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Abstract Carbon fibre-reinforced polymers (CFRPs) are commonly used in aviation, automotive and renewable energy markets, which are constantly growing. Increasing the production of composite parts leads to increased waste production and a future increase in end-of-life components. To improve the recyclability of CFRPs, new materials that fit in with the idea of a circular economy should be used as a composite matrix. One such material is a commercially available thermoplastic liquid resin, Elium® (Arkema, France). In this work, the authors investigated how the mechanical recycling process affects the properties of thermoplastic-based carbon fibre composites. CFRPs with neat Elium® resin and resin modified with 0.02 wt.% single-walled carbon nanotubes or 0.02 wt.% multi-walled carbon nanotubes were manufactured using the resin infusion process. Afterwards, prepared laminates were mechanically ground, and a new set of composites was manufactured by thermopressing. The microstructure, mechanical, thermal and electrical properties were investigated for both sets of composites. The results showed that mechanical grinding and thermopressing processes lead to a significant increase in the electrical conductivity of composites. Additionally, a sharp decrease in all mechanical properties was observed.

The skeletons of marine sponges are ancient biocomposite structures in which mineral phases are formed on 3D organic matrices. In addition to calcium- and silicate-containing biominerals, iron ions play an active role in skeleton formation in some species of bath sponges in the marine environment, which is a result of the biocorrosion of the metal structures on which these sponges settle. The interaction between iron ions and biopolymer spongin has motivated the development of selected extreme biomimetics approaches with the aim of creating new functional composites to use in environmental remediation and as adsorbents for heavy metals. In this study, for the first time, microporous 3D spongin scaffolds isolated from the cultivated marine bath sponge Hippospongia communis were used for electro-assisted deposition of iron oxides such as goethite [α-FeO(OH)] and lepidocrocite [γ-FeO(OH)]. The obtained iron oxide phases were characterized with the use of scanning electron microscopy, FTIR, and X-ray diffraction. In addition, mechanisms of electro-assisted deposition of iron oxides on the surface of spongin, as a sustainable biomaterial, are proposed and discussed.

Sponges (phylum Porifera) were among the first metazoans on Earth, and represent a unique global source of highly structured and diverse biosilica that has been formed and tested over more than 800 million years of evolution. Poriferans are recognized as a unique archive of siliceous multiscaled skeletal constructs with superficial micro-ornamentation patterned by biopolymers. In the present study, spicules and skeletal frameworks of selected representatives of sponges in such classes as Demospongiae, Homoscleromorpha, and Hexactinellida were desilicified using 10% HF with the aim of isolating axial filaments, which resemble the shape and size of the original structures. These filaments were unambiguously identified in all specimens under study as F-actin, using the highly specific indicators iFluor™ 594-Phalloidin, iFluor™ 488-Phalloidin, and iFluor™ 350-Phalloidin. The identification of this kind of F-actins, termed for the first time as silactins, as specific pattern drivers in skeletal constructs of sponges opens the way to the fundamental understanding of their skeletogenesis. Examples illustrating the biomimetic potential of sophisticated poriferan biosilica patterned by silactins are presented and discussed.

In this study, a facile approach for simultaneous determination of dopamine (DA) and tryptophan (TRP) using a 3D goethite–spongin-modified carbon paste electrode is reported. The prepared electrode exhibited excellent electrochemical catalytic activity towards DA and TRP oxidation. The electrochemical sensing of the modified electrode was investigated using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Through differential pulse voltammetry analysis, two well-separated oxidation peaks were observed at 28 and 77 mV, corresponding to the oxidation of DA and TRP at the working electrode, with a large peak separation of up to 490 mV. DA and TRP were determined both individually and simultaneously in their dualistic mixture. As a result, the anodic peak currents and the concentrations of DA and TRP were found to exhibit linearity within the ranges of 4–246 μM for DA and 2 to 150 μM for TRP. The detection limits (S/N = 3) as low as 1.9 μM and 0.37 μM were achieved for DA and TRP, respectively. The proposed sensor was successfully applied to the simultaneous determination of DA and TRP in human urine samples with satisfactory recoveries (101% to 116%).

