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At least 919 records · Page 51Linked to original sources
PubMed1991

Novel and sensitive noncompetitive enzyme immunoassay (hetero-two-site enzyme immunoassay) for alpha-human atrial natriuretic peptide in plasma.

A novel and sensitive noncompetitive enzyme immunoassay (hetero-two-site enzyme immunoassay) for alpha-human atrial natriuretic peptide (alpha-hANP) in plasma, which uses only one monoclonal IgG for the ring structure of alpha-hANP, is described. Plasma was filtered through polysaccharide membrane to separate peptides from proteins. The plasma filtrate was incubated with N-hydroxysuccinimidobiotin to biotinylate alpha-hANP and subsequently with a polystyrene ball coated with monoclonal IgG for the ring structure of alpha-hANP to trap biotinylated alpha-hANP. The polystyrene ball was washed to eliminate unreacted N-hydroxysuccinimidobiotin and other biotinylated substances, and biotinylated alpha-hANP was eluted from the polystyrene ball with HCl. The eluate was neutralized and incubated with horseradish peroxidase-labeled antibody IgG for the ring structure of alpha-hANP and subsequently with two streptavidin-coated polystyrene balls. Peroxidase activity bound to the streptavidin-coated polystyrene balls was assayed by fluorometry. The detection limit of alpha-hANP was 20 amol, and the assay range of plasma alpha-hANP was 0.8-1,200 ng/L using 100 microliters of plasma filtrates corresponding to 75 microliters of plasma. Plasma levels of hANP in healthy subjects were 9.8-21.5 ng/L. These values were significantly lower than those measured by a two-site enzyme immunoassay probably due to the presence of alpha-hANPs lacking some N-terminal amino acids, which were as reactive as alpha-hANP in the two-site enzyme immunoassay but less reactive in the hetero-two-site enzyme immunoassay.

Adult↗
PubMed1992

Sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (anti-human T-cell leukemia virus type I) IgG in serum using a synthetic peptide, Cys-env gp46(188-224), as antigen.

A sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (anti-human T-cell leukemia virus type I) IgG (anti-HTLV-I IgG) in serum using a synthetic peptide, Cys-env gp46(188-224) of HTLV-I, is described. Anti-HTLV-I IgG in test serum, which had been incubated with excess of inactive beta-D-galactosidase to eliminate interference by anti-beta-D-galactosidase antibodies, was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-Cys-env gp46 (188-224) conjugate and Cys-env gp46 (188-224)-beta-D-galactosidase conjugate. The complex formed consisting of the three components was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG. After washing to eliminate nonspecific IgG in the test serum and excess of the beta-D-galactosidase conjugate, the complex was eluted from the polystyrene balls with epsilon N-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. beta-D-Galactosidase activity bound to the (anti-human IgG gamma-chain) IgG-coated polystyrene balls was assayed by fluorometry. This assay was more sensitive and useful than the immune complex transfer enzyme immunoassay using Cys-Arg-env gp46(188-209) and other methods using HTLV-I as antigen.

Amino Acid Sequence↗
PubMed1992

Sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (antihuman T-cell leukemia virus type I) immunoglobulin G in serum using a synthetic peptide, Ala-Cys-Env gp46(237-262), as antigen.

A sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for (antihuman T-cell leukemia virus type I) IgG (anti-HTLV-I IgG) in serum using a synthetic peptide, Ala-Cys-env gp46(237-262), of HTLV-I is described. Anti-HTLV-I IgG in test serum, which had been incubated with excess of inactive beta-D-galactosidase to eliminate interference by anti-beta-D-galactosidase antibodies, was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-Ala-Cys-env gp46(237-262) conjugate and Ala-Cys-env gp46(237-262)-beta-D-galactosidase conjugate. The complex formed consisting of the three components was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG. After washing to eliminate nonspecific IgG in the test serum and excess of the beta-D-galactosidase conjugate, the complex was eluted from the polystyrene balls with epsilon N-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. beta-D-galactosidase activity bound to the (anti-human IgG gamma-chain) IgG-coated polystyrene balls was assayed by fluorometry. This assay was more sensitive than other methods using HTLV-I as antigen, and most negative and positive sera were discriminated. However, some results appeared to be false positive or false negative, and the peptide, Ala-Cys-env gp46(237-262), was suggested to be useful, in combination with other peptides, for improving the reliability of serodiagnosis by separately demonstrating antibodies against as many different epitopes of HTLV-I as possible.

