The core problem the authors confront is one of specificity. CRISPR-Cas9 can, in principle, rewrite the genome with nucleotide-level precision, disabling oncogenic drivers, restoring tumor suppressor pathways, or reprogramming regulatory noncoding elements. In practice, however, the Cas9 protein and its guide RNA are large, charged biological molecules that do not cross cell membranes on their own, degrade rapidly in the bloodstream, and can trigger off-target edits when they reach the wrong cells. Current viral vectors such as adeno-associated virus, or AAV, offer efficient delivery but raise concerns about insertional mutagenesis, limited cargo capacity, immunogenicity, and the sheer difficulty of restricting their tropism to cancer cells alone. Nonviral alternatives have historically suffered from low efficiency. The review positions aptamer-mediated delivery as a way out of this impasse.

Aptamers are selected through an iterative laboratory process known as SELEX, systematic evolution of ligands by exponential enrichment, which screens enormous random-sequence libraries for strands that bind a chosen target with high affinity. Unlike antibodies, aptamers are chemically synthesized, minimally immunogenic, small enough to penetrate dense tumor tissue, and can be modified at will with fluorescent tags, linker chemistries, or therapeutic payloads. The review catalogs aptamers directed against a who’s-who of tumor-associated surface markers: epithelial cell adhesion molecule (EpCAM) overexpressed on many carcinomas, epidermal growth factor receptor (EGFR) in lung and colon cancers, human epidermal growth factor receptor 2 (HER2) in breast cancer, prostate-specific membrane antigen (PSMA) in prostate cancer, nucleolin and protein tyrosine kinase 7 (PTK7) on a range of malignant cells, and the transferrin receptor, which is abundant on the blood-brain barrier and on glioblastoma cells. Each of these ligands can, in principle, be conjugated to a nanocarrier carrying Cas9 ribonucleoprotein complexes or plasmid DNA, converting a systemically administered particle into a homing missile for tumor cells.

One of the most technically interesting contributions of the review is its emphasis on structure-guided molecular docking as a design tool. Rather than relying purely on trial and error, the authors describe how computational docking and molecular dynamics simulations can predict the binding energetics of an aptamer-receptor pair before any wet-lab work begins. By modeling the three-dimensional folds that aptamers adopt, researchers can rationally introduce mutations that strengthen the binding interface, improve discrimination between the tumor target and closely related proteins on healthy cells, and truncate aptamers to the minimal binding domain, reducing manufacturing cost and immunogenic potential. This computational-first workflow, the review argues, is transforming aptamer engineering from an artisanal craft into a predictable engineering discipline.

Getting the particle bound to the cell surface, however, is only the first hurdle. The review devotes substantial attention to what happens next: receptor-mediated endocytosis, the process by which the cell swallows the bound particle into an endosome, followed by the equally critical step of endosomal escape. Most nanoparticles that successfully enter cells end up trapped and degraded in lysosomes, which is why delivery efficiency is often measured in frustratingly low single digits. The authors survey the escape strategies now being built into aptamer-functionalized carriers, including proton-sponge effects from polyethylenimine-based formulations, pH-responsive membrane-disruptive polymers, and fusogenic lipids that destabilize the endosomal membrane as its interior acidifies. Understanding which endocytic pathway, clathrin-mediated, caveolae-mediated, or macropinocytosis, a given aptamer-receptor pair exploits allows researchers to co-opt the cell’s own trafficking machinery and steer the cargo toward the cytosol and ultimately the nucleus, where Cas9 must arrive to do its work.

