Multicomponent Copolymer Planar Membranes with Nanoscale Domain Separation

Domain separation is crucial for proper cellular function and numerous biomedical technologies, especially artificial cells. While phase separation in hybrid membranes containing lipids and copolymers is well-known, the membranes' overall stability, limited by the lipid part, is hindering the technological applications. Here, we introduce a fully synthetic planar membrane undergoing phase separation into domains embedded within a continuous phase. The mono- and bilayer membranes are composed of two amphiphilic diblock copolymers (PEO 45 - b -PEHOx 20 and PMOXA 10 - b -PDMS 25 ) with distinct properties and mixed at various concentrations. The molar ratio of the copolymers in the mixture and the nature of the solid support were the key parameters inducing nanoscale phase separation of the planar membranes. The size of the domains and resulting morphology of the nanopatterned surfaces were tailored by adjusting the molar ratios of the copolymers and transfer conditions. Our approach opens new avenues for the development of biomimetic planar membranes with a nanoscale texture

Recent Advances in Hybrid Biomimetic Polymer-Based Films: from Assembly to Applications

Biological membranes, in addition to being a cell boundary, can host a variety of proteins that are involved in different biological functions, including selective nutrient transport, signal transduction, inter- and intra-cellular communication, and cell-cell recognition. Due to their extreme complexity, there has been an increasing interest in developing model membrane systems of controlled properties based on combinations of polymers and different biomacromolecules, i.e., polymer-based hybrid films. In this review, we have highlighted recent advances in the development and applications of hybrid biomimetic planar systems based on different polymeric species. We have focused in particular on hybrid films based on (i) polyelectrolytes, (ii) polymer brushes, as well as (iii) tethers and cushions formed from synthetic polymers, and (iv) block copolymers and their combinations with biomacromolecules, such as lipids, proteins, enzymes, biopolymers, and chosen nanoparticles. In this respect, multiple approaches to the synthesis, characterization, and processing of such hybrid films have been presented. The review has further exemplified their bioengineering, biomedical, and environmental applications, in dependence on the composition and properties of the respective hybrids. We believed that this comprehensive review would be of interest to both the specialists in the field of biomimicry as well as persons entering the field

A DNA-micropatterned surface for propagating biomolecular signals by positional on-off assembly of catalytic nanocompartments

Signal transduction is pivotal for the transfer of information between and within living cells. The composition and spatial organization of specified compartments are key to propagating soluble signals. Here, a high-throughput platform mimicking multistep signal transduction which is based on a geometrically defined array of immobilized catalytic nanocompartments (CNCs) that consist of distinct polymeric nanoassemblies encapsulating enzymes and DNA or enzymes alone is presented. The dual role of single entities or tandem CNCs in providing confined but communicating spaces for complex metabolic reactions and in protecting encapsulated compounds from denaturation is explored. To support a controlled spatial organization of CNCs, CNCs are patterned by means of DNA hybridization to a microprinted glass surface. Specifically, CNC-functionalized DNA microarrays are produced where individual reaction compartments are kept in close proximity by a distinct geometrical arrangement to promote effective communication. Besides a remarkable versatility and robustness, the most prominent feature of this platform is the reversibility of DNA-mediated CNC-anchoring which renders it reusable. Micropatterns of polymer-based nanocompartment assemblies offer an ideal scaffold for the development of the next generation responsive and communicative soft-matter analytical devices for applications in catalysis and medicine

Niskotemperaturowe, elektrochemiczne otrzymywanie filmów zawierajacych krzem i ich charakterystyka za pomocą technik elektrochemicznych, spektroskopowych i mikroskopowych.