Amino Acid Sequence↗
PubMed1992

Novel and ultrasensitive noncompetitive enzyme immunoassay (hetero-two-site complex transfer enzyme immunoassay) for alpha-human atrial natriuretic peptide.

A novel and ultrasensitive noncompetitive enzyme immunoassay (hetero-two-site complex transfer enzyme immunoassay) for alpha-human atrial natriuretic peptide (alpha-hANP) in plasma is described. alpha-hANP was biotinylated using N-hydroxysuccinimidobiotin and trapped onto an anti-alpha-hANP [6-28] IgG-coated polystyrene ball. After washing, biotinylated alpha-hANP was eluted from the polystyrene ball with HCI and was reacted with 2,4-dinitrophenyl-fluorescein-bovine serum albumin-disulfide-rabbit anti-alpha-hANP [6-28] IgG conjugate. The complex formed was trapped onto (anti-2,4-dinitrophenyl group) IgG-coated polystyrene balls and, after washing, reacted with avidin-beta-D-galactosidase conjugate. The polystyrene balls were washed, and the complex of the three components was eluted with epsilon N-2, 4-dinitrophenyl-L-lysine and transferred to anti-fluorescein IgG-coated polystyrene balls. After washing, the complex was released from the polystyrene balls by reduction with 2-mercaptoethylamine and transferred to (anti-rabbit IgG) IgG-coated polystyrene balls. beta-D-Galactosidase activity bound to the last polystyrene balls was assayed by fluorometry. The detection limit of alpha-hANP [1-28] was 3 fg (1 amol)/tube. Interference by plasma proteins was eliminated by separation of peptides from proteins using a molecular sieve. The assay range of plasma alpha-hANP [1-28] was 0.04-120 ng/L, and plasma levels of hANP in healthy subjects (11-56 ng/L) were measured without concentration.

Atrial Natriuretic Factor↗
PubMed1993

Measurement of anti-thyroglobulin IgG in urine of patients with autoimmune thyroid diseases by sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay).

Anti-thyroglobulin IgG in urine of patients with Graves' disease and chronic thyroiditis and healthy subjects was measured by a sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay). Anti-thyroglobulin IgG in dialyzed urine was reacted simultaneously with 2,4-dinitrophenylated thyroglobulin and thyroglobulin-beta-D-galactosidase conjugate. The immune complex formed consisting of the three components was trapped onto polystyrene balls coated with (anti-2,4-dinitrophenyl group) IgG, eluted with epsilon N-2,4-dinitrophenyl-L-lysine, and transferred onto polystyrene balls coated with (anti-human IgG gamma-chain) IgG. beta-D-Galactosidase activity bound to the last polystyrene balls was assayed by fluorometry. Anti-thyroglobulin IgG was detected in most of the patients, but not in most of the healthy subjects; levels of anti-thyroglobulin IgG in urine of the patients were well correlated to those in serum of the same patients. The measurement of anti-thyroglobulin IgG in urine by the immune complex transfer enzyme immunoassay was suggested to be useful as a diagnostic aid for autoimmune thyroid diseases. The conventional standard ELISA was not sufficiently sensitive for measuring anti-thyroglobulin IgG in urine.

Adolescent↗
PubMed1993

Detection of antibody IgG to HIV-1 in urine by sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant proteins as antigens for diagnosis of HIV-1 infection.

For diagnosis of HIV-1 infection, attempts were made to detect anti-HIV-1 IgG in urine by sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant reverse transcriptase (RT) and p17 as antigens. Anti-HIV-1 IgG in urine was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-recombinant protein conjugate and recombinant protein-enzyme conjugate. The enzymes used as labels were horseradish peroxidase for RT and Escherichia coli beta-D-galactosidase for p17. The complex formed, consisting of the three components, was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG, eluted with epsilon N-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. Finally, bound enzyme activity was assayed by fluorometry. Urine samples were collected from 100 seronegative subjects and 70 seropositive subjects. The sensitivity and specificity were both 100% with unconcentrated urine samples. The positivity was confirmed by preincubation of urine samples with excess of the antigens. The positivity and negativity with one of the two antigens could be confirmed with the other antigen. The positivity with low signals could be confirmed by concentration of urine samples. Detection of anti-HIV-1 IgG in urine by the immune complex transfer enzyme immunoassay using different antigens would make diagnosis of HIV-1 infection possible.

