# Synthesis of 99mTc-labeled polyaspartic acid/silica nanoassembly as a potential probe for bone imaging

## TL;DR

Researchers developed a new bone imaging probe using 99mTc-labeled silica nanoparticles coated with polyaspartic acid, which showed improved bone targeting and biocompatibility in mice.

## Contribution

A novel 99mTc-labeled PASP-coated mesoporous silica nanoassembly is introduced for enhanced bone imaging with high targeting efficiency and stability.

## Key findings

- The PASP-mSiO2-DTPA-99mTc nanoassembly achieved a high radiochemical yield of 92 ± 0.5%.
- In vivo studies showed significantly higher bone uptake (13 ± 0.6% IA/gram) compared to uncoated MSNs (5.4 ± 0.4% IA/gram).
- The nanoassembly demonstrated good in vitro stability in PBS and FBS for up to 24 hours.

## Abstract

Due to the efficient bone targeting of mesoporous silica nanoparticles (MSNs) and polyaspartic acid (PASP), 99mTc- labeled polyaspartic acid coated mesoporous silica nanoparticles (PASP-mSiO2-DTPA-99mTc) are proposed as a potential probe for bone imaging.

Polyaspartic acid-conjugated silica nanoparticles (PASP-mSiO2) were synthesized using aqueous carbodiimide chemistry and characterized by ATR-FTR, FE-SEM, EDX, TEM, TGA and XRD. Radiolabeling of the produced nanoassembly with 99mTc was carried out via a simple DTPA chelation procedure. Aqueous dispersion of the radiolabeled nanoparticles was intravenously injected into normal mice and the bone targeting efficiency was evaluated.

The PASP-mSiO2 nanoassembly was efficiently synthesized and radiolabeled with 99mTc with a high radiochemical yield (92 ± 0.5%) and sufficient in vitro stability in PBS and FBS for up to 24 h. In vivo biodistribution studies revealed a significant enhancement of radioactivity bone uptake after intravenous injection of PASP-mSiO2-DTPA-99mTc compared to radiolabeled uncoated MSNs (mSiO2-DTPA-99mTc), (13 ± 0.6% IA/gram and 5.4 ± 0.4, respectively).

PASP endowed MSNs with enhanced biocompatibility and highly selective bone targeting. Therefore, the proposed PASP-mSiO2-DTPA-99mTc nanoassembly has immense potential in the field of bone- imaging via single photon emitting computed tomography (SPECT).

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The online version contains supplementary material available at 10.1186/s13065-025-01508-z.