An Intelligent DNA Nanorobot with in Vitro Enhanced Protein Lysosomal Degradation of HER2.

DNA nanorobots have emerged as new tools for nanomedicine with the potential to ameliorate the delivery and anticancer efficacy of various drugs. DNA nanostructures have been considered one of the most promising nanocarriers. In the present study, we report a DNA framework-based intelligent DNA nanorobot for selective lysosomal degradation of tumor-specific proteins on cancer cells. We site-specifically anchored an anti-HER2 aptamer (HApt) on a tetrahedral framework nucleic acid (tFNA). This DNA nanorobot (HApt-tFNA) could target HER2-positive breast cancer cells and specifically induce the lysosomal degradation of the membrane protein HER2. An injection of the DNA nanorobot into a mouse model revealed that the presence of tFNA enhanced the stability and prolonged the blood circulation time of HApt, and HApt-tFNA could therefore drive HER2 into lysosomal degradation with a higher efficiency. The formation of the HER2-HApt-tFNA complexes resulted in the HER2-mediated endocytosis and digestion in lysosomes, which effectively reduced the amount of HER2 on the cell surfaces. An increased HER2 digestion through HApt-tFNA further induced cell apoptosis and arrested cell growth. Hence, this novel DNA nanorobot sheds new light on targeted protein degradation for precision breast cancer therapy.

Targeted and effective glioblastoma therapy via aptamer-modified tetrahedral framework nucleic acid-paclitaxel nanoconjugates that can pass the blood brain barrier.

Targeted DNA nanoparticles have been identified as one of the most promising nanocarriers in anti-glioma drug delivery. We established a multifunctional nanosystem for targeted glioma therapy. Tetrahedral framework nucleic acid (tFNA), entering U87MG cells and bEnd.3 cells, was chosen to deliver two aptamers, GMT8 and Gint4.T, and paclitaxel. GMT8 and Gint4.T, which specifically bind with U87MG cells and with PDGFRß, were linked with tFNA, to form Gint4.T-tFNA-GMT8 (GTG). GTG was efficiently internalized by U87MG and bEnd.3 cells and penetrated an in-vitro blood-brain-barrier model. GTG loaded with paclitaxel (GPC) had potentiated anti-glioma efficacy. It inhibited the proliferation, migration, and invasion of U87MG cells, and enhanced apoptosis induction in these cells. The expression of apoptosis-related proteins was significantly changed after treatment with GPC, confirming apoptosis induction. Our study demonstrated that the combination of GTG and paclitaxel has great potential for glioma treatment and tFNA shows great promise for use in drug delivery.

Regulating osteogenesis and adipogenesis in adipose-derived stem cells by controlling underlying substrate stiffness.

Cells reside in a complex microenvironment (niche) in which the biochemical and biophysical properties of the extracellular matrix profoundly affect cell behavior. Extracellular stiffness, one important bio-mechanical characteristic of the cell niche, is important in regulating cell proliferation, migration, and lineage specification. However, the mechanism by which mechanical signals guide osteogenic and adipogenic commitment of stem cells remains difficult to dissect. To explore this question, we generated a range of polydimethylsiloxane-based matrices with differing degrees of stiffness that mimicked the stiffness seen in natural tissues and examined adipose stem cell morphology, spreading, vinculin expression, and differentiation along the osteogenic and adipogenic pathways. Rigid matrices allowed broader cell spreading, faster growth rate and stronger expression of vinculin in adipose-derived stem cells. In the presence of inductive culture media, stiffness-dependent osteogenesis and adipogenesis of the adipose stem cells indicated that there was a combinatorial effect of biophysical and biochemical cues; no such lineage specification was observed in normal media. Osteogenic differentiation behavior showed a correlation with matrix rigidity, as well as with elevated expression of RhoA, ROCK-1/-2, and related proteins in the Wnt/ß-catenin pathway. The result provides a comprehensive understanding of how stem cells respond to the surrounding microenvironment and points to the fact that matrix stiffness is a critical element in biomaterial design and this will be an important advance in stem cell-based tissue engineering.

Divergent Total Syntheses of (-)-Daphnilongeranin†B and (-)-Daphenylline.

