Micro/nano-structured superhydrophobic surfaces in the biomedical field: part I: basic concepts and biomimetic approaches

Part II is available at: http://hdl.handle.net/1822/44292Inspired by natural structures, great attention has been devoted to the study and development of surfaces with extreme wettable properties. The meticulous study of natural systems revealed that the micro/nano-topography of the surface is critical to obtaining unique wettability features, including superhydrophobicity. However, the surface chemistry also has an important role in such surface characteristics. As the interaction of biomaterials with the biological milieu occurs at the surface of the materials, it is expected that synthetic substrates with extreme and controllable wettability ranging from superhydrophilic to superhydrophobic regimes could bring about the possibility of new investigations of cellâ material interactions on nonconventional surfaces and the development of alternative devices with biomedical utility. This first part of the review will describe in detail how proteins and cells interact with micro/nano-structured surfaces exhibiting extreme wettabilities.AC Lima is grateful for financial support from Portuguese Foundation for Science and Technology (FCT) through the grant SFRH/BD/71395/2010 (under the scope of QRENPOPH – Tipologia 4.1 – Formação Avançada subsidized by European Social Found as well as by national funds of MEC). The authors also acknowledge the national funds from the FCT in the scope of project PTDC/CTM-BIO/1814/2012. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript

Effects of Surface Topography on Bacterial Biofilm Formation

Biofilms are multicellular structures with bacterial cells attached to a surface and embedded in an extracellular matrix. With high-level resistance to antimicrobial agents, biofilms are the cause of chronic infections associated with implanted medical devices such as breast implants, orthopedic devices, pace markers, and many others. Besides the prevalence, biofilm infections are associated with high mortality, presenting an urgent need for more effective controls. Several strategies such as coating with antimicrobial agents and changing chemical, physical, and biological properties of biomaterials have been attempted, but bacteria have remarkable capabilities to overcome unfavorable conditions over time and long-term biofilm control remains challenging. In addition, most approaches are based on empirical experiments rather than rational designs, limiting their effects, especially in vivo. In this study, we engineered surface topography in two ways (static and dynamic) to better understand and control bacterial biofilm formation. For the static surface topography, a high-throughput approach to study bacterial attachment on PDMS surfaces with different textures was developed. By testing bacterial adhesion to samples with square-shaped recessive patterns with varying size and inter-pattern distance, surface features that promote biofilm formation were identified. E. coli attachment did not exhibit a monotonic, linear relationship with surface area, but depended on the 3D topography. For dynamic surface topography, we used shape memory polymers (SMPs) to obtain on-demand dynamic changes in substratum topography. Our results show that shape recovery of tert-butyl acrylate (tBA) based one-way SMP caused 99.9% detachment of 48 h Pseudomonas aeruginosa PAO1 biofilms. Interestingly, P. aeruginosa PAO1 biofilm cells detached by shape recovery showed 2,479 times higher antibiotic susceptibility compared to the original biofilm cells. The released biofilm cells also presented 4.1 times higher expression of the gene rrnB, encoding ribosomal RNA, and 11.8 times more production of adenosine triphosphate (ATP) than the control biofilm cells. To further develop this technology for long-term biofilm control, we synthesized reversible SMP with different molecular weights of poly(ɛ-caprolactone) diisocyanatoethyl dimethacrylate (PCLDIMA), with 25 wt.% of butyl acrylate (BA) as a linker, and 1 wt.% of benzoyl peroxide (BPO) as a thermal initiator. Among various combinations of molecular weight, 2:1 wt. ratio mixture of 15,000 g/mol PCLDIMA and 2,000 g/mol PCLDIMA showed a transition temperature of 36.7°C. The created rSMP has repeatable and reversible shape recovery for more than 3 cycles. With 18% stretch, 61.0±6.6% of 48 h P. aeruginosa PAO1 biofilm cells were removed in each shape recovery cycle on average, with a total of 94.3±1.0% biofilm removal after three consecutive shape recovery cycles. In summary, the results of this study demonstrated that surface topography has potent effects on bacterial adhesion and biofilm formation. We believe that these results not only provide important information for understanding the risk of medical devices but also helps the design of control methods for preventing chronic infections associated with implanted medical devices

