Current Knowledge on Mammalian Phospholipase A1, Brief History,Structures, Biochemical and Pathophysiological Roles

Phospholipase A₁ (PLA₁) is an enzyme that cleaves an ester bond at the sn-1 position of glycerophospholipids, producing a free fatty acid and a lysophospholipid. PLA₁ activities have been detected both extracellularly and intracellularly, which are well conserved in higher eukaryotes, including fish and mammals. All extracellular PLA₁s belong to the lipase family. In addition to PLA₁ activity, most mammalian extracellular PLA₁s exhibit lipase activity to hydrolyze triacylglycerol, cleaving the fatty acid and contributing to its absorption into the intestinal tract and tissues. Some extracellular PLA₁s exhibit PLA₁ activities specific to phosphatidic acid (PA) or phosphatidylserine (PS) and serve to produce lysophospholipid mediators such as lysophosphatidic acid (LPA) and lysophosphatidylserine (LysoPS). A high level of PLA₁ activity has been detected in the cytosol fractions, where PA-PLA₁/DDHD1/iPLA₁ was responsible for the activity. Many homologs of PA-PLA₁ and PLA₂ have been shown to exhibit PLA₁ activity. Although much has been learned about the pathophysiological roles of PLA₁ molecules through studies of knockout mice and human genetic diseases, many questions regarding their biochemical properties, including their genuine in vivo substrate, remain elusive.     

Mechanism and Influencing Factors of Wettability Alteration of Water-Wet Sandstone Surface by CTAB

Different experimental methods including ellipsometry, zeta potential measurements, imbibition studies, and contact angle measurements were used to study the mechanism and influencing factors of wettability alteration of water-wet sandstone surface caused by CTAB (hexadecyl trimethyl ammonium bromide). Results show that when the concentration of CTAB reaches a certain level (below CMC), due to the electrostatic attraction between the positively charged head groups of CTAB and the negatively charged sandstone surface, the monolayer of CTAB is formed and hydrophobic chains of CTAB molecules are toward the aqueous phase, making the solid surface oil-wet. When the concentration of CTAB continues to increase (above CMC), due to the hydrophobic interaction, the compact bilayer of CTAB is formed and hydrophilic head groups of CTAB molecules are toward the aqueous phase, rendering the solid surface water-wet. The contact angles between the oil–water interface and the surface treated with CTAB increase with the increase of the concentration of NaCl and CaCl_2. Compared to NaCl, the inorganic salt CaCl₂ has a greater impact on the contact angle. In addition, the contact angles increase with the increase of temperature and decrease with the increase of pH value of the aqueous solution.     

Changes of zeta potential and particles size of silica caused by DPPC adsorption and enzyme phospholipase A2 presence

The changes in electrokinetic properties of silica suspensions in the presence of 1,2-dipalmitoyl-sn-glycero-3-phospshocholine (DPPC) were investigated via zeta potential, mean diameter and transmittance determinations. Silica particles were precovered with monolayer (ML) or bilayer (BL) of the phospholopid from chloroform solution (SiO₂/DPPC) or covered by DPPC adsorption from aqueous solution (SiO₂+DPPC). The zeta potential and mean diameter of SiO₂/DPPC suspension were measured as a function of NaCl concentration and due to the phospholipase A₂(PLA₂) action in 10^?3 M NaCl solution and buffer Tris at pH=8 and 9. It was found that the DPPC adsorption onto silica surface decreases its the zeta potential, however the suspensions were stable during the experiment time, probably because of steric stabilization. During PLA₂ enzyme action the changes in zeta potential were observed, which were caused by the hydrolysis products, especially palmitic acid molecules, which also had influence on the stability of these systems.     

Effect of surface charge on adsorption of bovine serum albumin 2. Interaction of protein molecules with an anionic monolayer,as studied by ellipsometry,radiotracer and surface tension measurements

The adsorption of bovine serum albumin (BSA) onto an anionic monolayer of sodium docosylsulfate (SDocS) spread at the air/water interface was studied by ellipsometry. The adsorption behavior of BSA was estimated from the observed changes in phase differences and in the ratio of reflection coefficients. The dynamic process of BSA adsorption was measured after the injection of BSA solution into the aqueous substrate of SDocS monolayer. The gentle stirring of the substrate solution for 10 min was found to be enough to make the solution homogeneous without damaging the monolayer. The adsorption characteristics of BSA onto a negatively charged surface was compared with that onto a positively charged surface previously reported.The amount of adsorption depended on time and showed a maximum with an initial rapid rise, followed by gradual decrease toward the ultimate equilibrium value. The amount and time of the maximum adsorption depended on the concentration of BSA added to the aqueous substrate.Separate radiotracer measurement, using³⁵S-labeled SDocS monolayer, which is insoluble by itself, revealed that SDocS is solubilized into the bulk solution when BSA is added to the aqueous substrate.     

