Search

Nonthermal plasma processes recently emerged as promising therapeutic tools for the treatment of cancer. Most anticancer effects of plasma have been related to the induction of oxidative stress due to the release of reactive oxygen and nitrogen species (RONS), among other plasma components, during discharge. The exact mechanism of action in the eradication of cancer, though, is still far from being fully understood. In this research, three cancer-derived cell lines were exposed to pulsed dielectric barrier discharge (DBD) to investigate the effect of direct plasma exposure on cancer cells. Among many cellular functions, cell adhesion and morphology were found to be visibly influenced. Morphological assays showed the inhibition of intercellular adhesion, losses in cell clustering, and changes in the external shape and actin cytoskeleton. These effects were related to the decrease in cell viability and plasma operational conditions. The increased expression of the heat shock protein HSP70 in plasma-exposed Saos2 cells confirmed that changes in morphology and viability in cancer cells are representative of internal changes in the oxidative state of cells that are caused by plasma-induced oxidative stress.

Over the past decade, cold atmospheric plasmas have shown promising application in cancer therapy. The therapeutic use of plasma-activated media is a topic addressed in an emerging field known as plasma pharmacy. In oncology, plasma-activated media are used to harness the therapeutic effects of oxidant species when they come in contact with cancer cells. Among several factors that contribute to the anticancer effect of plasma-activated liquid media (PALM), H2O2 and NO derivatives likely play a key role in the apoptotic pathway. Despite the significant amount of literature produced in recent years, a full understanding of the mechanisms by which PALM exert their activity against cancer cells is limited. In this paper, a sealed dielectric-barrier discharge was used to disentangle the effect of reactive nitrogen species (RNS) from that of reactive oxygen species (ROS) on cancer cells. Two cancers characterized by poor prognosis have been investigated: metastatic melanoma and pancreatic cancer. Both tumour models exposed to PALM rich in H2O2 showed a reduction in proliferation and an increase in calreticulin exposure and ATP release, suggesting the potential use of activated media as an inducer of immunogenic cell death via activation of the innate immune system.

Plasma Treated Water Solutions (PTWS) recently emerged as a novel tool for the generation of Reactive Oxygen and Nitrogen Species (ROS and RNS) in liquids. The presence of ROS with a strong oxidative power, like hydrogen peroxide (H2O2), has been proposed as the main effector for the cancer-killing properties of PTWS. A protective role has been postulated for RNS, with nitric oxide (NO) being involved in the activation of antioxidant responses and cell survival. However, recent evidences proved that NO-derivatives in proper mixtures with ROS in PTWS could enhance rather than reduce the selectivity of PTWS-induced cancer cell death through the inhibition of specific antioxidant cancer defenses. In this paper we discuss the formation of RNS in different liquids with a Dielectric Barrier Discharge (DBD), to show that NO is absent in PTWS of complex composition like plasma treated (PT)-cell culture media used for in vitro experiments, as well as its supposed protective role. Nitrite anions (NO2-) instead, present in our PTWS, were found to improve the selective death of Saos2 cancer cells compared to EA.hy926 cells by decreasing the cytotoxic threshold of H2O2 to non-toxic values for the endothelial cell line.