The main goal of this work was an improvement in the mechanical and electrical properties of acrylic resin-based nanocomposites filled with chemically modified carbon nanotubes. For this purpose, the surface functionalization of multi-walled carbon nanotubes (MWCNTs) was carried out by means of aryl groups grafting via the diazotization reaction with selected aniline derivatives, and then nanocomposites based on ELIUM® resin were fabricated. FT-IR analysis confirmed the effectiveness of the carried-out chemical surface modification of MWCNTs as new bands on FT-IR spectra appeared in the measurements. TEM observations showed that carbon nanotube fragmentation did not occur during the modifications. According to the results from Raman spectroscopy, the least defective carbon nanotube structure was obtained for aniline modification. Transmission light microscopy analysis showed that the neat MWCNTs agglomerate strongly, while the proposed modifications improved their dispersion significantly. Viscosity tests confirmed, that as the nanofiller concentration increases, the viscosity of the mixture increases. The mixture with the highest dispersion of nanoparticles exhibited the most viscous behaviour. Finally, an enhancement in impact resistance and electrical conductivity was obtained for nanocomposites containing modified MWCNTs.

The structural biopolymer spongin in the form of a 3D scaffold resembles in shape and size numerous species of industrially useful marine keratosan demosponges. Due to the large-scale aquaculture of these sponges worldwide, it represents a unique renewable source of biological material, which has already been successfully applied in biomedicine and bioinspired materials science. In the present study, spongin from the demosponge Hippospongia communis was used as a microporous template for the development of a new 3D composite containing goethite [α-FeO(OH)]. For this purpose, an extreme biomimetic technique using iron powder, crystalline iodine, and fibrous spongin was applied under laboratory conditions for the first time. The product was characterized using SEM and digital light microscopy, infrared and Raman spectroscopy, XRD, thermogravimetry (TG/DTG), and confocal micro X-ray fluorescence spectroscopy (CMXRF). A potential application of the obtained goethite–spongin composite in the electrochemical sensing of dopamine (DA) in human urine samples was investigated, with satisfactory recoveries (96% to 116%) being obtained.

Skeletal constructs of diverse marine sponges remain to be a sustainable source of biocompatible porous biopolymer-based 3D scaffolds for tissue engineering and technology, especially structures isolated from cultivated demosponges, which belong to the Verongiida order, due to the renewability of their chitinous, fibre-containing architecture focused attention. These chitinous scaffolds have already shown excellent and promising results in biomimetics and tissue engineering with respect to their broad diversity of cells. However, the mechanical features of these constructs have been poorly studied before. For the first time, the elastic moduli characterising the chitinous samples have been determined. Moreover, nanoindentation of the selected bromotyrosine-containing as well as pigment-free chitinous scaffolds isolated from selected verongiids was used in the study for comparative purposes. It was shown that the removal of bromotyrosines from chitin scaffolds results in a reduced elastic modulus; however, their hardness was relatively unaffected.

Marine sponges of the subclass Keratosa originated on our planet about 900 million years ago and represent evolutionarily ancient and hierarchically structured biological materials. One of them, proteinaceous spongin, is responsible for the formation of 3D structured fibrous skeletons and remains enigmatic with complex chemistry. The objective of this study was to investigate the interaction of spongin with iron ions in a marine environment due to biocorrosion, leading to the occurrence of lepidocrocite. For this purpose, a biomimetic approach for the development of a new lepidocrocite-containing 3D spongin scaffold under laboratory conditions at 24 °C using artificial seawater and iron is described for the first time. This method helps to obtain a new composite as “Iron-Spongin”, which was characterized by infrared spectroscopy and thermogravimetry. Furthermore, sophisticated techniques such as X-ray fluorescence, microscope technique, and X-Ray diffraction were used to determine the structure. This research proposed a corresponding mechanism of lepidocrocite formation, which may be connected with the spongin amino acids functional groups. Moreover, the potential application of the biocomposite as an electrochemical dopamine sensor is proposed. The conducted research not only shows the mechanism or sensor properties of “Iron-spongin” but also opens the door to other applications of these multifunctional materials.

Didymosphenia geminata is a species of freshwater diatom that is known as invasive and is propagating quickly around the world. While invasive species are generally considered a nuisance, this paper attempts to find useful applications for D. geminata in the biomedical field and wastewater remediation. Here, we highlight the polysaccharide-based stalks of D. geminata that enable versatile potential applications and uses as a biopolymer, in drug delivery and wound healing, and as biocompatible scaffolding in cell adhesion and proliferation. Furthermore, this review focuses on how the polysaccharide nature of stalks and their metal-adsorption capacity allows them to have excellent wastewater remediation potential. This work also aims to assess the economic impact of D. geminata, as an invasive species, on its immediate environment. Potential government measures and legislation are recommended to prevent the spread of D. geminata, emphasizing the importance of education and collaboration between stakeholders.

