Biological responses to imazapic and methyl parathion pesticides in bioinspired lipid membranes and Tilapia fish.

Pesticide misuse has well-documented detrimental effects on ecosystems, with Nile tilapia (Oreochromis niloticus) being particularly vulnerable. The current study focuses on the impact of widely used sugarcane crop pesticides, Imazapic (IMZ) and Methyl Parathion (MP), on tilapia gill tissues and their lipid membranes. This investigation was motivated by the specific role of the lipid membrane in transport regulation. Bioinspired cell membrane models, including Langmuir monolayers and liposomes (LUVs and GUVs), were utilized to explore the interaction of IMZ and MP. The results revealed electrostatic interactions between IMZ and MP and the polar head groups of lipids, inducing morphological alterations in the lipid bilayer. Tilapia gill tissue exposed to the pesticides exhibited hypertrophic increases in primary and secondary lamellae, total lamellar fusion, vasodilation, and lifting of the secondary lamellar epithelium. These alterations can lead to compromised oxygen absorption by fish and subsequent mortality. This study not only highlights the harmful effects of the pesticides IMZ and MP, but also emphasizes the crucial role of water quality in ecosystem well-being, even at minimal pesticide concentrations. Understanding these impacts can better inform management practices to safeguard aquatic organisms and preserve ecosystem health in pesticide-affected environments.

Different compact hybrid Langmuir-Blodgett-film coatings modify biomineralization and the ability of osteoblasts to grow.

Calcium phosphates (CaPs) are biomaterials widely used in tissue regeneration with outstanding biological performance. Although the tremendous improvements achieved in CaP's materials research over the years, their interaction with physiological environments still need to be fully understood. The aim of this study is to explore a biomimetic Langmuir-Blodgett (LB) membrane to template the growth of hydroxyapatite (HAp) coatings on Ti surfaces and the ability of these coatings in inducing biomineralization by osteoblasts cultured in vitro. Changing the phospholipids (i.e., dihexadecyl phosphate (DHP) or octadecylphosphonic acid (OPA)), we also tuned the surface Ca2+ concentration. This structural feature gave rise to different LB-hybrid surfaces where the concentration of Ca2+ in the OPA/HAp was higher than the concentration of Ca2+ in DHP/HAp coating. The higher Ca2+ amount on OPA/HAp coatings, allied to the physical-chemical features, lead to different responses on osteoblasts, stimulating or inhibiting the natural biomineralization. The OPA/HAp coating caused a delay in the osteoblast proliferation as indicated by the decrease in the cell viability at the 7th culture day. Improved cell differentiation triggered by the DHP/HAp coating resulted in higher osteoblast biomineralization. The present data underscore that besides both coatings being composed by HAp, the final interfacial composition and physical-chemical properties influence differently the osteoblast behavior. Although the best osteoblast's viability was found to OPA/HAp, our dataset attested that DHP/HAp induced mineralization more effectively than that. This unexpected finding highlight the importance of deeply understanding the biomaterial interface and suggest a promising approach to the design of biofunctional LB-based coatings with tunable properties. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2524-2534, 2018.

Interaction between 17 α-ethynylestradiol hormone with Langmuir monolayers: The role of charged headgroups.

The persistence of steroid hormones disposed of in the environment may pose risks to the health of humans and wildlife, which brings the need of understanding their mode of action, believed to occur in cell membranes. In this study, we investigate the molecular-level interactions between the synthetic hormone 17 α-ethynylestradiol (EE2) and Langmuir monolayers that represent simplified cell membranes. In surface pressure isotherms, EE2 was found to expand the monolayers at low surface pressures of the positively charged dimethyldioctadecylammonium bromide (DODAB), zwitterionic 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC), negatively charged 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), and partially anionized stearic acid (StAc). The largest effects were observed for the charged DODAB and DPPG. At the pressure (30mN.m-1) corresponding to the molecular packing of a cell membrane, EE2 caused the compressibility modulus to decrease, again with the largest changes occurring for DODAB and DPPG. The effects from EE2 on the packing of the lipid molecules at this high pressure depended essentially on the size of the headgroups, with EE2 contributing to the area per lipid for StAc and DODAB, whose headgroups are small. EE2 interacted with the headgroups of all lipids and StAc, also affecting the ordering of the tails for DODAB, DPPG and DPPC, according to in situ polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). Based on the analysis with the two characterization methods, we propose a model for the EE2 positioning and molecular groups involved in the interaction, which should be relevant to unveil the endocrine disrupting action of EE2.

Biomimetic collagen/phospholipid coatings improve formation of hydroxyapatite nanoparticles on titanium.

Osseointegration between the surface of a certain material and the host tissue helps to evaluate the potential use of biomaterials in bone replacement. The physicochemical properties and biochemical composition of the material's surface regulates osseointegration. This study investigates how collagen into biomimetic matrixes affects hydroxyapatite (HAp) growth. Collagen was inserted into insoluble Langmuir monolayers containing either 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) or octadecylphosphonic acid (OPA) and transferred to titanium (Ti) supports by means of the Langmuir-Blodgett (LB) technique. The resulting films served as matrixes for HAp growth upon exposure of Ti discs to SBF. Scanning electron microscopy, atomic force microscopy, vibrational spectroscopy in the infrared region, X-ray diffraction, and energy dispersive X-ray spectroscopy aided characterization of the samples. Properties such as wettability, roughness, and surface free energy were also studied. The biocompatibility of the samples was investigated by osteoblast viability assays in vitro. Collagen interacted with DPPC and OPA at the air/water interface as evidenced by the pressure surface isotherms and the compressional modulus. Moreover, collagen in the subphase increased the stability of the phospholipid monolayer at high organization degree. Collagen incorporation into DPPC LB films induced formation of biomimetic HAp nanoparticles that resembled the HAp nanoparticles found in natural bone. Enhanced cell proliferation on the modified-Ti surfaces demonstrated that the coatings were not toxic to osteoblasts. These materials are potential candidates for bone-replacement applications.