Astrocyte proliferation and migration toward injured Central Nervous System (CNS) areas are key features of astrogliosis and glial scar formation. Even though it is known that intracellular and environmental Reactive Oxygen and Nitrogen Species (RONS) affect astrocyte behaviour in physiological and pathophysiological conditions, their effects on the migration and growth of astrocytes are still unclear. Plasma-technologies are emerging in medicine as a tool to generate RONS for treating cells directly or through Plasma Activated Liquid Media (PALM). In this paper, we show for the first time how the use of PALM can modulate both astrocyte growth and migration as a function of active species produced by plasma in liquids. Our results show that PALM, generated by means of cold atmospheric pressure plasmas fed with N2, air or O2, can modulate astrocyte behaviour depending on the content of hydrogen peroxide and nitrite in the liquid. In particular, H2O2 enriched PALM induced a negative effect on cell growth associated with the mild wound healing improvement of primary astrocytes, in a scratch assay. Nitrite enriched PALM induced a selective effect on the wound healing without affecting cell growth. PALM containing a more balanced level of H2O2 and NO2&minus, were able to affect cell growth, as well as significantly ameliorate wound healing. None of the PALM investigated induced upregulation of the gliotic inflammatory marker glial fibrillary acidic protein (GFAP), or of the astrocyte markers Aquaporin-4 (AQP4) and Connexin-43 (Cx-43) analysed by Western blot. Finally, immunofluorescence analysis revealed the presence of NO2- able to induce elongated protrusions at the front end of wounded astrocytes in the direction of cell migration. With our study we believe to have shown that PALM offer a novel tool to modulate astrocyte behaviour and that they are promising candidates for controlling astrogliosis in the case of CNS injuries.

Magnesium plays a pivotal role in the formation, growth, and repair of bone tissue, therefore, magnesium-based materials can be considered promising candidates for bone tissue engineering. This study aims to functionalize the surfaces of three-dimensional (3D) porous poly-ɛ caprolactone (PCL) scaffolds with magnesium-containing coatings using cold plasma-assisted deposition processes. For this purpose, the radiofrequency (RF) sputtering of a magnesium oxide target was carried out in a low-pressure plasma reactor using argon, water vapor, hydrogen, or mixtures of argon with one of the latter two options as the feed. Plasma processes produced significant differences in the chemical composition and wettability of the treated PCL samples, which are tightly related to the gas feed composition, as shown by X-ray photoelectron spectroscopy (XPS) and water contact angle (WCA) analyses. Cytocompatibility assays performed with Saos-2 osteoblast cells showed that deposited magnesium-containing thin films favor cell proliferation and adhesion on 3D scaffold surfaces, as well as cell colonization inside them. These films appear to be very promising for bone tissue regeneration.

Two requirements of a porous filler for Mixed Matrix Membranes [MMMs] are a good adhesion to the polymer and the openness of its pores. The surface of SAPO-34 has been grafted with moieties containing amino groups, aromatic rings, and fluorinated chains, for a good adhesion to glassy polyimides, aromatic polymers and perfluoropolymers. The controlled excess of the modification agent – preferably trichlorosilanes – in hydrophobic solvents and the strict control of moisture in the reaction environment prevent the growth of thick layers of grafts around the crystals. XPS confirms the success of the derivatizations and indicates a homogeneous and thin coverage of the surface. The negligible reduction of the surface area suggests that the modification of the surface does not plug the micropores. The counter-intuitive faster adsorption of n-heptane in silicalite-1 after modification with bulky fluorinated grafts indicates the openness of the pores even for large molecules, and the reduction of the resistance to the transport of mass across the surface of the molecular sieves, thanks to the reduced amount of water adsorbed on the hydrophobic outer surface of the crystals.

Cell colonization of the surrounding environment is a very significant process in both physiological and pathological events. In order to understand the tissue regeneration process and thereby provide guidance principles for designing new biomaterials, it is of paramount importance to study the cell colonization in the presence of physical, chemical, and biological cues. Flat "gradient" materials are generally used with this purpose. Three dimensional gradient scaffolds mimicking more precisely the situation in vivo are somewhat more complex to fabricate and characterize. Scaffolds for Tissue Engineering (TE) made of hydrophobic synthetic polymers do not allow good cell colonization: far from their periphery, in fact, internal cell colonization is usually low. In this research poly-ε caprolactone (PCL) scaffolds have been "decorated" with chemical gradients both on top and along their thickness by means of cold plasma processes, in order to improve cell colonization of their core. Plasma treatments with a mixture of argon and oxygen (Ar/O

Atmospheric pressure (AP) Dielectric Barrier Discharges (DBD) generated in air were performed on water, Phosphate Buffer Saline (PBS) and Dulbecco's Modified Eagle's Medium (DMEM) in order to evaluate their potential to generate hydrogen peroxide (H 2 O 2 ), nitrite ( NO 2 - ) and nitrate ( NO 3 - ) species. Differences in cell growth and morphology were found in two different types of eukaryotic cells, immortal and stem cells, incubated for 1 h in plasma treated DMEM, revealing a selectivity of the treatment.

