Article

Cell-specific internalization study of an aptamer from whole cell selection

Center for Research at the Bio/Nano Interface, Department of Chemistry, Shands Cancer Center and UF Genetics Institute, McKnight Brain Institute, University of Florida, Gainesville, FL 32611-7200, USA.
Chemistry (Impact Factor: 5.7). 02/2008; 14(6):1769-75. DOI: 10.1002/chem.200701330
Source: PubMed

ABSTRACT Nucleic acid aptamers have been shown many unique applications as excellent probes in molecular recognition. However, few examples are reported which show that aptamers can be internalized inside living cells for aptamer functional studies and for targeted intracellular delivery. This is mainly due to the limited number of aptamers available for cell-specific recognition, and the lack of research on their extra- and intracellular functions. One of the major difficulties in aptamers' in vivo application is that most of aptamers, unlike small molecules, cannot be directly taken up by cells without external assistance. In this work, we have studied a newly developed and cell-specific DNA aptamer, sgc8. This aptamer has been selected through a novel cell selection process (cell-SELEX), in which whole intact cells are used as targets while another related cell line is used as a negative control. The cell-SELEX enables generation of multiple aptamers for molecular recognition of the target cells and has significant advantages in discovering cell surface binding molecules for the selected aptamers. We have studied the cellular internalization of one of the selected aptamers. Our results show that sgc8 is internalized efficiently and specifically to the lymphoblastic leukemia cells. The internalized sgc8 aptamers are located inside the endosome. Comparison studies are done with the antibody for the binding protein of sgc8, PTK7 (Human protein tyrosine kinase-7) on cell surface. We also studied the internalization kinetics of both the aptamer and the antibody for the same protein on the living cell surface. We have further evaluated the effects of sgc8 on cell viability, and no cytotoxicity is observed. This study indicates that sgc8 is a promising agent for cell-type specific intracellular delivery.

0 Bookmarks
 · 
530 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Multifunctional nanoparticles integrated with imaging module and therapeutic drugs are promising candidates for future cancer diagnosis and therapy. Mesoporous silica-coated gold nanorods (AuNR@MS) have emerged as a novel multifunctional cancer theranostic platform combing the large specific surface area of mesoporous silica, which guarantees a high drug payload and photothermal modality of AuNRs. However, premature release and the side effects of exogenous stimulus still hinder the further application of AuNR@MS. To address these issues, herein, we proposed a glutathione (GSH)-responsive multifunctional AuNR@MS nanocarrier with in situ formed silver nanoparticles (AgNPs) as the capping agent. The inner AuNR core functions as hyperthermia agent, while outer mesoporous silica shell exhibits the potential to allow a high drug payload, thus posing itself as an effective drug carrier. With the incorporation of targeting aptamers, the constructed nanocarriers show drug release in accordance with intracellular GSH level with maximum drug release into tumors and minimum systemic release in the blood. Meanwhile, the photothermal effect of the AuNRs upon application to near infrared (NIR) light led to a rapid rise in the local temperature, resulting in an enhanced cell cytotoxicity. Such a versatile theranostic system as AuNR@MS@AgNPs is expected to have a wide biomedical application and may be particularly useful for cancer therapy.
    ACS Applied Materials & Interfaces 02/2015; DOI:10.1021/acsami.5b00368 · 5.90 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Here, we report reduced graphene oxide (rGO) nanosheets anchoring receptor-specific polyaptamer nanothreads for targeted drug delivery. DNA polyaptamer nanothreads of protein tyrosine kinase 7 receptor (PTK7) were synthesized by rolling cycle amplification. To strengthen the anchoring of polyaptamer nanothreads onto rGO, oligoT bridge domain was introduced between each repeating PTK7 aptamer sequence. As compared to PTK7 polyaptamer nanothreads alone, PTK7 polyaptamer nanothreads with 22-mer oligoT bridges (PNT) showed higher anchoring capacity onto rGO nanosheets. Nanothread-coated surface morphology of PNTrGO was observed. Coating of PNT did not affect the sizes of rGO, but reduced the zeta potential. In PTK7-negative Ramos cells, the uptake of PNT-anchored rGO (PNTrGO) did not differ from that of oligoT-bridged scrambled polyaptamer-anchored rGO (SNTrGO). However, in CCRF-CEM leukemia cells overexpressing PTK7, the uptake of PNTrGO was 2.1-fold higher than that of SNTrGO after 15 min pulse. In vivo distribution to CCRF-CEM tumor tissues was 2.8-fold higher in PNTrGO than in SNTrGO at 48 h post-injection. In CCRF-CEM xenografted mice, intravenously administered doxorubicin (Dox)-loaded PNTrGO showed the higher antitumor activity than other groups, reducing the tumor weight down to 12% of tumor weights of untreated mice. These results suggest the potential of PNTrGO for target-specific drug delivery nanoplatform. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Biomaterials 04/2015; 48. DOI:10.1016/j.biomaterials.2015.01.009 · 8.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanoscaled aptamers (Aps), as short single-stranded DNA or RNA oligonucleotides, are able to bind to their specific targets with high affinity, upon which they are considered as powerful diagnostic and analytical sensing tools (the so-called "aptasensors"). Aptamers are selected from a random pool of oligonucleotides through a procedure known as "systematic evolution of ligands by exponential enrichment". In this work, the most recent studies in the field of aptasensors are reviewed and discussed with a main focus on the potential of aptasensors for the multianalyte detection(s). Due to the specific folding capability of aptamers in the presence of analyte, aptasensors have substantially successfully been exploited for the detection of a wide range of small and large molecules (e.g., drugs and their metabolites, toxins, and associated biomarkers in various diseases) at very low concentrations in the biological fluids/samples even in presence of interfering species. Biological samples are generally considered as complexes in the real biological media. Hence, the development of aptasensors with capability to determine various targets simultaneously within a biological matrix seems to be our main challenge. To this end, integration of various key scientific dominions such as bioengineering and systems biology with biomedical researches are inevitable.
    12/2014; 4(4):205-15. DOI:10.15171/bi.2014.015

Full-text (2 Sources)

Download
42 Downloads
Available from
Jun 23, 2014