The goal of the PhD thesis was electrochemical deposition and characterization of the photoactive in aqueous solutions SiOx films for potential applications as a photoanode material. The experimental work of the thesis included electrodeposition of SiOx layers and their spectroscopic and microscopic analysis, photoelectrochemical characterization and optimization of the deposition conditions (potential and time of the deposition, type of the substrate, concentration of the SiHCl3 precursor) in order to obtain the highest photocurrent density in the studied systems. The SiOx layers were deposited on the surface of Au, Pt and Cu electrodes from propylene carbonate (PC) solutions with SiHCl3 as silicon source. Because of the low conductivity of SiHCl3/PC solutions 0.1 M tert-butyl ammonium bromide (TBAB) was used as the supporting electrolyte. It was shown that the chemical composition, thickness and photoactivity of the films depended on the type of the substrate, SiHCl3 concentration and the deposition potential value. In order to determine the electrochemical window (stability) of the electrolyte and the potential range of the SiHCl3 reduction cyclic voltammetry (CV) was used. The potential range of SiHCl3 reduction varied depending on the type of the substrate used. In case of each substrate the deposition potential was chosen in order to fit into the beginning, center and the end of the reduction wave. The thickness of the deposits varied from 1 to 24 μm and the highest thickness was observed for the deposits obtained on Cu electrode. The application of electrochemical, spectroscopic and microscopic techniques allowed the determination and optimization of the deposition conditions in order to obtain SiOx layers of the highest photoactivity and stability against the aqueous solutions. The SiOx layers obtained on Au and Pt showed an n-type photoactivity (photooxidation reaction) in PC solution whereas films produced on Cu showed a p-type behavior (arising from a photoreduction reaction). The photoactivity of the films in 0.1 M perchloric acid (HClO4) aqueous solution was of an n-type independently on the type of the electrode used for the electrodeposition and the photocurrent was stable in time. By application of FTIR and XPS, it was shown that in each case after photogalvanic measurements the films still contained SiOx and in some cases also Si:H. The highest value of the photocurrent (ca. 100 μm×cm-2) was registered for the deposit obtained on Au at -2.7 V vs. Ag. The photocurrent observed in water solution could result either from the reaction of oxygen (O2) photoevolution, or from the process of the films‘ photodecomposition, i.e. oxidation of a silicon based film (SiOx) to silica (SiO2). In order to distinguish between these two processes the charges required for film photodecomposition and the charge flowing during the photocurrent measurement were compared. It was shown that the photooxidation reaction observed during the illumination of the deposits in an aqueous solution corresponded to continuous O2 photoevolution. The possible negative influence of the mechanical degradation of the films (i. e. while drying) or eventually a non ideal ohmic deposit/electrode contact on the registered photocurrent density magnitude was mentioned as well. In this thesis, it was demonstrated for the first time that SiOx based films directly electrodeposited in an organic solution could be photoactive in an aqueous solution. The observed electrical energy saving resulting from the exploitation of light energy corresponded to ca. 1.3 V. The presented results can open possibilities of cheap and efficient silicon based photoelectrodes preparation for construction of photogalvanic cells (i.e. wet photocells) for the water splitting process.Celem pracy było elektrochemiczne otrzymywanie i charakterystyka fotoaktywnych w roztworach wodnych filmów SiOx w celu potencjalnego zastosowania ich jako fotoanod. Praca eksperymentalna obejmowała elektroosadzenie warstw SiOx i ich spektroskopową i mikroskopową analizę, fotoelektrochemiczną charakterystykę oraz optymalizację warunków nanoszenia (potencjał i czas nanoszenia, rodzaj substratu, stężenie prekursora SiHCl3) w celu zarejestrowania możliwie najwyższych gęstości fotoprądów w badanych układach. Filmy SiOx osadzane były na powierzchniach elektrod Au, Pt i Cu z roztworu węglanu propylenu (PC) z użyciem trichlorosilanu (SiHCl3) jako źródła krzemu. W związku z niskim przewodnictwem roztworu SiHCl3/PC, zastosowano 0.1 M bromek tert-butylo amoniowy (TBAB) jako elektrolit pomocniczy. Wykazano, że chemiczny skład osadów, ich grubość oraz fotoaktywność zależała od rodzaju substratu, stężenia SiHCl3 i wartości potencjału osadzania. Woltamperometria cykliczna (CV) używana była w celu określenia szerokości okna elektrochemicznego (trwałości) elektrolitu oraz określenia zakresu potencjału redukcji SiHCl3 w zależności od używanego substratu. Zakres redukcji SiHCl3 był różny w zależności od zastosowanej elektrody, jednak w każdym przypadku starano się tak dobrać wartość potencjału osadzania aby znajdowały się na początku, w centrum i na końcu zakresu sygnału. Grubość osadów wynosiła od 1 do 24 μm, przy czym największe wartości zaobserwowano dla osadów otrzymanych na elektrodzie Cu. Użycie technik elektrochemicznych, spektroskopowych i mikroskopowych pozwoliło na określenie i optymalizację warunków osadzania filmów tak, aby otrzymać warstwy SiOx możliwie jak najbardziej fotoaktywne i stabilne w roztworach wodnych. Warstwy SiOx otrzymane na Au i Pt charakteryzowały się fotoaktywnością n-typu (reakcja fotoutlenienia) podczas pomiarów fotowoltaicznych w roztworze organicznym, natomiast filmy utworzone na Cu wykazały zachowanie typu p (pochodzące od reakcji fotoredukcji) w roztworach PC. Fotoaktywność osadów w wodnym roztworze kwasu nadcholowego (HClO4) była typu n, niezależnie od tego, na jakiej elektrodzie lub przy jakiej wartości potencjału były one osadzone. Za pomocą technik FTIR i XPS wykazano, że w każdym przypadku po pomiarze fotogalwanicznym filmy nadal zawierały SiOx, a niekiedy także Si:H. Ze wszystkich osadzonych filmów najwyższą wartość gęstości fotoprądu (100 μAcm-2) zarejestrowano dla filmu otrzymanego na Au przy -2.7 V vs. Ag. Fotoprąd zaobserwowany w wodnym roztworze HClO4 mógł pochodzić zarówno z fotowydzielania tlenu (O2), jak i z procesu fotokorozjii filmu, na przykład utlenienia SiOx do krzemionki (SiO2). W celu rozróżnienia tych dwóch procesów porównane zostały wartości ładunków potrzebne do ich realizacji z ładunkiem fotoprocesu zachodzącego w układzie. Wykazano, że reakcja fotoutlenienia zaobserwowana w toku pomiaru fotoelektrochemicznego w wodnym roztworze pochodziła od ciągłego fotowydzielania O2. W rozprawie poruszone były również kwestie mogące negatywnie wpływać na wartości uzyskiwanych gęstości fotoprądów takie jak degradacja mechaniczna (na przykład na etapie suszenia osadu) lub też ewentualna niedoskonałość kontaktu omowego pomiędzy elektrodą a półprzewodzącym osadem SiOx. W toku niniejszej pracy po raz pierwszy zademonstrowano, że warstwy SiOx elektrochemicznie osadzone w roztworze organicznym były fotoaktywne w roztworze wodnym. Zaobserwowany zysk energetyczny uzyskany przy użyciu oświetlenia wynosił około 1.3 V. Zaprezentowane wyniki otwierają możliwość konstrukcji tanich i wydajnych fotoelektrod opartych na Si i zastosowania ich w ogniwach fotogalwanicznych (tzw. ogniwach mokrych)

