A simple, highly sensitive method to detect leukemia cells has been developed based on aptamer-modified fluorescent silica nanoparticles (FSNPs). In this strategy, the amine-labeled Sgc8 aptamer was conjugated to carboxyl-modified FSNPs via amide coupling between amino and carboxyl groups. Sensitivity and specificity of Sgc8-FSNPs were assessed using flow cytometry and fluorescence microscopy. These results showed that Sgc8-FSNPs detected leukemia cells with high sensitivity and specificity. Aptamer-modified FSNPs hold promise for sensitive and specific detection of leukemia cells. Changing the aptamer may allow the FSNPs to detect other types of cancer cells.

How to deliver chemotherapeutic drugs efficiently and selectively to tumor cells to improve therapeutic efficacy remains a difficult problem. We herein construct an efficient cell-targeting drug delivery system (Sgc8-MSN/Dox) based on aptamer-modified mesoporous silica nanoparticles that relies on the tumor-targeting ability of the aptamer Sgc8 to deliver doxorubicin (Dox) to leukemia cells in a targeted way, thereby improving therapeutic efficacy and reducing toxicity. In this work, Sgc8-MSN/Dox showed sustained Dox release, and they targeted and efficiently killed CCRF-CEM human acute T lymphocyte leukemia cells, suggesting potential as a cancer therapy.

Cytotoxic T-lymphocyte antigen-4 (CTLA-4) is a critical negative regulator of immune responses. CTLA-4 is rapidly upregulated following T-cell activation, and then binds to B7 molecules with a higher affinity than CD28. CTLA-4 may abolish the initiation of the responses of T cells by raising the threshold of signals required for full activation of T cells, and it also may terminate ongoing T-cell responses. This regulatory role has led to the development of monoclonal antibodies (mAbs) designed to block CTLA-4 activity for enhancing immune responses against cancer. mAbs have several disadvantages including high production cost and unstable behavior. Nanobodies (Nbs) are single-domain antigen-binding fragments derived from the camelid heavy-chain antibodies, which are highly attractive in cancer immunotherapy due to their small size, high specificity, and stability. We selected CTLA-4-specific Nbs from a high quality dromedary camel immune library by phage display technology. Four positive colonies were sequenced and classified based on the amino acids sequences in the CDR3 region. These Nbs recognized unique epitopes on CTLA-4 and displayed high binding rates when used on PHA-stimulated human T cells. Treatment of B16 melanoma-bearing C57BL/6 mice with anti-CTLA-4 nanobody 16 (Nb16) delayed melanoma growth and prolonged the survival time of mice. These data indicate that anti-CTLA-4 Nbs selected from a high quality phage display library may be effective for the treatment of patients with tumors.

Background: Tumor vessels can potentially serve as diagnostic, prognostic and therapeutic targets for solid tumors. Fluorescent dyes are commonly used as biological indicators, while photobleaching seriously hinders their application. In this study, we aim to generate a fluorescent silica nanoparticles (FSiNPs) theranostic system marked by the mouse endgolin (mEND) aptamer, YQ26.Methods: A highly specific YQ26 was selected by using gene-modified cell line-based SELEX technique. FSiNPs were prepared via the reverse microemulsion method. The YQ26-FSiNPs theranostic system was developed by combining YQ26 with the FSiNPs for in vivo tumor imaging, treatment and monitoring.Results: Both in vitro experiments (i.e. cellular and tumor tissue targeting assays) and in vivo animal studies (i.e. in vivo imaging and antitumor efficacy of YQ26-FSiNPs) clearly demonstrated that YQ26-FSiNPs could achieve prominently high targeting efficiency and therapeutic effects via aptamer YQ26-mediated binding to endoglin (END) molecule.Conclusion: This simple, sensitive, and specific YQ26-FSiNPs theranostic system has a great potential for clinical tumor targeting imaging and treatment.