To develop a method for the detection of surface-confined peptides containing cysteine residues or oligodeoxynucleotides (ODNs) whose 3' ends modified with thiol groups, and a thiol-specific fluorescent cross-linker, N-(9-acridinyl) maleimide (NAM) was used. The peptides studied herein include both the oxidized and reduced forms of glutathione, and a hexapeptide (FT). Peptides are first attached onto the activated 11-mercaptoundecanoic acid (MUA)-terminated alkanethiol self-assembled monolayers (SAMs) and then derivatized with NAM. The cysteine residues was determined by using electrochemical desorption and fluorescence detection. GSH concentration as low as 40 pmol x L(-1) can be measured. The fluorescence intensity in the case of FT is about 3 times as high as that for GSH, which is consistent with the molar ratio of cysteine residues in these two molecules. The analytical performance of gene analysis was also evaluated through the analyses of a complementary target and targets with varying numbers of mismatching bases. The method described here is simple, sensitive, reproducible, and does not require sophisticated analytical instrumentation and separation procedures.
Biosensing Techniques ; methods ; Cysteine ; analysis ; Electrochemistry ; methods ; Fluorescence ; Glutathione ; analysis ; chemistry ; Maleimides ; chemistry ; Oligodeoxyribonucleotides ; analysis ; Reproducibility of Results ; Sensitivity and Specificity

The specific association of drugs with deoxyoligonucleotides, containing a B-Z junction between left-handed Z-DNA and right-handed B-DNA, was examined by fluorescence and circular dichroism (CD) technique. Ethidium was chosen for a simple DNA binding compound because it binds to right-handed DNA and hybrid B-Z forms containing a B-Z junction in a highly cooperative manner. The binding isotherms were analyzed by an allosteric model in order to describe the cooperativity of association. Binding of ethidium to the DNA that are initially in the hybrid B-Z forms showed over an order of magnitude higher affinity than other DNA which were entirely in the B-form. The conformational transitions of deoxyoligonucleotides containing a B-Z junction as a result of ethidium binding were monitored by CD and the influence of NaCl on the complex formation was also determined by the CD spectra. The singular value decomposition (SVD) analysis was used to characterize a family of CD spectra of the species in binding equilibria. The results of SVD analysis showed a strikingly complex thermodynamic equilibria of cooperative binding of drugs to the allosterically converted DNA forms. The results also showed that these DNA forms in low- and high-salt were different in the absence or presence of drug. These results demonstrate that DNA-binding-drugs can preferentially interact with specific DNA structures and that these interactions are accompanied by allosteric changes of DNA conformations.
Allosteric Regulation/genetics ; Circular Dichroism ; DNA/chemistry* ; Ethidium/chemistry* ; Fluorescent Dyes/chemistry ; Nucleic Acid Conformation ; Oligodeoxyribonucleotides/chemistry ; Sodium Chloride/pharmacology ; Thermodynamics

DNA binding compounds were previously shown to bind to the right-handed DNA forms and hybrid B-Z forms in a highly cooperative manner and indicate that structural specificity plays a key role in a ligand binding to DNA. In this study, the modes of binding and structural specificity of agents to unusual DNA are examined by a variety of fluorescence techniques (intensity, polarization and quenching, etc.) to explore a reliable method to detect the association environment of ligands to deoxyoligonucleotides initially containing a B-Z junction between the left-handed Z-DNA and right-handed B-DNA. The results of fluorescence energy transfer measurement demonstrated that the ligand molecules bind to the allosterically converted DNA structures by intercalation. In the absence of high-resolution structural data, this fluorescence energy transfer measurement allowed reliable measures and infer the binding environment of ligands to the allosteric DNA structures.
Allosteric Regulation ; Circular Dichroism ; DNA/*chemistry/*metabolism ; Energy Transfer ; Ethidium/*metabolism ; Exodeoxyribonucleases/metabolism ; Ligands ; Motion ; Nucleic Acid Conformation ; Oligodeoxyribonucleotides/*metabolism

OBJECTIVETo observe the ability of triple helix-forming oligonucleotides (TFO) modified with manganese porphyrin to combine with and cleave HBV DNA fractions.