Bio-composite coatings, consisting of an organic matrix embedding a bioactive molecule, have been deposited by means of atomizer-assisted atmospheric pressure plasma. Ethylene was chosen as the precursor of the matrix, while the atomizer was fed with a water solution of lysozyme. Coatings chemical composition was investigated by XPS, FTIR and MALDI-TOF spectroscopies, and it has been proved that the one-step inclusion of protein domains in the composite coatings is successful and lysozyme chemical structure is only slightly altered. The amount of embedded lysozyme is as high as 14 μg/cm2 as evaluated from water release test. Finally, the activity of the plasma-embedded protein is close to that of pure lysozyme as verified against Micrococcus lysodeikticus ATCC 4698 through an agar plate diffusion test.

A primary research focus in tissue engineering addresses the factors that drive cell growth in scaffolds. Due to the inherent complexity of phenomena at the cell/biomaterial interface in cell-culture media, it is not easy to unambiguously disentangle the effects of different surface properties (e.g., chemical composition, roughness, porosity, etc.) in promoting specific cell behaviors, especially on porous scaffold materials. We have investigated fast low-pressure plasma treatments of porous PCL scaffolds for tissue engineering with neutral, acidic, and basic groups to obtain stable water absorbent materials. An increase of Saos2 cell growth was observed on plasma-treated scaffolds with respect to native samples; amphoteric surfaces were found very suitable for cell proliferation.

The atmospheric pressure plasma deposition of hydroxyl functionalized hydrocarbon films is reported in this work, with a reactor fed with water aerosol and ethylene. The effects of power and feed flow rates onto film chemistry have been investigated. Coatings produced with this approach can find application in the biomedical field, among others, as platforms for cell adhesion and proliferation. Results show that operating at 4 kHz provides a much higher amount of hydroxyl group in the coating compared with samples obtained at 11 kHz. After water immersion, the stability of the films and their amount of hydroxyl groups remain high. A simplified deposition mechanism is proposed.

Herein, plasma deposited thermally responsive thin polymer films from N-vinylcaprolactam (NVCL) is reported for the first time by using a low pressure RF plasma process. While FT-IR and XPS analyses highlight the film chemistry, ToF-SIMS combined with MALDI-MS analyses allow to accurately identify different oligomer distributions in the deposited film. The switching behavior of these smart surfaces is confirmed with water contact angle measurements at low and high temperatures, allowing also to estimate the Lower Critical Solution Temperature.

Atmospheric pressure plasmas are acquiring more interest in biomedical applications where synthetic biodegradable polymers modified to impart cells adhesion properties play a crucial role. This paper shows a new approach for the bio functionalization of such materials: inclusion of a biomolecule during the plasma deposition. A dielectric barrier discharge system was used for the coatings deposition, coupled with an atomizer for the lactic acid/elastin aerosol feeding. ATR-FTIR, XPS, and UV–VIS were used to investigate the chemical composition of the coatings. By properly tuning plasma parameters, a good retention of the monomer chemical structure could be obtained in the coatings, as well as the inclusion of elastin in its structure.