Abstract Background A basal spicule of the hexactinellid sponge Monorhaphis chuni may reach up to 3 m in length and 10 mm in diameter, an extreme case of large spicule size. Generally, sponge spicules are of scales from micrometers to centimeters. Due to its large size many researchers have described its structure and properties and have proposed it as a model of hexactinellid spicule development. Thorough examination of new material of this basal spicule has revealed numerous inconsistencies between our observations and earlier descriptions. In this work, we present the results of detailed examinations with transmitted light and epifluorescence microscopy, SEM, solid state NMR analysis, FTIR and X-ray analysis and staining of Monorhaphis chuni basal spicules of different sizes, collected from a number of deep sea locations, to better understand its structure and function. Results Three morphologically/structurally different silica layers i.e. plain glassy layer (PG), tuberculate layer (TL) and annular layer (AL), and an axial cylinder (AC) characterize adult spicules. Young, immature spicules display only plain glassy silica layers which dominate the spicule volume. All three layers i.e. PG, TL and AL can substitute for each other along the surface of the spicule, but equally they are superimposed in older parts of the spicules, with AL being the most external and occurring only in the lower part of the spicules and TL being intermediate between AL and PG. The TL, which is composed of several thinner layers, is formed by a progressive folding of its surface but its microstructure is the same as in the PG layer (glassy silica). The AL differs significantly from the PG and TL in being granular and porous in structure. The TL was found to display positive structures (tubercles), not depressions, as earlier suggested. The apparent perforated and non-perforated bands of the AL are an optical artefact. The new layer type that we called the Ripple Mark Layer (RML) was noted, as well as narrow spikes on the AL ridges, both structures not reported earlier. The interface of the TL and AL, where tubercles fit into depressions of the lower surface of the AL, represent tenon and mortise or dovetail joints, making the spicules more stiff/strong and thus less prone to breaking in the lower part. Early stages of the spicule growth are bidirectional, later growth is unidirectional toward the spicule apex. Growth in thickness proceeds by adding new layers. The spicules are composed of well condensed silica, but the outermost AL is characterized by slightly more condensed silica with less water than the rest. Organics permeating the silica are homogeneous and proteinaceous. The external organic net (most probably collagen) enveloping the basal spicule is a structural element that bounds the sponge body together with the spicule, rather than controlling tubercle formation. Growth of various layers may proceed simultaneously in different locations along the spicule and it is sclerosyncytium that controls formation of silica layers. The growth in spicule length is controlled by extension of the top of the axial filament that is not enclosed by silica and is not involved in further silica deposition. No structures that can be related to sclerocytes (as known in Demospongiae) in Monorhaphis were discovered during this study. Conclusions Our studies resulted in a new insight into the structure and growth of the basal Monorhaphis spicules that contradicts earlier results, and permitted us to propose a new model of this spicule’s formation. Due to its unique structure, associated with its function, the basal spicule of Monorhaphis chuni cannot serve as a general model of growth for all hexactinellid spicules.

The dissolution of the biogenic silica that constitutes the skeletons of silicifying organisms is an important mechanism for regenerating dissolved silicon in the ocean. The silica skeletons deposited to the seafloor after the organisms die keep dissolving until becoming definitively buried. The low dissolution rate of sponge skeletons compared to that of diatom skeletons favors their burial and makes sponges (Phylum Porifera) to function as important silicon sinks in the oceans. However, it remains poorly understood whether the large variety of siliceous skeletons existing in the Porifera involves similar variability in their dissolution rates, which would affect the general conceptualization of these organisms as silicon sinks. Herein we investigated kinetics of silica dissolution for major types of skeletons in the three siliceous lineages of Porifera, following standardized digestion conditions in 1% sodium carbonate with orbital agitation at 85°C. The results are compared with those of a previous study conducted under identical conditions, which considered diatom silica, sponge silica, and lithogenic silica. Unexpectedly, the silica of homoscleromorph sponges dissolved only a bit slower than that of freshly cultured diatoms and as fast as diatom earth. However, the rest of sponge skeletons were far more resistant, although with some differences: the isolated spicules of hexactinellid sponges dissolved slightly faster than when forming frameworks of fused spicules, being hexactinellid frameworks as resistant to dissolution as the silica of demosponges, irrespective of occurring in the form of isolated spicules or frameworks. The experiments also indicated that the complexation of sponge silica with aluminum and with chitin does not increase its resistance to dissolution. Because the rapidly-dissolving homoscleromorph sponges represent less than 1% of extant sponges, the sponge skeletons are still conceptualized as important silicon sinks due to their comparative resistance to dissolution. Yet, the turnover of silica into dissolved silicon will always be faster in environments dominated by hexactinellids with isolated spicules than in environments dominated by other hexactinellids and/or demosponges. We discuss whether the time required for a given silica type to completely dissolve in 1% sodium carbonate could be a predictor of its preservation ratio in marine sediments.