Adolescent↗
PubMed1994

Detection of antibody IgG to HIV-1 in urine by ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant p24 as antigen for diagnosis of HIV-1 infection.

Anti-HIV-1 IgG in urine was detected by an ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant p24 gag protein (p24) of HIV-1 as antigen and beta-D-galactosidase from Escherichia coli as label. Anti-HIV-1 IgG in urine was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-recombinant p24 conjugate and recombinant p24-beta-D-galactosidase conjugate. The complex formed, consisting of the three components, was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG, eluted with epsilon N-2,4-dinitrophenyl-L-lysine, and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. Bound beta-D-galactosidase activity was assayed by fluorometry. This assay was at least 3,000-fold more sensitive than conventional methods. The lowest signal among 49 asymptomatic carriers was 3.1-fold higher than the highest nonspecific signal among 100 seronegative subjects. The sensitivity and specificity were both 100%. The positivity could be confirmed by preincubation of urine samples with excess of the antigen. Thus, this assay would be a powerful tool for detecting IgG antibody to HIV-1 in urine.

Adolescent↗
PubMed1994

Anti-HTLV-I IgG in urine detected by sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using a synthetic peptide, Cys-env gp46(188-224), as antigen.

Antibody IgG to human T-cell leukemia virus type I (HTLV-I) in urine was detected by a sensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using a synthetic peptide, Cys-env gp46(188-224), as antigen, the sensitivity and specificity of which were 100 and 98.5%, respectively, using serum samples. Anti-HTLV-I IgG in urine was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-Cys-env gp46(188-224) conjugate and Cys-env gp46(188-224)-beta-D-galactosidase (Escherichia coli) conjugate. The complex formed, consisting of the three components, was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG, eluted with epsilon N-2,4-dinitrophenyl-L-lysine and transferred to polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. Finally, bound beta-D-galactosidase activity was assayed by fluorometry. Thirty-one urine samples from seropositive subjects and 100 urine samples from seronegative subjects were tested. The sensitivity and specificity were 87 and 100%, respectively, with unconcentrated urine samples and 94 and 100%, respectively, with approximately 10-fold concentrated urine samples. These results were superior to those by the conventional ELISA and gelatin particle agglutination test.

Adult↗
PubMed1994

Diagnosis of HIV-1 infection by detection of antibody IgG to HIV-1 in urine with ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant proteins as antigens.

Anti-HIV-1 IgG in urine was detected by an ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) using recombinant reverse transcriptase (RT), p17 and p24 as antigens, and beta-D-galactosidase from Escherichia coli as label. Anti-HIV-1 IgG in urine was reacted simultaneously with 2,4-dinitrophenyl-bovine serum albumin-recombinant protein conjugate and recombinant protein-beta-D-galactosidase conjugate. The immune complex formed, consisting of the three components, was trapped onto polystyrene balls coated with affinity-purified (anti-2,4-dinitrophenyl group) IgG. After washing, the immune complex was eluted from the polystyrene balls with excess of epsilon N-2,4-dinitrophenyl-L-lysine and transferred to clean polystyrene balls coated with affinity-purified (anti-human IgG gamma-chain) IgG. Finally, the enzyme activity bound to the last solid phase was assayed by fluorometry. Using recombinant RT as antigen, the sensitivity and specificity for 83 seropositives and 100 seronegatives were both 100%, and the lowest signal for 60 asymptomatic carriers was 8.2-fold higher than the highest signal for the seronegatives. The positivity with recombinant RT as antigen could be confirmed by using recombinant p17 and p24 as antigens. The sensitivity could be improved by a longer assay of bound beta-D-galactosidase activity by using concentrated urine samples and by the combined use of recombinant RT, p17, and p24. Thus, reliable diagnosis of HIV-1 infection was possible for asymptomatic carriers.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Studies on BrdU labeling of hematopoietic cells: stem cells and cell lines.

