Emphasizing the role of surface chemistry on hydrophobicity and cell adhesion behavior of polydimethylsiloxane/TiO2 nanocomposite films

Construction of Multifunctional Hierarchical Biofilms for Highly Sensitive and Weather-Resistant Fire Warning

Multifunctional biofilms with early fire-warning capabilities are highly necessary for various indoor and outdoor applications, but a rational design of intelligent fire alarm films with strong weather resistance remains a major challenge. Herein, a multiscale hierarchical biofilm based on lignocellulose nanofibrils (LCNFs), carbon nanotubes (CNTs) and TiO2 was developed through a vacuum-assisted alternate self-assembly and dipping method. Then, an early fire-warning system that changes from an insulating state to a conductive one was designed, relying on the rapid carbonization of LCNFs together with the unique electronic excitation characteristics of TiO2. Typically, the L-CNT-TiO2 film exhibited an ultrasensitive fire-response signal of ~0.30 s and a long-term warning time of ~1238 s when a fire disaster was about to occur, demonstrating a reliable fire-alarm performance and promising flame-resistance ability. More importantly, the L-CNT-TiO2 biofilm also possessed a water contact angle (WCA) of 166 ± 1° and an ultraviolet protection factor (UPF) as high as 2000, resulting in excellent superhydrophobicity, antifouling, self-cleaning as well as incredible anti-ultraviolet (UV) capabilities. This work offers an innovative strategy for developing advanced intelligent films for fire safety and prevention applications, which holds great promise for the field of building materials.

PDMS-TiO2 composite films combined with LC-MS/MS for determination of phospholipids of urine in non-small cell lung cancer patients with traditional Chinese medicine syndromes

Lung cancer is one of the most common malignant tumors in China. Most patients are already in the mid to advanced stages during the consultation and the survival rate is less than 23 % with a poor prognosis. Therefore, effective dialectical diagnosis of advanced cancer can guide individualized treatment to improve survival. Phospholipids are the building blocks of cell membranes and abnormal phospholipid metabolism is associated with plentiful diseases. Most studies of disease markers use blood as a sample. However, urine covers extensive metabolites that are produced during the body's metabolic processes. Therefore, the study of markers in urine can be used as a complement to improve the diagnosis rate of marker diseases. Moreover, urine is characterized by high water content, high polarity, and high inorganic salt, therefore the detection of phospholipids in urine is challenging. In this study, an original Polydimethylsiloxane (PDMS)-titanium dioxide (TiO₂) composite film for sample pre-treatment coupled with the LC-MS/MS method for the determination of phospholipids in the urine with high selectivity and low matrix effects was prepared and developed. The extraction process was scientifically optimized by the single-factor test. After systematic validation, the established method was successfully applied to the accurate determination of phospholipid substances in the urine of lung cancer patients and healthy subjects. In conclusion, the developed method has great potential for the development of lipid enrichment analysis in urine and can be used as a beneficial tool for cancer diagnosis and Chinese medicine syndrome typing.

Green synthesized polyvinylpyrrolidone/titanium dioxide hydrogel nanocomposite modified with agarose macromolecules for sustained and pH-responsive release of anticancer drug

Cancer, as one of the most challenging diseases of the last century, has a significant number of patients and deaths every year. Various strategies have been explored for the treatment of cancer. Chemotherapy is one of the methods of treating cancer. Doxorubicin is one of the compounds used in chemotherapy to kill cancer cells. Due to their unique properties and low toxicity, metal oxide nanoparticles are effective in combination therapy and increase the effectiveness of anti-cancer compounds. The limited in vivo circulatory period, poor solubility, and inadequate penetration of doxorubicin (DOX) restrict its use in cancer treatment, notwithstanding its attractive characteristics. It is possible to circumvent some of the difficulties in cancer therapy by using green synthesized pH-responsive nanocomposite consisting of polyvinylpyrrolidone (PVP), titanium dioxide (TiO₂) modified with agarose (Ag) macromolecules. TiO₂ incorporation into the PVP-Ag nanocomposite resulted in limited increased loading and encapsulation efficiencies from 41 % to 47 % and 84 % to 88.5 %, respectively. DOX diffusion among normal cells is prevented by the PVP-Ag-TiO₂ nanocarrier at pH = 7.4, though the acidic intracellular microenvironments activate the PVP-Ag-TiO₂ nanocarrier at pH = 5.4. Characterization of the nanocarrier was performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrophotometry, field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), and zeta potential. The average particle size and the zeta potential of the particles showed values of 349.8 nm and +57 mV, respectively. In vitro release after 96 h showed a release rate of 92 % at pH 7.4 and a release rate of 96 % at pH 5.4. Meanwhile, the initial release after 24 h was 42 % for pH 7.4 and 76 % for pH 5.4. As shown by an MTT analysis on MCF-7 cells, the toxicity of DOX-loaded PVP-Ag-TiO₂ nanocomposite was substantially greater than that of unbound DOX and PVP-Ag-TiO₂. After integrating TiO₂ nanomaterials into the PVP-Ag-DOX nanocarrier, flow cytometry data showed a greater stimulation of cell death. These data indicate that the DOX-loaded nanocomposite is a suitable alternative for drug delivery systems.

