# Biodegradable and Biocompatible Semiconductor Nanoparticles for Deep Tissue Imaging

> **NIH NIH R21** · BOSTON UNIVERSITY (CHARLES RIVER CAMPUS) · 2021 · $206,250

## Abstract

Project Summary/Abstract
Fluorescence has significant potential for biomedical imaging applications because of the relatively low cost of
imaging equipment, the nominal toxicity of non-ionizing radiation (i.e., light), the potential for molecular imaging
using target-specific contrast agents, and the prospect of multiplexed imaging using discretely colored
fluorophores. Molecules common in biological tissues including lipids, water, and hemoglobin scatter and absorb
light, rendering tissue opaque to visible wavelengths, but longer, near infrared (NIR) wavelengths penetrate
deeper, giving us optical windows into the body. The first, second, and third NIR optical windows (NIR-I, II, and
III) each have advantages ranging from use with accessible and economical Si detectors (NIR-I) to a reduction
in scattering, and thus a marked improvement in resolution, in the NIR-II and III. To see inside a tissue, we require
bright, photostable, highly absorbing, NIR fluorophores. In addition, the regular clinical use of any contrast agent
requires that it is biocompatible and removed from the body following its use. We propose a new materials
development effort to synthesize biocompatible and biodegradable semiconductor QDs that can be tuned for
imaging in the NIR-I, II, or III. We propose a novel, optically active semiconductor nanoparticle that fully
degrades in vivo for clinical molecular imaging. Inorganic contrast agents like semiconductor quantum dots
(QDs) have been the focus of extensive biomedical research, but hold little promise for clinical translation
because the materials comprise toxic constituents. Even inert, seemingly biocompatible inorganic materials like
gold nanoparticles carry the clinical risk of accumulating indefinitely in tissues like the liver. This is in stark
contrast to the only inorganic nanoparticle that has been FDA-approved to date: iron oxide nanoparticles (IONs)
for MRI contrast and the treatment of anemia. The absence of heavy metals in IONs avoids toxicity, while
degradation and bile excretion circumvent the potentially severe kidney strain experienced by patients receiving
molecular contrast agents. This material profile inspires our innovative approach to reinventing QDs for clinical
optical imaging. We hypothesize that heavy metal-free nanoparticles comprising only bioessential elements will
be degraded and excreted just like iron oxide. The choice of a material with a small bandgap (0.6 eV) indicates
that the absorption and emission will be size-tunable through NIR-I, II, and III wavelength regimes, enabling
paradigm shifting levels of light penetration through tissues and clarity in fluorescence imaging. We will use
computational approaches like density functional theory (DFT) modeling of various crystal structures to predict
and optimize nanomaterial optical properties to rationally design semiconductor nanoparticles for clinical
applications. Through this Exploratory Technology Development R21, we will synthesize and ...

## Key facts

- **NIH application ID:** 10131820
- **Project number:** 5R21GM135849-02
- **Recipient organization:** BOSTON UNIVERSITY (CHARLES RIVER CAMPUS)
- **Principal Investigator:** Allison Marie Dennis
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $206,250
- **Award type:** 5
- **Project period:** 2020-04-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10131820

## Citation

> US National Institutes of Health, RePORTER application 10131820, Biodegradable and Biocompatible Semiconductor Nanoparticles for Deep Tissue Imaging (5R21GM135849-02). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10131820. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*