The physical and chemical properties of MNPs make them uniquely hazardous environmental actors. Their small size gives them an exceptionally high surface-area-to-volume ratio, while their hydrophobic surfaces readily attract and adsorb a wide range of other contaminants. In aquatic environments, microplastics act as vectors for heavy metals, binding cadmium, arsenic, and other toxic elements and transporting them into organisms that ingest the particles. Studies cited in the review document synergistic toxicity when fish, zebrafish, and the planktonic crustacean Daphnia magna are exposed to both microplastics and metals simultaneously, with effects that exceed those of either stressor alone. Similar interactions have been reported with antibiotics, organic pollutants, and pathogenic microbial communities that colonize plastic surfaces in the so-called plastisphere.

The consequences ripple through entire ecosystems. In soil, MNPs alter aggregate formation, change hydraulic properties and pore characteristics of compacted earth, and disrupt the carbon, nitrogen, and phosphorus cycles that sustain farmland productivity. Meta-analyses referenced in the review show shifts in soil microbial diversity and community structure following exposure, while rice seedlings suffer increased arsenic toxicity in the presence of plastic particles. Crop plants can take up submicrometre plastics through a crack-entry mode at their roots, raising concerns about the food chain. In freshwater and marine systems, microplastics affect grazing behavior and mortality in plankton, impair growth and immunity in fish such as the yellow seahorse, and alter neurobehavioral and molecular rhythms in fish exposed to clean nanoplastics, demonstrating that the particles themselves—not just their chemical passengers—can disrupt biology.

Perhaps the most sobering findings concern human exposure. Researchers have now identified microplastics in human blood, sputum, breast milk, and the placenta, with pyrolysis gas chromatography mass spectrometry confirming accumulation in placental specimens. Microplastics have been associated with microbiota in placentas and meconium, found in maternal amniotic fluid with links to gestational age, and detected in the feces of expectant mothers. Experimental evidence indicates that micro- and nanoplastics can breach the blood–brain barrier, with a biomolecular corona of proteins facilitating their passage. Reviews of health impacts point to endocrine-disrupting effects, risks to the central nervous system, and potential reproductive consequences, although the review is careful to note that the full clinical significance of these exposures remains an active area of investigation.

Against this backdrop, the review’s central contribution is its critical evaluation of how MNPs are actually detected. Conventional approaches rely on sophisticated laboratory instrumentation. Fourier transform infrared spectroscopy and Raman spectroscopy can identify polymer types by their vibrational fingerprints, and surface-enhanced Raman spectroscopy using silver nanoparticles and nanodendrites pushes sensitivity further, enabling on-site detection of microplastics in water. Thermal methods such as thermogravimetric analysis coupled with mass spectrometry quantify polyethylene and polypropylene in environmental samples, while pyrolysis gas chromatography mass spectrometry has proven powerful for complex biological matrices. Fluorescent staining with Nile Red offers a rapid screening approach for microplastic fibers, distinguishing synthetic from natural materials. Mass spectrometry techniques have recently achieved detection of micro- and nanoplastics in seconds, illustrating how far analytical speed has advanced.

Yet each of these conventional techniques carries inherent limitations. The instruments are expensive, the workflows demand skilled personnel and extensive sample preparation, and most methods are poorly suited to rapid on-site analysis. Spectroscopic identification struggles with particles below a few micrometres, precisely where nanoplastics dominate, and distinguishing true environmental contamination from background laboratory plastic pollution remains a persistent challenge. For environmental monitoring at scale—thousands of water bodies, agricultural fields, and food products—these constraints mean that the true distribution of MNPs is likely far worse than current measurements suggest. The review concludes that this detection gap underscores the urgent need for innovative strategies offering high sensitivity, high selectivity, and real-time analytical capability.