Ascidian-Inspired Supramolecular Cellulose Nanocomposite Hydrogels with Antibacterial Activity

The design of ultratough hydrogels has recently emerged as a topic of great interest in the scientific community due to their ability to mimic the features of biological tissues. An outstanding strategy for preparing these materials relies on reversible and dynamic cross-links within the hydrogel matrix. In this work, inspired by the composition of ascidians' tunic, stretchable supramolecular hydrogels combining poly(vinyl alcohol), green tea-derived gallic acid, and rigid tannic acid-coated cellulose nanocrystals (TA@CNC) were designed. The addition of TA@CNC nanofillers in concentrations up to 1.2 wt % significantly impacted the mechanical and viscoelastic properties of the hydrogels due to the promotion of hydrogen bonding with the polymer matrix and polyphenols π-πstacking interactions. These supramolecular associations endow the hydrogels with excellent stretchability and strength (>340%, 540 kPa), low thermoreversible gel-sol transition (60 °C), and remolding ability, while the natural polyphenols provided potential antibacterial properties. These versatile materials can be anticipated to open up new prospects for the rational design of polyphenol-based cellulosic hydrogels for different biomedical applications.Fil: Carnicero, Anabela. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; ArgentinaFil: González, Agustín. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Dalosto, Sergio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; ArgentinaFil: Passeggi, Mario Cesar Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; ArgentinaFil: Minari, Roque Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Alvarez Igarzabal, Cecilia Ines. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Martinelli, Marisa. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina. Universidad Nacional de Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación y Desarrollo en Ingeniería de Procesos y Química Aplicada; ArgentinaFil: Picchio, Matías Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Novel Titanium Nanospike Structure Using Low-Energy Helium Ion Bombardment for the Transgingival Part of a Dental Implant.

AIM(S) The aim of the study was to fabricate a nanospike surface on a titanium alloy surface using a newly established method of low-energy helium ion bombardment. Various methods to achieve nanospike formation on titanium have been introduced recently, and their antibacterial properties have been mainly investigated with respect to Escherichia coli and Staphylococcus aureus. Oral pathogens such as Porphyromonas gingivalis play an important role in the development of peri-implantitis. For that reason, the antibacterial properties of the novel, nanostructured titanium surface against P. gingivalis were assessed, and a possible effect on the viability of gingival fibroblasts was evaluated. MATERIALS AND METHODS Helium sputtering was employed for developing titanium surfaces with nanospikes of 500 nm (ND) in height; commercially available smooth-machined (MD) and sandblasted and acid-etched titanium disks (SLA) were used as controls. Surface structure characterization was performed through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Following incubation with P. gingivalis, antibacterial properties were determined via conventional culturing and SEM. Additionally, the viability of human gingival fibroblasts (HGFs) was tested through MTT assay, and cell morphology was assessed through SEM. RESULTS SEM images confirmed the successful establishment of a nanospike surface with required heights, albeit with heterogeneity. AFM images of the 500 nm nanospike surface revealed that the roughness is dominated by large-scale hills and valleys. For frame sizes of 5 × 5 μm and smaller, the average roughness is dominated by the height of the titanium spikes. ND successfully induces dysmorphisms within P. gingivalis cultures following the incubation period, while conventional culturing reveals a 17% and 20% reduction for ND compared to MD and SLA, respectively. Moreover, the nanospike surfaces did not affect the viability of human growth fibroblasts despite their sharp surface. CONCLUSION(S) This study successfully developed a novel titanium-nanospike-based structuration technique for titanium surfaces. In addition, the nanospikes did not hinder gingival fibroblast viability. Enhanced antimicrobial effects for such a novel nanospike-based resurfacing technique can be achieved through further optimizations for nanospike spacing and height parameters

