Biocompatible near-infrared quantum dots delivered to the skin by microneedle patches record vaccination

Abstract

Accurate medical recordkeeping is a major challenge in many low-resource settings where well-maintained centralized databases do not exist, contributing to 1.5 million vaccine-preventable deaths annually. Here, we present an approach to encode medical history on a patient using the spatial distribution of biocompatible, near-infrared quantum dots (NIR QDs) in the dermis. QDs are invisible to the naked eye yet detectable when exposed to NIR light. QDs with a copper indium selenide core and aluminum-doped zinc sulfide shell were tuned to emit in the NIR spectrum by controlling stoichiometry and shelling time. The formulation showing the greatest resistance to photobleaching after simulated sunlight exposure (5-year equivalence) through pigmented human skin was encapsulated in microparticles for use in vivo. In parallel, microneedle geometry was optimized in silico and validated ex vivo using porcine and synthetic human skin. QD-containing microparticles were then embedded in dissolvable microneedles and administered to rats with or without a vaccine. Longitudinal in vivo imaging using a smartphone adapted to detect NIR light demonstrated that microneedle-delivered QD patterns remained bright and could be accurately identified using a machine learning algorithm 9 months after application. In addition, codelivery with inactivated poliovirus vaccine produced neutralizing antibody titers above the threshold considered protective. These findings suggest that intradermal QDs can be used to reliably encode information and can be delivered with a vaccine, which may be particularly valuable in the developing world and open up new avenues for decentralized data storage and biosensing.

A materials-science perspective on tackling COVID-19

“…Real-time data on the location and treatment responses could be generated by introducing NIR-II bioluminescence 173 , NIR-II chemiluminescence 174 or NIR-II fluorescence 175 to enable the rational design of nanoscale materials and bench-to-bedside translation of vaccines. Materials science also enables the design of self-administration platforms; for example, vaccines formulated as microneedle patches 176 , which slowly release payloads upon self-administration. Reproducibility and scalability also play major roles for the translation of nanomaterials for drug delivery.…”

Microneedle-based bioassays

“…[40][41][42] The designed master template can initially be produced via etching, lithography, micromachining, or 3D printing. 43,44 Complementary negative molds can be produced with curable materials such as polydimethylsiloxane (PDMS). Some negative molds are commercially available with customizable designs, which can enhance the productivity, reduce the batch-to-batch variability, and facilitate access to MN fabrication techniques.…”

Near-infrared fluorescent probes: a next-generation tool for protein-labeling applications

“…To date, various NIR-based uorophores have been developed based on small organic molecules, inorganic materials, or organic-inorganic hybrid materials, for various applications in material sciences, clinical research, or chemical biology. 8,9 Among the above mentioned NIR uorophores, small organic molecule-based NIR uorophores offer attractive imaging tools owing to their small size, biocompatibility, and high design exibility. 10 Many small molecule-based NIR uorophores have been developed, using various scaffolds such as cyanine, squaraine, bodipy, xanthene, and benzobisthiadiazole.…”