Sum-frequency spectroscopic study of Langmuir monolayers of lipids having oppositely charged headgroups

Sum-frequency vibrational spectroscopy, with the help of surface pressure-area (π-A) isotherm, was used to study lipid Langmuir monolayers composed of molecules with positively and negatively charged headgroups as well as a 1:1 neutral mixture of the two. The spectral profiles of the CH(x) stretch vibrations are similar for all monolayers in the liquid-condensed (LC) phase. They suggest a monolayer structure of closely packed alkyl chains that are nearly all-trans and well oriented along the surface normal. In the liquid-expanded (LE) phase, the spectra of all monolayers appear characteristic of loosely packed chains with significant gauche defects. The OH stretch spectra of interfacial water for both positively and negatively charged monolayers are significantly enhanced in comparison with a neutral water interface, but the phase measurement of SFVS indicates that OH in the two cases points toward the bulk and the interface, respectively. The enhancement results mainly from surface-field-induced polar ordering of interfacial water molecules. For a charge-neutral monolayer composed of an equal number of positively and negatively charged lipid molecules, no such enhancement is observed. This mixed monolayer exhibits a wide range of LC/LE coexistence region extended to very low surface pressure and its CH(x) spectral profile in the coexistence region resembles that of the LC phase. This result suggests that in the LC/LE coexistence region, the mixed monolayer consists of coexisting LC and LE patches in which oppositely charged lipid molecules are homogeneously mixed and dispersed.     

A procedure for studying the sorption of ethanol vapor on a monomolecular Langmuir-Blodgett arachic acid film

The paper presents the results of studies of the sorption of ethanol from the gas phase by a monomolecular arachic acid layer deposited by the Langmuir-Blodgett method onto the surface of a nickel substrate. Studies were performed using a working model based on a field-effect transistor. Sorption was accompanied by changes in the potential of the nickel substrate. The dependence of transistor current I _D on time t was related to the conditions of Langmuir-Blodgett film deposition. The value and characteristic time of signal variations as the atmosphere changed depended on the pressure of monolayer deposition and, therefore, monolayer phase state on the surface of water when it was transferred to the solid substrate. The experimental I _D (t) dependence was compared with the time dependence of arachic monolayer surface coverage with sorbent molecules calculated by the Langmuir model. The conclusion was drawn that the model was capable of describing the sorption of ethanol vapor by the Langmuir-Blodgett arachic acid monolayer at low partial pressures p ≤ 0.05p ₀, where p ₀ is the saturated vapor pressure.     

Adsorption monitoring of phospho-l-serine on hydroxyapatite

The adsorption of the aminoacid phospho-l-serine (PLS) on the surface of hydroxyapatite {Ca₅(PO₄)₃OH, HAP}, was investigated using streaming potential measurements. Solutions saturated with respect to HAP, containing different concentrations of PLS, were brought in contact under carefully controlled flow conditions through plugs made of well dispersed HAP powder. The measurement of PLS adsorption during the equilibration of the solute with the HAP substrate, showed a plateau regime corresponding, according to geometrical considerations, to monolayer surface coverage. The PLS uptake measurements on HAP suggested that it is possible to monitor in situ adsorption during the monolayer surface coverage measuring the streaming potential of HAP. Analysis of the surface potential measurements suggested that during the monolayer surface coverage step, the negatively charged (HL^2?) PLS species were adsorbed. The adsorbed HL^2? was located at the inner Helmholtz plane of the electrical double layer, forming surface complexes with the positively charged ≡CaOH ₂ ⁺ sites on the surface of HAP. The rate constants of adsorption and desorption were calculated from the kinetics of adsorption of PLS on HAP.     

