DNA Hybridization Research Articles

Detection of fucosylated extracellular vesicles miR-4732-5p related to diagnosis of early lung adenocarcinoma by the electrochemical biosensor

Our preliminary investigation has identified the potential of serum fucosylated extracellular vesicles (EVs) miR-4732-5p in the early diagnosis of lung adenocarcinoma (LUAD) by a fucose-captured strategy utilizing lentil lectin (LCA)-magnetic beads and subsequent screening of high throughput sequencing and validation of real-time quantitative polymerase chain reaction (RT-qPCR). Considering the relatively complicated procedure, expensive equipment, and stringent laboratory condition, we have constructed an electrochemical biosensor assay for the detection of miR-4732-5p. miR-4732-5p is extremely low in serum, down to the fM level, so it needs to be detected by highly sensitive electrochemical methods based on the Mg2+-dependent DNAzyme splitting nucleic acid lock (NAL) cycle and hybridization chain reaction (HCR) signal amplification. In this study, signal amplification is achieved through the dual amplification reactions using NAL cycle in combination with HCR. In addition, hybridized DNA strands bind to a large number of methylene blue (MB) molecules to enhance signaling. Based on the above strategy, we further enhance our signal amplification strategies to improve detection sensitivity and accuracy. The implementation of this assay proceeded as follows: initially, miR-4732-5p was combined with NAL, and then Mg2+-dependent DNAzyme splitted NAL to release auxiliary DNA (S1) strands, which were subsequently captured by the immobilized capture probe DNA (C1) strands on the electrode surface. Following this, abundant quantities of DNA1 (H1) and DNA2 (H2) tandems were generated by HCR, and S1 strands then hybridized with the H1 and H2 tandems through base complementary pairing. Finally, MB was bonded to the H1 and H2 tandems through π–π stacking interaction, leading to the generation of a signal current upon the detection of a potential capable of inducing a redox change of MB by the electrode. Furthermore, we evaluated the performance of our developed electrochemical biosensor assay. The results demonstrated that our assay is a reliable approach, characterized by its high sensitivity (with a detection limit of 2.6 × 10−17 M), excellent specificity, good accuracy, reproducibility, and stability. Additionally, it is cost-effective, requires simple operation, and is portable, making it suitable for the detection of serum fucosylated extracellular vesicles miR-4732-5p. Ultimately, this development has the potential to enhance the diagnostic efficiency for patients with early-stage LUAD.

AnoPrimer: Primer Design in malaria vectors informed by range-wide genomic variation

The major malaria mosquitoes, Anopheles gambiae s.l and Anopheles funestus, are some of the most studied organisms in medical research and also some of the most genetically diverse. When designing polymerase chain reaction (PCR) or hybridisation-based molecular assays, reliable primer and probe design is crucial. However, single nucleotide polymorphisms (SNPs) in primer binding sites can prevent primer binding, leading to null alleles, or bind suboptimally, leading to preferential amplification of specific alleles. Given the extreme genetic diversity of Anopheles mosquitoes, researchers need to consider this genetic variation when designing primers and probes to avoid amplification problems. In this note, we present a Python package, AnoPrimer, which exploits the Ag1000G and Af1000 datasets and allows users to rapidly design primers in An. gambiae or An. funestus, whilst summarising genetic variation in the primer binding sites and visualising the position of primer pairs. AnoPrimer allows the design of both genomic DNA and cDNA primers and hybridisation probes. By coupling this Python package with Google Colaboratory, AnoPrimer is an open and accessible platform for primer and probe design, hosted in the cloud for free. AnoPrimer is available here https://github.com/sanjaynagi/AnoPrimer and we hope it will be a useful resource for the community to design probe and primer sets that can be reliably deployed across the An. gambiae and funestus species ranges.