METHODSThe ends of TFO were modified with manganese porphyrin and acridine; At 37 degrees C and pH 7.4 condition in vitro, TFO modified with manganese porphyrin and acridine were bound with 32P labeled HBV DNA fragments, the affinity and specificity binding to target sequence were tested by electrophoretic mobility shift and DNase 1 footprinting assays, the ability to cleave HBV DNA fractions was observed with cleavage experiments.

RESULTSTFO modified with manganese porphyrin and acridine could bind to target sequence in a sequence-dependent manner with Kd values of 3.5 x 10(-7) mol/L and a relative affinity of 0.008. In the presence of KHSO5, TFO modified with manganese porphyrin and acridine could cleave target sequence in the region forming triple DNA.

CONCLUSIONIn the presence of KHSO5, TFO modified with manganese porphyrin and acridine could cleave target HBV-DNA in sequence-dependent manner.

Binding, Competitive ; DNA Fingerprinting ; Deoxyribonuclease I ; metabolism ; Electrophoretic Mobility Shift Assay ; Hepatitis B virus ; genetics ; Manganese ; chemistry ; Metalloporphyrins ; chemistry ; Nucleic Acid Conformation ; Oligodeoxyribonucleotides ; chemistry ; genetics ; metabolism

OBJECTIVETo prepare the superparamagnetic iron oxide (SPIO)-labeled antisense oligodeoxynucleotide (ASODN) probe and evaluate the application of this probe in cellular magnetic resonance imaging (MRI).

METHODSWe prepared the SPIO-labeled ASODN probe using chemical cross linking method to conjugate SPIO to ASODN, detected its configuration by atomic force microscopy, determined the conjugating rate and biology activation by high performance liquid chromatography, and detected the stability by polyacrylamide gel electrophoresis. After that, we transfected the SK-Br3 oncocytes which had over-expression of the c-erbB2 oncogene by this probes, observed the intracellular iron distribution by optical microscope, measured iron content by atomic absorption spectroscopy, and observed the signal change by MRI.

RESULTSAtomic force microscope showed that the SPIO-labeled ASODN probe was mostly spherical and well-distributed, with a diameter of 25-40 nm and a conjugating rate of 100%. This probe had inhered biological activity and stability. In addition, light microscopy revealed an intracellular uptake of iron oxides in the transfected SK-Br3 oncocyte, and the iron content of the group of transfected SK-Br3 oncocytes was significantly higher than those of other contrast groups (all P < 0.01). MRI showed that transfected SK-Br3 oncocyte had the lowest signal among all other cells (all P < 0.05).

CONCLUSIONSWe prepared the SPIO-labeled ASODN probe successfully. It can effectively transfect SK-Br3 oncocyte and enter SK-Br3 oncocyte, and thus reduce the signal intension in MRI.

Cell Line, Tumor ; DNA, Antisense ; chemistry ; genetics ; Ferric Compounds ; chemistry ; Humans ; Magnetic Resonance Imaging ; Magnetics ; Molecular Probe Techniques ; Oligodeoxyribonucleotides ; chemistry ; genetics ; Oxyphil Cells ; chemistry ; Receptor, ErbB-2 ; analysis ; genetics

