Nanoparticles functionalization with porphyrins

Functionalization of nanoparticles with porphyrins and analogous macrocycles opened the way to important applications, such as, to name only a few gelators [8], phototherapy of cancer [9], degradation of organic pollutants by singlet oxygen photosensitization [10], and photoexcited electron transfer [11]. The interest in porphyrin-based nanoreactors lies in the possibility of using a variety of metals that can enter in catalytic processes [12]. 

Meso-PSi nanoparticles have been used for the delivery of porphyrin drugs (see chapter Drug Delivery with Porous Silicon ) into breast cancer cells in vitro. The porphyrin was covalently immobilized onto the surface of PSi via a new chemical modification scheme, which retains the porphyrin photoactivity. The functionalized nanoparticles were better internalized by cancer cells compared to the plain photosensitizer, and a more efficient cell death was observed (Secret etal. 2013). 

Mixed SAMs on gold electrodes from azido alkane thiols and various a>-functionalized alkanethiols were prepared. In the presence of copper(l) catalysts, these azide-modified surfaces are shown to react rapidly and quantitatively with terminal acetylenes forming 1,2,3-triazoles via click chemistry (Figure 6). In this way, thiol SAMs have been modified with complex functional molecules such as single-stranded DNA, porphyrin redox catalysts, and receptors for gold nanoparticles and other materials. 

Most supramolecular nanotube modifications involve noncovalent interactions on the external surface of the CNT (i.e., exohedral. Figure 1). For example, n-n stacking is employed to attach pyrene " and porphyrin " molecules to the surface of CNTs. Hydrophobic and van der Waals interactions are necessary for micelle-forming compounds (i.e., surfactants and lipids ) and polymer (both syn-thetic " and natural ) to functionalize CNTs. The so-called r-cation interactions represent an additional exohedral approach for functionalizing CNTs. Finally, organometallic bonding is required for the decoration of CNT with metal nanoparticles (NP) at defect sites. ... 

Another interesting report presents the one-pot preparation of a ternary hybrid nanomaterial composed of a porphyrin-functionalized graphene, tin oxide, and gold nanoparticles [134]. This composite was applied to the simultaneous determination of epinephrine and uric acid. First, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin was linked to GO sheets dispersed in aqueous solution, then HAuCLt was added, followed by SnCl2. The latter ensured reduction to graphene and Au nanoparticles while forming Sn02. Reduction of GO was completed with hydrazine in alkaline medium. 

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