Pradimicin U, a promising antimicrobial agent isolated from a newly found Nonomuraea composti sp. nov

Pradimicin U is a new dihydrobenzo[a]naphthacenequinone compound found to be active on a screen designed to investigate compounds with antimicrobial activity, produced by the actinomycete designated strain FMUSA5-5T. The strain was isolated from a bio-fertilizer of Musa spp. collected from Suphanburi province, Thailand. The chemotaxonomic characteristics and 16S rRNA gene analysis revealed that strain FMUSA5-5T is a member of the genus Nonomuraea. Low genome-based taxonomic criteria, average nucleotide identity (ANI) (82.8–88.3%), average amino-acid identity (AAI) (79.4–87.3%), and digital DNA–DNA hybridization (dDDH) (29.5–38.5%) values and several phenotypic differences between strain FMUSA5-5T and its closest type strains of the genus Nonomuraea indicated that strain FMUSA5-5T represents a novel species of the genus Nonomuraea and the name Nonomuraea composti sp. nov. is proposed for the strain. The crude extract from the culture broth of strain FMUSA5-5T displayed promising antimicrobial activity against several pathogens and led to the isolation of a novel secondary metabolite, pradimicin U. Interestingly, this compound displayed a broad spectrum of biological activities such as antimalarial activity against Plasmodium falciparum K1 (IC50 value = 3.65 µg/mL), anti-Mycobacterium tuberculosis H37Ra (MIC value = 25.0 µg/mL), anti-Alternaria brassicicola BCC 42724 (MIC value = 25.0 µg/mL), anti-Bacillus cereus ATCC 11778 and anti-Staphylococcus aureus ATCC 29213 (MIC values = 6.25 and 1.56 µg/mL, respectively). Moreover, the compound possessed strong anti-human small cell lung cancer (NCI-H187) activity with IC50 value of 5.69 µg/mL, while cytotoxicity against human breast cancer (MCF-7) and Vero cells was very weak (IC50 values of 52.49 and 21.84 µg/mL, respectively).

A novel signal amplified sandwich aptamer-based visual lateral flow assay based on self-assembly bifunctional nucleic acid for rapid and sensitive detection of CKMB

At present, rapid and sensitive detection of disease biomarkers is still the focus of early clinical diagnosis. As a rapid response to point-of-care testing (POCT), lateral flow assay (LFA) has been given serious attention. Unfortunately, due to the sensitivity limitations, LFA, especially AuNPs-based LFA, was difficult to play an important role in the detection of trace biomarkers. The combination of different signal amplification methods increases the complexity of operation and use, or prolongs the detection time, which sacrifices the advantages of fast and convenient of LFA. Hence, a novel sandwich aptamer-based visual LFA based on bifunctional nucleic acid (bFNA-LFA) was proposed for rapid and sensitive detection of creatine kinase MB (CKMB) in this study. Based on hybridization chain reaction (HCR) and nucleic acid hybridization, a bifunctional nucleic acid with target recognition and signal amplification was prepared, which effectively improved the sensitivity of CKMB detection without increasing the reaction time and depending on the detecting equipment. Under optimal reaction conditions, the limit of detection of 7.92 ng/mL was observed, which was 20 times lower than that of sandwich aptamer-based AuNPs LFA in the previous study. The proposed bFNA-LFA assay expanded a new idea in improving the sensitivity of LFA, and provided a reference for the subsequent application of nucleic acid nanomaterials in the detection of protein biomarkers.

DNA Origami‐Directed Self‐Assembly of Gold Nanospheres for Plasmonic Metasurfaces

AbstractPlasmonic nanostructures are frequently utilized to create metasurfaces with a large variety of optical effects. Control over shape and positioning of the nanostructures is key to the function of such plasmonic metasurfaces. Next to lithographic means, directed self‐assembly is a viable route to create plasmonic structures on surfaces with the necessary precision. Here, a combined approach of DNA origami self‐assembly and electron beam lithography is presented for determinate positioning of gold nanospheres on a SiO2 surface. First, DNA origami structures bind to the electron beam‐patterned substrate and subsequently, gold nanoparticles attach to a defined binding site on the DNA origami structure via DNA hybridization. A sol‐gel reaction is then used to grow a silica layer around the DNA, thereby increasing the stability of the self‐assembled metasurface. A mean yield of 74% of single gold nanospheres is achieved located at the determinate positions with a spatial position accuracy of 9 nm. Gold nanosphere dimers and trimers are achieved with a rate of 65% and 60%, respectively. The applicability of this structuring method is demonstrated by the fabrication of metasurfaces whose optical response can be tuned by the polarization of the incoming and the scattered light.

