Effects of bovine serum albumin (BSA) on the excited-state properties of meso-tetrakis(sulfonatophenyl) porphyrin (TPPS4)

Absorption and Fluorescence Emission Investigations on Supramolecular Assemblies of Tetrakis-(4-sulfonatophenyl)porphyrin and Graphene Quantum Dots

The one-pot synthesis of N-doped graphene quantum dots (GQDs), capped with a positively charged polyamine (trien), has been realized through a microwave-assisted pyrolysis on solid L-glutamic acid and trien in equimolar amounts. The resulting positively charged nanoparticles are strongly emissive in aqueous solutions and are stable for months. The interaction with the anionic tetrakis(4-sulphonatophenyl)porphyrin (TPPS4) has been investigated at neutral and mild acidic pH using a combination of UV/vis absorption spectroscopy together with static and time-resolved fluorescence emission. At pH = 7, the experimental evidence points to the formation of a supramolecular adduct mainly stabilized by electrostatic interactions. The fluorescence emission of the porphyrin is substantially quenched while GQDs remain still emissive. On decreasing the pH, protonation of TPPS4 leads to formation of porphyrin J-aggregates through the intermediacy of the charged quantum dots.

Daylight photodynamic inactivation of cattle tick Rhipicephalus microplus by porphyrins: An alternative for the ectoparasite control

The bovine tick Rhipicephalus microplus, a primary ectoparasite of veterinary concern, contributes significantly to disease transmission and reduced cattle productivity, resulting in substantial economic losses. The overuse of chemical acaricides has led to the emergence of resistant strains, posing a considerable challenge to veterinary medicine. Consequently, the development of alternative parasite control methods is essential to ensure livestock quality and enhance food safety worldwide. Our study introduces an innovative approach to photodynamic inactivation (PDI) of the bovine tick, harnessing natural daylight for a potential field application. Reproductive parameters (female and egg mass, egg production index, and larval hatch) were evaluated in engorged female ticks under photodynamic action using the hematoporphyrin (HP) and tetra-cationic porphyrins free-base meso-tetra-ruthenated (4-pyridyl) (RuTPyP) and its zinc(II) complex (ZnRuTPyP) as photosensitizers (PS). The results showed that there was no significant difference between the groups treated with tetra‑ruthenium porphyrins and the control group. However, HP exhibits a control percentage of 97.9% at a concentration of 2.5 μmol.L-1, aligning with the expected control rates achieved by conventional chemical acaricides. Photophysical and physicochemical parameters such as the number of singlet oxygen produced and lipophilicity were discussed for each PS and related to tick control percentages. Furthermore, the interaction between HP and chitin, an important macromolecule presents in the tick's cuticle, considered as the primary target tick structure during PDI was observed by the absorption and fluorescence emission spectroscopic techniques. Therefore, the results presented here extend the potential for controlling R. microplus through photodynamic inactivation while utilizing sunlight as a source of natural irradiation.

Synergic vascular photodynamic activity by methylene blue-curcumin supramolecular assembly

A supramolecular assembly was obtained by combining methylene blue (MB) with a natural plant extract, curcumin (Curc), in a stoichiometric ratio of 1:4 in aqueous solution (90% PBS + 10% ethanol) at room temperature. The MB-Curc supramolecular assembly was evidenced by absorption and fluorescence spectroscopies, and the stoichiometry and bonding constant were obtained using Cieleńs model. Its stability and photostability were evaluated by chromatographic analysis and UV-Vis absorption. The MB-Curc avoids the aggregation of both isolated compounds and efficiently produces singlet oxygen (ΦΔ= 0.52 ± 0.03). Its potential for photodynamic antiangiogenic treatments was evaluated through the vascular effect observed in chicken chorioallantoic membrane (CAM) assay. The results showed intense damage in CAM vascular network by MB-Curc after irradiation, which is higher than the effect of isolated compounds, indicating a synergistic vascular effect. This combination can be essential to prevent cancer revascularization after photodynamic application and improve the efficacy of this approach. The characteristics exhibited by MB-Curc make it a potential candidate for use in cancer treatments through photodynamic antiangiogenic therapy.