Two-liquid wetting and phase electrowetting as a probe for surface chemistry of hydrophobic materials

Two-liquid contact angle measurement and electrowetting under low frequency are two measurement methods extremely sensitive to surface polarity and charge density. The theory underlying these two methods are described and have been applied to hydrophobic coatings. By combining these two methods, we successfully demonstrated the variations of the surface properties of polymer-based hydrophobic coatings when exposed to different chemical environments (pH modification or molecular grafting) with real-time phase electrowetting measurements.

Fabrication and Characterization of Superhydrophobic Graphene/Titanium Dioxide Nanoparticles Composite

Materials with superhydrophobic surfaces have received vast attention in various industries due to their valuable properties, such as their self-cleaning and antifouling effects. These promising superhydrophobic properties are taken into high priority, particularly for medical devices and applications. The development of an ideal superhydrophobic surface is a challenging task and is constantly progressing. Various strategies have been introduced; however, a minority of them are cost-effective. This work presents a facile fabrication of the superhydrophobic surface by using graphene and titanium dioxide (TiO₂) nanoparticles. The graphene and TiO₂ hybrid nanoparticles are dip-coated on a biodegradable thermoplastic poly(lactic acid) (PLA) substrate. The thermoplastic PLA is approved by the Food and Drug Administration (FDA), and is widely utilized in medical devices. The graphene/TiO₂ coating is substantiated to transform the hydrophilic PLA film into superhydrophobic biomaterials that can help to reduce hazardous medical-device complications. The surface wettability of the graphene/TiO₂ nanoparticle-coated PLA surface was evaluated by measuring the apparent water contact angle. The surface chemical composition and surface morphology were analyzed via Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The graphene/TiO₂-coated PLA film achieved superhydrophobic properties by demonstrating a water contact angle greater than 150°. The water contact angle of the graphene/TiO₂ coating increased along with the concentration of the nanoparticles and the ratio of TiO₂ to graphene. Moreover, the graphene/TiO₂ coating exhibited excellent durability, whereby the contact angle of the coated surface remained unchanged after water immersion for 24 h. The duration of the effectiveness of the superhydrophobic coating suggests its suitability for medical devices, for which a short duration of administration is involved. This study reports an easy-to-replicate and cost-effective method for fabricating superhydrophobic graphene/TiO₂-coated surfaces, which additionally substantiates a potential solution for the manufacturing of biomaterials in the future.

Fabrication of a novel one-step coating hyper-hydrophobic fluorine-free TiO2 decorated hollow composite membrane for use in longer-term VMD with enhanced flux, rejection, anti-wetting and anti-fouling performances

Despite recent efforts, there are still significant challenges in preparing hyper-hydrophobic membranes using environmental-friendly materials and simple methods. In this work, using phase separation theory, we prepared a fluorine-free hyper-hydrophobic porous hollow composite membrane using one-step ultrasound dip-coating. Then, fluorine-free modified titanium dioxide, polydimethylsilane and polypropylene was used to construct the porous membrane with a water contact angle of 161°. The distribution of surface elements, morphology, wetting and the scale of titanium on the membranes was characterized using X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), the water contact angle and acid-alkali stability, wetting resistance, and so on. The membrane was evaluated for desalination in the presence of organic-pollutants. Under longer-term vacuum membrane distillation, compared with the general polypropylene membrane, the flux of the hyper-hydrophobic membrane increased to 12.17 kg (m² h)^-1, and the rejection rate reached 99.99%. These results indicated that the free-fluorine hyper-hydrophobic membrane could be used for seawater desalination. Finally, our results indicate that the hyper-hydrophobic modified membrane has good potential for use in industrial desalination.