Flexible NH3 sensors fabricated by in situ self-assembly of polypyrrole

Novel flexible NH₃ gas sensors were formed by the in situ self-assembly of polypyrrole (PPy) on plastic substrates. A negatively charged substrate was prepared by the formation of an organic monolayer (3-mercapto-1-propanesulfonic acid sodium salt—MPS) on a polyester (PET) substrate using a pair of comb-like Au electrodes. Two-cycle poly(4-styrenesulfonic acid) sodium salt/poly(allylamine hydrochloride) (PSS/PAH) bilayers (precursor layer) were then layer-by-layer (LBL) deposited on an MPS-modified substrate. Finally, a monolayer of PPy self-assembled in situ and PPy multilayer thin films self-assembled LBL in situ on a (PSS/PAH)₂/MPS/Au/Cr/PET substrate. The thin films were analyzed by atomic force microscopy (AFM). The effects of the precursor layer (PSS), the deposition time of the monolayer of PPy and the number of PPy multilayers on the gas sensing properties (response) and the flexibility of the sensors were investigated to optimize the fabrication of the film. Additionally, other sensing properties such as sensing linearity, reproducibility, response and recovery times, as well as cross-sensitivity effects were studied. The flexible NH₃ gas sensor exhibited a strong response that was comparable to or even greater than that of sensors that were fabricated on rigid substrate at room temperature.     

Biomolecular Release Stimulated by Electrochemical Signals at a Very Small Potential Applied

DNA release electrochemically stimulated by applying ?10 mV on the modified electrode was studied. The release process was based on the local (interfacial) pH change produced upon H₂O₂ reduction electrocatalyzed by the immobilized microperoxidase‐11. SiO₂ nanoparticles attached to the electrode surface and functionalized with trigonelline and boronic acid species changed their electrical charge from positive to negative upon the interfacial pH change, thus allowing electrostatic adsorption of negatively charged DNA on the positive interface and then its repulsion/release from the negative interface. The loaded/released DNA molecules were labeled with a fluorescent dye to allow easy detection of the released DNA molecules. The important feature of the developed system is the controlled DNA release upon applying very small electrical potential on the modified electrode.     

Biochemical,Kinetic and Biological Properties of Group V Phospholipase A2 from Dromedary

Secretory group V phospholipase A2 (PLA₂-V) is known to be involved in inflammatory processes in cellular studies, nevertheless, the biochemical and the enzymatic characteristics of this important enzyme have been unclear yet. We reported, as a first step towards understanding the biochemical properties, catalytic characteristics, antimicrobial and cytotoxic effects of this PLA₂, the production of PLA₂-V from dromedary. The obtained DrPLA₂-V has an absolute requirement for Ca²⁺ and NaTDC for enzymatic activity with an optimum pH of 9 and temperature of 45 °C with phosphatidylethanolamine as a substrate. Kinetic parameters showed that K_cat/Km_app is 2.6 ± 0.02 mM⁻¹ s⁻¹. The enzyme was found to display potent Gram-positive bactericidal activity (with IC50 values of about 5 µg/mL) and antifungal activity (with IC50 values of about 25 µg/mL)in vitro. However, the purified enzyme did not display a cytotoxic effect against cancer cells.     

Substrate induced ordered structures in monomolecular adlayers

The monolayer structure of 1,4-didodecylbenzene (DDB) at the interface between organic solutions and the basal planes of single crystalline MoSe₂ and MoS₂ has been investigated in situ by scanning tunnelling microscopy (STM), and compared to the corresponding monolayer structures on graphite, as well as to the monolayer structure of a long-chain alkane, dotriacontane. Common to the structures on all substrates is the fact that they are (1) close packed, (2) oriented relative to the substrate lattices, and (3) not simply commensurate to the substrates. However, details of the structures, including the unit cell symmetries, do depend on the particular substrate. It is concluded that for flexible and non-covalently bound chain molecules the atomic flatness of the substrate generally favours a high degree of order in the molecular adsorbate. The specific molecular structures depend on the particular surface properties of the substrate, i.e. lattice constants and corrugation of the adsorption potential across the surface. The less symmetric unit cells of DDB on the molybdenum dichalcogenides, when compared to the unit cell on graphite, is attributed to the larger corrugation in the adsorption potentials, which in turn is due to the larger lattice constants of the dichalcogenides.     

