.56 electrons. Furthermore, the equilibrium distances between the Au surface and the C₆₀ molecule and nanocar chassis were estimated to be 2.20 Å and 2.30 Å, respectively. The BSSE correction was also considered in the binding energy estimation and the result show that the BSSE correction significantly affects the calculated binding energy for such systems.Finally, we have performed ab initio molecular dynamics simulation for a single C₆₀ fullerene on the gold surface at room temperature. Our first-principles result shows that ambient condition affect remarkably on the adsorption property of fullerene on the gold surface. We also observed that the C₆₀ fullerene wheel slips by approximately 3.90 Å within 5 ps of simulation time at 300 K.     

Combined XPS,electrochemical and Kelvin probe measurements of NaY zeolite

In the present study X-ray Photoelectron Spectroscopy (XPS) combined with in situ electrochemical and Kelvin probe measurements was used in order to get a deeper insight on the mechanism of the cation transport through NaY zeolite and the charge transfer through the Au electrode/zeolite interface. It is shown that by imposing a potential gradient across the NaY powder which is sandwiched between two electrodes, Na⁺ ions can be electrically transferred to or from the Au working electrode area, following the direction of the applied potential between the two electrodes. Two peaks corresponding to sodium species were detected by means of in situ XPS investigation during potential application. The first peak of Na1s photoelectrons with binding energy at 1072.2 ± 0.2 eV is attributed to Na adsorbed on the grounded Au electrode with its coverage remaining unchanged upon potential imposition. The second peak is directly associated with Na present in the zeolite and upon potential application its binding energy varies proportionally with the variation of the surface potential measured by Kelvin probe. Upon varying the potential from − 4 to + 4 V between the working and counter electrode, the Na⁺ concentration decreases by ca30% at the Au/zeolite interface. However the invariant amount of Na on the Au electrode under vacuum shows that the variation in Na⁺ concentration is not due to ionic transfer onto the Au surface but instead Na⁺ accumulation can be assumed at the Au/zeolite interface. On the other hand, current or potential application under O₂ atmosphere promotes the electrocatalytic reaction of Na⁺ towards the formation of Na₂O on the Au electrode surface.     

Interaction of aconitine with bovine serum albumin and effect of atropine sulphate and glycyrrhizic acid on the binding

The interaction of aconitine with bovine serum albumin (BSA) and effect of atropine sulphate and glycyrrhizic acid on binding constant, binding sites, and conformation were studied in an aqueous buffer solution (pH 7.40) by ultraviolet absorption and fluorescence spectroscopy. The study results show that aconitine quenched the endogenous fluorescence of BSA via a dynamic quenching procedure. Predominant intermolecular forces between aconitine and BSA were hydrophobic interactions, which stabilized the complex of aconitine–BSA. The distance between the donor and acceptor was 2.62 nm. The conformation of BSA was investigated by synchronous fluorescence techniques, indicating that the microenvironment around tryptophan (Trp) residues was changed. Furthermore, with the addition of atropine sulphate or glycyrrhizic acid, binding constant and the number of binding sites of aconitine to BSA were decreased, and the conformation had no change, which provide an important theoretical support for aconitine detoxification by atropine sulphate and glycyrrhizic acid.     

The effect of chemical pressure in rutheno-cuprates

We have studied the effect of negative chemical pressure in the RuGd_1.5(Ce_0.5?xPr_x)Sr₂Cu₂O_10?δ with Pr content of 0.0 ? x ? 0.2. This is also investigated using the bond length results obtained from the Rietveld refinement analysis. The c parameter and cell volume increase with x for 0.0 ? x ? 0.15. The width of the resistivity transition also increases with Pr concentration, indicating higher inhomogeneity and oxygen deficiency. The difference in the ionic valences of Pr^3+,4+ and Ce⁴⁺ causing different hole doping, the difference in the ionic radii, and oxygen stoichiometry affect the superconducting transition. The magnetoresistance shows a cusp around 135 K which lies between the antiferromagnetic and ferromagnetic transition temperatures, which is probably due to the presence of a spin glass region. There exist two magnetic transition temperatures for 0.0 ? x ? 0.2 which respectively change from T_M = 155 K to 144 K and from T_irr = 115 K to 70 K. The magnetization versus applied magnetic field isotherms at 77 K and 300 K show that the remanent magnetization and coercivity are lower for samples with higher Pr content.     

