AS1411 Aptamer Research Articles

Aptamer-Engineered Cu2O Nanocubes as a Surface-Modulated Catalytic Optical Sensor for Lung Cancer Cell Detection.

Herein, fine and homogeneous Cu2O nanocubes are synthesized and sensitized with a hairpin-structured AS1411 aptamer for the establishment of a biosensor for lung cancer cell detection. The Apt-Cu2O nanocubes feature a recognition function in identifying a cancer-associated surface nucleolin protein. The intrinsic reduction catalytic ability is also confirmed by the use of two benchmark substrates, methylene blue (MB) and 4-nitrophenol (4-NP). The aptamer grafting on Apt-Cu2O nanocubes is able to greatly prevent nonspecific-protein binding and to show specificity toward the nucleolin protein. The specific binding resulting from nucleolin protein leads to less exposure of the active area of the Apt-Cu2O nanocubes, so the catalytic ability of Apt-Cu2O nanocubes is thus diminished. The modulated catalytic ability led to less generation of the reduced 4-AP product, and the change in absorption of 4-AP allows the quantification of the nucleolin protein with a detection limit of 0.47 nM. The as-developed biosensor is applied to the detection of nucleolin-overexpressed A549 lung cancer cells, presenting a sensitive detection limit down to 20 cells. This may be ascribed to the clustering of surface nucleolin protein in a lipid raft membrane of cancer cells, as evidenced by a notable binding of Apt-Cu2O nanocubes on the cancer cell surface. Real human serum samples spiked with cancer cells were also investigated, and a recovery rate of 87 ± 2.4% for 20 extracted cells validates the surface-modulated Apt-Cu2O nanocubes-based catalytic optical biosensor as a promising tool for the detection of circulating tumor cells. The establishment of the Apt-Cu2O nanocubes may allow for further studies on their use as a potential theranostics tool for cancer therapy.

Aptamer-Functionalized Ce4+-Ion-Modified C-Dots: Peroxidase Mimicking Aptananozymes for the Oxidation of Dopamine and Cytotoxic Effects toward Cancer Cells.

Aptamer-functionalized Ce4+-ion-modified C-dots act as catalytic hybrid systems, aptananozymes, catalyzing the H2O2 oxidation of dopamine. A series of aptananozymes functionalized with different configurations of the dopamine binding aptamer, DBA, are introduced. All aptananozymes reveal substantially enhanced catalytic activities as compared to the separated Ce4+-ion-modified C-dots and aptamer constituents, and structure-catalytic functions between the structure and binding modes of the aptamers linked to the C-dots are demonstrated. The enhanced catalytic functions of the aptananozymes are attributed to the aptamer-induced concentration of the reaction substrates in spatial proximity to the Ce4+-ion-modified C-dots catalytic sites. The oxidation processes driven by the Ce4+-ion-modified C-dots involve the formation of reactive oxygen species (•OH radicals). Accordingly, Ce4+-ion-modified C-dots with the AS1411 aptamer or MUC1 aptamer, recognizing specific biomarkers associated with cancer cells, are employed as targeted catalytic agents for chemodynamic treatment of cancer cells. Treatment of MDA-MB-231 breast cancer cells and MCF-10A epithelial breast cells, as control, with the AS1411 aptamer- or MUC1 aptamer-modified Ce4+-ion-modified C-dots reveals selective cytotoxicity toward the cancer cells. In vivo experiments reveal that the aptamer-functionalized nanoparticles inhibit MDA-MB-231 tumor growth.

The Impact of PEGylation on Cellular Uptake and In Vivo Biodistribution of Gold Nanoparticle MRI Contrast Agents.

