# Multi-responsive upconversion/organic porous silicon nanocomposite for controlled drug release via NIR irradiation and tumor microenvironment stimuli

## TL;DR

Researchers created a nanocapsule that releases chemotherapy drugs on demand using light and the tumor environment, improving treatment precision.

## Contribution

A multi-responsive nanocapsule combining upconversion nanoparticles, pH/GSH sensitivity, and photoresponsive gating for controlled drug release is introduced.

## Key findings

- Nanocapsules achieved 12.2 wt% doxorubicin loading with minimal leakage at neutral pH.
- Synergistic NIR, pH, and GSH stimuli enabled maximal drug release in tumor-like conditions.
- The Baker-Lonsdale model quantified drug diffusion under various stimuli for system design.

## Abstract

We report the synthesis of an organic/inorganic architecture, a rare-earth upconversion nanoparticle (UCNP)-based core with organic porous silicon shell nanocapsules, that enables visible and ultraviolet light emission under 980 nm near-infrared (NIR) irradiation for photodegradation. A mesoporous organosilica shell containing disulfide bonds was uniformly coated onto UCNP cores via a combined sol–gel and hard-template strategy. Glutathione (GSH) – triggered degradation of the nanocarriers was quantified using the molybdenum blue method. A photoresponsive azobenzene derivative, activatable by both UV and visible light, was synthesized and grafted onto the nanocarrier surface. Doxorubicin (DOX) was loaded into the nanocapsules, achieving a drug-loading capacity of 12.2 wt%. At neutral pH, minimal DOX leakage occurred; maximal release was observed under a composite stimulus environment. The Baker-Lonsdale model was employed to calculate diffusion coefficients under varying release conditions, providing quantitative guidance for designing multi-responsive drug-release systems. In vitro cellular assays showed that synergistic stimuli—NIR irradiation combined with an acidic, GSH-rich microenvironment—trigger controllable DOX release, enabling efficient tumor cell ablation. This work demonstrates a versatile, multi-responsive delivery platform combining UCNP-based photoreactivity, GSH-triggered degradation, and photoactive surface gating to achieve targeted, low-toxicity, on-demand chemotherapy.

We developed UCNP@organosilica nanocapsules with GSH-triggered degradation and photoresponsive feature for on-demand DOX release. NIR/pH/GSH stimuli enable controlled drug release for targeted, low-toxicity chemotherapy and tumor cell ablation.