Structural and optical properties of chromotrope 2R thin films of different thicknesses

Chromotrope 2R (CHR) films of different thicknesses have been prepared using spin coater. The material has been characterized using FT-IR, DTA and X-ray diffraction. The XRD of the material in powder and thin film forms showed polycrystalline structure with triclinic phase. Preferred orientation at the (1 1 4) plane is observed for the deposited films. Initial indexing of the XRD pattern was performed using “Crystalfire” computer program. Miller indices, h k l, values for each diffraction line in X-ray diffraction (XRD) spectrum were calculated and indexed for the first time. The DTA thermograms of CHR powder have been recorded in the temperature range 25–350 °C with different heating rates. The spectra of the infra-red absorption allow characterization of vibration modes for the powder and thin film. The effect of film thickness on the optical properties has been studied in the UV-visible-NIR regions. The films show high transmittance exceeding 0.90 in the NIR region λ > 800 nm. The intensity of the absorption peaks for λ < 800 nm are enhanced as the film thickness increase. The absorption bands are attributed to the (π–π*) and (n–π*) molecular transitions. The optical properties have been analyzed according to the single-oscillator model and the dispersion energy parameters as well as the free charge carrier concentration have been determined. The optical energy gap as well as the oscillator strength and electric dipole strength have been calculated.     

A preliminary study on a new LiBOB/acetamide solid phase transition electrolyte

New solid electrolytes containing acetamide and lithium bioxalato borate (LiBOB) with different molar ratios have been investigated. Their melting points (T_m) are around 42 °C. The ionic conductivities and activation energies vary drastically below and above T_m, indicating a typical feature of phase transition electrolyte. The ionic conductivity of the LiBOB/acetamide electrolyte with a molar ratio of 1:8 is 5 × 10^? 8 S cm^? 1 at 25 °C but increases to 4 × 10^? 3 S cm^? 1 at 60 °C. It was found that anode materials, such as graphite and Li₄Ti₅O₁₂, could not discharge and charge properly in this electrolyte at 60 °C due to the difficulty in forming a stable passivating layer on the anodes. However, a Li/LiFePO₄ cell with this electrolyte can be charged properly after heating to 60 °C, but cannot be charged at room temperature. Although the LiBOB/acetamide electrolytes are not suitable for Li-ion batteries due to poor electrode compatibility, the current results indicate that a solid electrolyte with a slightly higher phase transition temperature than room temperature may find potential application in stationary battery for energy storage where the electrolyte is at high conductive liquid state at elevated temperature and low conductive solid state at low temperature. The interaction between acetamide and LiBOB in the electrolyte is also studied by Raman and FTIR spectroscopy.     

Interactions between imazethapyr and bovine serum albumin: Spectrofluorimetric study

The interaction between imazethapyr (IMA) and bovine serum albumin (BSA) was investigated by fluorescence spectroscopy. The Stern–Volmer quenching constant (K_SV) at three temperatures was evaluated in order to determine the quenching mechanism. The dependence of fluorescence quenching on viscosity was also evaluated for this purpose. The results showed that IMA quenches the fluorescence intensity of BSA through a static quenching process. The values of the binding constant for the formed BSA–IMA complex and the number of binding sites were found to be 1.51×10⁵ M^?1 and 0.77, respectively, at room temperature. Based on the calculated thermodynamic parameters, the forces that dominate the binding process are hydrogen bonds and van der Waals forces, and the binding process is spontaneous and exothermic. The quenching of protein fluorescence by iodide ion was used to probe the accessibility of tryptophan residues in BSA and the change in accessibility induced by the presence of IMA. According to the obtained results, the BSA–IMA complex is formed in the site where the Trp-134 is located, causing it to become less exposed to the solvent.     