Gold nanoparticles (GNPs) have immense potential in biomedicine, but understanding their interactions with serum proteins is crucial as it could change their biological profile due to the formation of a protein corona, which could then affect their ultimate biodistribution in the body. Grafting GNPs with polyethylene glycol (PEG) is a widely used practice in research in order to decrease opsonization of the particles by serum proteins and to decrease particle uptake by the mononuclear phagocyte system. We investigated the impact of PEGylation on the formation of protein coronae and the subsequent uptake by macrophages and MDA-MB-231 cancer cells. Furthermore, we investigated the in vivo biodistribution in xenograft tumor-bearing mice using a library of 4 and 10 nm GNPs conjugated with a gadolinium chelate as MRI contrast agent, cancer-targeting aptamer AS1411 (or CRO control oligonucleotide), and with or without PEG molecules of different molecular weight (Mw: 1, 2, and 5 kDa). In vitro results showed that PEG failed to decrease the adsorption of proteins; moreover, the cellular uptake by macrophage cells was contingent on the different configurations of the aptamers and the length of the PEG chain. In vivo biodistribution studies showed that PEG increased the uptake by tumor cells for some GNPs, albeit it did not decrease the uptake of GNPs by macrophage-rich organs.

AS1411 aptamer improves therapeutic efficacy of PEGylated nanoliposomes loaded with gefitinib in the mice bearing CT26 colon carcinoma

AS1411 aptamer improves therapeutic efficacy of PEGylated nanoliposomes loaded with gefitinib in the mice bearing CT26 colon carcinoma

Folate-Functionalization Enhances Cytotoxicity of Multivalent DNA Nanocages on Triple-Negative Breast Cancer Cells.

DNA is an excellent programmable polymer for the generation of self-assembled multivalent nanostructures useful for biomedical applications. Herein, we developed (i) folate-functionalized nanocages (Fol-NC), very efficiently internalized by tumor cells overexpressing the α isoform of the folate receptor; (ii) AS1411-linked nanocages (Apt-NC), internalized through nucleolin, a protein overexpressed in the cell surface of many types of cancers; and (iii) nanostructures that harbor both folate and AS1411 aptamer functionalization (Fol-Apt-NC). We analyzed the specific miRNA silencing activity of all types of nanostructures harboring miRNA sequestering sequences complementary to miR-21 and the cytotoxic effect when loaded with doxorubicin in a drug-resistant triple-negative breast cancer cell line. We demonstrate that the presence of folate as a targeting ligand increases the efficiency in miR-21 silencing compared to nanocages functionalized with AS1411. Double-functionalized nanocages (Fol-Apt-NC), loaded with doxorubicin, resulted in an increase of over 51% of the cytotoxic effect on MDA-MB-231 cells compared to free doxorubicin, demonstrating, besides selectivity, the ability of nanocages to overcome Dox chemoresistance. The higher efficiency of the folate-functionalized nanocages is due to the way of entrance, which induces more than four times higher intracellular stability and indicates that the folate-mediated route of cell entry is more efficient than the nucleolin-mediated one when both folate and AS1411 modifications are present.

Improved Tumor Infiltration and Immunomodulation for Tumor Therapy: A Pathway Based on Tetrahedral Framework Nucleic Acids Coupled Bacterial Nanocells.

Growing evidence indicates that the tumor microenvironment (TME) can be combined with other therapeutic modalities, including cytotoxic chemotherapy and targeted therapies, to produce unanticipated results in oncology treatment. Here, we proposed a novel bacterial nanomaterial capable of targeting peritumoral biofilm and modulating TME. It was based on tetrahedral framework nucleic acids (T) that were chemically attached to aptamer AS1411 and 5-fluorouracil (AT5). Additionally, the oral pathogenic bacterium Streptococcus mutans (S.m) was employed as a biocarrier for synergetic biofilm targeting and immunomodulation. In this article, the effect of AT5-coupled S.m-derived nanocells (S.m-AT5) was investigated in vitro and in vivo. Due to bacteria aggregation in the tumor-specific biofilm, these nanocells released greater medication concentrations. Furthermore, they exerted an immunomodulatory effect by stimulating the maturation of dendritic cells (DCs) and regulation of T cells. This chemo-immunostimulation combination has a powerful antitumor impact. It may also be an advanced approach for boosting the survival rate of cancer patients.