Action of Humicola lanuginosa lipase on long-chain lipid substrates: 2. Hydrolysis of diolein monolayers

The hydrolysis of 1,2-diolein (DO) monomolecular films by Humicola lanuginosa lipase (HLL) was studied by simultaneous measuring the decrease in the film area and the changes in the surface potential in the “zero-order trough” at constant surface pressure and in the presence of β-cyclodextrin (β-CD). The decrease with time in the film area reflects both the reduction in the area per molecule due to the transformation of substrate DO molecules into the products molecules of monoolein (MO) and oleic acid (OA) and the desorption of the soluble inclusion complexes β-CD–MO and β-CD–OA. The surface potential data were interpreted as an accumulation at the interface of negatively charged products of OA and insoluble β-CD–DO complexes. In the proposed kinetic model, the product solubilization rates in the presence of β-CD and the flux supplied progressively by the moving barrier from the reservoir to the reaction compartment in order to keep the constant surface pressure were taken into account. The surface concentrations of MO and OA transiently present at the interface were determined. The values of the global kinetic constant Q_m′ of hydrolysis of DO to MO were obtained. Comparison with the values of the global kinetic constant of hydrolysis of monoglyceride MO to OA shows that the rates of hydrolysis of diglyceride and monoglyceride by HLL are of the same order of magnitude.     

A rapid fluorometric assay for the determination of serum phospholipase A2 activity

Phospholipase A₂ (PLA₂) is an enzyme that cleaves fatty acids from the sn-2 position of membrane phospholipids. Intracellular PLA₂ has been shown to be important for the generation of arachidonic acid, which leads to the synthesis of a wide range of eicosanoid paracrine hormones. Furthermore, secretory PLA₂ in the serum has been reported to exhibit important immune activities. In this study, BODIPY™ FL C₁₆ was used as a fluorescent probe to measure PLA₂ activity in the serum of the American alligator. The activity measured was dependent on the amounts of serum and labeled bacteria incubated. The phospholipase activity was also time-dependent, with near peak activities observed within 20-30 min. In addition, the observed activity was titrated away by increasing concentrations of unlabeled bacteria, indicating that the activity observed was specifically due to the presence of PLA₂. The assay provides rapid results and requires only small amounts of serum.     

Fast method for monitoring phospholipase A2 activity by liquid chromatography–electrospray ionization mass spectrometry

A new liquid chromatography–electrospray ionization mass spectrometry (LC–ESI-MS) method for the fast determination of phospholipase A₂ (PLA₂) activity has been developed. For the first time, the method allows the parallel detection of glycerophosphatidylcholine (GroPCho) as PLA₂ substrate as well as of its products fatty acid (FA) and lyso-GroPCho. ESI-MS was carried out in negative ion mode, detecting the FA as [M − H]⁻ ions and the lyso-GroPCho and GroPCho as acetate adducts [M + Ac]⁻. Utilizing a fast gradient on a short C₅-modified silica gel column with 3 μm particles, five GroPChos, five FAs and six lyso-GroPChos could be separated according to their chain length in less than 3 min. A very high average chromatographic efficiency of 41,200 theoretical plates (plate height 0.5 μm) was achieved for the separation of the GroPChos. The method was applied for monitoring the release of arachidonic acid (20:4 FA) and 1-stearoyl-lyso-sn-GroPCho (18:0 GroPCho) from unilamellar vesicles of 1-stearoyl-2-arachidonoyl-sn-GroPCho (18:0/20:4 GroPCho). With a limit of detection of 0.5 pmol (total amount injected on column) for the FAs and lyso-GroPChos and 1.5 pmol for the GroPChos as well as a linear range of 1.5 decades, the method has proven to be suitable for the monitoring of different secretory PLA₂ (sPLA₂) conversions. Furthermore, it was applied to screen a small library of PLA₂ inhibitors for their activity towards sPLA₂ type V and snake venom of Bothrops moojeni. In both cases, active samples could be directly identified. With its short analysis time, its high chromatographic efficiency and the parallel detection of substrate and all products, the developed LC–ESI-MS method is well suited for the analysis of PLA₂ activity.     

