Yan-Fu Lin

National Chung Hsing University, 臺中市, Taiwan, Taiwan

Are you Yan-Fu Lin?

Claim your profile

Publications (9)25.31 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Photodynamic therapy (PDT) is an innovative method for cancer treatment that involves the administration of a photosensitizing agent followed by exposure to visible light. An appreciable amount of a particular light source is a key to activate photosensitizers in PDT. However, the external excitation light source is a problem for clinical application because of the limitation of tissue-penetrating properties. Additionally, the wavelength of laser emission should match the absorption wavelength of each photosensitizer for efficient generation of reactive oxygen species and cell killing. In this study, Renilla luciferase-immobilized quantum dots-655 (QD-RLuc8) was used for bioluminescence resonance energy transfer (BRET)-mediated PDT to resolve these problems. The bioluminescent QD-RLuc8 conjugate exhibits self-illumination at 655 nm after coelenterazine addition, which can activate the photosensitizer, Foscan(®)-loaded micelles for PDT. Our results show that BRET-mediated PDT by QD-RLuc8 plus coelenterazine (20 μg/mL) successfully generated reactive oxygen species (40.8%), killed ∼ 50% A549 cells at 2 μg/mL equivalent Foscan(®)in vitro and significantly delayed tumor growth in vivo due to cell apoptosis under TUNEL analysis without obvious weight loss. Based on immunohistochemical observations, the proliferating cell nuclear antigen (PCNA)-negative area of tumor sections after BRET-mediated PDT was obviously increased compared to the PDT-untreated groups without an external light source. We conclude that this nanotechnology-based PDT possesses several clinical benefits, such as overcoming light penetration issues and treating deeper lesions that are intractable by PDT alone.
    Biomaterials 10/2012; · 8.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 1,1-Di(t-butylperoxy)-3,3,5-trimethylcyclohexane (TMCH) 88 mass% and 1,1-di(tertial butyl peroxy)cyclohexane (CH) 70 mass% are widely used in the polymer industry. Both are peroxyketal peroxides. Mixing peroxides with incompatible materials could induce runaway reactions in an upset situation. This is study of how acetone affects the peroxide decomposition reaction. We used differential scanning calorimetry (DSC) to detect the decomposition reaction with various ratio of acetone mixed with both peroxides. Our results showed that the acetone change from low concentration to higher concentration had a diverse effect on the peroxide decomposition reactions. A lower concentration of the acetone indicated an accelerated effect for the mixture conditions. The decomposition rates of peroxides decreased gradually as the concentration of acetone increased.
    Thermochimica Acta 01/2011; · 1.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Runaway reactions by methyl ethyl ketone peroxide (MEKPO) are an important issue in Asia, due to its unstable structure and extensive heat release during upset situations. This study employed differential scanning calorimetry (DSC) to draw the experimental data for MEKPO 31 mass% and with acetone 99 mass% on three types of heating rate of 2, 4, and 10 degrees C/min; the kinetic and safety parameters were then evaluated via curve fitting. Through the reproducible tests in each condition, the results show that acetone is not a contaminant, because it could increase the activation energy (Ea) and onset temperature (To) when combined with MEKPO, which differs from the hazard information of the material safety data sheet (MSDS).
    Journal of Hazardous Materials 06/2008; 153(3):1071-7. · 4.33 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Methyl ethyl ketone peroxide (MEKPO) is an unstable material that is classified as an explosive substance. We evaluated MEKPO 10 mass% under mixing with three inorganic acids (6 N HNO3, 6 N H3PO4, and 6 N H2SO4) by adiabatic system of vent sizing package 2 (VSP2). Results from evaluation and testing indicated that these three inorganic acids could increase the degree of hazard while combined with pure MEKPO. Therefore, information on the hazards and phenomena of runaway reaction should be provided in order to lessen the degree of hazard.
    Korean Journal of Chemical Engineering 04/2008; 25(3):419-422. · 1.06 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 1,2-Ethylene-di-N-n-propylcarbamate (1) is characterized as an essential activator of Pseudomonas species lipase while 1,2-ethylene-di-N-n-butyl-, t-butyl-, n-heptyl-, and n-octyl-carbamates (2-5) are characterized as the pseudo substrate inhibitors of the enzyme in the presence of the detergent taurocholate or triton X-100. The inhibition and activation reactions are more sensitive in taurocholate than in triton X-100. From CD studies, the enzyme changes conformations in the presence of the detergent and further alters conformations by addition of the carbamate activator or inhibitor into the enzyme-detergent adduct. Therefore, this study suggests that the conformational change of lipase during interfacial activation is a continuous process to expose the active site of the enzyme to substrate. From 600 MHz (1)H NMR studies, the conformations of the alpha- and beta-methylene moieties of the activator 1,2-ethylene-di-N-n-propylcarbamate in the presence of substrate change after adding taurocholate into the mixture, and the conformations of the beta-methylene moieties of the inhibitor 1,2-ethylene-di-N-n-butylcarbamate in the presence of substrate alter after adding taurocholate into the mixture.