Microwave-assisted synthesis of [52Mn]Mn-porphyrins: Applications in cell and liposome radiolabelling

BACKGROUND

Manganese porphyrins have several therapeutic/imaging applications, including their use as radioprotectants (in clinical trials) and as paramagnetic MRI contrast agents. The affinity of porphyrins for lipid bilayers also makes them candidates for cell/liposome labelling. We hypothesised that metalation with the positron emission tomography (PET) radionuclide 52Mn (t1/2 = 5.6 d) would allow long-term in vivo biodistribution studies of Mn-porphyrins, as well as a method to label and track cells/liposomes, but methods for fast and efficient radiolabelling are lacking.

RESULTS

Several porphyrins were produced and radiolabelled by addition to neutralised [52Mn]MnCl2 and heating using a microwave (MW) synthesiser, and compared with non-MW heating. MW radiosynthesis allowed >95 % radiochemical yields (RCY) in just 1 h. Conversely, non-MW heating at 70 °C for 1 h resulted in low RCY (0-25 % RCY) and most porphyrins did not reach radiolabelling completion after 24 h. Formation of the 52Mn-complexes were confirmed with radio-HPLC by comparison with their non-radioactive 55Mn counterparts. Following this, several [52Mn]Mn-porphyrins were used to radiolabel liposomes resulting in 75-86 % labelling efficiency (LE). Two lead [52Mn]Mn-porphyrins were taken forward to label MDA-MB-231 cancer cells in vitro, achieving ca. 11 % LE. After 24 h, 32-45 % of the [52Mn]Mn-porphyrins was retained in cells.

CONCLUSIONS

In contrast to standard methods, MW heating allows the fast synthesis of [52Mn]Mn-porphyrins with >95 % radiochemical yields that avoid purification. [52Mn]Mn-porphyrins also show promising cell/liposome labelling properties. Our reported technique can potentially be exploited for the in vivo imaging of Mn-porphyrin therapeutics, as well as for the accurate in vivo quantification of Mn-porphyrin MRI agents.

Effects of serum albumin on the photophysical characteristics of synthetic and endogenous protoporphyrin IX

The study of the interaction of synthetic protoporphyrin IX (PpIXs) and protoporphyrin IX extracted from Harderian glands of ssp Rattus novergicus albinus rats (PpIXe) with bovine serum albumin (BSA) was conducted in water at pH 7.3 and pH 4.5 by optical absorption and fluorescence spectroscopies. PpIXs is present as H- and J-aggregates in equilibrium with themselves and with monomers. The PpIXs charge is 2- at pH 7.3 and 1- at pH 4.5. This increases its aggregation at pH 4.5 and shifts the equilibrium in favor of J-aggregates. In spite of electrostatic attraction at pH 4.5, where BSA is positive, the binding constant (Kb) of PpIXs to BSA is 20% less than that at pH 7.3, where BSA is negative. This occurs because higher aggregation of PpIXs at pH 4.5 reduces the observed Kb value. At both pHs, water-soluble PpIXe exists in the monomeric form with the charge of 1- and its Kb exceeds that of PpIXs. At pH 4.5, its Kb is 12 times higher than that at pH 7.3 due to electrostatic attraction between the positively charged BSA and the negatively charged PpIXe. The higher probability of PpIXe binding to BSA makes PpIXe more promising as a fluorescence probe for fluorescence diagnostics and as a photosensitizer for photodynamic therapy. The existence of PpIXe in the monomeric form can explain its faster cell internalization. Aggregation reduces quantum yields and lifetimes of the PpIXs excited states, which explains higher phototoxicity of PpIXe toward malignant cells compared with PpIXs.