(-)-Daphnilongeranin B and (-)-daphenylline are two hexacyclic Daphniphyllum alkaloids, each containing a complex cagelike backbone. Described herein are the first asymmetric total synthesis of (-)-daphnilongeranin B and a bioinspired synthesis of (-)-daphenylline with an unusual E ring embedded in a cagelike framework. The key features include an intermolecular [3+2] cycloaddition, a late-stage aldol cyclization to install the F ring of daphnilongeranin B, and a bioinspired cationic rearrangement leading to the tetrasubstituted benzene ring of daphenylline.

Tetrahedral DNA Nanostructure: A Potential Promoter for Cartilage Tissue Regeneration via Regulating Chondrocyte Phenotype and Proliferation.

Utilizing biomaterials to regulate the phenotype and proliferation of chondrocytes is a promising approach for effective cartilage tissue regeneration. Recently, a significant amount of effort has been invested into directing chondrocytes toward a desired location and function by utilizing biomaterials to control the dedifferentiation and phenotypic loss of chondrocytes during in vitro monolayer culture. Here, the transmission signals resulting from tetrahedral DNA nanostructures (TDNs) in the regulation of chondrocyte phenotype and proliferation are exploited. TDNs, new DNA nanomaterials, have been considered as promising materials in biomedical fields. Upon exposure to TDNs, chondrocyte phenotype is significantly enhanced, accompanied by lower gene expression related to Notch signaling pathway and higher expression of type II collagen. In addition, the cell proliferation and morphology of chondrocytes are changed after exposure to TDNs. In conclusion, this work demonstrates that TDNs are potentially useful mechanism in cartilage tissue regeneration from chondrocytes, whereby chondrocyte phenotype and proliferation can be retained.

Effect of tetrahedral DNA nanostructures on osteogenic differentiation of mesenchymal stem cells via activation of the Wnt/ß-catenin signaling pathway.

Adipose-derived stem cells (ADSCs) are considered to be ideal stem cell sources for bone regeneration owing to their ability to differentiate into osteo-like cells. Therefore, they have attracted increasing attention in recent years. Tetrahedral DNA nanostructures (TDNs), a new type of DNA-based biomaterials, have shown great potential for biomedical applications. In the present work, we aimed to investigate the role played by TDNs in osteogenic differentiation and proliferation of ADSCs and tried to explore if the canonical Wnt signal pathway could be the vital biological mechanism driving these cellular responses. Upon exposure to TDNs, ADSCs proliferation and osteogenic differentiation were significantly enhanced, accompanied by the up-regulation of genes correlated with the Wnt/ß-catenin pathway. In conclusion, our results indicate that TDNs are crucial regulators of the increase in osteogenic potential and ADSCs proliferation, and this noteworthy discovery could provide a promising novel approach toward ADSCs-based bone defect regeneration.

A Chiral Nitrogen Ligand for Enantioselective, Iridium-Catalyzed Silylation of Aromatic C-H Bonds.

Iridium catalysts containing dative nitrogen ligands are highly active for the borylation and silylation of C-H bonds, but chiral analogs of these catalysts for enantioselective silylation reactions have not been developed. We report a new chiral pyridinyloxazoline ligand for enantioselective, intramolecular silylation of symmetrical diarylmethoxy diethylsilanes. Regioselective and enantioselective silylation of unsymmetrical substrates was also achieved in the presence of this newly developed system. Preliminary mechanistic studies imply that C-H bond cleavage is irreversible, but not the rate-determining step.

Effects of tension on mitochondrial autophagy and osteogenic differentiation of periodontal ligament stem cells.