Analysis of Tb3+- and melittin-binding with the C-terminal domain of centrin in Euplotes octocarinatus

Centrin is a low molecular mass (20 KDa) protein that belongs to the EF-hand superfamily. In this work, the interaction between the Tb³⁺-saturated C-terminal domain of Euplotes octocarinatus centrin (Tb₂-C-EoCen) and 2-p-toluidinylnaphthalene-6-sulfonate (TNS) was investigated using difference UV–vis spectra and the fluorescence spectra methods. In 100 mM N-2-hydroxy-ethylpiperazine-N-2-ethanesulfonic acid (Hepes) at pH 7.4, with the addition of Tb₂-C-EoCen, four new peaks were observed at 265 nm, 278 nm, 317 nm and 360 nm by absorptivity compared with blank solution of TNS. At the same time, the reaction could be measured by fluorescence spectra. The fluorescence emission of TNS was shifted from 480 nm to 445 nm in the presence of Tb₂-C-EoCen. Meanwhile, its fluorescence intensity was increased markedly. The 1:1 stoichiometric ratio of C-EoCen to TNS was confirmed by fluorescence titration curves. The conditional binding constants of TNS with C-EoCen and Tb₂-C-EoCen were calculated to be log K_{(C-EoCen-TNS)}=5.32±0.04  M^?1 and log K_{(Tb2-C-EoCen-TNS)}=5.58±0.12 M^?1, respectively. In addition, the protein of Tb₂-C-EoCen binding with melittin was also studied. Based on the fluorescence titration curves, the 1:1 stoichiometric ratio of Tb₂-C-EoCen to melittin was confirmed. And the conditional binding constant of C-EoCen with melittin was calculated to be log Ka′=6.79±0.17 M^?1.     

Effect of temperature and pH on interaction between bovine serum albumin and cetylpyridinium bromide: Fluorescence spectroscopic approach

The fluorescence spectroscopic technique has been efficiently employed to investigate the interaction between bovine serum albumin (BSA) and cetylpyridinium bromide (CPB) under different pH and temperature conditions. The binding constant, number of binding sites, thermodynamic parameters such as ΔG, ΔH, ΔS, and nature of binding forces between BSA and CPB were obtained by measuring the steady state fluorescence quenching of BSA by CPB. The experimental results showed that the fluorescence quenching of BSA by CPB was a result of the formation of CPB-BSA complex. The static quenching was confirmed from the Stern-Volmer quenching constant at different temperatures. The effect of CPB on the conformation of BSA was analyzed using synchronous and three-dimensional fluorescence spectroscopy. pH dependence complex formation between BSA-CPB is due to the interaction between cationic side chain of CPB and the net charge developed on BSA. The distance ‘r’ between BSA and CPB was obtained according to the fluorescence resonance energy transfer.     

The oscillation condition and optical detection of series photodetector frequency circuit system matched with PMMA

In this study, the oscillation conditions for series photodetector frequency circuit system were proposed and verified experimentally. The effect of the capacitance C_p and oscillator phase θ on the oscillation ability of series photodetector frequency circuit system was investigated. It revealed that series photodetector frequency circuit system possessed excellent oscillation ability, but the oscillation ability decreased with increasing oscillator phase or decreasing capacitance C_p, even resulted in a cease-to oscillate zone. Moreover, this study elucidated the frequency response and optical detection of series photodetector frequency circuit system matched with PMMA for fluorescence dye concentration. In accordance with Hex fluorescence dye concentrations and frequency responses, the detection limit of fluorescence dye concentration 3.3 pmol/L can be measured by 100 MHz sensor system matched with PMMA. The results also showed that the frequency shift of 100 MHz sensor system matched with PMMA was linearly related to the logarithm of fluorescence dye concentration from 3.3 pmol/L to 33.3 μmol/L.