Thermal and Medium Stability Study of Polyvidone-Modified Graphene Oxide-Coated Gold Nanorods with High Photothermal Efficiency

Coating gold nanorods (AuNRs) with different materials, such as polymers and graphene-based materials, has improved their biocompatibility. However, these materials have been shown to cause the instability of AuNRs in thermal and culture mediums. In addressing this issue, we herein report the synthesis, thermal and culture medium stability, and photothermal profiling of Polyvidone (PVP)-modified graphene oxide (GO)-coated AuNRs (mGO@AuNRs). The AuNRs, with a size of 40.70 nm × 9.16 nm and absorbing at 820 nm, were coated with PVP, GO, and mGO. The colloidal stability of the nanocomposites was tested in three commonly used cell culture mediums: the Roswell Park Memorial Institute 1640 (RPMI-1640), Dulbecco's Modified Eagle Medium, (DMEM) and Dulbecco's phosphate-buffered saline (PBS) using UV-Vis-NIR and dynamic light scattering. The GO-based nanocomposites were stable compared to PVP@AuNRs and AuNRs in all mediums. The photothermal profiling of mGO@AuNRs showed higher heat production, with the photothermal conversion efficiency of 54.8%, which is higher than the bare AuNRs, GO@AuNRs, and PVP@AuNRs. In addition, the mGO@AuNRs also showed good thermal stability at 70 °C for more than 24 h. These results present the dual coating of PVP and GO as excellent stabilising agents for AuNRs with good photothermal profiling.

Graphene Oxide-Gold Nanorods Nanocomposite-Porphyrin Conjugate as Promising Tool for Cancer Phototherapy Performance

The cancer mortality rate has increased, and conventional cancer treatments are known for having many side effects. Therefore, it is imperative to find a new therapeutic agent or modify the existing therapeutic agents for better performance and efficiency. Herein, a synergetic phototherapeutic agent based on a combination of photothermal and photodynamic therapy is proposed. The phototherapeutic agent consists of water-soluble cationic porphyrin (5,10,15,20-tetrakis(N-methylpyridinium-3-yl)porphyrin, TMePyP), and gold nanorods (AuNRs) anchored on graphene-oxide (GO) sheet. The TMePyP was initially synthesized by Adler method, followed by methylation, while GO and AuNRs were synthesized using Hummer’s and seed-mediated methods, respectively. The structural and optical properties of TMePyP were confirmed using UV-Vis, zeta analyzer, PL, FTIR and NMR. The formation of both GO and AuNRs was confirmed by UV-Vis-NIR, FTIR, TEM and zeta analyzer. TMePyP and AuNRs were anchored on GO to form GO@AuNRs-TMePyP nanocomposite. The as-synthesized nanocomposite was stable in RPMI and PBS medium, and, on irradiation, produced high heat than the bare AuNRs, with high photothermal efficiency. In addition, the nanocomposite produced higher singlet oxygen than TMePyP with high biocompatibility in the absence of light. These results indicated that the as-synthesized nanocomposite is a promising dual photodynamic and photothermal agent for cancer therapy.

Immunoconjugates to increase photoinactivation of bovine alphaherpesvirus 1 in semen

Artificial insemination and in vitro embryo production are increasingly used to improve the reproductive efficiency of herds, however success of these techniques depends on the sanitary quality of the semen. Insemination centers commonly use antibiotics in their routine procedure, but they are not able against viruses. In this paper, we demonstrate a new approach for disinfecting virus in bovine semen using photoimmunoinactivation, an adaptation of the photodynamic inactivation (PDI) methodology. The photosensitizers (PSs), hematoporphyrin (HP) and zinc tetracarboxy-phthalocyanine (ZnPc) were conjugated to Immunoglobulin Y (IgY) anti-bovine alphaherpesvirus 1 (BoHV-1) and used for PDI against the BoHV-1 viruses in cell culture and compared to the unconjugated PSs. Both treatments proved to be efficient, but a significant decrease in the irradiation time required to completely eliminate the virus was observed in the samples treated with the immunoconjugates. Photophysical measurements help us to understand the coupling between PSs and IgY and the evaluated production of singlet oxygen. Following the cell culture test, the same approach was applied in semen artificially infected with BoHV-1. The immunoconjugates were also efficient for complete virus inactivation up to 5 min of irradiation and proved to be safe using several parameters of sperm viability, demonstrating the feasibility of our strategy for disinfection viruses in semen.