Studies using chronic in vivo BrdU exposure, isolating primitive stem cells, and determining BrdU labeling, indicate that stem cells cycle. BrdU is also incorporated into DNA during damage/repair. DNA, which has incorporated BrdU due to cycle transit is heavier than normal, while the density of DNA with damage/repair incorporation is intermediate. DNA density of purified lineage-rhodamine low (rho(low)) Hoechst low (Ho(low)) stem cells or FDC-P1 cell line cells-was assessed in vitro, after exposure to cytokines and BrdU (cycling model) or cytokines and BrdU with bleomycin to induce strand breaks and hydroxyurea to halt cycle progression (damage/repair model). We determined DNA density using cesium chloride (CsCl) gradients and either fluorometry or dot blot chemiluminesence. DNA from BrdU labeled cycling Lin-rho(lo)Ho(lo) or FDC-P1 cells was heavier than normal DNA, while damage repair DNA had an intermediate density. We then assessed BrdU labeling of Lin-rho(lo)Ho(lo) cells in vivo. We found that 70.9% of lin-rho(lo)Ho(lo) cells labeled at 5 weeks. DNA density of these cells was low, in the damage/repair range, but similar results were obtained with stem cells, which had proliferated in vivo. Dilution of BrdU in in vitro culture of proliferating FDC-P1 cells also resulted in damage/repair density. We conclude that in vitro BrdU labeling models can distinguish between proliferation and damage/repair, but that we cannot obtain high enough in vivo levels to address this issue. All together, while we cannot absolutely exclude damage/repair as contributing to stem cell BrdU labeling, the data indicate that primitive bone marrow stem cells are probably a cycling population.

Animals↗
PubMed2003

Defective P2Y purinergic receptor function: A possible novel mechanism for impaired glucose transport.

Extracellular ATP is an ubiquitous mediator that regulates several cellular functions via specific P2 plasma membrane receptors (P2Rs), for which a role in modulating intracellular glucose metabolism has been recently suggested. We have investigated glucose uptake in response to P2Rs stimulation in fibroblasts from type 2 diabetic (T2D) patients and control subjects. P2Rs expression was evaluated by RT-PCR; intracellular calcium release by fluorometry; glucose transporter (GLUT1) translocation by immunoblotting and chemiluminescence; glucose uptake was measured with 2-deoxy-D-[1-(3)H]glucose (2-DOG) and ATP by luminometry. Cells from T2D patients, in contrast to those from healthy controls, showed no increase in glucose uptake after ATP stimulation; extracellular ATP caused, however, a similar GLUT1 recruitment to the plasma membrane in both groups. P2Rs expression did not differ between fibroblasts from diabetic and healthy subjects, but while plasma membrane depolarization, a P2X-mediated response was similar in both groups, no evident intracellular calcium increase was detectable in the cells from the former group. The calcium response in fibroblasts from diabetics was restored by co-incubation with apyrase or hexokinase, suggesting that P2YRs in those cells were normally expressed but chronically desensitised. In support to this finding, fibroblasts from T2D subjects secreted a two-fold larger amount of ATP compared to controls. Pre-treatment with apyrase or hexokinase also restored ATP stimulated glucose uptake in fibroblasts from diabetic subjects. These results suggest that extracellular ATP plays a role in the modulation of glucose transport via GLUT1, and that the P2Y-dependent GLUT1 activation is deficient in fibroblasts from T2D individuals. Our observations may point to additional therapeutic targets for improving glucose utilization in diabetes.

Adenosine Triphosphate↗
PubMed1987

Kinetics and temperature dependence of exposure of endocytosed material to proteolytic enzymes and low pH: evidence for a maturation model for the formation of lysosomes.

The temperature dependence of acidification of internalized dextran by Swiss 3T3 cells was determined using dual fluorescence flow cytometry. Essentially no acidification was observed at 11 degrees C; acidification was limited to pH 6-6.5 at temperatures between 13 degrees C and 17 degrees C. In contrast, a rapid drop to pH 6-6.5 followed by acidification to pH 5-5.5 was observed at temperatures above 19 degrees C. These results confirm the biphasic nature of the acidification process (J. Cell Biol. (1984) 98: 1757-1762). The timing of exposure of material internalized by fluid-phase endocytosis to lysosomal enzymes was determined for Swiss 3T3 cells by using a fluorogenic substrate specific for Cathepsin B. Hydrolysis of the substrate, as measured by both fluorometry and flow cytometry, began within minutes of its addition to cells at 37 degrees C, and was inhibited by coincubation with leupeptin, a competitive inhibitor of the enzyme, or by weak bases, which raise the pH of acidic compartments. At temperatures between 13 degrees (and 21 degrees C, the rate of hydrolysis was reduced to 31-44% of that at 37 degrees C. Thus, in contrast to previous reports, exposure of endocytosed material to at least one lysosomal enzyme is not inhibited below 20 degrees C; the reduction in hydrolysis rate may be explained by the temperature effects on the efficiency of the enzyme. The results for acidification and proteolysis are consistent with, but do not prove, a maturation model for the formation of lysosomes. We suggest that at lower temperatures, part of the maturation involving recycling and/or concentration of the contents of the endosome is inhibited. This causes the endosome to remain as a mildly acidic, low-density organelle containing lysosomal enzymes.

