Physical surface modification is an approach that has been investigated over the last decade to reduce bacterial adhesion and improve cell attachment to biomaterials. Many techniques have been reported to modify surfaces, including the use of natural sources as inspiration to fabricate topographies on artificial surfaces. Biomimetics is a tool to take advantage of nature to solve human problems. Physical surface modification using animal and vegetal topographies as inspiration to reduce bacterial adhesion and improve cell attachment has been investigated in the last years, and the results have been very promising. However, just a few animal and plant surfaces have been used to modify the surface of biomaterials with these objectives, and only a small number of bacterial species and cell types have been tested. The purpose of this review is to present the most current results on topographic surface modification using animal and plant surfaces as inspiration to modify the surface of biomedical materials with the objective of reducing bacterial adhesion and improving cell behavior.

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Bioinspired Topographic Surface Modification of Biomaterials

Tunable hydrophobicity and roughness on PVDF surface by grafting to mode – approach to enhance membrane performance in membrane distillation process

Emergence of antibiotic‐resistance pathogens has caused serious health issues and if the current trend is to continue, treatment of the infection will become complicated and even unsuccessful due to new antimicrobial resistance (AMR). Therefore, there is a global drive to identify new methods to treat infection and develop better antibacterial materials and therapy. Although new and more potent antibiotics have aided the fight against microbes, they only offer a temporary solution because future bacteria strains may become resistant to these antibiotics and drugs. Recently, application of non‐biological methods such as, electrical currents and photothermal/dynamic therapies to kill bacteria, reveal new approaches to design antimicrobial biomaterials, as complications stemming from drug‐resistant bacteria can be obviated. Furthermore, recent research has focused on mimicking the surface patterns on plants and insects such as lotus leaves and dragonfly wings. Bio‐inspired micro/nano patterns have been replicated on a variety of biomaterials to improve the bacterial resistance and other properties with good success. This is an exciting research area with immense practical and clinical potentials. In this review, recent advances in the application of chemical/biological approaches to combat bacterial infection and AMR are summarized and the related mechanisms are discussed.

Design and Properties of Antimicrobial Biomaterials Surfaces

Antibacterial activity of graphene oxide (GO) has been extensively studied, wherein penetration of the bacterial cell membrane and oxidative stress are considered to play a major role in the bactericidal activity of GO. However, the specific mechanism responsible for the antibacterial activity of GO remains largely unknown. Hence, the goal of this study was to explore the mode of action of GO, via an in-depth proteomic analysis of the targeted bacteria.Staphylococcus aureus was grown in the presence of GO and samples were collected at different growth phases to examine the cell viability and to analyze the changes in protein expression. Antimicrobial efficiency of GO was tested by assessing bacterial viability, live/dead staining and scanning electron microscopy. The intracellular reactive oxygen species (ROS) induced by GO treatment were examined by fluorescence microscopy. Label-free quantitative proteomics analysis was performed to examine the differentially regulated proteins in S. aureus after GO treatment.GO treatment was observed to reduce S. aureus viability, from 50 ± 17% after 4 h, to 93 ± 2% after 24 h. The live/dead staining confirmed this progressive antimicrobial effect of GO. SEM images revealed the wrapping of bacterial cells and their morphological disruption by means of pore formation due to GO insertion. GO treatment was observed to generate intracellular ROS, correlating to the loss of cell viability. The proteomics analysis revealed alteration in the expression of cell membrane, oxidative stress response, general stress response, and virulence-associated proteins in GO-treated bacterial cells. The time-dependent bactericidal activity of GO correlated with a higher number of differentially regulated proteins involved in the above.-mentioned processes.The obtained results suggest that the time-dependent bactericidal effect of GO is attributed to its wrapping/trapping ability, ROS production and due to physical disruption of the cell membrane. 

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Antimicrobial Activity of Graphene Oxide Contributes to Alteration of Key Stress-Related and Membrane Bound Proteins

Development of superhydrophobic and corrosion resistant coatings on carbon steel by hydrothermal treatment and fluoroalkyl silane self-assembly

Bioinspired micro/nano structured aluminum with multifaceted applications

Development of superhydrophobic metallic surfaces with tuned morphology through microwave processing

Antimicrobial coatings on metallic surfaces are rapidly emerging to combat bacterial pathogens. The excess use of conventional antibiotics increases the number of resistant strains at an alarming rate, which in turn leads to detrimental implications in the healthcare sector. Hence, it is of great importance in developing a new class of material with inherent bactericidal activity and good biocompatibility. In the present study, we have modified the aluminium surfaces by a coating of graphene oxide (GO) due to its excellent physicochemical properties, water dispersity and low cytotoxicity. Coatings were developed through facile and enviornment-friendly transfer method. The antimicrobial properties of GO coated aluminium are investigated against Gram-negative strain E. coli through agar plate counting and ‘Live/Dead’ fluorescence staining. Further, to shed light into the mechanism of antibacterial activity of GO at the molecular level, we have performed X-ray reflectivity (XRR) study considering a phospholipid multilayer as a model system to mimic bacteria cell membrane. Results show a significant bactericidal activity of the GO coatings compared to uncoated aluminium with lower concentration showing slightly better antibacterial property due to higher roughness. The obtained results may pave the way for engineering graphene-based antimicrobial coatings on a material surface using an easy, environment-friendly, cost-effective and straight forward processing route. 

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Papers

Bioinspired micro/nano structured aluminum with multifaceted applications

Development of superhydrophobic metallic surfaces with tuned morphology through microwave processing

Development of superhydrophobic metallic surfaces with tuned morphology through microwave processing

Graphene oxide coated aluminium as an efficient antibacterial surface