This study aimed to explore the osteogenic ability and mitochondrial autophagy of periodontal ligament stem cells (PDLSCs) under cyclic tensile stress (CTS). Primary PDLSCs were isolated from the periodontal membrane and cultured by passage. Alizarin red staining, alkaline phosphatase detection, reverse transcription polymerase chain reaction (RT-PCR), and Western blotting were used to detect the osteogenic differentiation level of PDLSCs. Mitochondrial autophagy in PDLSCs after CTS was measured using a mitochondrial autophagy detection kit, and the expression levels of autophagy-related proteins LC3B, LAMP1 and Beclin1 were measured using cellular immunofluorescence technology, RT-PCR and Western blot. After applying CTS, the osteogenic differentiation ability of PDLSCs was significantly improved, and the expression of alkaline phosphatase on the surface of the cell membrane and the formation of calcium nodules in PDLSCs were significantly increased respectively. We also studied the relevant mechanism of action and found that applying CTS can promote the osteogenic differentiation of PDLSCs and is related to the activation of mitochondrial autophagy. This study provides new insights into the mechanism of increased osteogenic differentiation on the tension side of orthodontic teeth and provides new experimental evidence for the involvement of mitochondrial autophagy in the regulation of osteogenic differentiation.

MiR-26a-tetrahedral framework nucleic acids mediated osteogenesis of adipose-derived mesenchymal stem cells.

OBJECTIVES: Delivery systems that provide time and space control have a good application prospect in tissue regeneration applications, as they can effectively improve the process of wound healing and tissue repair. In our experiments, we constructed a novel micro-RNA delivery system by linking framework nucleic acid nanomaterials to micro-RNAs to promote osteogenic differentiation of mesenchymal stem cells. MATERIALS AND METHODS: To verify the successful preparation of tFNAs-miR-26a, the size of tFNAs-miR-26a were observed by non-denaturing polyacrylamide gel electrophoresis and dynamic light scattering techniques. The expression of osteogenic differentiation-related genes and proteins was investigated by confocal microscope, PCR and western blot to detect the impact of tFNAs-miR-26a on ADSCs. And finally, Wnt/ß-catenin signaling pathway related proteins and genes were detected by confocal microscope, PCR and western blot to study the relevant mechanism. RESULTS: By adding this novel complex, the osteogenic differentiation ability of mesenchymal stem cells was significantly improved, and the expression of alkaline phosphatase (ALP) on the surface of the cell membrane and the formation of calcium nodules in mesenchymal stem cells were significantly increased on days 7 and 14 of induction of osteogenic differentiation, respectively. Gene and protein expression levels of ALP (an early marker associated with osteogenic differentiation), RUNX2 (a metaphase marker), and OPN (a late marker) were significantly increased. We also studied the relevant mechanism of action and found that the novel nucleic acid complex promoted osteogenic differentiation of mesenchymal stem cells by activating the canonical Wnt signaling pathway. CONCLUSIONS: This study may provide a new research direction for the application of novel nucleic acid nanomaterials in bone tissue regeneration.

Palladium-Catalyzed Arylation of C(sp2)-H Bonds with 2-(1-Methylhydrazinyl)pyridine as the Bidentate Directing Group.

Palladium-catalyzed C(sp2)-H arylation of ortho C-H bonds involving 2-(1-methylhydrazinyl)pyridine (MHP) as the directing group has been investigated. The reaction proceeds smoothly under an air atmosphere to generate biaryl derivatives in an environmentally friendly manner while tolerating a wide range of functional groups. Notably, the directing group present in the product could be easily removed under mild reductive conditions.

Diversity of DNA Nanostructures and Applications in Oncotherapy.

DNA nanotechnology is a new frontier in the field of tumor biotherapy. Simple DNA strands can be precisely constructed for integration into nanostructures of desired shapes and sizes, with excellent stability and biocompatibility. In this review, an account of the wide range of nanostructures composed of DNA sequences and related advances in oncotherapy using aptamers and chemical drugs is given. Functional ligands, including enzymes, antibodies, and agents, have been appended to DNA frameworks based on their external and internal modifiability. Hence, additional functionalities, such as immunogenicity and enzymatic activity, have been obtained, which extend their practical applications. Importantly, aptamers and drugs can be attached to or incorporated into the wireframes, bringing in highly selective targeting and killing abilities for the modified DNA nanostructures (DNs). In conclusion, distinct DNA sequences, various functional molecules, and different interactions and modifications lead to the diversity of DNs. Currently, one of the leading areas is their applications in tumor therapy. But beyond that, DNs should have much wider application prospects.

Multi-targeted Antisense Oligonucleotide Delivery by a Framework Nucleic Acid for Inhibiting Biofilm Formation and Virulence.

