Application of calcium phosphate nanoparticles in biology and medicine

University and Research Context
📌 The speaker is from the University of Duisburg-Essen in Germany, established in 2003 from the union of two universities.
🏫 The Essen campus hosts 42,000 students and approximately 410 professors, with research focusing on nanoscience and medical sciences.
🌐 The university is highly international, collaborating with 105 partners globally.

Calcium Phosphate Nanoparticles (CPNPs) Fundamentals
📌 CPNPs are abundant in the body (bones, teeth), offering excellent biocompatibility, low toxicity, and biodegradability.
📌 Nanoparticles for biological applications are typically under 100 nm to facilitate passage through cell membranes.
📌 CPNPs can be synthesized via precipitation, controlled by parameters like pH and room temperature.
📌 Stabilization involves electrostatic interaction between the negatively charged phosphate groups on CPNPs and charged biomolecules (like DNA).

CPNP Functionalization and Stabilization
📌 Multi-shell structures are synthesized by alternating layers of calcium phosphate and biomolecules to protect payloads and ensure colloidal stability.
📌 The inner shell is designed for biological purposes, while the outer shell provides colloidal stabilization.
📌 Purification is crucial after synthesis, involving repeated steps of centrifugation and ultrasonication to remove free biomolecules.
📌 For long-distance transport, CPNPs are stabilized by embedding them in a matrix like trehalose via lyophilization, turning them into a stable powder.

Applications of CPNPs
📌 Dental Regeneration: CPNPs are used in active pastes to regenerate teeth, with potential future application in long-lasting protective dental coatings that reduce the need for brushing.
📌 Drug and Biomolecule Delivery: CPNPs successfully deliver fluorescent molecules and plasmids into cells, as demonstrated by enhanced uptake in LHP and HeLa cells compared to bare biomolecules.
📌 Gene Silencing and Transfection: CPNPs can carry siRNA for gene silencing (inhibiting protein synthesis) or plasmid DNA for protein synthesis (e.g., green fluorescent protein), showing ~44% transfection efficiency in certain cells.
📌 Immunization: CPNPs carrying antigens and adjuvants are effective in activating dendritic cells in mice, significantly reducing viral load (e.g., Friend virus) in the spleen after challenge, suggesting a protective effect against viruses.
📌 Imaging and Bone Remodeling Studies: In collaboration with Singapore, CPNPs were used to study bone remodeling in transparent Medaka fish, where bone cells glow green, allowing observation of nanoparticle distribution in relation to osteoblasts and osteoclasts.

Key Points & Insights
➡️ For complex payloads like antibodies, simple electrostatic interaction is insufficient; adding a silica shell enables covalent binding for stronger attachment.
➡️ Long-term storage and distribution of active nanoparticles are best achieved through lyophilization using a matrix like trehalose, resulting in a stable powder that can be reconstituted with water.
➡️ CPNPs degrade rapidly (dissolve) when the pH drops below 5, which occurs naturally in lysosomes inside cells, enabling controlled release of encapsulated biomolecules.
➡️ While systemic intravenous injection leads to broad distribution (high accumulation often in the lung/liver), achieving 100% targeted delivery remains a significant challenge in nanomedicine.

📸 Video summarized with SummaryTube.com on Feb 24, 2026, 12:08 UTC