The role of the central metal ion of ethane-bridged bis-porphyrins in histidine sensing

Porphysome Engineered With Specific Protein Binding Sites as a Multimodal Theranostic Nanocarrier for Targeted Protein Delivery

The immobilization of proteins on the surface of carriers is challenging due to the loss of protein structure and function in this process. Here, we report the development of the protein immobilization on the surface of the metallated-porphyrin complex in the porphysome nanocarrier. The conjugated Ni-porphyrin to fatty acid (as a tail) has been synthesized and independently placed at the depth of the bilayer center of Dipalmitoylphosphatidylcholine (DPPC) in which the Ni-porphyrin was at the polar region of the membrane and is thus superficial. This porphysome (DPPC: Ni-porphyrin, 4 : 1 mole ratio) was formed by supramolecular self-assembly with a diameter of 173±7 nm and zeta potential -8.5±3.4 mv, which exhibited no significant toxicity at the experimental concentrations and acceptable cellular uptake on MCF-7 cells. The physicochemical properties and specific protein binding sites of the firefly luciferase as a model protein into the porphysome (1 : 2 mole ratio) show the conjugation efficiency about 80 % and the conformation of protein was completely maintained. Furthermore, bioluminescence assay and SDS-PAGE confirmed the preservation of protein function. The stabilized platform of porphyrin-lipid structure can potentially improve the efficacy of protein functionality for a particular display, shifting porphysomes from a simple carrier to a therapeutic agent.

Synergistic antibacterial effect of the pistachio green hull extract-loaded porphysome decorated with 4-nitroimidazole against bacteria

'Active targeting' refers to modifying a nanocarrier's surface with targeting ligands. This study introduced an efficient approach for immobilizing imidazole-based drugs onto the metallated-porphyrin complex within the porphysome nanocarrier. To enhance cellular and bacterial uptake, a Ni-porphyrin with a fatty acid tail was synthesized and placed in the bilayer center of DPPC, facilitating receptor-mediated endocytosis. The Ni-porphyrin in the head group of the Ni-porphyrin-tail was placed superficially in the polar region of the membrane. Spherical unilamellar vesicle formation (DPPC: Ni-porphyrin-tail 4:1 mole ratio), as metallo-porphysome, was achieved through supramolecular self-assembly in an aqueous buffer. These vesicles exhibited a diameter of 279 ± 7 nm and a zeta potential of -15.3 ± 2.5 mV, showcasing their unique cytocompatibility. Nitroimidazole was decorated on the surface of metallo-porphysomes and pistachio green hull extract (PGHE) was loaded into the carrier for synergistic activity against (E. coli) and (S. aureus) bacteria strains. The physicochemical properties of Nitroimidazole-porphysome-PGHE, including size, zeta potential, morphology, loading efficiency, and release profile under various pH and temperature conditions in simulated gastrointestinal fluids were characterized. This combination therapy prevented bacterial cell attachment and biofilm formation in Caco-2 cells, as colon epithelial cells. The remarkable benefit of this system is that it does not affect cell viability even at 0.5 mg/ml. This study demonstrates the potential of a new co-delivery system using biocompatible metallo-porphysomes to decrease bacterial infections.

Causal associations of histidine and 12 site-specific cancers: a bidirectional Mendelian randomization study

An increasing number of studies indicate that cancer patients' histidine (HIS) circulating levels have changed. However, the causality between HIS and cancer is still not well established. Thus, to ascertain the causal link between HIS and cancers, we performed a bidirectional Mendelian randomization (MR) analysis. Summary-level data are derived from publicly available genome-wide association studies (GWAS). The causal effects were mainly estimated using the inverse-variance weighted method (IVW). The weighted-median (WM) method and MR-Egger regression were conducted as sensitivity analyses. In the forward-MR, we found malignant neoplasm of respiratory system and intrathoracic organs (OR: 1.020; 95% CI: 1.006-1.035; pIVW = 0.007) genetically associated with circulating HIS. And there was no significant genetic correlation between HIS and another 11 site-specific cancers using IVW method. In the reversed-MR, we did not observe the causal relationship between HIS and 12 site-specific cancers. Our findings help clarify that HIS, as a biomarker for malignant neoplasms of respiratory system and intrathoracic organs, is causal rather than a secondary biomarker of the cancerous progression. The mechanism between histidine and cancer progression deserves further investigation.

Organic-Inorganic Porphyrinoid Frameworks for Biomolecule Sensing

Porphyrinoids and their analogous compounds play an important role in biosensing applications on account of their unique and versatile catalytic, coordination, photophysical, and electrochemical properties. Their remarkable arrays of properties can be finely tuned by synthetically modifying the porphyrinoid ring and varying the various structural parameters such as peripheral functionalization, metal coordination, and covalent or physical conjugation with other organic or inorganic scaffolds such as nanoparticles, metal-organic frameworks, and polymers. Porphyrinoids and their organic-inorganic conjugates are not only used as responsive materials but also utilized for the immobilization and embedding of biomolecules for applications in wearable devices, fast sensing devices, and other functional materials. The present review delineates the impact of different porphyrinoid conjugates on their physicochemical properties and their specificity as biosensors in a range of applications. The newest porphyrinoid types and their synthesis, modification, and functionalization are presented along with their advantages and performance improvements.

Functionalization of an extended-gate field-effect transistor (EGFET) for bacteria detection

Traditional sensing technologies have drawbacks as they are time-consuming, cost-intensive, and do not attain the required accuracy and reproducibility. Therefore, new methods of measurements are necessary to improve the detection of bacteria. Well-established electrical measurement methods can connect high sensitive sensing systems with biological requirements. One approach is to functionalize an extended-gate field-effect transistor's (EGFET) sensing area with modified porphyrins containing two different linkers. One linker connects the electrode surface with the porphyrin. The other linker bonds bacteria on the functional layer through a specific peptide chain. The negative charge on the surface of the cells regulates the surface potential which has an impact on the electrical behavior of the EGFET. The attendance of attached bacteria on the functionalized sensing area could successfully be detected.

