Towards optimisation of surface enhanced photodynamic therapy of breast cancer cells using gold nanoparticle-photosensitiser conjugates

Abstract

Gold nanoparticles (AuNPs; ca. 4 nm) were synthesised and functionalised with a mixed monolayer of polyethylene glycol (PEG) and one of two zinc phthalocyanines (ZnPcs), the difference between the two molecules was the length of the carbon chain that connects the Pc to the gold core. The chain was composed of either three (C3Pc) or eleven (C11Pc) carbon atoms. The C11Pc photosensitiser displayed higher fluorescence emission intensity than the C3Pc in solution. By contrast, the C3Pc photosensitiser exhibited higher fluorescence when bound to the surface of the AuNPs than the C11Pc, despite the shorter carbon chain which was expected to quench the fluorescence. In addition, the C3Pc nanoparticle conjugates exhibited an enhancement in the production of singlet oxygen (O). The metal-enhanced O production led to a remarkable photodynamic efficacy for the treatment of human breast cancer cells.

Targeted photodynamic therapy of breast cancer cells using lactose-phthalocyanine functionalized gold nanoparticles

“…Both nanoparticle systems were shown to generate 1 O 2 , as shown in Figure 2f, with the lactose-C3Pc-AuNPs producing more 1 O 2 than the lactose-C11Pc-AuNPs, which is thought to be due to surface enhanced effects with the C3Pc molecule. [42] Additionally, control AuNPs, used to evaluate the targeting ability of lactose within the lactose-C3Pc-AuNPs, were synthesized. For the control AuNPs, the lactose ligand was substituted for a polyethylene glycol ligand of a short length (sPEG), thiol-dPEG® 4 -acid shown in Figure 3a, resembling the length of the lactose ligand.…”

“…Two Pcs were explored, differing in the length of the carbon chain that connects the Pc to the gold core, consisting of either 3 or 11 carbon atoms. [42] The lactose disaccharide is made up of glucose and galactose residues. Galectin-1 has been shown to recognize and bind to both sugar units.…”

“…The phthalocyanines used for this study were two octa-alkyl substituted zinc (II) phthalocyanines, differing in the length of the carbon chain connecting the macrocycle to the disulfide bond, either three carbon atoms (C3Pc) or eleven carbon atoms (C11Pc). [42] Schematic representations of the synthesized gold nanoparticles functionalized with a mixed monolayer of lactose and either C3Pc (lactose-C3Pc-AuNPs) or C11Pc (lactose-C11Pc-AuNPs) are shown in [43] Schematic representation of the (b) lactose-C3Pc-AuNPs and (c) lactose-C11Pc-AuNPs.…”

Photosensitiser-gold nanoparticle conjugates for photodynamic therapy of cancer

“…However, metal-enhanced fluorescence (MEF), by which the fluorescence of fluorophores placed near the surface of metallic nanoparticles can be enhanced, is gaining interest for PDT. 10,11 MEF has been shown to be related to metal-enhanced singlet oxygen production (ME 1 O2), which would thus lead to an enhanced PDT effect. 12 Both MEF and ME 1 O2…”

Photosensitiser functionalised luminescent upconverting nanoparticles for efficient photodynamic therapy of breast cancer cells

“…1 Particularly effective photosensitisers are hydrophobic in nature, since they can be efficiently internalised by the cells through interaction with the lipid layers of the cell membrane. 2,3 However, such hydrophobicity restricts the delivery and transportation of the photosensitisers through the body. 2,4 Another issue with photosensitisers that are activated with visible light is the difficulty to treat deep-lying tumours.…”