Facile Preparation and Photoactivation of Prodrug-Dye Nanoassemblies

Summary

This protocol describes the fabrication and characterization of a photoresponsive prodrug-dye nanoassembly. The methodology for drug release from the nanoparticles by light-triggered disassembly, including the light irradiation setup, is explicitly described. The drugs released from the nanoparticles following light irradiation exhibited excellent anti-proliferation effects on human colorectal tumor cells.

Abstract

Self-assembly is a simple yet reliable method for constructing nanoscale drug delivery systems. Photoactivatable prodrugs enable controllable drug release from nanocarriers at target sites modulated by light irradiation. In this protocol, a facile method for fabricating photoactivatable prodrug-dye nanoparticles via molecular self-assembly is presented. The procedures for prodrug synthesis, nanoparticle fabrication, physical characterization of the nanoassembly, photocleavage demonstration, and in vitro cytotoxicity verification are described in detail. A photocleavable boron-dipyrromethene-chlorambucil (BC) prodrug was first synthesized. BC and a near-infrared dye, IR-783, at an optimized ratio, could self-assemble into nanoparticles (IR783/BC NPs). The synthesized nanoparticles had an average size of 87.22 nm and a surface charge of -29.8 mV. The nanoparticles disassembled upon light irradiation, which could be observed by transmission electronic microscopy. The photocleavage of BC was completed within 10 min, with a 22% recovery efficiency for chlorambucil. The nanoparticles displayed enhanced cytotoxicity under light irradiation at 530 nm compared with the non-irradiated nanoparticles and irradiated free BC prodrug. This protocol provides a reference for the construction and evaluation of photoresponsive drug delivery systems.

Introduction

Chemotherapy is a common cancer treatment that employs cytotoxic agents to kill cancer cells and thus inhibits tumor growth¹. However, patients may suffer from side effects such as cardiotoxicity and hepatotoxicity due to the off-target absorption of the chemotherapy drugs^2,3,4. Therefore, localized drug delivery through the spatiotemporal control of drug release/activation in tumors is essential to minimize drug exposure in normal tissues.

Prodrugs are chemically modified drugs that exhibit reduced tox....

Protocol

1. Synthesis of boron-dipyrromethene-chlorambucil (BC) prodrug (Figure 2)²²

1. Synthesis of BODIPY-OAc
   1. Weigh 1.903 g of 2,4-dimethyl pyrrole and dissolve it in 20 mL of anhydrous dichloromethane (DCM) in a round-bottom flask under a nitrogen atmosphere. Weigh 1.638 g of acetoxy acetyl chloride and add it dropwise into the solution. Keep stirring for 10 min at room temperature and then reflux the solution for 1 h a.......

Discussion

This protocol outlines a facile flash precipitation method for the fabrication of prodrug-dye nanoparticles, which offers a simple and convenient approach for nanoparticle formation. There are several critical steps in this method. Firstly, for all steps of synthesis, fabrication, and characterization, containers like microtubes should be covered with foil to avoid unnecessary photocleavage of the BC prodrug by environmental light. Moreover, in the flash precipitation step, the microtube containing the IR-783 solution sh.......

Materials

Name	Company	Catalog Number	Comments
1260 Infinity II HPLC	Agilent Technologies
2,4-Dimethyl pyrrole	J&K Scientific	315305
3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)	Gibco	M6494
4-Dimethylaminopyridine (4-DMAP)	J&K Scientific	212279
90 mm Petri Dish Clear Treated Sterile	SPL	11090
96-well Tissue Culture Plate Clear Treated Sterile	SPL	30096
Acetoxyacetyl chloride	J&K Scientific	192001
Boron trifluoride diethyl etherate	J&K Scientific	921076
Büchner funnel	AS ONE	3-6466-01
Chlorambucil	J&K Scientific	321407-1G
CM100 Transmission Electron Microscope	Philips
CombiFlash RF chromatography system	Teledyne ISCO
Dichloromethane	DUKSAN Pure Chemicals	JT9315-88
Dimethyl sulfoxide	DUKSAN Pure Chemicals	2762
Disposable cuvette	Malvern Panalytical	DTS1070	Zeta potential measurement
Disposable cuvette	Malvern Panalytical	ZEN0040
Empty Disposable Sample Load Cartridges	Teledyne ISCO	693873225	can hold up to 65 g
Fetal bovine serum	Gibco	10270106
Filtering flask	AS ONE	3-7089-03
Hexane	DUKSAN Pure Chemicals	4198
Holey carbon film on copper grid	Beijing Zhongjingkeyi Technology Co.,Ltd	BZ10023a
HPLC column (InfinityLab Poroshell 120)	Agilent Technologies	695975-902T
Integrating sphere photodiode power sensor	Thorlabs	S142C
IR783	Tokyo Chemical Industry (TCI) Co., Ltd	I1031
LED	Mightex	LCS-0530-15-11
LED Driver Control Panel V3.2.0 (Software)	Mightex
Lithium Hydroxide Anhydrous	TCI	L0225
Methylmagnesium iodide, 3M solution in diethyl ether	Aladdin	M140783
N,N-Diisopropyl ethyl amine (DIPEA)	J&K Scientific	203402
N,N'-Dicyclohexylcarbodiimide (DCC)	J&K Scientific	275928
penicillin–streptomycin	Gibco	15140122
Phosphate-buffered saline (10×)	Sigma-Aldrich	P5493
Power and energy meter	Thorlabs	PM100 USB
Rotavapor	BUCHI Rotavapor R300
RMPI 1640	Gibco	21870076
Separatory funnel (125 mL)	Synthware	F474125L
Silver Silica Gel Disposable Flash Columns, 40 g	Teledyne ISCO	692203340
Sodium sulfate, anhydrous	Alfa Aesar	A19890
SpectraMax M4	Molecular Devices LLC
Tetrahydrofuran (THF), anhydrous	J&K Scientific	943616
Trypsin-EDTA (0.25%), phenol red	Gibco	25200056
Vortex	DLAB Scientific Co., Ltd	MX-S
Zetasizer Nano ZS90	Malvern Instrument