Multifunctional mussel inspired coatings for orthopaedic applications

Dissertação de mestrado em Engenharia BiomédicaCurrently, there is still a significant rate of implant failures in clinical practice. Current solutions would consist of the development of robust, biocompatible, biodegradable coatings with enhanced adhesive and bioactive properties. So, in this work the development of multifunctional coatings inspired by adhesive properties of mussels and the robust nacre structure were proposed. Based on the configuration of the 3,4-dihydroxy-L-phenylalanine (DOPA) amino-acid of the mussel’s adhesive proteins, catechol groups were conjugated to chitosan (CHT) and hyaluronic acid (HA). Layer-by-layer (LbL) assembly was used to mimic the nacre structure, where the organic phase consisted of both polymers and the inorganic phase of bioactive glass nanoparticles (BGNPs). In parallel, polymeric LbL coatings were constructed for the sake of comparison. The modified polymers were characterized by ultraviolet-visible (UV-Vis) spectroscopy. The construction of various LbL configurations was monitored by quartz crystal microbalance and the adhesive properties were evaluated by lap shear adhesive tests. The bioactivity and the in-vitro cell behaviour were analysed for the coatings with and without BGNPs. In-vitro tests were conducted using the cell line L929. Hydroxyapatite deposition was evaluated by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) and X-ray powder diffraction (XRD). Since the structure and topography play an important role in the functional performance of the films, two LbL assembly methods, dip- and spin-coating, were compared using three different substrates: glass, stainless steel, and titanium. The coatings were characterized by SEM, Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and water contact angle (WCA). Given the enhanced adhesion and bioactivity of the developed films, they could be used as coatings of a variety of implants. In addition, spin-coating was found to be a particularly suitable method for the build-up, since films with smoother and more uniform surfaces were produced.Atualmente, ainda há uma percentagem significativa de falhas dos implantes na prática clínica. Soluções atuais envolveriam o desenvolvimento de revestimentos robustos, biocompatíveis, biodegradáveis, com propriedades adesivas e bioativas melhoradas. Assim, neste trabalho foi proposto o desenvolvimento de revestimentos multifuncionais inspirados nas propriedades adesivas dos mexilhões e na estrutura robusta do nácar. Baseado na configuração do aminoácido 3,4-dihidroxi-L-fenilalanina (DOPA) das proteínas adesivas dos mexilhões, foram conjugados grupos catecóis ao quitosano (CHT) e ao ácido hialurónico (HA). A montagem camada-a-camada (LbL) foi utilizada para mimetizar a estrutura do nácar, onde a fase orgânica consistiu em ambos os polímeros e a fase inorgânica nas nanopartículas de vidro bioativas (BGNPs). Paralelamente, foram construídos revestimentos LbL poliméricos para fins de comparação. Os polímeros modificados foram caracterizados por espectroscopia ultravioleta-visível (UV-Vis). A construção das várias configurações LbL foi monitorizada através da microbalança de cristal de quartzo e as suas propriedades adesivas avaliadas através de testes adesivos sob tensão de corte. A bioatividade e o comportamento celular in-vitro foram analisados para os revestimentos com e sem BGNPs. Os testes in-vitro foram realizados usando a linha celular L929. A deposição de hidroxiapatita foi avaliada por microscopia eletrónica de varrimento (SEM) acoplada com espectroscopia de energia dispersiva de raios-X (EDS) e por difração de raios-X (XRD). Uma vez que a estrutura e topografia apresentam um papel importante no desempenho funcional dos filmes, dois métodos de montagem LbL, revestimento por imersão e por rotação, foram comparados usando três substratos diferentes: vidro, aço inoxidável e titânio. Os revestimentos foram caracterizados por SEM, espectroscopia de infravermelho por transformada de Fourier (FT-IR), microscopia de força atómica (AFM) e ângulo de contacto da água (WCA). Dado à adesão e bioatividade melhoradas dos filmes desenvolvidos, estes poderiam ser utilizados como revestimentos para uma variedade de implantes. Além disso, verificou-se que o revestimento por rotação foi um método particularmente adequado para a construção, uma vez que foram produzidos filmes com superfícies mais lisas e uniformes