The research of versatile, simple and inexpensive approaches for chemically decorating micro-nanomaterials is a challenge in the field of functional surfaces in general, and in particular in plasma processing. Decorating ceramic particles with oxygen containing (O-containing) functionalities can render such materials very suitable as catalyst supports and adsorbents, or for manufacturing membranes and sensors. This paper describes a material processing consisting of a plasma-deposition step with CO2/C2H4 mixtures followed, or not, by a plasma-grafting step in CO2/H2 blends. In this way, alumina mesoporous microparticles have been functionalized with coatings decorated with carboxylic groups (COOH surface density up to 3.3 ± 0.6 × 10−9 mol/cm2) stable up to 1 month both in air and in water. A home-made rotating radiofrequency (RF, 13.56 MHz) driven plasma reactor has been used, whose gentle agitation allows homogeneous coating of the particles. The low environmental impact, the safety of the reagents used, together with the effective coating of the particles, render the proposed approach highly competitive with respect to conventional functionalization processes based on wet chemistry.

The present study investigates the effect of a silver (Ag)-containing nanocomposite coating on Staphylococcus epidermidis adhesion and icaA gene expression. Bacterial interactions with organic coatings with and without Ag nanoclusters were assessed through a combination of both conventional phenotypic analysis, using microscopy, and genotypic analysis, using the relative reverse transcription Real-Time Polymerase Chain Reaction (RT-PCR). The results suggest that the incorporation of Ag in organic coatings can significantly decrease bacterial adhesion and viability with time, in comparison to the organic coating alone. The initial Ag release though at concentrations lower than the bactericidal, significantly increased icaA gene expression for the bacteria interacting with the Ag containing coating two hours post adhesion, especially under the higher shear rate. Stress-inducing conditions such as sub-bactericidal concentrations of Ag and high shear rate can therefore increase icaA expression, indicating that analysis of gene expression can not only refine our knowledge of bacterial-material interactions, but also yield novel biomarkers for potential use in assessing biomaterials antimicrobial performance.

Polymeric free-standing nanofilms are emerging as appealing materials for many applications, including biomedical ones. This communication describes a new and versatile method to obtain self-supported plasma-deposited coatings. Coupling a soluble sacrificial layer with low or atmospheric pressure plasma processes, free-standing films have been prepared. Vancomycin-embedded bio-composite coatings have been deposited at atmospheric pressure with an aerosol-assisted plasma process, while PolyEthylene Oxide-like (antifouling and cross-linked) coatings and silver-containing (antibacterial) nanocomposite coatings have been plasma-deposited at low pressure. The described approach can certainly be extended to many possible free-standing nanofilms of different nature that can be synthesized by means of customized plasma processes, and it is a valid alternative to conventional wet methods to nanofilm synthesis.

Stainless steel surfaces were processed by means of plasma enhanced chemical vapor deposition (PE-CVD) fed with acrylic acid vapors in order to functionalize them with carboxyl groups, which were subsequently activated for covalent immobilization of heparin-loaded (HEP) NH2 group-functionalized (Fun) nanoliposomes (NLs). Empty Fun or HEP non-functionalized (control) NLs were used as controls. NLs were characterized for mean diameter, surface charge and heparin encapsulation/release. Different lipid compositions were used for NL construction; PC/Chol (2:1 mol/mol) or PC/Chol (4:1 mol/mol) (fluid type vesicles) [ which allow gradual release of heparin] and DSPC/Chol (2:1 mol/mol) (rigid type vesicles). Surface haemocompatibility was tested by measuring blood clotting time. Platelet adhesion on surfaces was evaluated morphologically by SEM and CLSM. The haemocompatibility of plasma-processed surfaces was improved (compared to untreated surfaces); Fun-HEP NL-coated surfaces demonstrated highest coagulation times. For short surface/blood incubation periods, surfaces coated with Fun-HEP NLs consisting of PC/Chol (2:1) had higher coagulation times (compared to DSPC/Chol NLs) due to faster release of heparin. Heparin release rate from the various NL types and surface platelet adhesion results were in agreement with the corresponding blood coagulation times. Concluding, covalent immobilization of drug entrapping NLs on plasma processed surfaces is a potential method for preparation of controlled-rate drug-eluting metallic stents or devices.