Technetium‐99m radiolabeled nucleolin-targeted aptamer for glioma tumor imaging in murine models

Aptamers are small molecule DNA or RNA fragments that fold into well-defined 3D structures with high specificity and affinity towards target molecules, therefore emerging as a new class of probes for radiopharmaceutical applications. In this study, a technetium‐99m (99mTc) radiolabeled nucleolin-targeted aptamer AS1411 was developed for identifying glioma in murine models. MethodsA six-carbon amine group was linked at the 5′ end of AS1411 by DNA synthesis. Following the conjugation to NHS-MAG3, AS1411 was radiolabeled with 99mTc. Radiochemical purity and stability were evaluated by radio-TLC and gel electrophoresis. Cellular uptake and MTT assays were carried out in the nucleon-overexpressed U87 cell line to assess the biological ability of AS1411 after conjugating with FITC or radiolabeling with 99mTc. In vivo imaging of 99mTc-AS1411 was performed in glioma tumor xenografts and 99mTc and a 99mTc-labeled non-specific negative control (NC) nucleotide were used as control groups. Biodistribution studies were performed at the terminal time point of SPECT imaging. ResultsAS1411 was successfully labeled with 99mTc with the labeling yields of 81.5% ± 3.6% (n = 5) and was verified by gel electrophoresis and gel imaging. 99mTc-AS1411 was proved to be stable in fresh human serum at room temperature for 12 h. In U87 cells, 99mTc-AS1411 showed significantly higher cellular uptake than 99mTc-NC and 99mTc (9.4% ± 2.1% vs 1.9% ± 0.4% and 0.9% ± 0.1%, P < 0.01, n = 3). FITC-conjugated AS1411 demonstrated more fluorescent signals in U87 cells than NC. In addition, 99mTc-AS1411 displayed similar cellular inhibitory ability with AS1411, which was measured by MTT assay. In U87 tumor-bearing mice, 99mTc-AS1411 demonstrated high radioactive accumulation, whereas 99mTc-NC and 99mTc only showed weak tumor uptake, suggesting the specific uptake of 99mTc-AS1411 in nucleolin-positive U87 tumors in vivo. Biodistribution results further verified the imaging results. The tumor uptake of 99mTc-AS1411 was significantly higher than that of 99mTc-NC (5.81 ± 1.55%ID/g vs 0.51 ± 0.16%ID/g, n = 4, P < 0.01). Conclusion99mTc-AS1411 can be successfully prepared via the conjugation of NHS-MAG3 and be considered a promising imaging agent capable of identifying nucleolin-positive glioma tumors.

Aptamer-Protein Structures Guide In Silico and Experimental Discovery of Aptamer-Short Peptide Recognition Complexes or Aptamer-Amino Acid Cluster Complexes.

A method to computationally and experimentally identify aptamers against short peptides or amino acid clusters is introduced. The method involves the selection of a well-defined protein aptamer complex and the extraction of the peptide sequence participating in the binding of the protein to the aptamer. The subsequent fragmentation of the peptide sequence into short peptides and the in silico docking-guided identification of affinity complexes between the miniaturized peptides and the antiprotein aptamer, followed by experimental validation of the binding features of the short peptides with the antiprotein aptamers, leads to the identification of new short peptide-aptamer complexes. This is exemplified with the identification of the pentapeptide RYERN as the scaffold that binds thrombin to the DNA thrombin aptamer (DNA TA). In silico docking studies followed by microscale thermophoresis (MST) experiments demonstrate that the miniaturized tripeptides RYE, YER, and ERN reveal selective binding affinities toward the DNA TA. In addition, docking and MST experiments show that the ribonucleotide-translated RNA TA shows related binding affinities of YER to the DNA TA. Most importantly, we demonstrate that the separated amino acids Y/E/R assemble as a three amino acid cluster on the DNA TA and RNA TA aptamers in spatial configurations similar to the tripeptide YER on the respective aptamers. The clustering phenomenon is selective for the YER tripeptide system. The method to identify binding affinities of miniaturized peptides to known antiprotein aptamers and the specific clustering of single amino acids on the aptamers is further demonstrated by in silico and experimental identification of the binding of the tripeptide RET and the selective clustering of the separated amino acids R/E/T onto a derivative of the AS1411 aptamer against the nucleolin receptor protein.