Cells behavior on superhydrophobic surfaces with different topographies

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Biomateriais, Reabilitação e Biomecânica)In the study of cell-material interaction, the nature of material surface has been shown to be essential for biocompatibility. Surface wettability and topography are recognized as critical factors that influence protein adsorption and, consequently, cell behavior. So far only few works have reported cell response on surfaces exhibiting extreme wettability, therefore, the influence of topography combined with this environment is still sparse in literature. The work presented in this thesis aimed to study the influence of superhydrophobic surfaces with different topographies on cell behavior. Bioinspired superhydrophobic rough surfaces of polystyrene (PS-R) and poly (L-acid lactic) (PLLA-R) with different micro- and nanotopographies have been obtained from smooth surfaces of the same polymers (PS-S and PLLA-S) using a simple phase-separation based methodology. Mouse osteoblastic cell line (MC3T3-E1) and a primary cell culture of bovine articular chondrocytes (bch) were used as model systems for cell response evaluation on these surfaces. Scanning electron microscopy (SEM) analysis showed that PS-R surfaces exhibited randomly distributed spheres at nanometer-scale that were agglomerated in larger micrometer structures while PLLA-R surfaces showed individual well define papilla-like structures at micrometer level with nanometer rough texture, very similar to the hierarchical architecture of lotus leaf. The water contact angle (WCA) of all surfaces was investigated over 12 weeks and showed to be stable over time. WCA measurements along with x-ray photoelectron spectroscopy (XPS) comproved that, whilst having the same surface chemistry, the superhydrophobic rough surfaces differ in wettability from the smooth ones as a consequence of the particular surface micro/nanostructures. A preliminary assay for total protein quantification was performed and demonstrated a reduction of bovine serum albumin (BSA) adsorption onto rough surfaces as compared with the correspondent smooth ones, though similar amount of protein adsorbed onto the same type of PS or PLLA surfaces. Biological assays were performed to test the ability of PS and PLLA surfaces to support cell adhesion and proliferation. Live-dead, metabolically activity assays and DNA quantification indicated that in general cells adhere and proliferate faster in the smooth surfaces as compared to the rough substrates. Nevertheless, cells were metabolically active and able to adhere and survive up to 7 days of culture on PS-R surfaces and even slightly proliferate on PLLA-R surfaces with preferential cell adhesion in specific areas as shown by SEM analysis. Both types of cells showed similar behavior when in contact with the surfaces, although MC3T3-E1 cell line showed enhanced performance. Such results indicate the relevant influence of wettability on cell behavior, which was shown to be not very influenced by the topography of the superhydrophobic surfaces or by the nature of both polymers.No estudo das interacções entre célula e material, a natureza da superfície do material tem-se mostrado essencial para a sua biocompatibilidade. A molhabilidade e a topografia da superfície são reconhecidas como factores críticos que influenciam a adsorção de proteínas e consequentemente o comportamento das células. Até à data apenas alguns trabalhos têm relatado a resposta celular face a superfícies exibindo extrema molhabilidade, assim sendo, a influência da topografia combinada com este ambiente ainda é escassa na literatura. O trabalho apresentado nesta tese teve como objectivo o estudo da influência de superfícies superhidrofóbicas com diferentes topografias no comportamento celular. Superfícies superhidrofóbicas bioinspiradas de poliestireno (PS-R) e poli (L-ácido láctico) (PLLA-R) com diferentes micro- e nanotopografias foram obtidas a partir de superfícies lisas dos mesmos polímeros (PS-S e PLLA-S) utilizando uma simples metodologia baseada na separação de fases. A linha celular osteoblástica de ratos (MC3T3-E1) e a cultura primária de condrócitos articulares bovinos (bch) foram utilizadas como sistemas modelo para a avaliação da resposta celular a estas superfícies. A análise efectuada por microscopia electrónica de varrimento (SEM) revelou que as superfícies de PS-R exibiam esferas a escala nanométrica distribuídas aleatoriamente que se aglomeravam em estruturas maiores a escala micro métrica, enquanto as superfícies de PLLA-R mostraram estruturas individuais, bem definidas do género de papilas a nível micrométrico, com textura rugosa a nano-escala, muito semelhantes à arquitectura hierárquica da folha de lótus. O ângulo de contacto (WCA) de todas as superfícies foi avaliado ao longo de 12 semanas e mostrou-se estável ao longo do tempo. As medições de WCA juntamente com a técnica de espectroscopia fotoelectrónica de raios X (XPS) comprovou que, embora tendo a mesma superfície química, as superfícies rugosas superhidrofóbicas diferem em molhabilidade das superfícies lisas como consequência das micro- e nano - estruturas particulares da superfície. Um ensaio preliminar de quantificação total de proteína foi realizado e demonstrou uma redução da adsorção de albumina de soro bovino (BSA) em superfícies rugosas em comparação com as superfícies lisas correspondentes, embora quantidades similares de proteína tenham sido adsorvidas no mesmo tipo de superfícies de PS ou PLLA. Foram realizados ensaios biológicos a fim de testar a capacidade das superfícies de PS e PLLA para suportar a adesão e proliferação celular. Ensaios de viabilidade celular, actividade metabólica e quantificação de DNA indicaram que, em geral, as células aderem e proliferam mais rapidamente em superfícies lisas em comparação com as superfícies rugosas. No entanto, as células estiveram metabolicamente activas e foram capaz de aderir e sobreviver até 7 dias de cultura em superfícies de PS-R e até mesmo proliferar um pouco em superfícies de PLLA-R, com adesão celular preferencial em áreas específicas, como revelado pela análise SEM. Ambos os tipos de células mostraram comportamentos semelhantes quando em contacto com as superfícies, embora a linha celular MC3T3-E1 tenha demonstrado melhor desempenho. Estes resultados indicam a relevante influência da molhabilidade sobre o comportamento celular, o que demonstrou não ser muito influenciado pela topografia das superfícies superhidrofóbicas ou pela natureza dos dois polímeros