Poly e-caprolactone (PCL) and poly D,L -lactic acid (P D,L LA) scaffolds with controlled pore dimensions (100–200 μm) were processed in low pressure RF (13.56 MHz) Glow Discharges. Ethylene/N 2 mixtures (for PCL) and allyl amine (for P D,L LA) were used to plasma deposit cell-adhesive coatings with controlled conditions to increase the affinity of Saos2 osteoblast and 3T3 fibroblast cell lines, respectively. Very promising results were obtained in terms of N-containing species penetration, by plasma processes, inside the core regions of scaffolds. In particular, a new double deposition process from allyl amine (core) and hexane (periphery), created a chemical gradient from the top to the bottom of the scaffolds, that increased the metabolic activity of cells inside the scaffolds.

The behavior of cells in terms of cell-substrate and cell-cell interaction is dramatically affected by topographical characteristics as shape, height, and distance, encountered in their physiological environment. The combination of chemistry and topography of a biomaterial surface influences in turns, important biological responses as inflammatory events at tissue-implant interface, angiogenesis, and differentiation of cells. By disentangling the effect of material chemistry from the topographical one, the possibility of controlling the cell behavior can be provided. In this paper, surfaces with different roughness and morphology were produced by radiofrequency (RF, 13.56 MHz) glow discharges, fed with hexafluoropropylene oxide (C(3)F(6)O), in a single process. Coatings with different micro/nanopatterns and the same uppermost chemical composition were produced by combining two plasma deposition processes, with C(3)F(6)O and tetrafluoroethylene (C(2)F(4)), respectively. The behavior of osteoblast-like cells toward these substrates clearly shows a strict dependence of cell adhesion and proliferation on surface roughness and morphology.

Microcantilevers are miniaturized mechanical sensors which pro- vide a specifi c, real-time and label-free detection of bio/molecules and chemical reactions in different environments with a fast response time and low reagent consumption. The typical trans-duction mechanism is based on the cantilever defl ection due to selective physical and chemical processes occurring on one side of the probe surface.

In this work semiconductor nanocrystals (NCs) were assembled by means of a layer-by-layer procedure, by properly combining RF (13.56 MHz) glow discharge-assisted processes with wet chemistry approaches. Colloidal core shell type NCs formed by CdSe coated with an epitaxial layer of ZnS (CdSe@ZnS) were then assembled, from aqueous solution, onto the plasma modified materials. The obtained results show that spatially resolved NC assembling can be successfully achieved on micro-structured domains obtained by means of plasma assisted processes. Layers of functionalized NCs are thus demonstrated to be materials that can be effectively integrated into devices for application in photovoltaics, electronic nano-devices and biological sensors.

Fluorocarbon coatings have drawn much attention in the biomedical field for their peculiar chemical and topographical characteristics. It is well known that topography and chemistry of a material surface can modulate different cellular responses, including adhesion, proliferation and expression of differentiated phenotypes. In this work, PECVD processes were run and micro/nanostructured fluorocarbon coatings were obtained by varying both gas feed (C3F6O and C3F6 feeds) and substrate position in an RF (13.56 MHz) reactor. The interesting results demonstrated that the cell behaviour can be dramatically influenced by surface topography of fluorine containing coatings.

Cell-adhesive and cell-repulsive coatings have been plasma-deposited on poly(ethylene terephthalate) surfaces previously structured with nano-metric conical features by means of colloidal lithography. Surface analysis revealed that both coatings are conformal on mono-structured substrates, with their wettability depending on the substrate morphology. The effect of surface chemistry and surface topography on cell adhesion has been investigated and clarified. The adhesion of a human keratinocyte cell-line was found to be strongly dependent on the surface topography for plasma-deposited acrylic acid (cell-adhesive), and on the surface chemistry for poly(ethylene oxide)-like (cell-repulsive) coatings.