The role of interface in photo processes in photoconductive heterophase composites based on monolayer dispersions of molybdenum disulfide

Two-layer heterostructures with a high yield of charged current carriers were obtained and investigated. The heterostructures comprised monolayer dispersions of MoS₂ in polyvinyl alcohol as the lower layer and the upper p-, n-, or bipolar transport layer (TL). It was found that dark conductivity of the two-layer heterostructures increased considerably compared with the conductivity of reference samples based on TL but containing no MoS₂. After excitation from the TL side, maximum photoelectric sensitivity was obtained where TL long-wave absorption decreased and there was a high concentration of TL excited states at the interface that interacted with the surface of MoS₂ particles. This interaction quenched the luminescence of TL transport centers and led to the photogeneration of both positively and negatively charged current carriers at the interface. Luminescence quenching could be of 50–60% at high MoS₂ contents in the lower layer (90–100 wt %). This was evidence that the contact area of MoS₂ particles with the polymeric transport layer exceeded the geometric interface dimensions and the interface had a relief surface (was fairly thick). It was found that the donor-acceptor properties of both MoS₂ and the polymeric TL were very important for the photogeneration of charge carriers at the interface. When the MoS₂ content in the lower layer was maximum, the effectiveness of the accumulation of minority carriers increased because of the formation of an alternative transport network associated with MoS₂ particles. The conclusion was drawn that the photogeneration of charges at the interface resulted from the phototransfer of electrons between MoS₂ particles and TL excited states.     

Influence of environmental conditions on the interfacial organisation of fengycin, a bioactive lipopeptide produced by Bacillus subtilis

The effect of the environmental conditions both on the behaviour of fengycin at the air-aqueous interface and on its interaction with DPPC was studied using surface pressure-area isotherms and AFM. The ionisation state of fengycin is at the origin of its monolayer interfacial properties. The most organised interfacial arrangement is obtained when fengycin behaves as if having zero net charge (pH 2). In a fully ionised state (pH 7.4), the organisation and the stability of fengycin monolayers depend on the ionic strength in the subphase. This can modulate the surface potential of fengycin and consequently the electrostatic repulsions inside the interfacial monolayer, as well as the lipopeptide interaction with the layer of water molecules forming the air-water interface. Intermolecular interactions of fengycin with DPPC are also strongly affected by the ionisation state of lipopeptide and the surface pressure (Pi) of the monolayer. A better miscibility between both interfacial components is observed at pH 2, while negatively charged lipopeptide molecules are segregated from the DPPC phase. A progressive desorption of fengycin from the interface is observed at pH 7.4 when Pi increases while at pH 2, fengycin desorption brutally occurs when Pi rises above Pi value of the intermediate plateau.     

Efficacy and Limitations of Chemically Diverse Small-Molecule Enzyme-Inhibitors against the Synergistic Coagulotoxic Activities of Bitis Viper Venoms

Snakebite remains a significant public health burden globally, disproportionately affecting low-income and impoverished regions of the world. Recently, researchers have begun to focus on the use of small-molecule inhibitors as potential candidates for the neutralisation of key snake venom toxins and as potential field therapies. Bitis vipers represent some of the most medically important as well as frequently encountered snake species in Africa, with a number of species possessing anticoagulant phospholipase A₂ (PLA₂) toxins that prevent the prothrombinase complex from inducing clot formation. Additionally, species within the genus are known to exert pseudo-procoagulant activity, whereby kallikrein enzymatic toxins cleave fibrinogen to form a weak fibrin clot that rapidly degrades, thereby depleting fibrinogen levels and contributing to the net anticoagulant state. Utilising well-validated coagulation assays measuring time until clot formation, this study addresses the in vitro efficacy of three small molecule enzyme inhibitors (marimastat, prinomastat and varespladib) in neutralising these aforementioned activities. The PLA₂ inhibitor varespladib showed the greatest efficacy for the neutralisation of PLA₂-driven anticoagulant venom activity, with the metalloproteinase inhibitors prinomastat and marimastat both showing low and highly variable degrees of cross-neutralisation with PLA₂ anticoagulant toxicity. However, none of the inhibitors showed efficacy in neutralising the pseudo-procoagulant venom activity exerted by the venom of B. caudalis. Our results highlight the complex nature of snake venoms, for which single-compound treatments will not be universally effective, but combinations might prove highly effective. Despite the limitations of these inhibitors with regards to in vitro kallikrein enzyme pseudo-procoagulant venom activity, our results further support the growing body of literature indicating the potential use of small molecule inhibitors to enhance first-aid treatment of snakebite envenoming, particularly in cases where hospital and thus antivenom treatment is either unavailable or far away.     