Gaseous Plastron on Natural and Biomimetic Surfaces for Resisting Marine Biofouling

In recent years, various biomimetic materials capable of forming gaseous plastron on their surfaces have been fabricated and widely used in various disciplines and fields. In particular, on submerged surfaces, gaseous plastron has been widely studied for antifouling applications due to its ecological and economic advantages. Gaseous plastron can be formed on the surfaces of various natural living things, including plants, insects, and animals. Gaseous plastron has shown inherent anti-biofouling properties, which has inspired the development of novel theories and strategies toward resisting biofouling formation on different surfaces. In this review, we focused on the research progress of gaseous plastron and its antifouling applications.

Patterned dextran ester films as a tailorable cell culture platform

The elucidation of cell-surface interactions and the development of model platforms to help uncover their underlying mechanisms remains vital to the design of effective biomaterials. To this end, dextran palmitates with varying degrees of substitution were synthesised with a multipurpose functionality: an ability to modulate surface energy through surface chemistry, and an ideal thermal behaviour for patterning. Herein, dextran palmitate films are produced by spin coating, and patterned by thermal nanoimprint lithography with nano-to-microscale topographies. These films of moderately hydrophobic polysaccharide esters with low nanoscale roughness performed as well as fibronectin coatings in the culture of bovine aortic endothelial cells. Upon patterning, they display distinct regions of roughness, restricting cell adhesion to the smoothest surfaces, while guiding multicellular arrangements in the patterned topographies. The development of biomaterial interfaces through topochemical fabrication such as this could prove useful in understanding protein and cell-surface interactions.

Biocompatibility and Cytotoxicity Study of Polydimethylsiloxane (PDMS) and Palm Oil Fuel Ash (POFA) Sustainable Super-Hydrophobic Coating for Biomedical Applications

A sustainable super-hydrophobic coating composed of silica from palm oil fuel ash (POFA) and polydimethylsiloxane (PDMS) was synthesised using isopropanol as a solvent and coated on a glass substrate. FESEM and AFM analyses were conducted to study the surface morphology of the coating. The super-hydrophobicity of the material was validated through goniometry, which showed a water contact angle of 151°. Cytotoxicity studies were conducted by assessing the cell viability and cell morphology of mouse fibroblast cell line (L929) and hamster lung fibroblast cell line (V79) via tetrazolium salt 3-(4–dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and microscopic methods, respectively. The clonogenic assay was performed on cell line V79 and the cell proliferation assay was performed on cell line L929. Both results validate that the toxicity of PDMS: SS coatings is dependent on the concentration of the super-hydrophobic coating. The results also indicate that concentrations above 12.5 mg/mL invariably leads to cell toxicity. These results conclusively support the possible utilisation of the synthesised super-hydrophobic coating for biomedical applications.

Bioinspired surfaces with wettability: biomolecule adhesion behaviors

Surface wettability plays an important role in regulating biomolecule adhesion behaviors. The biomolecule adhesion behaviors of superwettable surfaces have become an important topic as an important part of the interactions between materials and organisms. In addition to general research on the moderate wettability of surfaces, the studies of biomolecule adhesion behaviors extend to extreme wettability ranges such as superhydrophobic, superhydrophilic and slippery surfaces and attract both fundamental and practical interest. In this review, we summarize the recent studies on biomolecule adhesion behaviors on superwettable surfaces, especially superhydrophobic, superhydrophilic and slippery surfaces. The first part will focus on the influence of extreme wettability on cell adhesion behaviors. The second part will concentrate on the adhesion behaviors of biomacromolecules on superwettable surfaces including proteins and nucleic acids. Finally, the influences of wettability on small molecule adhesion behaviors on material surfaces have also been investigated. The mechanism of superwettable surfaces and their influences on biomolecule adhesion behaviors have been studied and highlighted.