Resveratrol-loaded gold nanoparticles enhance caspase-mediated apoptosis in PANC-1 pancreatic cells via mitochondrial intrinsic apoptotic pathway

BackgroundPancreatic ductal adenocarcinoma (PDAC) remains one of the most fatal malignancies. Several chemotherapies employing fluorouracil (5-FU) and gemcitabine were attempted, but the survival rate was extremely low. Resveratrol (RVT), known as a polyphenol compound and phytoalexin, was demonstrated to induce intrinsic apoptosis in cancer cells. However, its low delivery performance and efficiency at tumor sites remain an obstacle to exploit RVT as a drug. To address these problems, we bio-conjugated resveratrol with gold nanoparticles (GNPs) via polyvinylpyrrolidone as a cross-linker (RVT@PVP-GNPs) and investigated whether the fabrications could enhance the delivery performance and anti-tumor efficacy of RVT.ResultsThe fabrication of gold nanoparticles (GNPs) and bio-conjugated with resveratrol (RVT@PVP-GNPs) was conducted firstly. TEM image, spectrophotometry and zeta-potential revealed that the GNPs and RVT@PVP-GNPs having a size of approximately 40 nm were successfully synthesized and exhibited moderate stability. GNPs alone represented no damage in PANC-1 cells and moreover diminished the cytotoxicity of RVT in Raw264.7 murine macrophage cells, demonstrating the superiority of gold nanoparticles as a drug carrier. Evaluation using dialysis showed a burst release rate of RVT within 96 h at pH 5.0, demonstrating the possibility of enhanced efficiency of RVT delivery through blood vessels to the tumor. The RVT@PVP-GNPs induced increased rates of S-phase cell cycle arrest and apoptosis compared with free RVT. Notably, RVT@PVP-GNPs diminished the proportion of necrotic cells, whereas free RVT increased it. We also demonstrated that the RVT@PVP-GNPs may induce an apoptosis via intrinsic mitochondria with higher degree compared with free RVT, indicating the possibility of enhanced anti-tumor agents. In animal studies, RVT@PVP-GNPs conjugated with AS1411 aptamer induced efficient tumor volume suppression without accumulation in or damage to the kidneys in vivo.ConclusionsThe results demonstrate that RVT@PVP-GNPs enhance the anti-tumor efficacy of free RVT by activating the intrinsic apoptotic pathway and could be considered as potential anti-tumor drug candidates against pancreatic cancer cells.

Aptamer-Modified Au Nanoparticles: Functional Nanozyme Bioreactors for Cascaded Catalysis and Catalysts for Chemodynamic Treatment of Cancer Cells.

Polyadenine-stabilized Au nanoparticles (pA-AuNPs) reveal dual nanozyme catalytic activities toward the H2O2-mediated oxidation of dopamine to aminochrome and toward the aerobic oxidation of glucose to gluconic acid and H2O2. The conjugation of a dopamine-binding aptamer (DBA) to the pA-AuNPs yields aptananozyme structures catalyzing simultaneously the H2O2-mediated oxidation of dopamine to aminochrome through the aerobic oxidation of glucose. A set of aptananozymes consisting of DBA conjugated through the 5'- or 3'-end directly or spacer bridges to pA-AuNPs were synthesized. The set of aptananozymes revealed enhanced catalytic activities toward the H2O2-catalyzed oxidation of dopamine to dopachrome, as compared to the separated pA-AuNPs and DBA constituents, and structure-function relationships within the series of aptananozymes were demonstrated. The enhanced catalytic function of the aptananozymes was attributed to the concentration of the dopamine at the catalytic interfaces by means of aptamer-dopamine complexes. The dual catalytic activities of aptananozymes were further applied to design bioreactors catalyzing the effective aerobic oxidation of dopamine in the presence of glucose. Mechanistic studies demonstrated that the aptananozymes generate reactive oxygen species. Accordingly, the AS1411 aptamer, recognizing the nucleolin receptor associated with cancer cells, was conjugated to the pA-AuNPs, yielding a nanozyme for the chemodynamic treatment of cancer cells. The AS1411 aptamer targets the aptananozyme to the cancer cells and facilitates the selective permeation of the nanozyme into the cells. Selective cytotoxicity toward MDA-MB-231 breast cancer cells (ca. 70% cell death) as compared to MCF-10A epithelial cells (ca. 2% cell death) is demonstrated.