Machine learning based DNA melt curve profiling enables automated novel genotype detection

Surveillance for genetic variation of microbial pathogens, both within and among species, plays an important role in informing research, diagnostic, prevention, and treatment activities for disease control. However, large-scale systematic screening for novel genotypes remains challenging in part due to technological limitations. Towards addressing this challenge, we present an advancement in universal microbial high resolution melting (HRM) analysis that is capable of accomplishing both known genotype identification and novel genotype detection. Specifically, this novel surveillance functionality is achieved through time-series modeling of sequence-defined HRM curves, which is uniquely enabled by the large-scale melt curve datasets generated using our high-throughput digital HRM platform. Taking the detection of bacterial genotypes as a model application, we demonstrate that our algorithms accomplish an overall classification accuracy over 99.7% and perform novelty detection with a sensitivity of 0.96, specificity of 0.96 and Youden index of 0.92. Since HRM-based DNA profiling is an inexpensive and rapid technique, our results add support for the feasibility of its use in surveillance applications.

On the thermodynamics of DNA double strand in the Peyrard-Bishop-Dauxois model

The temperature dependence of energy, partition function, entropy and free energy, describing a first-order-like phase transition of a DNA molecule is calculated based on the direct method of molecular dynamics for the classical Peyrard-Bishop-Dauxois model. It is shown that without taking into account the quantum freezing of the degrees of freedom at low temperatures, the relationship between these quantities is not determined. The latent heat of DNA melting is calculated for homogeneous PolyA/PolyT and PolyG/PolyC DNA chains. It is shown that this melting transition corresponds to a sharp temperature dependence of the heat capacity.

Bimetallic DNAsome Decorated with G4-DNA as a Nanozyme for Targeted and Enhanced Chemo/Chemodynamic Cancer Therapy.

Cancer is indisputably one of the major threats to mankind, and hence the design of new approaches for the improvement of existing therapeutic strategies is always wanted. Herein, the design of a tumor microenvironment-responsive, DNA-based chemodynamic therapy (CDT) nanoagent with dual Fenton reaction centers for targeted cancer therapy is reported. Self-assembly of DNA amphiphile containing copper complex as the hydrophobic Fenton reaction center results in the formation of CDT-active DNAsome with Cu2+-based Fenton catalytic site as the hydrophobic core and hydrophilic ssDNA protrude on the surface. DNA-based surface addressability of the DNAsome is then used for the integration of second Fenton reaction center, which is a peroxidase-mimicking DNAzyme noncovalently loaded with Hemin and Doxorubicin, via DNA hybridization to give a CDT agent having dual Fenton reaction centers. Targeted internalization of the CDT nanoagent and selective generation of •OH inside HeLa cell are also shown. Excellent therapeutic efficiency is observed for the CDT nanoagent both in vitro and in vivo, and the enhanced efficacy is attributed to the combined and synergetic action of CDT and chemotherapy.