Dynamics of protein interactions with new biomimetic interfaces: toward blood-compatible biomaterials

2019 Fall.Includes bibliographical references.Nonspecific blood protein adsorption on the surfaces is the first event that occurs within seconds when a biomaterial comes into contact with blood. This phenomenon may ultimately lead to significant adverse biological responses. Therefore, preventing blood protein adsorption on biomaterial surfaces is a prerequisite towards designing blood-compatible artificial surfaces. This project aims to address this problem by engineering surfaces that mimic the inside surface of blood vessels, which is the only known material that is completely blood-compatible. The inside surface of blood vessels presents a carbohydrate-rich, gel-like, dynamic surface layer called the endothelial glycocalyx. The polysaccharides in the glycocalyx include polyanionic glycosaminoglycans (GAGs). This polysaccharide-rich surface has excellent and unique blood compatibility. We developed a technique for preparing and characterizing dense GAG surfaces that can serve as models of the vascular endothelial glycocalyx. The glycocalyx-mimetic surfaces were prepared by adsorbing heparin- or chondroitin sulfate-containing polyelectrolyte complex nanoparticles (PCNs) to chitosan-hyaluronan polyelectrolyte multilayers (PEMs). We then studied in detail the interactions of two important blood proteins (albumin and fibrinogen) with these glycocalyx mimics. Surface plasmon resonance (SPR) is a common ensemble averaging technique for detection of biomolecular interactions. SPR was used to quantify the amount of protein adsorption on these surfaces. Moreover, single-molecule microscopy along with advanced particle tracking were used to directly study the interaction of single-molecule proteins with synthetic surfaces. Finally, we developed a groundwork for a kinetic model of long-term protein adsorption on biomaterial surfaces. In the first chapter, we thoroughly summarize the important blood-material interactions that regulate blood compatibility, organize recent developments in this field from a materials perspective, and recommend areas for future research. In the second chapter, we report the preparation and characterization of dense GAG surfaces that can serve as models of the vascular endothelial glycocalyx. In the third chapter, we investigate how combining surface plasmon resonance, X-ray spectroscopy, atomic force microscopy, and single-molecule total internal reflection fluorescence microscopy provides a more complete picture of protein adsorption on ultralow fouling polyelectrolyte multilayer and polymer brush surfaces, over different regimes of protein concentration. In the fourth chapter, the interactions of two important proteins from the blood (albumin and fibrinogen) with glycocalyx-mimetic surfaces are revealed in detail using surface plasmon resonance and single-molecule microscopy. Finally, in the fifth chapter, the long-term protein interactions with different biomaterial surfaces are studied with single-molecule microscopy an