The content of trace metals, namely Zn, Cu, Fe, Mn, Pb, Cd, and Hg, in four types of media, i.e., soft tissues, shells, and the products of shell demineralization (organic matrix—conchix and extract) of the Mediterranean mussel Mytilus galloprovicialis L., at three sites in the Boka Kotorska Bay of the Adriatic Sea were determined. The main aim was to investigate the accumulation patterns of trace metals in conchix and their possible relationship with other tested media. Conchix weight within a group of mussels from Sv. Nedjelja was significantly higher in comparison with the IMB, while conchix % in the shell showed a negative correlation with dry shell weight. The highest metal pollution index (MPI) values found in the soft tissues of mussels from Sv. Nedjelja, Cogi, and the IMB were 2.319, 2.711, and 2.929 µg g−1, respectively. PCA analysis showed similarities in trace metal accumulation in all media except conchix. According to CCA analysis, conchixes were grouped around Cu, Fe, and Hg, while Cd and Zn were in correlation with the soft tissues. Moreover, the shells were in correlation with Mn. Simple isolation with high yield, close contact to the environment in comparison with calcified shell layers, and susceptibility to possible pollution sources due to the accumulation of specific metals are the main reasons to consider conchix of M. galloprovincialis as a medium with potential in trace metal assessments of marine ecosystems.

Structural bioinspiration in modern material science and biomimetics represents an actual trend that was originally based on the bioarchitectural diversity of invertebrate skeletons, specifically, honeycomb constructs of natural origin, which have been in humanities focus since ancient times. We conducted a study on the principles of bioarchitecture regarding the unique biosilica-based honeycomb-like skeleton of the deep-sea glass sponge Aphrocallistes beatrix. Experimental data show, with compelling evidence, the location of actin filaments within honeycomb-formed hierarchical siliceous walls. Principles of the unique hierarchical organization of such formations are discussed. Inspired by poriferan honeycomb biosilica, we designed diverse models, including 3D printing, using PLA-, resin-, and synthetic-glass-prepared corresponding microtomography-based 3D reconstruction.

Aminopolysaccharide chitin is one of the main structural biopolymers in sponges that is responsible for the mechanical stability of their unique 3D-structured microfibrous and porous skeletons. Chitin in representatives of exclusively marine Verongiida demosponges exists in the form of biocomposite-based scaffolds chemically bounded with biominerals, lipids, proteins, and bromotyrosines. Treatment with alkalis remains one of the classical approaches to isolate pure chitin from the sponge skeleton. For the first time, we carried out extraction of multilayered, tube-like chitin from skeletons of cultivated Aplysina aerophoba demosponge using 1% LiOH solution at 65 °C following sonication. Surprisingly, this approach leads not only to the isolation of chitinous scaffolds but also to their dissolution and the formation of amorphous-like matter. Simultaneously, isofistularin-containing extracts have been obtained. Due to the absence of any changes between the chitin standard derived from arthropods and the sponge-derived chitin treated with LiOH under the same experimental conditions, we suggest that bromotyrosines in A. aerophoba sponge represent the target for lithium ion activity with respect to the formation of LiBr. This compound, however, is a well-recognized solubilizing reagent of diverse biopolymers including cellulose and chitosan. We propose a possible dissolution mechanism of this very special kind of sponge chitin.