Quantum Dot-Based Screening Identifies F3 Peptide and Reveals Cell Surface Nucleolin as a Therapeutic Target for Rhabdomyosarcoma.

Simple SummaryRhabdomyosarcoma accounts for more than 50% of all soft tissue sarcomas in childhood and adolescence. Despite intensified multimodality treatment, prognosis is extremely poor, with an overall survival rate of approximately 20% in the advanced stage. Therefore, there is an urgent need for targeted treatment options to improve overall survival rates, and to limit long-term side effects. Tumor-targeting peptides offer the possibility to deliver drugs selectively to the tumor site. Here, we select F3 as the best rhabdomyosarcoma-targeting peptide among a panel of 20 different tumor-targeting peptides. F3 peptide showed strong and specific binding to rhabdomyosarcoma, but not to normal cells, and efficient internalization with effective cytoplasmic delivery of the toxin Saporin. We show that nucleolin, the target of F3 peptide, is expressed on the surface of rhabdomyosarcoma cells. F3 peptide is a promising candidate for targeted drug delivery to rhabdomyosarcoma, e.g., by targeting drug-loaded nanoparticles.Active drug delivery by tumor-targeting peptides is a promising approach to improve existing therapies for rhabdomyosarcoma (RMS), by increasing the therapeutic effect and decreasing the systemic toxicity, e.g., by drug-loaded peptide-targeted nanoparticles. Here, we tested 20 different tumor-targeting peptides for their ability to bind to two RMS cell lines, Rh30 and RD, using quantum dots Streptavidin and biotin-peptides conjugates as a model for nanoparticles. Four peptides revealed a very strong binding to RMS cells: NCAM-1-targeting NTP peptide, nucleolin-targeting F3 peptide, and two Furin-targeting peptides, TmR and shTmR. F3 peptide showed the strongest binding to all RMS cell lines tested, low binding to normal control myoblasts and fibroblasts, and efficient internalization into RMS cells demonstrated by the cytoplasmic delivery of the Saporin toxin. The expression of the nucleophosphoprotein nucleolin, the target of F3, on the surface of RMS cell lines was validated by competition with the natural ligand lactoferrin, by colocalization with the nucleolin-binding aptamer AS1411, and by the marked sensitivity of RMS cell lines to the growth inhibitory nucleolin-binding N6L pseudopeptide. Taken together, our results indicate that nucleolin-targeting by F3 peptide represents a potential therapeutic approach for RMS.

Aptamer-modified carbon dots for enhancement of photodynamic therapy of cancer cells

Carbon dots (CDs) have emerged as promising materials for photodynamic therapy (PDT) because of their intriguing photochemical properties, high stability, and low toxicity. However, achieving accurate delivery of CDs based photosensitizers into tumor sites remains a grand challenge. Herein, AS1411 aptamer, a short oligonucleotide sequence with high binding specificity to tumor cells, was chemically decorated to the surface of Asp-CDs to obtain Asp-CDs@AS1411. The aptamer modified Asp-CDs@AS1411 not only retains the excellent properties of Asp-CDs such as high singlet oxygen quantum yield (up to 50%), bright photoluminescence, and good stability, but also features specific recognition and markedly enhanced phototoxicity (4 times) to tumor cells. These combined attributes make Asp-CDs@AS1411 a promising PDT agent for efficient tumor treatment. More importantly, the reported strategy paves a new avenue for developing high performance PDT materials from surface functionalized CDs featuring high photosensitivity and targeting ability.

