The successful covalent functionalization of graphene oxide (GO) with 5-(4-aminophenyl)-10,15,20-triphenyl-21,23H-porphyrin (H₂P) has been reported. The resulting GO–H₂P hybrid material forms stable dispersions in DMF and has been thoroughly characterized by spectroscopic (UV-vis, ATR-IR, Raman) and thermal (TGA) tools. Microscopy techniques (AFM and TEM) have been employed to probe the morphological characteristics as well as to investigate the exfoliation of graphene sheets. Steady-state and time-resolved fluorescence emission studies have shown efficient fluorescence quenching, suggesting that electron transfer occurs from the singlet excited state of the H₂P moiety to the GO sheet. Photoexcitation resulted in the one-electron oxidation of the H₂P with the simultaneous one-electron reduction of GO, yielding (GO)˙⁻–(H₂P)˙⁺, as revealed by transient absorption measurements. The electrochemical redox potentials of the graphene–H₂P material were studied by cyclic voltammetry (CV) and differential pulsed voltammetry (DPV) and the energy gap for the charge-separated state of (GO)˙⁻–(H₂P)˙⁺ has been calculated as 0.87 eV, while, the negative free-energy change for the photoinduced charge-separation of GO–H₂P has been evaluated to be −1.00 eV, which confirms the thermodynamically favorable formation of (GO)˙⁻–(H₂P)˙⁺. Eventually, the GO–H₂P hybrid material was deposited by electrophoretic deposition onto SnO₂ electrodes, and the OTE/SnO₂/GO–H₂P electrode exhibited an incident photon-to-photocurrent-efficiency IPCE of 1.3% in a standard photoelectrochemical cell.

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Photodynamic therapy (PDT) involves the action of photons on photosensitive molecules, where atomic oxygen or OH⁻molecular species are locally released on pathogenic human cells, which are mainly carcinogenic, thus causing cell necrosis. The efficacy of PDT depends on the local nanothermodynamic conditions near the cell/nanodrug system that control both the level of intracellular translocation of nanoparticles in the pathogenic cell and their agglomeration on the cell membrane. Dendrimers are considered one of the most effective and promising drug carriers because of their relatively low toxicity and negligible activation of complementary reactions. Polyamidoamine (PAMAM) dendrite delivery of PDT agents has been investigated in the last few years for tumour selectivity, retention, pharmacokinetics and water solubility. Nevertheless, their use as drug carriers of photosensitizing molecules in PDT for cardiovascular disease, targeting the selective necrosis of macrophage cells responsible for atheromatous plaque growth, has never been investigated. Furthermore, the level of aggregation, translocation and nanodrug delivery efficacy of PAMAM dendrimers or PAMAM/zinc phthalocyanine (ZnPc) conjugates on human atheromatous tissue and endothelial cells is still unknown.In this work, the aggregation of PAMAM zero generation dendrimers (G0) acting as drug delivery carriers, as well as conjugated G0 PAMAM dendrimers with a ZnPc photosensitizer, to symptomatic and asymptomatic human carotid tissues was investigated by using atomic force microscopy (AFM). For the evaluation of the texture characteristics of the AFM images, statistical surface morphological and fractal analytical methodologies and Minkowski functionals were used. All statistical quantities showed that the deposition of nanodrug carriers on healthy tissue has an inverse impact when comparing to the deposition on atheromatous tissue with different aggregation features between G0 and G0/ZnPc nanoparticles and with considerably larger G0/ZnPc aggregations on the atheromatous plaque. The results highlight the importance of using PAMAM dendrimer carriers as a novel and promising PDT platform for atherosclerosis therapies.

The Raman spectra of tetragonal CaMoO₄ (scheelite structure, C_4h⁶ space group) have been measured in the temperature range 12–1300 K. At high temperatures, the frequency and linewidth of all Raman-active phonons vary almost linearly with temperature, indicating that the three-phonon decay processes are dominant over the four-phonon ones. All Raman phonons display normal negative (∂ω/∂T) slopes throughout the temperature range, except for the lowest-frequency B_g phonon at 111.5 cm⁻¹ which is almost temperature independent in the region 12–400 K, but then for T > 400 K it shows a slight (normal) softening with temperature. The reduced (∂ω/∂T)/ω slopes of the internal modes (vibrations of atoms within the tetrahedral MoO₄²⁻ units) are an order of magnitude smaller than the respective slopes of the external ones (pure lattice modes). There are no discontinuities or sharp changes of slope in the ω(T) plots, implying that CaMoO₄ remains stable over the entire temperature range. Combining the temperature-dependent Raman data of this work and the previously reported pressure-dependent Raman data on this crystal (Christofilos D, Kourouklis G A and Ves S 1995 J. Phys. Chem. Solids 56 1125), as well as the thermal expansion coefficient β(T) and compressibility κ(T) data, it has been possible to separate and evaluate quantitatively the volume (expansion) Δω_vol and the pure temperature (anharmonic) Δω_anh contributions to the total Δω_tot shift of phonons with temperature. It has been found that for most phonons at high temperatures, the volume effect is greater than the pure temperature one, thus indicating that most of the bonds in CaMoO₄ are predominantly ionic in character.