Animals↗
PubMed1990

Participation of transient-type Ca2+ channels in the sustained increase of Ca2+ level in GH3 cells.

Participation of two types of Ca2+ channels (T- and L-types) in the sustained increase of cytosolic-free Ca2+ concentration [( Ca2+]i) was studied in thyrotropin-releasing hormone (TRH)-stimulated clonal GH3 pituitary cells. The effects of Ca2+ channel blockers were analyzed by measuring Ca2+ channel current and [Ca2+]i, using whole-cell voltage-clamp and Fura-2 fluorometry, respectively. Phenytoin (100 microM) and Ni2+ (100 microM) selectively blocked T-type Ca2+ channels and suppressed the TRH-induced sustained [Ca2+]i increase in single cells. Synthetic omega-conotoxin (omega-CgTX, 2 microM) preferentially blocked L-type Ca2+ channels, but it did not suppress the TRH-induced sustained [Ca2+]i increase. The present results suggest that the sustained elevations of [Ca2+]i triggered by TRH may be mediated by T-type Ca2+ channels in GH3 cells.

Animals↗
PubMed1991

Histamine inhibits cell spreading and C3bi receptor clustering and diminishes hydrogen peroxide production by adherent human neutrophils.

Cell adherence plays a central role in many host defense mechanisms. Human peripheral blood neutrophils possess cell surface receptors that contribute to cell adherence or detachment. Receptors specific for the C3bi cleavage fragment of the third component of complement (CR3) promote adhesion, whereas histamine receptors promote detachment. In the present study, we tested the ability of histamine to down-regulate the physiological effects of CR3 receptors. Histamine decreased the binding of 51Cr-labeled neutrophils to complement-coated surfaces (C3-coated surfaces) in a dose-dependent fashion. Scanning electron microscopic and optical microscopic observations of neutrophils on C3-coated surfaces revealed polarized or spherical cell morphologies in the absence or presence of histamine, respectively. Histamine inhibited the ability of CR3 to cluster on plasma membranes of neutrophils adherent to C3-coated surfaces as shown by fluorescence microscopy. In addition, histamine diminished but did not abolish the FMLP-stimulated increase in plasma membrane CR3 expression as measured by fluorometry. Histamine did not inhibit the release of marker proteins from specific or gelatinase containing granules by neutrophils in suspension. Histamine also diminished the FMLP-stimulated production of respiratory burst oxidants from cells in suspension or cells allowed to adhere to fibrinogen substrates. We suggest that histamine may modulate selective changes in neutrophil function by diminishing adherence and preventing changes in cell shape following cell activation.

Cell Adhesion↗
PubMed2004

Mechanistic study of the uptake of wheat germ agglutinin-conjugated PLGA nanoparticles by A549 cells.

The purpose of this study was to evaluate the extent and mechanism of uptake of wheat germ agglutinin-conjugated PLGA nanoparticles by A549 cells. PLGA nanoparticles of 150 nm were prepared by a solvent diffusion method and covalently conjugated to FITC-WGA (fWGA) or FITC-bovine serum albumin (fBSA) by a two-step carbodiimide method. Uptake of fWGA-PLGA and fBSA-PLGA nanoparticles by confluent A549 cells was quantified by fluorometry. A549 cellular uptake of fWGA-PLGA nanoparticles at 2 h, 37 degrees C was 5.02-fold that of fBSA-PLGA nanoparticles at a loading concentration of 2.65 mg/mL. The difference in uptake between the two types of nanoparticles was increased to 7.84-fold at a higher loading concentration of 5.3 mg/mL, but was reduced to 2.07-fold by lowering the uptake temperature to 4 degrees C. Coincubation with 5 mg/mL of unlabeled WGA negated the differential uptake of fWGA-PLGA nanoparticles at 4 degrees C, suggesting that the nanoparticles interacted with a specific WGA-binding receptor on the cell membrane. Internalization of the fWGA-PLGA nanoparticles by the A549 cells was confirmed by confocal microscopy. Filipin (1 microg/mL), a known inhibitor of caveolae, reduced the 1-h uptake of the nanoparticles by 75%. Surface modification of PLGA nanoparticles with WGA significantly enhanced its endocytosis by A549 cells by a receptor-mediated, caveola-dependent pathway.