Biofilm formation is responsible for numerous chronic infections and represents a serious health challenge. Bacteria and the extracellular polysaccharides (EPS) cause biofilms to become adherent, toxic, resistant to antibiotics, and ultimately difficult to remove. Inhibition of EPS synthesis can prevent the formation of bacterial biofilms, reduce their robustness, and promote removal. Here, we have developed a framework nucleic acid delivery system with a tetrahedral configuration. It can easily access bacterial cells and functions by delivering antisense oligonucleotides that target specific genes. We designed antisense oligonucleotide sequences with multiple targets based on conserved regions of the VicK protein-binding site. Once delivered to bacterial cells, they significantly decreased EPS synthesis and biofilm thickness. Compared to existing approaches, this system is highly efficacious because it simultaneously reduces the expression of all targeted genes (gtfBCD, gbpB, ftf). We demonstrate a novel nucleic acid-based nanomaterial with multi-targeted inhibition that has great potential for the treatment of chronic infections caused by biofilms.

Treatment of Alzheimer's disease with framework nucleic acids.

OBJECTIVES: To provide a new research direction for nerve regeneration and strategy for Alzheimer's disease treatment, tetrahedral DNA nanostructures (TDNs)-novel tetrahedral framework nucleic acid molecule nanoparticles (tFNA) that can inhibit the apoptosis of nerve cells are employed in the experiment. MATERIALS AND METHODS: To verify the successful preparation of TDNs, the morphology of TDNs was observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The expression of apoptosis-related genes and proteins was investigated by confocal microscope, flow cytometry, PCR and Western blot to detect the impact of TDNs on the Alzheimer's model. And finally, Morris water maze experiment was used to test behavioural changes and Nissl stain was detected to observe the morphology and quantity of neurons in the hippocampus. Immunofluorescence stain was used to observe the Aß stain, and TUNEL dyeing was utilized to observe neuronal apoptosis. RESULTS: In vitro and in vivo experiments confirm that TDNs, in a specific concentration range, have no toxic or side effects on nerve cells, can effectively inhibit apoptosis in an Alzheimer's disease cell model and effectively improve memory and learning ability in a rat model of Alzheimer's disease. CONCLUSIONS: These findings suggest that TDNs may be a promising drug for the treatment of Alzheimer's disease.

PEGylated Protamine-Based Adsorbing Improves the Biological Properties and Stability of Tetrahedral Framework Nucleic Acids.

Recently, many researchers have reported that DNA nanostructures, such as tetrahedral framework nucleic acids (tFNAs), have great potential to be useful tools in clinical and laboratory applications due to their programmable shapes, functional sites, and biological responses. However, finite endocytosis and stability in cells and body fluids compromise the functions of DNA nanostructures as a result of various adverse factors. In this study, we successfully synthesized PEGylated protamine, and tFNAs were adsorbed to it in a proper ratio of nitrogen in protamine to phosphorus in tFNAs (N/P ratio) as the functional complex. Furthermore, we demonstrated that PEGylated protamine-adsorbed tFNAs show a more prominent positive effect on cell viability and proliferation than naked tFNAs do. An increase in endocytosis can be observed in three different tissue-derived cells with the PEG-protamine-tFNA (PPT) complex. The increased endocytic ability is mediated by multiple pathways; moreover, the stimulatory effect of the PPT complex on the endocytic ability is dramatically blocked by the inhibition of the caveola-dependent pathway. Consistently, when tFNAs are stabilized by PEGylated protamine, they often tend to escape from lysosomes and survive for a longer period in biological fluids rather than being rapidly eliminated from the kidneys. The in vitro and in vivo results of our study demonstrate that the PPT complex method is a feasible, potent, and low-cost strategy that improves tFNA biocompatibility, stability, and internalization. This study provides evidence supporting the possibility of implementing PPTs for use in drug delivery, bioimaging, and gene transfection in the future.

Aptamer-targeted DNA nanostructures with doxorubicin to treat protein tyrosine kinase 7-positive tumours.