Linker histone H1 regulates homeostasis of heterochromatin-associated cRNAs

Chromatin-associated RNAs (cRNAs) are a poorly characterized fraction of cellular RNAs that co-purify with chromatin. Their full complexity and the mechanisms regulating their packaging and chromatin association remain poorly understood. Here, we address these questions in Drosophila. We find that cRNAs constitute a heterogeneous group of RNA species that is abundant in heterochromatic transcripts. We show that heterochromatic cRNAs interact with the heterogeneous nuclear ribonucleoproteins (hnRNP) hrp36/hrp48 and that depletion of linker histone dH1 impairs this interaction. dH1 depletion induces the accumulation of RNA::DNA hybrids (R-loops) in heterochromatin and, as a consequence, increases retention of heterochromatic cRNAs. These effects correlate with increased RNA polymerase II (RNAPII) occupancy at heterochromatin. Notably, impairing cRNA assembly by depletion of hrp36/hrp48 mimics heterochromatic R-loop accumulation induced by dH1 depletion. We also show that dH1 depletion alters nucleosome organization, increasing accessibility of heterochromatin. Altogether, these perturbations facilitate annealing of cRNAs to the DNA template, enhancing R-loop formation and cRNA retention at heterochromatin.

Characterizing the Loss and Acquisition of Tn2-like Transposon in Klebsiella pneumoniae: Implications for Carbapemase Gene Dissemination

Over one year, two KPC-producing and two non-KPC-producing Klebsiella pneumoniae strains were isolated from a patient. Genome and DNA hybridization analyses revealed the first three strains as a clonal lineage, with carbapenem resistance changes due to a Tn2-like transposon on an IncR/IncFII plasmid. The fourth strain, carrying three plasmids, caused a lethal infection and represented a different lineage. All strains belonged to the ST11-SL47-OL101 type. This study highlights the Tn2-like transposon's role in carbapenemase gene spread and the importance of distinguishing between bacterial colonization and infection.

Simulation-Guided Rational Design of DNA Walker-Based Theranostic Platform.

Biomolecule-functionalized nanoparticles represent a type of promising biomaterials in biomedical applications owing to their excellent biocompatibility and versatility. DNA-based reactions on nanoparticles have enabled emerging applications including intelligent biosensors, drug delivery, and biomimetic devices. Among the reactions, strand hybridization is the critical step to control the sensitivity and specificity of biosensing, and the efficiency of drug delivery. However, a comprehensive understanding of DNA hybridization on nanoparticles is still lacking, which may differ from the process in homogeneous solutions. To address this limitation, coarse-grained model-based molecular dynamic simulation is harnessed to disclose the critical factors involved in intermolecular hybridization. Based on simulation guidance, DNA walker-based smart theranostic platform (DWTP) based on "on-particle" hybridization is developed, showing excellent consistency with simulation. DWTP is successfully applied for highly sensitive miRNA 21 detection and tumor-specific miRNA 21 imaging, driven by tumor-endogenous APE 1 enzyme. It enables the precise release of antisense oligonucleotide triggered by tumor-endogenous dual-switch miRNA 21 and APE 1, facilitating effective gene silencing therapy with high biosafety. The simulation of "on-particle" DNA hybridization has improved the corresponding biosensing performance and the release efficiency of therapeutic agents, representing a conceptually new approach for DNA-based device design.

Development of supramolecular anticoagulants with on-demand reversibility.

Drugs are administered at a dosing schedule set by their therapeutic index, and termination of action is achieved by clearance and metabolism of the drug. In some cases, such as anticoagulant drugs or immunotherapeutics, it is important to be able to quickly reverse the drug's action. Here, we report a general strategy to achieve on-demand reversibility by designing a supramolecular drug (a noncovalent assembly of two cooperatively interacting drug fragments held together by transient hybridization of peptide nucleic acid (PNA)) that can be reversed with a PNA antidote that outcompetes the hybridization between the fragments. We demonstrate the approach with thrombin-inhibiting anticoagulants, creating very potent and reversible bivalent direct thrombin inhibitors (Ki = 74 pM). The supramolecular inhibitor effectively inhibited thrombus formation in mice in a needle injury thrombosis model, and this activity could be reversed by administration of the PNA antidote. This design is applicable to therapeutic targets where two binding sites can be identified.

Oerskovia flava sp. nov., a deoxynivalenol (DON)-degrading actinomycete isolated from the rhizosphere soil of long-term continuous cropping cucumber.

