ABSTRACT
Nanocarrier for augmenting the efficacy of reactive oxygen species (ROS) by tumor microenvironment (TME) has become an emerging strategy for cancer treatment. Herein, a smart biodegradable drug delivery nanoplatform with mitochondrial-targeted ability, pH-responsive drug release and enzyme-like catalytic function is designed. This efficient ROS-generating platform uses ultrasound with deeper penetration capability as excitation source for combined chemotherapy and sonodynamic therapy (SDT) of tumor. In vitro experiments show that the nanoplatform can co-load Ce6 and DOX and be degraded in slight acid environment, and the DOX release rate is 63.91 ± 1.67%. In vivo experiments show that the nanoplatform has extremely biosafety and can be enriched in tumor site and excluded from body after 24 h. More significantly, after combined treatment, the tumors are eliminated and the mice still survive healthily without recurrence after 60 d. This is because not only it can achieve mitochondrial targeting and use platinum particle to increase oxygen content in TME to enhance the effect of SDT, but also it can use weak acidic TME to accelerate drug release to achieve the combination of chemotherapy and SDT. The probe provides a new strategy for designing ROS-based nanoplatform for the treatment of malignant tumor.
Subject(s)
Nanoparticles , Neoplasms , Animals , Cell Line, Tumor , Drug Delivery Systems , Mice , Neoplasms/drug therapy , Reactive Oxygen Species , Tumor MicroenvironmentABSTRACT
A fluorescence method for the detection of DNA methylation and the assay of methyltransferase activity is proposed using gold nanorods as a fluorescence quencher on the basis of fluorescence resonance energy transfer. It is demonstrated that this method is capable of detecting methyltransferase with a detection limit of 0.25 U mL(-1), which might make this method a good candidate for monitoring DNA methylation in the future.
Subject(s)
DNA Methylation , Enzyme Assays/methods , Escherichia coli Proteins/metabolism , Escherichia coli/enzymology , Fluorescence Resonance Energy Transfer/methods , Gold/chemistry , Nanotubes/chemistry , Site-Specific DNA-Methyltransferase (Adenine-Specific)/metabolism , Biosensing Techniques/methods , Escherichia coli Proteins/analysis , Limit of Detection , Nanotubes/ultrastructure , Site-Specific DNA-Methyltransferase (Adenine-Specific)/analysisABSTRACT
The present work demonstrates a novel signal-off electrochemical method for the determination of DNA methylation and the assay of methyltransferase activity using the electroactive complex [Ru(NH3)6](3+) (RuHex) as a signal transducer. The assay exploits the electrostatic interactions between RuHex and DNA strands. Thiolated single strand DNA1 was firstly self-assembled on a gold electrode via Au-S bonding, followed by hybridization with single strand DNA2 to form double strand DNA containing specific recognition sequence of DNA adenine methylation MTase and methylation-responsive restriction endonuclease Dpn I. The double strand DNA may adsorb lots of electrochemical species ([Ru(NH3)6](3+)) via the electrostatic interaction, thus resulting in a high electrochemical signal. In the presence of DNA adenine methylation methyltransferase and S-adenosyl-l-methionine, the formed double strand DNA was methylated by DNA adenine methylation methyltransferase, then the double strand DNA can be cleaved by methylation-responsive restriction endonuclease Dpn I, leading to the dissociation of a large amount of signaling probes from the electrode. As a result, the adsorption amount of RuHex reduced, resulting in a decrease in electrochemical signal. Thus, a sensitive electrochemical method for detection of DNA methylation is proposed. The proposed method yielded a linear response to concentration of Dam MTase ranging from 0.25 to 10UmL(-1) with a detection limit of 0.18UmL(-1) (S/N=3), which might promise this method as a good candidate for monitoring DNA methylation in the future.
Subject(s)
DNA Methylation , DNA/analysis , Electrochemical Techniques , Coordination Complexes/chemistry , DNA/chemistry , Electrodes , Nucleic Acid Hybridization , Ruthenium/chemistry , Site-Specific DNA-Methyltransferase (Adenine-Specific)/metabolism , Static ElectricityABSTRACT
The focus of this work was on designing a label-free DNA biosensor based on a super-sandwich assay using the electrochemical impedance spectroscopy technique. For this purpose, we designed a signal-up configuration whose linker probes could hybridize with two regions of the target DNA. In this configuration, the presented target DNA would effectively decrease the electron transfer, which would improve the sensitivity of the sensor. Ultimately, we employed gel electrophoresis to further confirm the formation of the proposed super-sandwich structure.
Subject(s)
Biosensing Techniques/methods , DNA/analysis , Dielectric Spectroscopy/methods , Electrochemistry/methods , Base Sequence , DNA/chemistry , DNA/genetics , Models, Molecular , Nucleic Acid Conformation , Nucleic Acid Hybridization , Oligonucleotides/chemistry , Oligonucleotides/genetics , Osmolar Concentration , Time FactorsABSTRACT
Nanosilver antibiotic devices for gynecological external use are the third-class products of medical devices, whose biological safety and efficiency should be strictly controlled. But there is not yet the national standard or industry standard for the products to control the production process, so their testing method of biological evaluation mainly refers to GB/T16886 "The Guide to Implementation of Biological Evaluation of Medical Devices". To control the biological safety effectively, it's necessary to work out the testing items and methods of the biological evaluation for such products.
