Electrochemical DNA-Sensor Based on Macrocyclic Dendrimers with Terminal Amino Groups and Carbon Nanomaterials

DNA-mediated self-assembly oxidative damage amplifier combined with copper and MTH1 inhibitor for cancer therapy

Chemo-dynamic therapy (CDT) has a great potential in tumor extirpation. It entails producing hypertoxic reactive oxygen species (ROS) that damage the DNA of tumor cells and other biomacromolecules. However, the efficiency of CDT is severely hampered by the massive presence of glutathione (GSH) in tumor cells and the interference of ROS defense systems, such as Mutt homolog 1 (MTH1) protein sanitizes ROS-oxidized nucleotide pools. In this research, DNA-mediated self-assembly nanoparticles (HTCG@TA NPs) were engineered with high-performance amplified oxidative damage and gene therapy effect for synergistic anti-tumor treatment. Cu2+ was converted into Cu + by redox reactions to deplete GSH while H2O2 was catalyzed to generate hydroxyl radicals (·OH). As a result, the ROS level was evidently improved. Moreover, controllable-released TH588 prevented MTH1-mediated DNA repairing, thus aggravated oxidative damage to tumor cells. Meanwhile, the released functional nucleic acid G3139 downregulated the expression of Bcl-2, and accelerated the apoptosis of tumor cells. In conclusion, the HTCG@TA demonstrated significant effect in oxidative damage amplification and tumor inhibition both in vitro and in vivo, which has provided a new outlook for the clinical application of chemo-dynamic tumor treatment and synergistic gene therapy with self-delivery nanoplatforms.

PAMAM-Calix-Dendrimers: Third Generation Synthesis and Impact of Generation and Macrocyclic Core Conformation on Hemotoxicity and Calf Thymus DNA Binding

Background/Objectives: Current promising treatments for many diseases are based on the use of therapeutic nucleic acids, including DNA. However, the list of nanocarriers is limited due to their low biocompatibility, high cost, and toxicity. The design of synthetic building blocks for creating universal delivery systems for genetic material is an unsolved problem. In this work, we propose PAMAM dendrimers with rigid thiacalixarene core in various conformations, i.e., PAMAM-calix-dendrimers, as a platform for a supramolecular universal constructor for nanomedicine. Results: Third generation PAMAM dendrimers with a macrocyclic core in three conformations (cone, partial cone, and 1,3-alternate) were synthesized for the first time. The obtained dendrimers were capable of binding and compacting calf thymus DNA, whereby the binding efficiency improved with increasing generation, while the influence of the macrocyclic core was reduced. A dramatic effect of the macrocyclic core conformation on the hemolytic activity of PAMAM-calix-dendrimers was observed. Specifically, a notable reduction in hemotoxicity was associated with a decrease in compound amphiphilicity. Conclusions: We hope the results will help reduce financial and labor costs in developing new drug delivery systems based on dendrimers.

Flow-Through Amperometric Biosensor System Based on Functionalized Aryl Derivative of Phenothiazine and PAMAM-Calix-Dendrimers for the Determination of Uric Acid

A flow-through biosensor system for the determination of uric acid was developed on the platform of flow-through electrochemical cell manufactured by 3D printing from poly(lactic acid) and equipped with a modified screen-printed graphite electrode (SPE). Uricase was immobilized to the inner surface of a replaceable reactor chamber. Its working volume was reduced to 10 μL against a previously reported similar cell. SPE was modified independently of the enzyme reactor with carbon black, pillar[5]arene, poly(amidoamine) dendrimers based on the p-tert-butylthiacalix[4]arene (PAMAM-calix-dendrimers) platform and electropolymerized 3,7-bis(4-aminophenylamino) phenothiazin-5-ium chloride. Introduction of the PAMAM-calix-dendrimers into the electrode coating led to a fivefold increase in the redox currents of the electroactive polymer. It was found that higher generations of the PAMAM-calix-dendrimers led to a greater increase in the currents measured. Coatings consisted of products of the electropolymerization of the phenothiazine with implemented pillar[5]arene and PAMAM-calix-dendrimers showing high efficiency in the electrochemical reduction of hydrogen peroxide that was formed in the enzymatic oxidation of uric acid. The presence of PAMAM-calix-dendrimer G2 in the coating increased the redox signal related to the uric acid assay by more than 1.5 times. The biosensor system was successfully applied for the enzymatic determination of uric acid in chronoamperometric mode. The following optimal parameters for the chronoamperometric determination of uric acid in flow-through conditions were established: pH 8.0, flow rate 0.2 mL·min-1, 5 U of uricase per reactor. Under these conditions, the biosensor system made it possible to determine from 10 nM to 20 μM of uric acid with the limit of detection (LOD) of 4 nM. Glucose (up to 1 mM), dopamine (up to 0.5 mM), and ascorbic acid (up to 50 μM) did not affect the signal of the biosensor toward uric acid. The biosensor was tested on spiked artificial urine samples, and showed 101% recovery for tenfold diluted samples. The ease of assembly of the flow cell and the low cost of the replacement parts make for a promising future application of the biosensor system in routine clinical analyses.