The deoxynivalenol (DON)-degrading bacterium JB1-3-2T was isolated from a rhizosphere soil sample of cucumber collected from a greenhouse located in Zhenjiang, Eastern China. The JB1-3-2T strain is a Gram-stain-positive, nonmotile and round actinomycete. Growth was observed at temperatures between 15 and 40 ℃ (optimum, 35 ℃), in the presence of 15% (w/v) NaCl (optimum, 3%), and at pH 3 and 11 (optimum, 7). The major cellular fatty acids identified were anteiso-C15:0, iso-C16:0 and anteiso-C17:0. Genome sequencing revealed a genome size of 4.11Mb and a DNA G + C content of 72.5mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the JB1-3-2T strain was most closely related to type strains of the Oerskovia species, with the highest sequence similarity to Oerskovia turbata NRRL B-8019T (98.2%), and shared 98.1% sequence identity with other valid type strains of this genus. Digital DNA‒DNA hybridization (dDDH) and average nucleotide identity (ANI) showed 21.8-22.2% and 77.2-77.3% relatedness, respectively, between JB1-3-2T and type strains of the genus Oerskovia. Based on genotypic, phylogenetic, chemotaxonomic, physiological and biochemical characterization, Oerskovia flava, a novel species in the genus Oerskovia, was proposed, and the type strain was JB1-3-2T (= CGMCC 1.18555T = JCM 35248T). Additionally, this novel strain has a DON degradation ability that other species in the genus Oerskovia do not possess, and glutathione-S-transferase was speculated to be the key enzyme for strain JB1-3-2T to degrade DON.

Structure-based drug design of DNA minor groove binders and evaluation of their antibacterial and anticancer properties

Antimicrobial and chemotherapy resistance are escalating medical problem of paramount importance. Yet, research for novel antimicrobial and anticancer agents remains lagging behind. With their reported medical applications, DNA minor groove binders (MGBs) are worthy of exploration. In this study, the approach of structure-based drug design was implemented to generate 11 MGB compounds including a novel class of bioactive alkyne-linked MGBs. The NCI screening protocol was utilized to evaluate the antitumor activity of the target MGBs. Furthermore, a variety of bactericidal, cytopathogenicity, MIC90, and cytotoxicity assays were carried out using these MGBs against 6 medically relevant bacteria: Salmonella enterica, Escherichia coli, Serratia marcescens, Bacillus cereus, Streptococcus pneumoniae and Streptococcus pyogenes. Moreover, molecular docking, molecular dynamic simulations, DNA melting, and isothermal titration calorimetry (ITC) analyses were utilized to explore the binding mode and interactions between the most potent MGBs and the DNA duplex d(CGACTAGTCG)2. NCI results showed that alkyne-linked MGBs (26 & 28) displayed the most significant growth inhibition among the NCI-60 panel. In addition, compounds MGB3, MGB4, MGB28, and MGB32 showed significant bactericidal effects, inhibited B. cereus and S. enterica-mediated cytopathogenicity, and exhibited low cytotoxicity. MGB28 and MGB32 demonstrated significant inhibition of S. pyogenes, whereas MGB28 notably inhibited S. marcescens and all four minor groove binders significantly inhibited B. cereus. The ability of these compounds to bind with DNA and distort its groove dimensions provides the molecular basis for the allosteric perturbation of proteins-DNA interactions by MGBs. This study shed light on the mechanism of action of MGBs and revealed the important structural features for their antitumor and antibacterial activities, which are important to guide future development of MGB derivatives as novel antibacterial and anticancer agents.

Multimodal Tetrahedral DNA Nanoplatform for Surprisingly Rapid and Significant Treatment of Acute Liver Failure.