Gallic acid (GA) is one of the most important polyphenols, being widely used in the food, cosmetic, and pharmaceutical industries due to its biological effects such as antioxidant, antibacterial, anticancer, antiviral, anti-inflammatory, and cardioprotective properties. Hence, simple, fast, and sensitive determination of GA is of particular importance. Considering the fact that GA is an electroactive compound, electrochemical sensors offer great potential for GA quantitation due to their fast response time, high sensitivity, and ease of use. A simple, fast, and sensitive GA sensor was fabricated on the basis of a high-performance bio-nanocomposite using spongin as a natural 3D polymer, atacamite, and multi-walled carbon nanotubes (MWCNTs). The developed sensor showed an excellent response toward GA oxidation with remarkable electrochemical features due to the synergistic effects of 3D porous spongin and MWCNTs, which provide a large surface area and enhance the electrocatalytic activity of atacamite. At optimal conditions by differential pulse voltammetry (DPV), a good linear relationship was obtained between peak currents and GA concentrations in a wild linear range of 500 nM to 1 mM. Subsequently, the proposed sensor was used to detect GA in red wine as well as in green and black tea, confirming its great potential as a reliable alternative to conventional methods for GA determination.

This study reports the synthesis of a nanocomposite consisting of spongin and its applicability in the development of an aptasensing platform with high performance. The spongin was carefully extracted from a marine sponge and decorated with copper tungsten oxide hydroxide. The resulting spongin-copper tungsten oxide hydroxide was functionalized by silver nanoparticles and utilized in electrochemical aptasensor fabrication. The nanocomposite covered on a glassy carbon electrode surface amplified the electron transfer and increased active electrochemical sites. The aptasensor was fabricated by loading of thiolated aptamer on the embedded surface via thiol-AgNPs linkage. The applicability of the aptasensor was tested in detecting the Staphylococcus aureus bacterium as one of the five most common causes of nosocomial infectious diseases. The aptasensor measured S. aureus under a linear concentration range of 10–108 colony-forming units per milliliter and a limit of quantification and detection of 12 and 1 colony-forming unit per milliliter, respectively. The highly selective diagnosis of S. aureus in the presence of some common bacterial strains was satisfactorily evaluated. The acceptable results of the human serum analysis as the real sample may be promising in the bacteria tracking in clinical samples underlying the green chemistry principle.

Abstract Actin is a fundamental member of an ancient superfamily of structural intracellular proteins and plays a crucial role in cytoskeleton dynamics, ciliogenesis, phagocytosis, and force generation in both prokaryotes and eukaryotes. It is shown that actin has another function in metazoans: patterning biosilica deposition, a role that has spanned over 500 million years. Species of glass sponges (Hexactinellida) and demosponges (Demospongiae), representatives of the first metazoans, with a broad diversity of skeletal structures with hierarchical architecture unchanged since the late Precambrian, are studied. By etching their skeletons, organic templates dominated by individual F‐actin filaments, including branched fibers and the longest, thickest actin fiber bundles ever reported, are isolated. It is proposed that these actin‐rich filaments are not the primary site of biosilicification, but this highly sophisticated and multi‐scale form of biomineralization in metazoans is ptterned.

Three-dimensional chitinous scaffolds often used in regenerative medicine, tissue engineering, biomimetics and technology are mostly isolated from marine organisms, such as marine sponges (Porifera). In this work, we report the results of the electrochemical isolation of the ready to use chitinous matrices from three species of verongiid demosponges (Aplysina archeri, Ianthella basta and Suberea clavata) as a perfect example of possible morphological and chemical dimorphism in the case of the marine chitin sources. The electrolysis of concentrated Na2SO4 aqueous solution showed its superiority over the chemical chitin isolation method in terms of the treatment time reduction: only 5.5 h for A. archeri, 16.5 h for I. basta and 20 h for the S. clavata sample. Further investigation of the isolated scaffolds by digital microscopy and SEM showed that the electrolysis-supported isolation process obtains chitinous scaffolds with well-preserved spatial structure and it can be competitive to other alternative chitin isolation techniques that use external accelerating factors such as microwave irradiation or atmospheric plasma. Moreover, the infrared spectroscopy (ATR-FTIR) proved that with the applied electrochemical conditions, the transformation into chitosan does not take place.