Current Advances in Anisotropic Structures for Enhanced Osteogenesis

Bone defects are a challenge to healthcare systems, as the aging population experiences an increase in bone defects. Despite the development of biomaterials for bone fillers and scaffolds, there is still an unmet need for a bone-mimetic material. Cortical bone is highly anisotropic and displays a biological liquid crystalline (LC) arrangement, giving it exceptional mechanical properties and a distinctive microenvironment. However, the biofunctions, cell-tissue interactions, and molecular mechanisms of cortical bone anisotropic structure are not well understood. Incorporating anisotropic structures in bone-facilitated scaffolds has been recognised as essential for better outcomes. Various approaches have been used to create anisotropic micro/nanostructures, but biomimetic bone anisotropic structures are still in the early stages of development. Most scaffolds lack features at the nanoscale, and there is no comprehensive evaluation of molecular mechanisms or characterisation of calcium secretion. This manuscript provides a review of the latest development of anisotropic designs for osteogenesis and discusses current findings on cell-anisotropic structure interactions. It also emphasises the need for further research. Filling knowledge gaps will enable the fabrication of scaffolds for improved and more controllable bone regeneration

Special Issue: Biomimetic Organic–Inorganic Composites

In the world of increasing demand for novel, advanced materials, biomimetic organic–inorganic composites are emerging as promising materials for an increasing number of applications in biomedicine, pharmacy, photonics, catalysis, and environmental protection. Combining inspiration by natural materials, both in design and synthetic routes, with the newest developments not only in materials science, but also biology and nanotechnology, has opened a wide range of possibilities for tailoring materials properties while keeping them environmentally friendly and sustainable. The large variety of inorganic and organic materials that can be used in developing biomimetic organic–inorganic composites additionally contributes to their importance. However, despite the significant progress made in recent years, the rational design and synthesis of such materials can still present a challenge. This Special Issue is dedicated to the recent developments in the field of biomimetic organic–inorganic composites, from fundamental understanding of functioning of natural materials and mechanisms of organic-inorganic interactions in complex systems, to advances in processing routes and development of multifunctional materials

Characterization of the mandible atta laevigata and the bioinspiration for the development of a biomimetic surgical clamp

Approximately thousand years ago it was reported the use of mandibles of ants for suture. In this sense, bioinspired components, as absorbable surgical clamps, can be designed. This study is aimed to characterize the mandible of the ant Atta laevigata in order to help the selection of candidate biomaterials for application as surgical clamps. Three pairs of mandibles were used and ten nanoindenations were performed in each pair. The average hardness for the samples in the internal and external regions were 0.36 ± 0.06 GPa and 0.19 ± 0.04 GPa, respectively and the average elastic modulus for the internal and external regions were 6.16 ± 0.23 GPa and 2.74 ± 0.44 GPa, respectively. The morphology of the mandible was observed in detail by scanning electron microscopy, as well as Energy-dispersive X-ray spectroscopy. The average roughnesses on the internal and external regions, measured by atomic force microscopy, were 6.73 ± 0.90 nm and 11.87 ± 1.42 nm, respectively. From these results, it was possible to identify biomaterials that mimic the mandible behaviour for surgical clamp. © 2017