Acute liver failure (ALF) is a life-threatening disease associated with the rapid development of inflammatory storms, level elevation of reactive oxygen species (ROS), and hepatocyte necrosis, which results in high short-term mortality. Except for liver transplantation, no effective strategies are available for ALF therapy due to the rapid disease progression and narrow window of therapeutic time. Therefore, there is an urgent demand to explore the fast and effective modalities for ALF treatment. Herein, a multifunctional tetrahedral DNA nanoplatform (TDN) is constructed by incorporating tumor necrosis factor-α siRNA (siTNF-α) through DNA hybridization and antioxidant manganese porphyrin (MnP4) via π-π stacking interaction with G-quadruplex (G4) for surprisingly rapid and significant ALF therapy. TDN-siTNF-α/-G4-MnP4 silences TNF-α of macrophages by siTNF-α and polarizes them to the anti-inflammatory M2 phenotype, providing appropriate microenvironments for hepatocyte viability. Additionally, TDN-siTNF-α/-G4-MnP4 scavenges intracellular ROS by MnP4, protecting hepatocytes from oxidative-stress-associated cell death. Furthermore, TDN itself promotes hepatocyte proliferation by modulating the cell cycle. TDN-siTNF-α/-G4-MnP4 shows almost complete liver accumulation after intravenous injection and exhibits excellent therapeutic efficacy of ALF within 2h. The multifunctional DNA nanoformulation provides an effective strategy for rapid ALF therapy, expanding its application for innovative treatments of liver diseases.

Bimetallic interface on an optical microfiber nucleic acid sensor: Early detection in body fluids

Nucleic acid detection, which is not limited by the “window period”, is an efficacious approach for detecting human immunodeficiency virus (HIV) infection at an early time. Here, method with a short turn-around time, portability, connectivity and cost-effectiveness is developed to suppress HIV disease in the early stage, especially in remote areas. Specifically, an optical microfiber sensor enhanced by a bimetallic interface is developed for the HIV-related DNA detection in body fluids. A bimetallic interface is constructed on the optical microfiber surface to ensure that target nucleic acid hybridization occurs between two gold nanostructures where the evanescent field is strongest. The selective enhancement of the evanescent field at the binding site prevents nonspecific amplification of the whole fiber surface, which may lead to false-positive results. With the enhancement in the bimetallic interface, the sensor can detect HIV-related DNA at concentrations from 1 aM to 0.1 pM, with a limit of detection (LOD) of 0.3 aM. The portability, flexibility and selectivity of the sensor enable its application in detecting in several body fluids, such as whole serum and artificial saliva, with LODs of 1.15 aM and 1.64 aM, respectively. This work provides a powerful tool for diagnosing HIV in early stages. Ultrasensitive nucleic acid detection in artificial saliva also provides a possibility for noninvasive detection.

Designer peptide-DNA cytoskeletons regulate the function of synthetic cells.

The bottom-up engineering of artificial cells requires a reconfigurable cytoskeleton that can organize at distinct locations and dynamically modulate its structural and mechanical properties. Here, inspired by the vast array of actin-binding proteins and their ability to reversibly crosslink or bundle filaments, we have designed a library of peptide-DNA crosslinkers varying in length, valency and geometry. Peptide filaments conjoint through DNA hybridization give rise to tactoid-shaped bundles with tunable aspect ratios and mechanics. When confined in cell-sized water-in-oil droplets, the DNA crosslinker design guides the localization of cytoskeletal structures at the cortex or within the lumen of the synthetic cells. The tunable spatial arrangement regulates the passive diffusion of payloads within the droplets and complementary DNA handles allow for the reversible recruitment and release of payloads on and off the cytoskeleton. Heat-induced reconfiguration of peptide-DNA architectures triggers shape deformations of droplets, regulated by DNA melting temperatures. Altogether, the modular design of peptide-DNA architectures is a powerful strategy towards the bottom-up assembly of synthetic cells.

Replicative senescence and high glucose induce the accrual of self-derived cytosolic nucleic acids in human endothelial cells.