Ion-Imprinted Nanofilms Based on Tannic Acid and Silver Nanoparticles for Sensing of Al(III)

International audienceElectrochemically triggered self-assembly can be effectively utilized to produce electroactive materials of tailored properties for various applications, such as sensor development. Here, we present a thin sensor film based on tannic acid (TA) and silver nanoparticles (AgNPs), ionically imprinted via electrodeposition and tailor-designed for electrochemical tracing of aluminum ions, Al(III). In the first stage, the conditions for the Al(III) printing of TA films onto an indium-tin-oxide (ITO) electrode via electrodeposition are established and optimized. To form an AgNPs-containing film, AgNPs are presynthesized via a direct reduction of Ag(I) by TA resulting in TA-stabilized AgNPs (TA@AgNPs) of 1–4 nm in size, as observed by dynamic light scattering. Next, Al(III) ions are added to complex the TA molecules adsorbed on the surface of AgNPs. The resulting Al(III)/TA@AgNPs mixture is then electrodeposited onto the ITO surface by applying an anodic potential to form a film. As a result, a mesh-structured layer composed of AgNPs with TA on their surface and electrochemically cross-linked via TA–TA covalent bonds at the Al(III)-free coordination sites is formed. The introduction of Al(III) ions bonded via coordination bonds with TA and their consecutive removal using sodium fluoride formed vacancies ready to bind Al(III) ions from the analyzed solution allowing their electrochemical sensing, as monitored by cyclic voltammetry, quartz crystal microbalance, and X-ray photoelectron spectroscopy. The film was employed for sensing of neurotoxic Al(III) in human serum. A linear correlation between the current value at 0.9 V and the concentration of Al(III) was obtained in the range between 0.10 and 0.298 μM

Spectroscopic characterization and photoactivity of SiOx-based films electrochemically grown on Cu surfaces

Electrodeposited SiOx electrodes were shown to be photoactive and exhibit n- and p-type effects for electrodes placed in aqueous and organic solutions, respectively. As seen by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron (XPS) spectroscopy, the mechanism of the electrodeposition included reactions with the used electrolyte as well as with traces of water as sources of oxygen and hydrogen. The lowest band gap energy (E-g) of the films of approximately 1.6 eV was observed for the film electrodeposited at -2.5 V in comparison to 1.9 eV for the films obtained at -2.25 and -2.75 V. The depth profiles of Si and O in the films were registered by XPS, secondary ion mass spectrometry (SIMS), and glow discharge optical emission spectroscopy (GD-OES), which showed that Si and O were relatively uniformly distributed across the entire layer of the film. The n-type photoactivity was associated with the evolution of oxygen from the aqueous solution, and the p-type was attributed to the reductive deterioration of the amorphous SiOx deposit and simultaneous photodecomposition of the electrolyte