Insights into the binding mode of AS1411 aptamer to nucleolin.

AS1411 aptamer can function as a recognition probe to detect the cell surface nucleolin overexpressed in cancer cells, however, little is known about their binding process. This study proposed a feasible binding mode for the first time and provided atomic-level descriptions for the high affinity and specific binding of AS1411. The binding pose predicted by docking was screened using knowledge-based criteria, and a microsecond molecular dynamics (MD) simulation showed the stable existence of the predicted structure in the solution. Structural analysis shows that the unique capping of the 5′ end of AS1411 provides the specific binding with RBD1, and the interactions of hydrogen bond, salt bridge, and water-mediated network between AS1411 and RBD1,2 stabilize the binding. The calculation of per-residue decomposition emphasizes the dominant contribution of van der Waals energy and critical residues are screened. Our study provides the molecular basis of this specific binding and can guide rational AS1411-based aptamers design. Further insights require tight collaborations between the experiments and in silico studies.

Anti-nucleolin Aptamer as a Boom in Rehabilitation of Breast Cancer.

Breast cancer is the second leading cause of cancer-related deaths. It is important to target the complex pathways using a suitable targeted delivery system. Targeted delivery systems can effectively act on cancer cells and lead to the annihilation of tumor proliferation. They mainly employ targeting agents like aptamers linked to the formulation. Based on the expression of the receptors on the surface of the cancer cells, suitable aptamers can be developed. AS1411 is one such aptamer that has the ability to bind to the over-expressed nucleolin present in breast cancer cells. Nucleolin is a phosphoprotein that is involved in various aspects, like cell growth, differentiation and survival. Mostly they are found in the nucleolus, nucleus, cytoplasm and cell surface. The shuttling effect of the nucleolin between the nucleus and cytoplasm serves as a bonus for the AS1411 aptamer. Because of the shutting effect, the internalization of the drug compound or chemotherapeutic drug inside the cell can be achieved. In this article, we have discussed nucleolin, anti-nucleolin aptamer, namely, AS1411, and its application in exhibiting various anticancer activities, including apoptosis, anti-angiogenesis, anti-metastasis, stimulation of tumor suppressor (i.e., P53), and inhibition of tumor inducer. Further, the ways of internalization, namely macropinocytosis, are also discussed. Additionally, we have also discussed the superiority of the aptamer compared to the antibodies as well as the limitations of the aptamers. By considering all the above parameters, we hope this aptamer will be effective in the management and eradication of breast cancer cells.

Development of a novel PROTAC using the nucleic acid aptamer as a targeting ligand for tumor selective degradation of nucleolin

PROteolysis TArgeting Chimeras (PROTACs) induce targeted protein degradation by hijacking the intracellular ubiquitin proteasome system, thus emerging as a new strategy for drug development. However, most PROTACs generated lack cell-type selectivity and are poorly soluble in water. To address this drawback, we developed a novel PROTAC ZL216 using aptamer AS1411 as a targeting ligand of nucleolin to conjugate with a small molecule ligand of E3 ligase VHL, which shows high aqueous solubility and serum stability. Based on the differential expression of nucleolin on the cell surface, ZL216 could bind to and internalize into breast cancer cells, but not normal breast cells. Furthermore, we revealed that ZL216 promoted the formation of a nucleolin-ZL216-VHL ternary complex in breast cancer cells and potently induced nucleolin degradation in vitro and in vivo. As a result, ZL216 inhibited the proliferation and migration of breast cancer cells. These studies demonstrate that in addition to peptides and small molecule compounds, nuclei acid aptamers can also be used to generate PROTACs, which broadens the toolbox constructing PROTACs and provides a promising strategy for development of tumor-selective PROTACs.