Recent literature shows that loss of replicative ability and acquisition of a proinflammatory secretory phenotype in senescent cells is coupled with the build-in of nucleic acids in the cytoplasm. Its implication in human age-related diseases is under scrutiny. In human endothelial cells (ECs), we assessed the accumulation of intracellular nucleic acids during in vitro replicative senescence and after exposure to high glucose concentrations, which mimic an in vivo condition of hyperglycemia. We showed that exposure to high glucose induces senescent-like features in ECs, including telomere shortening and proinflammatory cytokine release, coupled with the accrual in the cytoplasm of telomeres, double-stranded DNA and RNA (dsDNA, dsRNA), as well as RNA:DNA hybrid molecules. Senescent ECs showed an activation of the dsRNA sensors RIG-I and MDA5 and of the DNA sensor TLR9, which was not paralleled by the involvement of the canonical (cGAS) and non-canonical (IFI16) activation of the STING pathway. Under high glucose conditions, only a sustained activation of TLR9 was observed. Notably, senescent cells exhibit increased proinflammatory cytokine (IL-1β, IL-6, IL-8) production without a detectable secretion of type I interferon (IFN), a phenomenon that can be explained, at least in part, by the accumulation of methyl-adenosine containing RNAs. At variance, exposure to exogenous nucleic acids enhances both IL-6 and IFN-β1 expression in senescent cells. This study highlights the accrual of cytoplasmic nucleic acids as a marker of senescence-related endothelial dysfunction, that may play a role in dysmetabolic age-related diseases.

Deep eutectic solvent-assisted synthesis of gold nanoflowers supported on glassy carbon electrode for DNA sensor application

Gold nanoflowers (AuNF) were synthesized on a glassy carbon electrode via a one-step, eco-friendly protocol in deep eutectic solvent (DES) of choline choloride and urea, called reline, for label-free detection of DNA hybridization. DES is eco-friendly, low-cost, biocompatible, and nontoxic, and it can be used as an electrolyte to synthesize nanomaterials by using the electrochemical method. In this protocol, highly branched and stable AuNFs were obtained without using any surfactants for DNA sensor application. The electrochemical performance of the AuNF-modified electrode was studied by cyclic voltammetry and electrochemical impedance spectroscopy. Under optimal conditions, the AuNF-based DNA biosensor exhibited a sensitivity of 294.9 Ω nM−1cm−2 and 218 μA nM−1cm−2 and a limit of detection (LOD) of 10−9 M. The remarkable sensitivity and low LOD could be attributed to the good conductivity of AuNFs for accelerating electron transfer, resulting in obvious signal amplification. The DNA biosensor showed good reproducibility (RSD <3.65 %) and acceptable stability and selectivity. Its excellent performance in DNA detection suggested that the proposed electrochemical DNA sensor has great application potential in clinical diagnosis.

Adduct of fullerene C60 with l-arginine: interaction with DNA, genotoxic and mutagenic properties

The paper presents a physicochemical study of the water-soluble adduct of C60 with l-arginine, including a quantum chemical determination of the stability of isomers, measurement of antiradical activity towards the ABTS radical, determination of the lipophilicity coefficient, particle size distribution in aqueous solutions and calculation of ζ-potentials. A separate part of the article is devoted to the study of the effect of the C60 adduct with l-arginine on DNA in in vitro experiments (determination of the binding constant using isothermal titration calorimetry, study of genotoxicity, DNA melting temperature, effect on DNA circular dichroism spectra). Data are also presented on the biodistribution of the C60 adduct with l-arginine in the organs and tissues of animals and its effect on clinical and biochemical blood parameters. The mutagenic effect of the C60 adduct with l-arginine was determined in vivo on a model of mice abnormal sperm heads. It was shown that the adduct is in a neutral state in physiological solution, has an affinity to both aqueous and lipid phases (logP ow = 0.23), and forms a complex with DNA (Ka = 4.59 106 M −1), while it does not have cyto- and genotoxicity in vitro and mutagenicity in vivo.