The production and verification of pristine semi-fluorinated thiol monolayers on gold

In this work the interaction between human serum albumin (HSA) and a monofluorinated phospholipid, 1-palmitoyl-2-[16-fluoropalmitoyl-phosphatidylcholine] (F-DPPC), was studied by using Langmuir monolayer and Brewster angle microscopy (BAM) techniques. Different amounts of F-DPPC were spread on a previously formed HSA monolayer located at the air/water interface at 25 °C and the mixed monolayers thus obtained showed the existence of a liquid expanded-liquid condensed (LE-LC) phase transition (at 14 mN/m), attributed to the pure F-DPPC monolayer, coexisting with a second transition (at 22-24 mN/m) corresponding to the protein conformational change from an unfolded state to another in “loops” configuration. Relative thickness measurements recorded during the compression of the mixed monolayers showed the existence of an “exclusion” surface pressure (π_exc), above which the protein is squeezed out the interface, but not totally. BAM images reveal that some protein molecules in a packed “loops” configuration remain at the interface at surface pressures higher than the “exclusion” surface pressure. The application of the Defay-Crisp phase rule to the phase diagram of the F-DPPC/HSA system can explain the existence of certain regions of surface pressure in which the mixed monolayer components are miscible, as well as those others that they are immiscible.     

Phloroglucinol as a Potential Candidate against Trypanosoma congolense Infection: Insights from In Vivo,In Vitro,Molecular Docking and Molecular Dynamic Simulation Analyses

Sub-Saharan Africa is profoundly challenged with African Animal Trypanosomiasis and the available trypanocides are faced with drawbacks, necessitating the search for novel agents. Herein, the chemotherapeutic potential of phloroglucinol on T. congolense infection and its inhibitory effects on the partially purified T. congolense sialidase and phospholipase A₂ (PLA₂) were investigated. Treatment with phloroglucinol for 14 days significantly (p < 0.05) suppressed T. congolense proliferation, increased animal survival and ameliorated anemia induced by the parasite. Using biochemical and histopathological analyses, phloroglucinol was found to prevent renal damages and splenomegaly, besides its protection against T. congolense-associated increase in free serum sialic acids in infected animals. Moreover, the compound inhibited bloodstream T. congolense sialidase via mixed inhibition pattern with inhibition binding constant (Ki) of 0.181 µM, but a very low uncompetitive inhibitory effects against PLA₂ (Ki > 9000 µM) was recorded. Molecular docking studies revealed binding energies of −4.9 and −5.3 kcal/mol between phloroglucinol with modeled sialidase and PLA₂ respectively, while a 50 ns molecular dynamics simulation using GROMACS revealed the sialidase-phloroglucinol complex to be more compact and stable with higher free binding energy (−67.84 ± 0.50 kJ/mol) than PLA₂-phloroglucinol complex (−77.17 ± 0.52 kJ/mol), based on MM-PBSA analysis. The sialidase-phloroglucinol complex had a single hydrogen bond interaction with Ser453 while none was observed for the PLA₂-phloroglucinol complex. In conclusion, phloroglucinol showed moderate trypanostatic activity with great potential in ameliorating some of the parasite-induced pathologies and its anti-anemic effects might be linked to inhibition of sialidase rather than PLA₂.     

Photoelectrochemical study of organic–inorganic hybrid thin films via electrostatic layer-by-layer assembly

The stepwise assembly of negatively charged organic molecules (poly(sodium 4-styrenesulfonate) (PSS) or tetrasodium-meso-tetra(4-sulfonatophenyl) porphine (TPPS)) and positively charged TiO₂ colloids on pretreated substrate surfaces utilizing the layer-by-layer (LbL) approach was investigated. The step-by-step formation of these films was studied by UV–vis spectrophotometry and electrochemistry. Photocurrent was generated upon light irradiation of the hybrid thin films assembled on fluorine-doped tin oxide (FTO) conducting glass, which increased linearly as the deposited bilayers increased. In addition, compared to PSS/TiO₂ hybrid thin films, the enhancement of the generated photocurrent and the photocurrent response within the wavelength range from 400 to 450 nm were observed in the TPPS/TiO₂ hybrid thin films. This was attributed to the dye-sensitized effect of the layered TPPS molecules. It was demonstrated that electrostatic LbL films were attractive systems for the photoelectrochemical investigation, and the control of the generated photocurrent could be achieved by the structure of the multilayered films.