To prepare AS1411 targeted nano-ultrasonic contrast agent with liquid core, and to evaluate its ability for ultrasonic contrast enhancement and targeting MCF-7 cell in vitro.
 Methods: The modified solvent evaporation, self-synthesized membrane material and perfluorobrominane (PFOB) was used to form nano-ultrasonic contrast agent with PFOB core (nanoparticles, NP); then N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide (EDC/NHS) catalysis was used to connect AS1411 to the surface of NP to prepare NP-AS1411. The transmission electron microscopy was chosen to check the morphology of NP-AS1411. The size, surface charge, encapsulation efficiency, biocompatibility, the contrast grey value and the stability of NP-AS1411 and NP were compared. Whether AS411 was attached to the surface of NP was checked by gel electrophoresis. Fluorescence microscopy and flow cytometry were performed to examine the targeting ability of AS1411.
 Results: NP-AS1411 was a shell-nuclear structure under the electron microscope. Its size was at (245.4±16.5) nm, which was larger than that of NP (P=0.05). There was no significant difference in surface charge and encapsulation efficiency between NP-AS1411 and NP (P>0.05). In the MTT experiment, the cell viability decreased significantly at high concentration of NP-AS411 (25 mg/mL) after incubation for 24 h compared with the control group (0 mg/mL ) (P<0.05). The contrast gray value of NP-AS1411 was at 86.1+ 6.7, which was significantly higher than that of deionized water (P<0.05), and equivalent to that of NP (P>0.05). The contrast grey value of AS1411-NP was 80.1±9.2 after keeping at room temperature for 24 h, which showed no obviously change comparing with that before the treatment (P>0.05). The size of NP-AS1411didn't change too (P>0.05). The results of gel electrophoresis demonstrated that the AS1411 connecting to the surface of NP was the most when the molar ratio of NP:AS1411 was at 40:1. Flow cytometry analysis confirmed that NP and NP-AS1411 were combined with MCF-7 cells separately but the fluorescence produced by the combination of NP-AS1411 and MCF-7 was more intense.
 Conclusion: The modified solvent evaporation and EDC/NHS catalysis could successfully prepare ultrasound contrast agents with aptamer-conjugated nanoparticles with liquid core. The targeted ultrasonic contrast agents with liquid core possess good ultrasonic contrast enhancement ability in vitro, stability and specificity as well.
Cell Survival ; Contrast Media ; chemical synthesis ; Fluorocarbons ; Humans ; MCF-7 Cells ; Microscopy, Electron, Scanning Transmission ; Nanoparticles ; chemistry ; ultrastructure ; Oligodeoxyribonucleotides ; chemical synthesis

The aim of the paper is to prepare stable antisense oligodeoxynucleotides-loaded cationic liposomes and evaluate the transfection efficiency of asODN to MCF-7 oophoroma cells and study their distribution to different tissues in mice. Antisense oligodeoxynucleotides (asODN)-loaded cationic liposomes were prepared by a thin film-adsorption-lyophilization method which is simple and can overcome crucial pharmaceutical defects (e.g. instability) of liposomes during storage. The morphology was investigated by transmission electron microscope. The size and surface charge of the liposomes were determined by laser particle analyter. The dissociated ligodeoxynucleotides were separated from the liposomes by sephadex column and the entrapment efficiency was determined by using an ultraviolet photometer. Trehalose, mannitol, and glycine were suitable for lyophilization especially trehalose. The resulting liposomes were global microcapsule in a narrow particle size with a mean diameter of 175 nm and 320 nm before and after lyophilization, and a high zeta potentials of +32 mV. The dissociated asODN were separated from the liposomes by sephadex G-50 column and the entrapment coefficient of asODN was 88.4% pre and 83.2% post-lyophilization separately for trehalose. The growth of MCF-7 oophoroma cells were inhibited in vitro obviously (P < 0.05) and transfection efficiency of asODN was 18%, 26%, 44% after 2 h, 4 h and 8 h, respectively. The formulation and method can be used to prepare stable cationic liposomes which can effectively inhibit the growth of MCF-7 oophoroma cells and obtain a high transfection efficiency. This system can improve distribution amount of asODN to tissues especially tumors in mice.
Animals ; Breast Neoplasms ; metabolism ; pathology ; Cations ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Drug Carriers ; Female ; Freeze Drying ; Humans ; Liposomes ; chemistry ; pharmacokinetics ; pharmacology ; Mice ; Mice, Inbred BALB C ; Neoplasm Transplantation ; Oligodeoxyribonucleotides, Antisense ; chemistry ; genetics ; Particle Size ; Transfection

AIMTo survey the uptake behavior and subcellular distribution of antisense oligodeoxynucleotide polymethacrylate submicroparticles (AS-ODN-SMP) and infer its mechanism in MGC cell lines.

METHODSMGC cells were incubated at certain concentration of AS-ODN-SMP or AS-ODN for 8 h at 4 degrees C or 37 degrees C. Then the fluorescence oligodeoxynucleotide- labeled cells were counted by flow cytometer and the intracellular fluorescence intensity was determined after incubated with chloroquine for 2 h.

RESULTSCellular uptake of oligodeoxynucleotides was significantly increased following application of AS-ODN-SMP and total intracellular fluorescence intensity was enhanced by 683 folds with the vehicle concentration of 20 microg x mL(-1). AS-ODN-SMP entranced to cells profoundly with temperature-dependent manner. Rare cells took on fluorescence when incubated at 4 degrees C, while 37 degrees C they were significantly increased. But the intracellular fluorescence intensity appeared same level in present or absent of chloroquine.