OBJECTIVES: Aptamer sgc8c is a short DNA sequence that can target protein tyrosine kinase 7 (PTK7), which was overexpressed on many tumour cells. This study aimed to fabricate a novelty DNA nanostructure drug delivery system target on PTK7-positive cells-CCRF-CEM (human T-cell ALL). METHODS: Aptamer-modified tetrahedron DNA was synthesized through one-step thermal annealing process. The sgc8c-TDNs (s-TDNs) loading DOX complexes were applied to investigate the effect to PTK7-negative and -positive cells. RESULTS: When s-TDN:DOX acted on PTK7-positive and -negative cells respectively, the complexes exhibited specific toxic effect on PTK7-positive cells but not on PTK7-negative Ramos cells in vitro research. CONCLUSIONS: In this work, we successfully constructed a PTK7-targeting aptamer-guided DNA tetrahedral nanostructure (s-TDN) as a drug delivery system via a facile one-pot synthesis method. The results showed that s-TDN:DOX exhibited enhanced cytotoxicity against PTK7-positive CCRF-CEM cells, with a minor effect against PTK7-negative Ramos cells. Hence, this functionalized TDNs drug delivery system displayed its potential application in targeting PTK7-positive tumour T-cell acute lymphoblastic leukaemia.

DNA-Based Nanomedicine with Targeting and Enhancement of Therapeutic Efficacy of Breast Cancer Cells.

Recently, a DNA tetrahedron has been reported to be a novel nanomedicine and promising drug vector because of its compactness, biocompatibility, biosafety, and editability. Here, we modified the DNA tetrahedron with a DNA aptamer (AS1411) as a DNA-based delivery system, which could bind to nucleolin for its cancer cell selectivity. Nucleolin is a specific biomarker protein overexpressed on membranes of malignant cancer cells and its deregulation is implicated in cell proliferation. The antimetabolite drug 5-fluorouracil (5-FU) is an extensively used anticancer agent; however, its major limitation is the lack of target specificity. Cyanine 5 (Cy5), a fluorescent probe, can be used to label DNA tetrahedron and enhance photostability with minimal effects on its basic functions. In this study, we additionally attached 5-FU to the DNA-based delivery system as a new tumor-targeting nanomedicine (AS1411-T-5-FU) to enhance the therapeutic efficacy and targeting of breast cancer. We examined the difference of the cellular uptake of AS1411-T-5-FU between breast cancer cells and normal breast cells and concluded that AS1411-T-5-FU had a better targeting ability to kill breast cancer cells than 5-FU. We further evaluated the expressions of cell apoptosis-related proteins and genes, which are associated with the mitochondrial apoptotic pathway. Ultimately, our results suggest the potential of DNA tetrahedron in cancer therapies, and we develop a novel approach to endow 5-FU with targeting property.

Potent anti-angiogenesis and anti-tumour activity of pegaptanib-loaded tetrahedral DNA nanostructure.

OBJECTIVES: Pegaptanib might be a promising anti-tumour drug targeting VEGF to inhibit tumour vascular endothelial cell proliferation. However, the poor biostability limited its application. In this study, we took tetrahedron DNA nanostructures (TDNs) as drug nanocarrier for pegaptanib to explore the potent anti-angiogenesis and anti-tumour activity of this drug delivery system. MATERIALS AND METHODS: The successful synthesis of TDNs and pegaptanib-TDNs was determined by 8% polyacrylamide gel electrophoresis (PAGE), capillary electrophoresis and dynamic light scattering (DLS). The cytotoxicity of pegaptanib alone and pegaptanib-TDNs on HUVECs and Cal27 was evaluated by the cell count kit-8 (CCK-8) assay. The effect of pegaptanib and pegaptanib-TDNs on proliferation, migration and tube formation of HUVECs induced by VEGF was examined by CCK-8 assay, wound healing assay and tubule formation experiment. The cell binding capacity and serum stability were detected by flow cytometry and PAGE, respectively. RESULTS: Pegaptanib-TDNs had stronger killing ability than pegaptanib alone, and the inhibiting effect was in a concentration-dependent manner. What's more, pegaptanib-loaded TDNs could effectively enhance the ability of pegaptanib to inhibit proliferation, migration and tube formation of HUVECs induced by VEGF. These might attribute to the stronger binding affinity to the cell membrane and greater serum stability of pegaptanib-TDNs. CONCLUSIONS: These results suggested that pegaptanib-TDNs might be a novel strategy to improve anti-angiogenesis and anti-tumour ability of pegaptanib.