Enantioselective Discrimination of Histidine by Means of an Achiral Cubane-Bridged Bis-Porphyrin

A Langmuir film of cubane-bridged bisporphyrin (H₂por-cubane-H₂por) at the air/water interface was developed and characterized. The floating film was successfully employed for the chiral discrimination between l- and d-histidine. The enantioselective behavior persisted after the deposition of the film on a solid support using the Langmuir-Schaefer method. Distinct absorption and reflection spectra were observed in the presence of l- or d-histidine, revealing that conformational switching was governed by the interaction between H₂por-cubane-H₂por and the histidine enantiomer. The mechanism of chiral selection was investigated using an ad hoc modified nulling ellipsometer, indicating the anti-conformation was dominant in the presence of l-histidine, whereas the presence of d-histidine promoted the formation of tweezer conformation.

A2BC-Type Porphyrin SAM on Gold Surface for Bacteria Detection Applications: Synthesis and Surface Functionalization

Currently used elaborate technologies for the detection of bacteria can be improved in regard to their time consumption, labor intensity, accuracy and reproducibility. Well-known electrical measurement methods might connect highly sensitive sensing systems with biological requirements. The development of modified sensor surfaces with self-assembled monolayers (SAMs) from functionalized porphyrin for bacteria trapping can lead to a highly sensitive sensor for bacteria detection. Different A₂BC-type porphyrin structures were synthesized and examined regarding their optical behavior. We achieved the synthesis of a porphyrin for SAM formation on a gold surface as electrode material. Two possible bio linkers were attached on the opposite meso-position of the porphyrin, which allows the porphyrin to react as a linker on the surface for bacteria trapping. Different porphyrin structures were attached to a gold surface, the SAM formation and the respective coverage was investigated.

Porphyrins as Colorimetric and Photometric Biosensors in Modern Bioanalytical Systems

Advances in porphyrin chemistry have provided novel materials and exciting technologies for bioanalysis such as colorimetric sensor array (CSA), photo-electrochemical (PEC) biosensing, and nanocomposites as peroxidase mimetics for glucose detection. This review highlights selected recent advances in the construction of supramolecular assemblies based on the porphyrin macrocycle that provide recognition of various biologically important entities through the unique porphyrin properties associated with colorimetry, spectrophotometry, and photo-electrochemistry.

Perylene Bisimide Aggregates as Probes for Subnanomolar Discrimination of Aromatic Biogenic Amines

Perylene bisimide derivatives show peculiar physical chemical features, such as a highly conjugated system, high extinction coefficients and elevated fluorescence quantum yields, making them suitable for the development of optical sensors of compounds of interest. In particular, they are characterized by the tendency to aggregate into π-π stacked supramolecular structures. In this contribution, the behavior of the PBI derivative N, N'-bis(2-(trimethylammonium)ethylene)perylene bisimide dichloride was investigated both in aqueous solution and on solid support. The electronic communication between PBI aggregates and biogenic amines was exploited in order to discriminate aromatic amines down to subnanomolar concentrations by observing PBI fluorescence variations in the presence of various amines and at different concentrations. The experimental findings were corroborated by density functional theory calculations. In particular, phenylethylamine and tyramine were demonstrated to be selectively detected down to 10^-10 M concentration. Then, in order to develop a surface plasmon resonance (SPR) device, PBI was deposited onto a SPR support by means of the layer-by-layer method. PBI was deposited in the aggregated form and was demonstrated to preserve the capability to discriminate, selectively and with an outstanding analytical sensitivity, tyramine in the vapor phase and even if mixed with other aromatic amines.

Carbon nanodot-based heterostructures for improving the charge separation and the photocurrent generation

The possibility to employ carbon nanodots (CNDs) in solar devices was exploited by combining them with a fulleropyrrolidine derivative (FP2). The interaction between the two species was promoted by the presence of opposite electrostatic charges on CNDs (negatively charged) and FP2 (positively charged). The supramolecular dyad CNDs/FP2 generation was induced at the air/water interface of a Langmuir trough: water soluble CNDs were dissolved in the subphase and FP2 chloroform solution was spread on the subphase; the electrostatic interaction promoted the formation of the supramolecular adduct FP2/CNDs, which was then transferred onto solid substrates. Photo-induced charge transfer was promoted in the FP2/CNDs dyad and we demonstrated that the presence of CNDs increased the short-circuit current density, under light illumination, of a porphyrin-FP2/CNDs thin film by about 300% when compared with a more traditional porphyrin-FP2 solar device.

Subtle chemical modification for enrichment of Fmoc-amino acid at a phospholipid interface

Amino acids including the Fmoc group (9-fluorenylmethyloxycarbonyl) are bioinspired molecules that display intriguing features in self-assembly and biological applications. The influence of a delicate chemical modification between Fmoc-F and Fmoc-Y on the interaction with a phospholipid surface was analyzed. Langmuir monolayers of the 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA) phospholipid were used to mimic the eukaryotic cell membrane. In situ Brewster angle microscopy and UV-vis reflection spectroscopy provided insights on the effect of the Fmoc-amino acid derivatives on the DMPA phospholipid. The formation of H-bonds between the Fmoc-Y and the DMPA molecules was assessed, demonstrating the crucial role of the hydroxyl group of Fmoc-Y in enhancing the interaction with biosurfaces.

A modest chemical modification of the Fmoc-amino acids led to enhanced interaction with a model surface for biomembrane.