AS1411 aptamer-functionalized exosomes in the targeted delivery of doxorubicin in fighting colorectal cancer

Severe side effects of chemotherapy agents on vital organs are the major causes of cancer-related mortality, not merely cancer disease. Encapsulating chemotherapeutic molecules in nanocarriers is a justifiable solution in decreasing the risk of their side effects and boosting the efficiency of treatment. The present study has developed the doxorubicin (DOX)-loaded AS1411 (anti-nucleolin) aptamer surface-functionalized exosome (DOX-Apt-Exo) to treat colorectal cancer in both in-vitro and in-vivo experimental models. HEK293-derived exosomes were loaded with DOX through the incubation method with a nearly 13% encapsulation efficiency. Afterwards, the 5-terminal carboxyl group of AS1411-aptamer was converted into amine-reactive NHS esters with EDC/NHS amide coupling chemistry before being conjugated to the amine groups on the exosome surface. DLS and TEM estimated the designed formulation (DOX-Apt-Exo) size of about 200 nm. Aptamer-binding affinity and cellular uptake of DOX-Apt-Exo by nucleolin-overexpressing cancer cells were depicted through fluorescence microscopy. Comparing the in-vitro cytotoxicity impact of DOX-loaded exosomes, either targeted or non-targeted by MTT assay, clearly verified a high effectiveness of ligand-receptor mediated target therapy. Subsequently, in-vivo experiments which were conducted on four groups of ectopic mouse models of colon cancer (5 in each group) demonstrated the tumor growth suppression through professional long-term accumulation and retention of DOX-Apt-Exo at the tumor site by ligand-receptor interaction. The results suggested that AS1411 aptamer-functionalized exosomes can be recommended as a safe and effective system to site-specific drug delivery in possible clinical applications of colon cancer.

Aptamer-functionalized quercetin thermosensitive liposomes for targeting drug delivery and antitumor therapy

Chemo-thermotherapy, as a promising cancer combination therapy strategy, has attracted widespread attention. In this study, a novel aptamer functionalized thermosensitive liposome encapsulating hydrophobic drug quercetin was fabricated as an efficient drug delivery system. This aptamer-functionalized quercetin thermosensitive liposomes (AQTSL) combined the merits of high-loading yield, sustained drug release, long-term circulation in the body of PEGylated liposomes, passive targeting provided by 100–200 nm nanoparticles, active targeting and improved internalization effects offered by AS1411 aptamer, and temperature-responsive of quercetin release. In addition, AQTSL tail vein injection combined with 42 °C water bath heating on tumor site (AQTSL + 42 °C)treatment inhibited the tumor growth significantly compared with the normal saline administration (p < 0.01), and the inhibition rate reached 75%. Furthermore, AQTSL + 42 °C treatment also slowed down the tumor growth significantly compared with QTSL combined with 42 °C administration (p < 0.05), confirming that AS1411 decoration on QTSL increased the active targeting and internalization effects of the drug delivery system, and AS1411 aptamer itself might also contribute to the tumor inhibition. These data indicate that AQTSL is a potential carrier candidate for different hydrophobic drugs and tumor targeting delivery, and this kind of targeted drug delivery system combined with temperature responsive drug release mode is expected to achieve an ideal tumor therapy effect.

An entropy-driven three-dimensional multipedal-DNA walker for ultrasensitive detection of cancer cells

Sensitive and accurate detection of cancer cells is of great significance for the early diagnosis and treatment of cancer. In this work, we developed a simple fluorescent signal amplification biosensor based on an entropy-driven three-dimensional (3D) multipedal-DNA walker for highly sensitive detection of cancer cells. Firstly, DNA tetrahedron nanostructures (DTNs) combined with AS1411 aptamer were used as the capture probe to achieve efficient capture of cancer cells. Then, the bipedal hairpin fuel chain hybridized with DTNs and exposed two catalytic “legs” to form a walker probe. Finally, the walker probe autonomously walked on polystyrene microspheres (PS) via entropy-driven catalytic reaction. DTNs rolled on the PS to achieve multipedal walking, realizing fluorescence signal amplification due to fluorescence recovery of DNA-CdTe quantum dots on the PS surface. This fluorescence signal amplification strategy showed excellent selectivity and sensitivity toward cancer cells with the detection limit of 7 cell mL−1. This entropy-driven 3D multipedal DNA walker fluorescence exhibited great potential in detecting circulating tumor cells and tumor markers used for early diagnosis and clinical treatment of cancer.