Radiofrequency (13.56 MHz) glow discharges fed with vapors of (3S)-cis-3,6-dimethyl-1,4-dioxane-2,5-dione (cyclic L-lactide) were used to deposit stable dense COOH groups. The L-lactide is the solid intermediate compound formed during the conventional polymerization reaction of poly lactic acid (PLA), a biodegradable polymer used in biomaterials. The coatings have been characterized by means of X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and water contact angle (WCA) measurements. The percentage of surface carboxyl groups was determined by the Toluidine Blue O (TBO) test.

TiO 2 nanorods (NRs) and γ-Fe 2 O 3 nanocrystals (NCs) passivated with unsaturated long-chain carboxylic acids, namely 10-undecylenic acid (10UDA) and oleic acid (OLEA), are covalently anchored to Si(100) at room temperature by UV-light-driven reaction of hydrogenated silicon with the carbon-carbon double bond (-C=C-) moieties of the capping surfactants. The high reactivity of vinyl groups towards Si provides a general tool for attaching particles of both materials via Si-C bonds. Interestingly, TiO 2 NRs were efficiently attached to silicon even when capped by OLEA. This latter finding has been explained by a photocatalytic mechanism involving the primary role of hydroxyl radicals that can be generated upon bandgap TiO 2 photoexcitation with UV light. The increased oxide coverage achievable on Si opens access to further surface manipulation, as demonstrated by the possibility of depositing an additional film of Au nanoparticles onto TiO 2 via TiO 2 -catalyzed visible-light-driven reduction of aqueous AuCl 4 - ions. Extensive morphological and chemical characterization of the obtained NC-functionalized Si substrates is provided to support the effectiveness of proposed photochemical approaches.

Summary: Micro- and nanofabrication methods are essential today in microelectronics, optoelectronics, catalysis, and analytics. Recent advances in biomaterials show that micro- and nanofeatures, either at the surface or embedded in materials, can drive specific responses both in in vivo and in vitro biological systems. With such an approach, scientists can understand better, and possibly exploit, biological responses stimulated by properly designed biomedical surfaces. Because of their versatility, plasma treatment, deposition, and etching processes are often part of procedures optimized to create micro- and nanofeatures of different shape, size, and position, onto and inside materials. Presented here are recent examples of such processes developed in our group for biomedical applications. Residuals of self-assembled polystyrene (PS) beads (600 ± 50 nm in diameter) on NH3 plasma-treated PS substrate, after O2 plasma etching.

A photo-immobilisation procedure was utilised to create two different rnicro-patterned surfaces (tracks 25 and 5 mu m wide) of hyaluronan (Hyal) on polyethylene-terephthalate (PET) previously plasma activated. Aim of the study was to investigate the proliferation and re-clifferentiation capacity of articular chondrocytes Cultured on micro-patterned Hyal, compared to homogeneous Hyal and plain plasma-treated (pt-)PET substrates. Cytotoxicity, cell proliferation, activation and differentiation of articular knee cartilage chondrocytes (Mongrel sheep) were evaluated after 14 days of culture. It was found that micro-patterned Hyal surfaces induced the adhesion, migration and alignment of chondrocytes, as shown by light and scanning electron microscopy. Furthermore, the same surfaces induced chondrocyte differentiation, with a significant increase of aggrecan and collagen type II production, while homogeneous Hyal and pt-PET surfaces did not. (c) 2005 Elsevier Ltd. All rights reserved.

