Anti-Nucleolin Aptamer [AS1411] (Biotin) (A321259)

This study introduces advanced nanoparticle-based drug delivery systems (NDDS) designed for targeted colorectal cancer treatment. We developed and characterized three distinct formulations: Bevacizumab-loaded chitosan nanoparticles (BEV-CHI-NP), polymeric micelles (BEV-PM), and BEV-conjugated exosomes enriched with AS1411 and N1-methyladenosine (AP-BEV?+?M1A-EXO). Each formulation exhibited optimized physicochemical properties, with particle sizes between 150 and 250 nm and surface charges ranging from?+?14.4 to?+?43 mV, ensuring stability and targeted delivery. The AP-BEV?+?M1A-EXO formulation demonstrated targeted delivery to VEGF, a protein commonly overexpressed in colorectal cancer cells, as indicated by localized staining. This suggests a more precise delivery of the therapeutic agent to VEGF-enriched regions. In contrast, the BEV-CHI-NP formulation exhibited a broader pattern of tumor suppression, evidenced by reduced overall staining intensity. The BEV-PM group showed moderate effects, with a relatively uniform protein expression across tumor tissues. In vivo studies indicated that the AP-BEV?+?M1A-EXO formulation achieved a notable reduction in tumor volume (~?65.4%) and decreased levels of tumor biomarkers, including CEA and CA 19–9, compared to conventional BEV-API treatment. In vitro experiments using human colon tumor organoids (HCTOs) further supported these findings, showing a significant reduction in cell viability following exposure to AP-BEV?+?M1A-EXO. These results suggest that combining aptamer specificity with exosome-based delivery systems could enhance the precision and effectiveness of colorectal cancer therapies, representing a potential advancement in treatment strategies. In vivo experiments further revealed that the AP-BEV?+?M1A-EXO formulation outperformed conventional BEV-API treatment, achieving a four-fold increase in tumor suppression. This formulation resulted in a 65.4% reduction in tumor volume and a significant decrease in tumor biomarkers, including CEA and CA 19–9. In vitro studies also demonstrated a significant reduction in cell viability in human colon tumor organoids exposed to AP-BEV?+?M1A-EXO. These findings highlight the potential of combining aptamer specificity with exosome-based delivery systems to enhance the precision and efficacy of colorectal cancer therapies, marking a promising step forward in cancer treatment innovation.

Aptamers are single-stranded DNA or RNA molecules capable of recognizing targets via specific three-dimensional structures. Taking advantage of this unique targeting function, aptamers have been extensively applied to bioanalysis and disease theranostics. However, the targeting functionality of aptamers in the physiological milieu is greatly impeded compared with their in vitro applications. To investigate the physiological factors that adversely affect the in vivo targeting ability of aptamers, we herein systematically studied the interactions between human plasma proteins and aptamers and the specific effects of plasma proteins on aptamer targeting. Microscale thermophoresis and flow cytometry analysis showed that plasma interacted with aptamers, restricting their affinity toward targeted tumor cells. Further pull-down assay and proteomic identification verified that the interactions between aptamers and plasma proteins were mainly involved in complement activation and immune response as well as showed structure-selective and sequence-specific features. Particularly, the fibronectin 1 (FN1) protein showed dramatically specific interactions with nucleolin (NCL) targeting aptamer AS1411. The competitive binding between FN1 and NCL almost deprived the AS1411 aptamer's targeting ability in vivo. In order to maintain the targeting function in the physiological milieu, a series of optimizations were performed via the chemical modifications of AS1411 aptamer, and 3'-terminal pegylation was demonstrated to be resistant to the interaction with FN1, leading to improved tumor-targeting effects. This work emphasizes the physiological environment influences on aptamers targeting functionality and suggests that rational design and modification of aptamers to minimize the nonspecific interaction with plasma proteins might be effective to maintain aptamer functionality in future clinical uses.