Biomechanical Phenomena↗
PubMed1982

Influence of ethylene oxide exposure on the extraction of indomethacin from dimethicone polymeric rods.

Dimethicone polymeric rods were made to contain 0.3, 2.0, or 3.3% by weight of indomethacin. For each different loading of indomethacin, some of the rods were treated with ethylene oxide at 55 degrees for 1 hr, while others were not exposed to the gas. Treated and untreated rods were sliced, placed in ethanol to extract the indomethacin, and the concentrations of indomethacin in the extracts determined by fluorometry and high-performance liquid chromatography (HPLC). After ethylene oxide treatment, the quantity of indomethacin in the extracts was significantly reduced in rods containing 0.3 and 2.0% indomethacin. For the rods containing 3.3% indomethacin, the recovery of the drug from treated rods was not significantly different from those not exposed.

Chemical Phenomena↗
PubMed2005

Novel copolyanhydrides combining strong inherent fluorescence and a wide range of biodegradability: synthesis, characterization and in vitro degradation.

In this work, a novel diacid monomer was synthesized in a very convenient scheme. The monomer is derived from naturally occurring products and emits strong fluorescence when polymerized to polyanhydride. The chemical structure of the monomer dCPS is as follows: HOC(O)ArOC(O)(CH2)2C(O)O--Ar--COOH. Copolyanhydrides composed of dCPS and sebacic acid were further prepared by melt copolycondensation, and characterized by IR, NMR, UV-Vis, DSC and fluorometry. The emission wavelength (lambda(em)) of the copolymers could be tuned by the excitation wavelength (lambda(ex)). Fluorescence intensity increased with the increase of dCPS content. The microspheres fabricated from the copolymer with dCPS content as low as 10% could be clearly visualized with fluorescence microscopy. Either blue or green images of the microspheres could be captured with an excitation of UV and visible light. The degradation rate of the copolyanhydrides decreased as the dCPS fraction increased, and the degradation duration could be modulated from several days to more than three months. In addition, it was found that the copolyanhydrides displayed surface degradation characteristics. In view of the advantages of the novel copolyanhydrides, such as easy preparation, unique inherent luminescent properties, and widely adjustable degradation rate, they might be useful for biomedical engineering.

Decanoic Acids↗
PubMed2005

Multilayer microcapsules as anti-cancer drug delivery vehicle: deposition, Sustained release, and in vitro bioactivity.

A drug delivery system based on spontaneous deposition of soluble, low-molecular-weight therapeutic agents has been developed for the purpose of sustaining drug release. Layer-by-layer assembly of oppositely charged polyelectrolytes onto melamine formaldehyde (MF) colloidal particles, followed by removal of the cores at low pH has yielded intact hollow microcapsules having the ability to induce deposition of various water-soluble substances. Dynamic observation by confocal laser scanning microscopy provided direct evidence of such deposition. Dependence of loading rate on molecular weight was investigated. Efficient loading of an anti-cancer drug, daunorubicin (DNR), was confirmed by transmission electron microscopy (TEM). Its release was quantified by fluorometry. The results indicated that loading, and subsequent release, could be tuned by factors such as feeding concentrations, temperature, and salt concentrations. The intrinsic mechanism of loading and release was discussed taking into account the interaction between the drugs and the poly(styrene sulfonate)/MF complex existing in the hollow capsules. With culture of the HL-60 cell line, a kind of human leukemia cell, the presence of DNR-loaded capsules was seen to steadily decrease the cyto-viability. Fluorescence intensity averaged from inside the circles as a function of incubation time.

Antibiotics, Antineoplastic↗