Phosphorescent palladium-tetrabenzoporphyrin indicators for immunosensing of small molecules with a novel optical device

Small-molecule detection is important for many applications including clinical diagnostics, drug discovery, environmental screening, and food technology. Current techniques suffer from various limitations including cost, complex sample processing, massive instrumentation, and need for expertise. To overcome these limitations, a new optical immunosensing assay for the detection of small molecules was developed and assessed with the targets estrone (E1) and estradiol (E2). For this purpose, phosphorescent indicators were designed based on the tetrabenzoporphyrin skeleton directly linked to E1 or E2, or attached through a linker, with phosphorescence lifetimes in the range of ~100-~300 μs. The assay is an indicator displacement assay (IDA). The best performances of our optical immunosensor were obtained with the indicators E1-L-Por and E2-L-Por. As they bound to specific polyclonal antibodies, their phosphorescence (τ ~200 μs) was quenched. When an endogenous competitor was added, the indicator was displaced, and the phosphorescence was immediately recovered. These effects were measured with a new optical device, described here, and able to detect picograms of luminescent molecules emitting in the NIR range, simply by measuring phosphorescence decay. This radical switch-off/switch on process demonstrates that E1-L-Por and E2-L-Por are good candidates for in vivo and in vitro immunosensing of E1 and E2. Importantly, the present immunosensing assay can be easily adapted to other small molecules such as other hormones and drugs.

In Vitro Photodynamic Activity of N-Methylated and N-Oxidised Tripyridyl Porphyrins with Long Alkyl Chains and Their Inhibitory Activity in Sphingolipid Metabolism

A series of N-methylated and N-oxidised tripyridyl porphyrins were synthesised, characterised, and their PDT activity was studied with six cell lines. All the tested porphyrins with a long alkyl chain, except one, were more efficient for PDT than an N-methylated hydrophilic porphyrin and N-oxidised porphyrin without the long alkyl chain. Generally, N-methylated tripyridyl porphyrins were more active than those N-oxidised, but IC₅₀ values for phototoxicity of two N-oxides, named TOPyP3-C₁₇ H₃₃ O and TOPyP3-C₁₇ H₃₅ , were still in the nanomolar concentration range for most of the tested cell lines. However, TOPyP3-C₁₇ H₃₅ did not show phototoxicity on human foreskin fibroblast cells. Two methylated amphiphilic porphyrins, named TMPyP3-C₁₇ H₃₃ and TMPyP4-C₁₇ H_35, showed significant dark toxicity, whereas none of the oxidopyridyl porphyrins were toxic without light activation. The selected photosensitisers were shown to be apoptosis inducers, and had inhibitory effects on the clonogenic growth of HCT116 and HeLa cells. All three N-methylated amphiphilic porphyrins significantly reduced the migratory potential of HCT116 cells. Porphyrins TMPyP3-C₁₇ H₃₅ and TOPyP3-C₁₇ H₃₅ reduced the activity of acid ceramidase, whereas TOPyP3-C₁₇ H₃₃ O had a significant inhibitory effect on sphingosine kinase 1 activity in HeLa cells. Compounds with this dual activity were shown to be the most promising photosensitisers, with potential to treat invasive cancers.

A photocatalyst immobilized on fibrous and porous monolithic cellulose for heterogeneous catalysis of controlled radical polymerization

Fibrous and porous monolithic cellulose was employed to immobilize a photocatalyst for heterogeneously catalysing controlled radical polymerization, which provides superior catalyst recyclability.