The third pillar of the framework is nanocarrier engineering, and here the review offers a sweeping comparison of the leading platforms. Lipid nanoparticles, validated clinically by the mRNA vaccine campaigns, remain the front-runner, with refinements in PEG-lipid architectures, such as cleavable DSPE-PEG anchors and optimized PEG densities, improving colloidal stability while avoiding accelerated blood clearance on repeat dosing. Polymeric carriers built from PLGA and PAMAM dendrimers offer controlled release profiles, while inorganic platforms, including mesoporous silica nanoparticles and gold nanoparticles, provide stimulus-responsive gates that open in the acidic tumor microenvironment. Extracellular vesicles, the natural nanoshuttles secreted by cells themselves, offer innate biocompatibility and the ability to cross biological barriers, and hybrid viral-nonviral platforms attempt to marry viral entry efficiency with the safety and tunability of synthetic materials.

What distinguishes this review from earlier surveys of CRISPR delivery is its insistence that these three elements, targeting ligand, trafficking route, and carrier chemistry, must be co-optimized rather than designed in isolation. A particle decorated with a superb aptamer but lacking endosomal escape capability will never deliver an active nuclease. A carrier with perfect intracellular performance but rapid serum clearance will never reach the tumor. The authors highlight how the dense, fibrotic extracellular matrix of many tumors physically blocks nanoparticle penetration, and how aptamer-mediated binding to receptors expressed deep within tumor spheroids can enhance accumulation in poorly perfused regions. They also discuss spatiotemporally controlled editing, in which carriers release their cargo only in response to tumor-specific cues such as hypoxia, low pH, or externally applied light or ultrasound, limiting genome modification to the tumor microenvironment.

The potential clinical applications span the full breadth of oncology. Targeted knockout of oncogenic drivers such as mutant EGFR in non-small cell lung cancer, disruption of the Wnt pathway via adenomatous polyposis coli-related targets in colorectal cancer, editing of immune checkpoints such as PD-1 to unleash antitumor immunity, and correction of tumor suppressor defects through homology-directed repair are all within the conceptual scope of aptamer-guided delivery. The authors also note synergies with established modalities: aptamer-targeted carriers could deliver Cas9 engineered to knock out drug-resistance genes alongside conventional chemotherapy, or complement CAR T-cell therapy by editing immune cells ex vivo with higher efficiency and lower toxicity than viral transduction.

The authors are admirably candid about the obstacles that remain. In vivo stability of both aptamers and Cas9 cargos in the face of nucleases and proteases, the scalability and reproducibility of GMP-grade nanomanufacturing, the persistent specter of off-target double-strand breaks, and the dearth of rigorous long-term preclinical and clinical validation all stand between the current state of the art and routine bedside use. Aptamer affinity measured in a culture dish does not always translate to four-hour circulation in human plasma, and off-target editing in non-tumor tissue remains the field’s most serious safety concern. Yet the trajectory is unmistakable. By integrating rational aptamer design, mechanistic understanding of intracellular trafficking, and increasingly sophisticated nanocarrier engineering, the field is assembling the complete delivery toolkit that precision genome editing oncology has been waiting for. If the remaining challenges can be met, aptamer-guided CRISPR-Cas9 systems could move genome surgery from the laboratory bench to the cancer clinic, offering patients therapies that edit the disease at its genetic source while sparing healthy tissue entirely.

Subject of Research: Aptamer-mediated CRISPR-Cas9 delivery systems for targeted cancer genome editing

Article Title: Aptamer-mediated CRISPR-Cas9 delivery for precision oncology: integrating molecular targeting, intracellular trafficking, and nanocarrier engineering

Article References: Saffari Natanzi, A., Ahmadi, E., Shahraki, S., Eslamian Koupaei, A., & Haddad Kashani, H. (2026). Aptamer-mediated CRISPR-Cas9 delivery for precision oncology: integrating molecular targeting, intracellular trafficking, and nanocarrier engineering. Advanced Composites and Hybrid Materials. https://doi.org/10.1007/s42114-026-02049-2

Image Credits: AI Generated

DOI: 10.1007/s42114-026-02049-2

Keywords: aptamers, CRISPR-Cas9, precision oncology, targeted delivery, nanocarriers, lipid nanoparticles, gene editing, endosomal escape, molecular docking, SELEX, tumor microenvironment, cancer therapy