Polyacrylic acid modified upconversion nanoparticles for simultaneous pH-triggered drug delivery and release imaging

Area of Science:

• Nanotechnology
• Materials Science
• Biomedical Engineering

Background:

• Upconversion nanoparticles (UCNPs) offer unique optical properties for bioimaging.
• Developing targeted and stimuli-responsive drug delivery systems is crucial for cancer therapy.
• Poly(acrylic acid) (PAA) can be utilized for surface modification of nanoparticles to impart specific functionalities.

Purpose of the Study:

• To develop poly(acrylic acid)-modified NaYF4:Yb, Er upconversion nanoparticles (PAA-UCNPs) for dual drug delivery and release imaging.
• To evaluate the pH-responsive drug loading and release characteristics of PAA-UCNPs using doxorubicin hydrochloride (DOX) as a model drug.
• To assess the in vitro cytotoxicity and intracellular delivery of DOX-loaded PAA-UCNPs.

Main Methods:

• Surface modification of NaYF4:Yb, Er UCNPs with poly(acrylic acid) (PAA).
• Drug loading of doxorubicin hydrochloride (DOX) onto PAA-UCNPs via electrostatic interaction.
• pH-dependent drug release studies.
• In vitro cytotoxicity assays using HeLa cell lines.
• Upconversion fluorescence resonance energy transfer (UFRET) imaging via two-photon laser scanning microscopy (TLSM).

Main Results:

• PAA-UCNPs exhibited pH-sensitive drug loading and release, with high encapsulation in weak alkaline conditions and increased release in acidic environments.
• DOX-loaded PAA-UCNPs (DOX@PAA-UCNPs) demonstrated significant cytotoxicity against HeLa cells.
• PAA-UCNPs showed high biocompatibility, confirming their suitability as drug carriers.
• UFRET imaging visualized the intracellular delivery of DOX from DOX@PAA-UCNPs over time.

Conclusions:

• PAA-UCNPs are effective for constructing pH-responsive controlled drug delivery systems.
• The developed system holds potential for multi-functional cancer therapy and imaging.
• The combination of drug delivery and imaging capabilities in a single nanoplatform offers advantages for cancer treatment monitoring.