CONCLUSIONWith the help of polyacrylate submicroparticles, oligonucleotides efficiently entranced the cells via endocytosis and could successfully escape the degradation in lysosome.

Animals ; Cell Line ; Drug Carriers ; Drug Delivery Systems ; Endocytosis ; drug effects ; Giant Cells ; cytology ; Lysosomes ; metabolism ; Nanoparticles ; Oligodeoxyribonucleotides, Antisense ; administration & dosage ; pharmacokinetics ; Particle Size ; Polymethacrylic Acids ; chemistry ; pharmacology ; Temperature

AIMTo investigate the effect of nanoparticles for antisense oligodeoxynucleotide (ASODN) of hTERT mRNA on A549 cells.

METHODSThe cationic polybutylcyanoacrylate nanoparticles (NPs) were prepared by an emulsion polymerization process in the presence of DEAE-dextran. Antisense oligodeoxynucleotides were loaded on the particles by adsorption. The cytotoxicity of NPs and proliferation of A549 cells were detected by MTT assay. Intracellular fluorescence intensity after transfecting the 5'-FITC-labelled ASODN (FASODN) and cell cycles were determined by flow cytometry (FCM). Inverse microscope was used to observe the modality of A549 cell transfected by NPs for ASODN. The protein expression of hTERT was measured by immunocytochemistry.

RESULTSThe cytotoxicity increased evidently with the increasing concentration of NPs over 2.5 g x L(-1). The intracellular fluorescence in FASODN-NP group was obviously stronger than that in FASODN group (NPs free) after transfection for 24 h (P < 0.01). The inhibitory rate for cell modality change and proliferation after the treatment with ASODN-NP at 72 h reached peak , 62.4% , 44.6% and 36.4% for ASODN1-NP group, ASODN2-NP group and ASODN3-NP group, respectively; The cell cycle in ASODN-NP group varied observably compared with control group and sense oligodeoxynucleotide-nanoparticle (SODN-NP) group and the cell cycle was blocked in G1 phase, the cell number in S phase decreased obviously (P < 0.01); The hTERT protein expression of ASODN-NP group reduced clearly.

CONCLUSIONASODN-NP of hTERT can inhibit the proliferation of A549 cells effectively and cause the change of cell cycle, restraint of protein expression of hTERT and cell viability.

Adenocarcinoma ; enzymology ; pathology ; Cell Cycle ; drug effects ; Cell Death ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Enbucrilate ; chemistry ; Humans ; Lung Neoplasms ; enzymology ; pathology ; Nanoparticles ; Oligodeoxyribonucleotides, Antisense ; genetics ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Telomerase ; genetics ; metabolism ; Transfection

The present paper is aimed to detect superparamagnetic iron oxide labeled c-erbB2 oncogene antisense oligonucleotide probe (magnetic antisense probe) connected with SK-Br-3 oncocyte mRNA nucleotide by high resolution atomic force microscope (AFM). We transfected SK-Br-3 oncocyte with magnetic antisense probe, then observed the cells by AFM with high resolution and detected protein expression and magnetic resonance imagine (MRI). The high resolution AFM clearly showed the connection of the oligonucleotide remote end of magnetic antisense probe with the mRNA nucleotide of oncocyte. The expression of e-erbB2 protein in SK-Br3 cells were highly inhibited by using magnetic antisense probe. We then obtained the lowest signal to noise ratio (SNR) of SK-Br-3 oncocyte transfected with magnetic antisense probe by MRI (P<0.05). These experiments demonstrated that the high resolution AFM could be used to show the binding of magnetic antisense probe and SK-Br-3 mRNA of tumor cell nuclear.
Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; DNA, Antisense ; chemistry ; genetics ; Female ; Ferric Compounds ; chemistry ; Genes, erbB-2 ; genetics ; Humans ; Magnetics ; Microscopy, Atomic Force ; methods ; Molecular Probe Techniques ; Nucleic Acid Probes ; chemistry ; genetics ; Oligodeoxyribonucleotides ; chemistry ; genetics ; Oxyphil Cells ; ultrastructure ; RNA, Messenger ; genetics ; metabolism