Researchers at the National University of Singapore have made a groundbreaking advancement in precision cancer therapy by developing DNA-barcoded gold nanoparticles capable of targeting the mitochondria within tumor cells. This innovative approach, led by Assistant Professor Andy Tay from the Department of Biomedical Engineering in the College of Design and Engineering and the Institute for Health Innovation & Technology, allows for high-throughput screening of nanoparticle designs directly in living tumor models. By attaching unique DNA sequences—known as barcodes—to gold nanoparticles of varying shapes, sizes, and surface modifications, the team can track which particles successfully navigate the body's complex biological barriers to reach the cancer cell's power source.

Mitochondria, the organelles responsible for energy production and regulating cell death, represent a prime target for disrupting cancer growth. Traditional chemotherapy often fails to penetrate these subcellular structures effectively, leading to incomplete tumor elimination and side effects on healthy tissues. The NUS breakthrough addresses this by enabling simultaneous evaluation of dozens of nanoparticle variants, generating thousands of data points on their performance in vivo with far fewer experimental models than conventional methods.

The Science Behind DNA Barcoding in Nanomedicine

Gold nanoparticles, or AuNPs, have long been prized in biomedical engineering for their biocompatibility, tunable optical properties, and ability to carry therapeutic payloads like small interfering RNA (siRNA) or generate heat under near-infrared light for photothermal therapy. However, their journey from injection to tumor mitochondria involves multiple hurdles: circulation in the bloodstream, extravasation into tumor tissue, cellular uptake, endosomal escape, and precise subcellular trafficking.

The NUS team's DNA barcoding system transforms this challenge into a solvable puzzle. Each nanoparticle variant is functionalized with a thiol group to securely anchor a unique short DNA sequence—its barcode—resistant to degradation by DNases in the body. These barcodes do not interfere with the nanoparticles' interactions with cells or proteins, ensuring natural behavior during testing.

In practice, a pooled library of 30 distinct AuNP designs is injected into tumor-bearing mice. After allowing time for distribution, tumors are harvested, mitochondria isolated, and DNA extracted. Next-generation sequencing reads the barcodes present, quantifying enrichment for each design. This multiplexed readout provides hierarchical data: organ-level biodistribution, tumor accumulation, cell-type specificity, and mitochondrial delivery—all from a single experiment.

Step-by-Step: How the NUS Screening Platform Works

• Design Library Creation: Synthesize AuNPs varying in shape (spheres, cubes, triangles, rods), size (40-80 nm), and ligands (e.g., folic acid for tumor targeting).
• Barcode Attachment: Couple unique DNA oligos via thiol-gold chemistry.
• In Vivo Dosing: Administer pooled library intravenously to preclinical models.
• Organ/Tumor Isolation: Dissect and process tissues.
• Subcellular Fractionation: Isolate mitochondria using differential centrifugation.
• Barcode Sequencing: PCR amplify, sequence, and analyze relative abundances.
• Data Analysis: Identify top performers and correlate properties.

This process yields over 1,000 data points per run, 30 times more efficient than testing each variant separately.

Key Discoveries: Shapes That Conquer Cancer Cells

The screening revealed counterintuitive results. While spherical AuNPs showed poor uptake in cell cultures, they excelled in vivo tumor accumulation thanks to a protective protein corona extending circulation time and reducing macrophage clearance. Cubic AuNPs, modified with folic acid, stood out for cellular entry via clathrin-mediated endocytosis and efficient mitochondrial trafficking.

Triangular and star-shaped particles promoted endosomal escape, a critical step for cytosolic and organelle access. When loaded with mitochondria-targeted siRNA and subjected to mild photothermal therapy, the optimal cubic formulation achieved 99% tumor regression after one dose in breast cancer models. Remarkably, these nanoparticles also reprogrammed tumor-associated macrophages—from pro-tumor M2 to anti-tumor M1 phenotypes—enhancing immune surveillance.

"Nanoparticle design is not governed by a single factor such as shape or size. Instead, multiple properties interact in complex ways," explains Asst Prof Tay. This insight underscores the power of in vivo multiplexing over in vitro predictions.

Photo by CDC on Unsplash

NUS's Biomedical Engineering: A Hub for Nanomedicine Innovation

The National University of Singapore's Department of Biomedical Engineering, part of the College of Design and Engineering, fosters interdisciplinary research blending engineering, biology, and medicine. Asst Prof Tay's lab at iHealthtech exemplifies this, leveraging state-of-the-art facilities for nanomaterial synthesis, high-throughput sequencing, and preclinical imaging. Singapore's investment in biomedicine—over S$25 billion via the Research, Innovation and Enterprise 2025 plan—positions NUS as Asia's leader in translational nanotech.

This work builds on prior NUS achievements, including DNA-barcoded profiling of subcellular proteins and shape-dependent tumor targeting studies published in Advanced Functional Materials. For aspiring researchers, NUS offers PhD programs, research assistantships, and postdocs in nanomedicine, attracting global talent to Singapore's vibrant ecosystem.

Implications for Precision Oncology in Singapore

Singapore faces rising cancer incidence, with over 16,000 new cases annually. NUS's platform promises therapies sparing healthy tissues, reducing recurrence, and minimizing side effects. By enabling personalized nanoparticle selection based on patient tumor profiles, it paves the way for stratified medicine. Integration with Singapore's precision health initiatives, like the National Precision Medicine program, could accelerate clinical trials.Learn more from NUS's official release.

Challenges Overcome and Lessons Learned

Barcode stability was paramount; thiol linkage prevented detachment, and designs resisted nuclease attack. The study highlighted discrepancies between in vitro and in vivo performance, emphasizing live-model necessity. Future challenges include scaling to human trials, regulatory approval for barcoded therapeutics, and AI-driven design optimization.

• Benefit: 30x efficiency in screening.
• Risk Mitigation: Reduced animal use aligns with 3Rs principles.
• Comparisons: Superior to fluorescence tracking, as barcodes enable multiplexing without spectral overlap.

Future Directions: From Bench to Bedside

The team plans library expansion to 100+ variants, AI integration for predictive modeling, and targeting other organelles like lysosomes or nuclei. Collaborations with A*STAR and hospitals could fast-track GMP production. For Singapore higher education, this cements NUS's role in global biomed, inspiring curricula in nanotech and attracting funding.Read the full study in Advanced Materials.

Photo by Vagaro on Unsplash

Career Opportunities in Singapore's Nanomedicine Landscape

NUS and peers like NTU drive Singapore's biotech sector, employing thousands in research roles. Positions in nanoparticle engineering, sequencing analysis, and preclinical modeling abound. With government grants via NRF and IMCB, early-career scientists find ample support. Programs like NUS Graduate School for Integrative Sciences equip students for this frontier.

Stakeholders—from patients to policymakers—hail the potential. As Asst Prof Tay notes, "High-throughput screening platforms like ours allow us to uncover these relationships and move beyond trial-and-error."

Singapore's Biomedical Ecosystem: NUS at the Forefront

Singapore's Biopolis anchors Asia's biomed hub, with NUS contributing pivotal innovations. This DNA barcoding feat aligns with national goals for health tech sovereignty, fostering spin-offs and attracting FDI. For universities, it highlights the value of cross-disciplinary teams in addressing grand challenges like cancer.