Albumin-Coated Framework Nucleic Acids as Bionic Delivery System for Triple-Negative Breast Cancer Therapy

Triple-negative breast cancer (TNBC) is a subtype of breast cancer, and it has aggressive and more frequent tissue metastases than other breast cancer subtypes. Because the proliferation of TNBC tumor cells does not depend on estrogen receptor (ER), progesterone receptor (PR), and Erb-B2 receptor tyrosine kinase 2 (HER2) and lacks accurate drug targets, conventional chemotherapy is challenging to be effective, and adverse reactions are severe. At present, the treatment strategy for TNBC generally depends on a combination of surgery, radiotherapy, and chemotherapy. Conventional administration methods have minimal effects on TNBC and cause severe damage to normal tissues. Therefore, it is an urgent task to develop an efficient and practical way of drug delivery and open up a new horizon of targeted therapy for TNBC. In our work, bovine serum albumin (BSA) acted as the protective film to prolong the circulation time of the tetrahedral framework nucleic acid (tFNA) delivery system and resist immune clearance in vivo. tFNA was used as a carrier loaded with DOX and AS1411 aptamers for the targeted treatment of triple-negative breast cancer. Compared with existing approaches, this optimized system exhibits stronger tumor-targeting so that tFNAs can be more concentrated around the tumor tissue, reducing DOX toxicity to other organs. This bionic delivery system exhibited effective tumor growth inhibition in the TNBC mice model, offering the clinical potential to promote the treatment of TNBC with great potential for clinical translation.

Targeted delivery of doxorubicin to tumor cells using engineered circular bivalent aptamer

Breast cancer is among the most frequent tumors in women and one of the main reasons of cancer death globally. Chemotherapy is among the leading cancer treatments, but because of its lack of selectivity, it can cause severe side effects. Therapeutic oligonucleotides and targeted drug delivery systems can largely overcome this problem. In this study, a targeted therapeutic complex containing doxorubicin (Dox), a chemotherapy drug, and AS1411 aptamer was designed using a circular bivalent system to treat breast cancer. The reason for naming the engineered circular bivalent aptamer system is the presence of AS1411 aptamers in circular shape on both sides of the system, and the engineered part includes a complementary sequence in the middle of the system. Finally, the therapeutic capability of the prepared targeted platform was assessed in vitro and in vivo. To prepare the system using two engineered AS1411 aptamers, both of them were incubated together at room temperature. Finally, a targeted therapeutic complex was formed by loading Dox between two complementary sequences. To analyze the properties and efficacy of the prepared complex, the loading rate of Dox in the complex, drug release at different pHs, and complex stability were verified. Also toxicity assay, flow cytometry analysis and fluorescence imaging were examined in nontarget cells (CHO cells, Chinese hamster ovary cells), and target cells (MCF-7 cells, human breast cancer cells, and 4T1 cells, mouse breast cancer cell). Also, the anti-tumor efficiency of the formulation was evaluated in mice bearing 4T1 tumor cells. The results showed that the targeted drug complex (Cb-Apt-Dox) has advantages such as high specificity for target cells, high stability in serum and simple preparation. According to results of the drug release test, the designed system is steady in the serum and blood environment. Cb-Apt-Dox could significantly increase cell uptake in MCF-7 and 4T1 cells (target, nucleolin positive) compared with CHO cells (nontarget, nucleolin negative). Based on the results of toxicity assay, Cb-Apt-Dox remarkably reduced cell viability in MCF-7 and 4T1 cells compared to CHO cells. Also, Cb-Apt-Dox significantly declined tumor growth in tumor-bearing mice compared to Dox and Cb-Apt. Our results verify that Cb-Apt-Dox can enhance antitumor effectiveness, minimize side effects of Dox and open up a new platform for breast cancer treatment.