Surface Engineering of Cardiovascular Devices for Improved Hemocompatibility and Rapid Endothelialization

Cardiovascular devices have been widely applied in the clinical treatment of cardiovascular diseases. However, poor hemocompatibility and slow endothelialization on their surface still exist. Numerous surface engineering strategies have mainly sought to modify the device surface through physical, chemical, and biological approaches to improve surface hemocompatibility and endothelialization. The alteration of physical characteristics and pattern topographies brings some hopeful outcomes and plays a notable role in this respect. The chemical and biological approaches can provide potential signs of success in the endothelialization of vascular device surfaces. They usually involve therapeutic drugs, specific peptides, adhesive proteins, antibodies, growth factors and nitric oxide (NO) donors. The gene engineering can enhance the proliferation, growth, and migration of vascular cells, thus boosting the endothelialization. In this review, the surface engineering strategies are highlighted and summarized to improve hemocompatibility and rapid endothelialization on the cardiovascular devices. The potential outlook is also briefly discussed to help guide endothelialization strategies and inspire further innovations. It is hoped that this review can assist with the surface engineering of cardiovascular devices and promote future advancements in this emerging research field.

Regenerable Superhydrophobic Coatings for Biomedical Fabrics

Coatings with high water repellence represent a promising field for biomedical applications. Superhydrophobicity (SH) can be used for preventing adhesion, controlling cell deposition, and spreading by inhibition of adsorption processes at liquid–solid interfaces. The recyclability of medical aids like fabrics can open the way for lower cost and more environmentally-friendly solutions. In this case, two different coatings form recyclable and low global warming potential materials and green solvents have been prepared and characterized based on their wettability properties. The resulting substrates have been used for the adhesion and spreading of representative skin cell lines, both tumoral and non-tumoral, showing a strong decrease in cell viability with values < 10%. The coated substrates showed a complete recovery on initial SH properties after rinsing with suitable solvents.

Role of Stiffness versus Wettability in Regulating Cell Behaviors on Polymeric Surfaces

Substrate wettability and stiffness, two factors impacting cell behaviors simultaneously, have been attracting much attention to elaborate which one dominates. In this study, hydrophilic poly(2-hydroxyethyl methacrylate) brushes were grafted onto the surfaces of poly(dimethylsiloxane) (PDMS) with elastic moduli of 3.66, 101.65 and 214.97 MPa and decreasing water contact angle from 120.4° to 38.5°. Cell behaviors of three cell lines including mBMSCs, ATDC-5, and C28/I2 were then investigated on the hydrophilic and hydrophobic PDMS with different stiffness, respectively. The proliferation of three cell lines was faster on the hydrophilic PDMS than the hydrophobic PDMS, but the stiffness of the hydrophilic or hydrophobic PDMS did not have a significant impact on cell proliferation. The increase of the stiffness enhanced cell migration, the cell spread and the gene expression proportion of extracellular matrix/intercellular adhesion molecules (integrin + FAK/NCAM + N-cadherin) for all three cell lines, but the increase of the wettability showed small enhancement in cell migration, cell spread and gene expression. Moreover, the cartilage-specific gene expression of SOX9 and COL2 downregulated for all three cell lines with the increasing stiffness. The interpretation of the effect of substrate wettability and stiffness on cell behaviors would function as very useful guideline to direct scaffold fabrication.

Mammalian Cell Behavior on Hydrophobic Substrates: Influence of Surface Properties

The influence of different surface properties holding to a modification of the substrate towards hydrophobic or superhydrophobic behavior was reviewed in this paper. Cell adhesion, their communication, and proliferation can be strongly manipulated, acting on interfacial relationship involving stiffness, surface charge, surface chemistry, roughness, or wettability. All these features can play mutual roles in determining the final properties of biomedical applications ranging from fabrics to cell biology devices. The focus of this work is the mammalian cell viability in contact with moderate to highly water repellent coatings or materials and also in combination with hydrophilic areas for more specific application. Few case studies illustrate a range of examples in which these surface properties and design can be fruitfully matched to the specific aim.

Surface Modification of Aliphatic Polyester to Enhance Biocompatibility

Aliphatic polyester is a kind of biodegradable implantable polymers, which shows promise as scaffolds in tissue engineering, drug carrier, medical device, and so on. To further improve its biocompatibility and cell affinity, many techniques have been used to modify the surface of the polyester. In the present paper, the key factors of influencing biocompatibility of aliphatic polyester were illuminated, and the different surface modification methods such as physical, chemical, and plasma processing methods were also demonstrated. The advantages and disadvantages of each method were also discussed with the hope that this review can serve as a resource for selection of surface modification of aliphatic products.