The Clearance Effect of Tetrahedral DNA Nanostructures on Senescent Human Dermal Fibroblasts.

Senescent cells are characterized by their resistance to apoptosis, and upon their long-term survival senescent cells affect tissue function and eventually become deleterious to the organism. Thus, far, it has been gradually accepted that clearance of these senescent cells could reduce tissue dysfunction. This study aimed to investigate biological effects of tetrahedral DNA nanostructures (TDNs) on senescent cells. The results revealed a different biological effect of TDNs, and their clearance effect on senescent cells. TDNs can induce phenotypic changes in senescent cells, suppressing antiapoptotic BCL-2 family proteins and upregulating BAX, a BCL-2 family proapoptotic protein, to influence the expression levels and function of downstream proteins. Consequently, cytochrome C releasing promoted cleavage-mediated activation of pro-caspase-3 and its nuclear translocation from the cytoplasm to mediate apoptosis. The present results provide a foundation for further studies on the application of TDNs in studies on aging.

Neuroprotective and Neurotherapeutic Effects of Tetrahedral Framework Nucleic Acids on Parkinson's Disease in Vitro.

Parkinson's disease (PD) is a neurodegenerative disease characterized by a series of progressive motor disorders. PD is caused by dysfunction of basal ganglia, decrease of dopaminergic neurons in substantia nigra, and abnormal accumulation of Lewy bodies and Lewy neurites. Antiparkinsonian agents, which are currently used for treatment of PD, exhibit unsatisfactory effects on disease control. In recent years, tetrahedral framework nucleic acids (TFNAs) have been considered as multifunctional nanomaterials, and their scope of application has been extended to a wide range of areas. In previous studies, TFNAs were shown to exert positive effects on various cell types in processes such as cell proliferation, cell differentiation, and apoptosis. In the present study, we explored the role of TFNAs in the treatment and prevention of PD in vitro and elucidated its underlying mechanisms of action. On the basis of the experiments conducted, we demonstrated that TFNAs could inhibit and repair the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced apoptosis of PC12 cells through decreasing the accumulation of α-synuclein, one of the characteristic biomarkers of PD. Genes and proteins related to the AKT/PI3K signaling and mitochondrial apoptotic pathways were examined to further support this finding. Most importantly, TFNAs exhibited unexpected neuroprotective and neurorestorative effects on PC12 cells, providing a novel approach for reducing the neuropathological changes caused by PD.

Nucleic acids and analogs for bone regeneration.

With the incidence of different bone diseases increasing, effective therapies are needed that coordinate a combination of various technologies and biological materials. Bone tissue engineering has also been considered as a promising strategy to repair various bone defects. Therefore, different biological materials that can promote stem cell proliferation, migration, and osteoblastic differentiation to accelerate bone tissue regeneration and repair have also become the focus of research in multiple fields. Stem cell therapy, biomaterial scaffolds, and biological growth factors have shown potential for bone tissue engineering; however, off-target effects and cytotoxicity have limited their clinical use. The application of nucleic acids (deoxyribonucleic acid or ribonucleic acid) and nucleic acid analogs (peptide nucleic acids or locked nucleic acids), which are designed based on foreign genes or with special structures, can be taken up by target cells to exert different effects such as modulating protein expression, replacing a missing gene, or targeting specific gens or proteins. Due to some drawbacks, nucleic acids and nucleic acid analogs are combined with various delivery systems to exert enhanced effects, but current studies of these molecules have not yet satisfied clinical requirements. In-depth studies of nucleic acid or nucleic acid analog delivery systems have been performed, with a particular focus on bone tissue regeneration and repair. In this review, we mainly introduce delivery systems for nucleic acids and nucleic acid analogs and their applications in bone repair and regeneration. At the same time, the application of conventional scaffold materials for the delivery of nucleic acids and nucleic acid analogs is also discussed.