Mixtures of diethyl glycol dimethyl ether vapors and argon were used to feed RF (13.56 MHz) glowdischarges and coat polystyrene substrates with poly(ethylene oxide) (PEO)-like thin films. Different power input values have been used to obtain coatings with different cell-adhesive properties. Cell-culture experiments showed a tight correlation between the adhesion/morphology of cultured cell-lines and the chemical composition of the coatings; the ability of PEOlike coatings to discourage or promote cell adhesion could thus easily be related to the power delivered to the plasma. Combined deposition processes of different PEO-like coatings have been performed, with the method of physical masking, to produce surfaces micro-patterned with celladhesive tracks alternating with cell-repulsive domains. The micro-arrangement of different cell-adhesive domains enabled the patterning of cell cultures and induced the alignment of cells along predefined directions. The adhesion pattern of 3T3 murine fibroblasts on a substrate of PEO10W patterned with a PEO5W coating deposited through a G50p mask after 24 h.

Plasma processes of interest for tissue engineering, biosensors and related applications have been utilized for micro-scale patterning polymers with ‘physical masks’. The surface of polystyrene substrates has been patterned with different chemical micro-domains, each one able to induce different adhesion, spreading and growth behavior of cells. Cell adhesive tracks spaced with wider non-fouling PEO-like zones have been developed at the surface of the substrates, and utilized in cell growth experiments.

This short contribution is aimed to describe two plasma processes utilized at the group of the authors for biomedical applications, namely: the grafting process of polar groups intended to obtain stable hydrophilic surfaces on hydrophobic polymers, and the deposition of thin organic coatings highly functionalized with carboxylic groups. Both processes can develop cell-adhesive surfaces onto biomedical polymers. Combined with plasma deposition processes of non fouling coatings through a "physical mask", such methods can provide substrates patterned with diverse micrometric domains that can drive adhesion, spreading and growth of cells along predefined directions, an useful approach utilized in tissue engineering.

Cold plasmas are continuously developed for biomaterials engineering as well as for therapeutic treatments of cells and tissues. For this last application plasma activated media (PAM) and reactive oxygen and nitrogen species (RONS) gained attention as key players. Here, the use of cold atmospheric pressure (AP) plasma is described, for generating RONS in Dulbecco's Modified Eagles Medium (DMEM); superoxide anion (O2−), hydrogen peroxide (H2O2), nitrates (NO3−), and nitrites (NO2−) were detected. PAM was applied to Bone Marrow Stem Cells (BMSC) and SAOS-2 osteoblasts. Both native and plasma-modified polymeric scaffolds were used as three dimensional (3D) supports for cell cultures. The cell activity was found dependent on both PAM and cell type. BMSCs grown on plasma-coated scaffolds tolerated better PAM with respect to those on native scaffolds.

Low temperature plasma deposition and treatment processes can be successfully employed in order to modify surfaces of biomedical interest, as well as to improve membrane properties. In particular, plasma processes can be used to improve the adhesion, spreading and proliferation of cells at the surface of materials, to tune the hydrophilic/hydrophobic and non fouling properties, and to provide surfaces suitable for immobilizing molecules (catalysts, biomolecules, etc.).

In this work a genuine combination of a bottom-up approach, which is based on synthesis and functionalization of emitting nanocrystals (NCs), with a top-down strategy, which relies on a flexible and versatile cold plasma process, is shown. Luminescent semiconducting colloidal NCs consisting of a CdSe core coated with a ZnS shell (CdSe@ZnS) are directly assembled onto micro-patterned substrates previously functionalized by means of glow discharges performed through physical masks. The NC assembly is driven by electrostatic interactions that led to their successful organization into spatially resolved domains. Two distinct protocols are tested, the former using a plasma deposition process combined with an electrostatic layer-by-layer procedure, the latter based on a two-step plasma deposition/treatment process. The procedures are thoroughly monitored with fluorescence microscopy, atomic force microscopy, x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The two-step plasma protocol is demonstrated to be more efficient in directing a uniform and specific assembly of luminescent NCs with respect to the hybrid procedure. The presented 'mix and match' approach offers great potential for integrating NCs, with their unique size-dependent properties, into microstructures, providing a universal platform for the fabrication of sensors, biochips, displays and switches.