    Chemistry and Physics of Lipids 05/2007; 146(2):85-93. · 2.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Carbamates are used to treat Alzheimer's disease. These compounds inhibit acetylcholinesterase and butyrylcholinesterase. The goal of this work is to use the substrate analogs of butyrylcholinesterase, 3,3-dimethylbutyl-N-n-butylcarbamate (1) and 2-trimethylsilyl-ethyl-N-n-butylcarbamate (2) to probe the substrate activation mechanism of butyrylcholinesterase. Compounds 1 and 2 are characterized as the pseudo substrate inhibitors of acetylcholinesterase; however, compounds 1 and 2 are characterized as the essential activators of butyrylcholinesterase. Therefore, compounds 1 and 2 mimic the substrate in the acetylcholinesterase-catalyzed reactions, but the behavior of compounds 1 and 2 mimics the substrate activation in the butyrylcholinesterase-catalyzed reactions.
    Journal of Biochemical and Molecular Toxicology 02/2007; 21(1):24-31. · 1.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The goal of this work is to study kinetics and quantitative structure-activity relationships for steady states of Pseudomonas sp. lipase-catalyzed hydrolysis of both diesters and monoesters of ethylene glycol. Based on the steady-state kinetics of the enzyme-catalyzed hydrolysis of the diesters of ethylene glycol, the diesters and the monoesters react simultaneously as soon as monoester has started to build up in the reaction medium. In other words, the apparent K m values of the diesters are the K m values of the diesters (K mA) plus the K m values of the monoesters (K mB), and all V max values are about the same. Moreover, the pH-stat titration curve of the enzyme-catalyzed hydrolysis of the diesters of ethylene glycol is initially hyperbolic, then there is a sharp falloff in the hydrolysis rate. The abrupt stoppage of the reaction (relaxation stage) may be due to the existence of two phases in the reaction medium, that is, the product (ethylene glycol) and the substrates (the diesters of ethylene glycol) are not miscible. Furthermore, quantitative structure-activity relationships for varied acyl groups of mono-and diesters of ethylene glycol are studied. The fact that both pK mA and pK mB values are linearly correlated with the hydrophobicity constant (π) but not with the electronic substituent constants (σ*) indicates that the affinity of these substrates for the enzyme depends only on the hydrophobicity of substrates.
    Journal of Oil & Fat Industries 02/2006; 83(3):201-207. · 1.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ortho-substituted phenyl-N-butyl carbamates (1-9) are characterized as "pseudo-pseudo-substrate" inhibitors of acetylcholinesterase. Since the inhibitors protonate at pH 7.0 buffer solution, the virtual inhibition constants (K'is) of the protonated inhibitors are calculated from the equation, - logK'i = - logKi - logKb. The logarithms of the inhibition constant (Ki), the carbamylation constant (k(c)), and the bimolecular inhibition constant (k(i)) for the enzyme inhibitions by carbamates 1-9 are multiply linearly correlated with the Hammett para-substituent constant (sigma(p)), the Taft-Kutter-Hansch ortho steric constant (E(S)), and the Swan-Lupton ortho polar constant (F). Values of rho, delta, and f for the - logKi-, logk(c)-, and logk(i)-correlations are -0.6, -0.16, 0.7; 0.11, 0.03, -0.3; and - 0.5, - 0.12, 0.4, respectively. The Ki step further divides into two steps: 1) the pre-equilibrium protonation of the inhibitors, Kb step and 2) formation of a negatively charged enzyme-inhibitor Michaelis-Menten complex--virtual inhibition, K'i step. The Ki step has little ortho steric enhancement effect; moreover, the k(c)step is insensitive to the ortho steric effect. The f value of 0.7 for the Ki step indicates that ortho electron-withdrawing substituents of the inhibitors accelerate the inhibition reactions from the ortho polar effect; however, the f value of -0.3 for the k(c)step implies that ortho electron-withdrawing substituents of the inhibitors lessen the inhibition reactions from the ortho polar effect.
    Journal of Enzyme Inhibition and Medicinal Chemistry 11/2004; 19(5):395-401. · 1.50 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Conformationally constrained 1,2-, 1,3-, and 1,4-benzene-di-N-octylcarbamates are potent reversible competitive inhibitors of Naja mocambique mocambique phospholipase A(2) with the K(i) values of 11, 4, and 15 microM, respectively. With the angle of 120(o) between two C(benzene)-O bonds, 1,3-benzene-di-N-octylcarbamate mimics the preferable eclipsed C(sn-2)-O/C(sn-3)-O conformer of phospholipid in the enzyme-phospholipid complex. Further, a three-step phospholipase A(2) inhibition mechanism by the inhibitor is proposed.
    Bioorganic & Medicinal Chemistry Letters 03/2004; 14(3):751-5. · 2.34 Impact Factor

Publication Stats

37 Citations
25.31 Total Impact Points

Institutions

  • 2006–2011
    • National Chung Hsing University
      • Department of Chemistry
      臺中市, Taiwan, Taiwan
  • 2008
    • National Yunlin University of Science and Technology
      • Department of Safety, Health and Environmental Engineering
      Tou-liu, Taiwan, Taiwan
  • 2007
    • Chung Shan Medical University
      • Institute of Medicine
      Taichung, Taiwan, Taiwan