# Bioconjugates of Toluidine Blue Derivatives with Human Serum Albumin and Their Complexes with Cucurbit[7]uril as Drug Delivery Vehicles for Photodynamic Therapy

## TL;DR

This study explores using modified toluidine blue derivatives with human serum albumin and cucurbit[7]uril to improve drug delivery and effectiveness in photodynamic cancer therapy.

## Contribution

A novel drug delivery system combining HSA conjugation and CB[7] encapsulation for enhanced photodynamic therapy.

## Key findings

- HSA-bound TBO derivatives showed increased cellular uptake in HeLa cells.
- CB[7] complexes improved the photophysical properties of the photosensitizers.
- Conjugation type (disulfide vs. thia-Michael) significantly influenced phototoxicity.

## Abstract

Photodynamic therapy (PDT) is a promising cancer treatment.
The
present work used two toluidine blue O (TBO) derivatives covalently
conjugated to human serum albumin (HSA) as a drug delivery system
and bound to cucurbit[7]­uril (CB[7]) as a protective nanocapsule in
order to study their effect of cellular uptake and phototoxicity in
HeLa cells. This study explored covalent and noncovalent interactions
with the delivery systems, including HSA-PS@CB[7] complexes, to optimize
PDT efficacy. Supramolecular complexes between TBO derivatives and
CB­[7] exhibited high binding affinities, significantly improving the
photophysical properties of the photosensitizers. In vitro studies
in cancer cells demonstrated that HSA covalently bound to TBO derivatives
led to significant increases in cellular uptake and was strongly influenced
by the type of conjugation (disulfide bond versus thia-Michael adduct).
The results suggest that combining the properties of HSA as a carrier
and CB[7] as a protective nanocapsule could be exploited for improved
PDT applications.