The most promising candidates, according to the review, are biosensors, and in particular aptamer-based platforms. Aptamers are short single-stranded DNA or RNA molecules selected to bind specific targets with antibody-like affinity, first described in 1990 through in vitro selection experiments. They are generated through SELEX—Systematic Evolution of Ligands by Exponential Enrichment—an iterative process of binding, partitioning, and amplification, with newer non-SELEX approaches and computational, in silico library design strategies accelerating discovery. Chemical modifications can dramatically increase binding affinity and nuclease resistance, and structured library approaches are producing a next generation of aptamers with improved performance. Because aptamers are chemically synthesized, they are cheaper, more reproducible, and more easily engineered than antibodies, making them attractive for mass-deployed environmental sensors.

Recent demonstrations show how aptamers can be coupled to different transduction modes for MNP detection. Colorimetric aptasensors exploit gold nanoparticle aggregation to produce visible readouts, including a gold nanoparticle-assisted platform for rapid sensing of polyethylene terephthalate microplastics. Electrochemical and photoelectrochemical designs include a switch-type aptasensor built on a two-dimensional organic–inorganic heterojunction for detecting micro- and nanoplastics. Surface plasmon resonance biosensors have measured very low microplastic concentrations through bioaffinity-induced particle retention, and engineered peptide biosensors have achieved sensitive, specific capture of polystyrene and polypropylene particles. Perhaps most strikingly, CRISPR-based colorimetric aptasensors combined with smartphone imaging and deep learning now enable selective recycling and visual prediction of microplastics in the environment, while a label-free electrochemical aptasensor uses CRISPR/Cas12a-mediated cascade strand displacement for sensitive and selective detection. Smartphone-enabled quantification and low-cost microfluidic identification further point toward field-deployable, citizen-accessible monitoring.

The review is candid about the obstacles that remain. Selecting aptamers against chemically heterogeneous, weathered plastic particles is far harder than selecting them against purified biomolecules, and critical evaluations of past aptamer work have shown that some celebrated binding claims do not survive scrutiny. Reproducibility of SELEX outcomes, the stability of aptamers in complex environmental matrices, and the challenge of distinguishing polymer types in mixtures all limit current platforms. Scaling from laboratory prototypes to robust, large-scale applications will require standardized target materials, validated binding characterization, and integration of sample preparation with sensing. The authors identify these knowledge gaps explicitly and outline future research directions, including non-SELEX selection methods, computational modeling of aptamer-target interactions, and hybrid systems that combine aptamer recognition with machine learning-assisted readout.

The stakes of closing the detection gap could hardly be higher. Plastic production continues to grow, tire wear, plastic mulches, landfill liners, and wastewater treatment plants all release MNPs into the environment, and atmospheric deposition now carries microplastics into remote coastal zones. Without accurate, affordable, real-time monitoring, regulators cannot set meaningful exposure limits, wastewater operators cannot optimize removal, and the public cannot judge the safety of drinking water, tap water, or food. The Birla Institute team argues that aptamer-based biosensors, by combining molecular specificity with low cost and portability, could transform MNP monitoring from a specialized laboratory pursuit into routine environmental practice—giving researchers and policymakers, for the first time, the measurement infrastructure needed to confront a pollutant that has already reached human blood, brains, and the placenta.

Subject of Research: Environmental impacts of micro- and nanoplastics and advances in aptamer-based biosensor detection strategies

Article Title: Effect of micro/nano-plastics on environment and recent advances in their detection strategies

Article References: S., L. J., Manjuladevi, V., Panwar, J., & Verma, S. K. (2026). Effect of micro/nano-plastics on environment and recent advances in their detection strategies. Environmental Monitoring and Assessment, 198(11), Article 1174. https://doi.org/10.1007/s10661-026-15995-7

Image Credits: AI Generated

DOI: 10.1007/s10661-026-15995-7

Keywords: microplastics, nanoplastics, plastic pollution, biosensors, aptamers, SELEX, environmental monitoring, Raman spectroscopy, CRISPR, heavy metals, toxicology, water quality

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