The kinetic parameters of thermal degradation of 3D skeletal biopolymer spongin - isolated from the marine demosponge Hippospongia communis, using thermogravimetric analysis (TG) were evaluated. The kinetic parameters of the pyrolysis in a nitrogen atmosphere were calculated using standard methods, including a model-fitting approach (Coats–Redfern method) and the model-free iso-conversional Friedman, Kissinger–Akahira–Sunose (KAS) and Ozawa–Flynn–Wall (OFW) methods. Based on the kinetic parameters obtained from the respective equations, the changes of entropy (ΔS), enthalpy (ΔH), and free Gibbs energy (ΔG) were evaluated using the theory of the active complex of the reagent. It was found that the chemical reaction model best describes the experimental data. The activation energies calculated by the Coats–Redfern method were in the range 39.3–48.7 kJ/mol. The calculated values of kinetics parameters are slightly lower than for the commercial polyurethane foams. Nevertheless, this study provides a comprehensive insight into the pathway, mechanism, and outcomes of pyrolysis of spongin-based scaffolds with the relation to the physicochemical characteristics of finally obtained carbon materials. Moreover, a critical discussion of the obtained results is given, with regard to the physical meaning of the applied approximations.

The occurrence of 17α-ethinylestradiol (EE2) in the environment and its removal have drawn special attention from the scientific community in recent years, due to its hazardous effects on human and wildlife around the world. Therefore, the aim of this study was to produce an efficient enzymatic system for the removal of EE2 from aqueous solutions. For the first time, commercial silica nanopowder and 3D fibrous chitinous scaffolds from Aplysina fistularis marine sponge were used as supports for horseradish peroxidase (HRP) immobilization. The effect of several process parameters onto the removal mechanism of EE2 by enzymatic conversion and adsorption of EE2 were investigated here, including system type, pH, temperature and concentrations of H2O2 and EE2. It was possible to fully remove EE2 from aqueous solutions using system SiO2(HRP)–chitin(HRP) over a wide investigated pH range (5–9) and temperature ranges (4–45 °C). Moreover, the most suitable process conditions have been determined at pH 7, temperature 25 °C and H2O2 and EE2 concentrations equaling 2 mM and 1 mg/L, respectively. As determined, it was possible to reuse the nanoSiO2(HRP)–chitin(HRP) system to obtain even 55% EE2 degradation efficiency after five consecutive catalytic cycles.

The new nanocomposite with various molar ratios along with magnetic properties was fabricated via precipitation (assisted by ultrasonic) procedure. The photocatalytic effects of methylene blue (∼90% degradation for optimized sample in 100 min) for finding the optimized sample performed under visible light irradiation. Moreover, the photo-antibacterial impacts of bacteria culture environments were found with an optimized sample that had effective destruction of bacteria in comparison to control group. The cytotoxicity properties of panc1 cells and magnetic behaviors of the obtained nanomaterials were evaluated and its IC50 was about 500 mg/L. As an initial step, the structural, morphological and magnetic characteristics of the fabricated nanocomposites were evaluated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and MAP, UV-visible diffuse reflectance spectroscopy (DRS), and vibrating sample magnetometry (VSM) approaches. Based on SEM results, the size of nanoparticles in fabricated nanocomposite was nearly 50–70 nm for Fe3O4/SiO2/TiO2 and 80–100 nm for Fe3O4/SiO2/TiO2/CeVO4. XRD results showed that desired nanocomposites were truly synthesized without any impurities.

Marine sponges were among the first multicellular organisms on our planet and have survived to this day thanks to their unique mechanisms of chemical defense and the specific design of their skeletons, which have been optimized over millions of years of evolution to effectively inhabit the aquatic environment. In this work, we carried out studies to elucidate the nature and nanostructural organization of three-dimensional skeletal microfibers of the giant marine demosponge Ianthella basta, the body of which is a micro-reticular, durable structure that determines the ideal filtration function of this organism. For the first time, using the battery of analytical tools including three-dimensional micro—X-ray Fluorescence (3D-µXRF), X-ray diffraction (XRD), infra-red (FTIR), Raman and Near Edge X-ray Fine Structure (NEXAFS) spectroscopy, we have shown that biomineral calcite is responsible for nano-tuning the skeletal fibers of this sponge species. This is the first report on the presence of a calcitic mineral phase in representatives of verongiid sponges which belong to the class Demospongiae. Our experimental data suggest a possible role for structural amino polysaccharide chitin as a template for calcification. Our study suggests further experiments to elucidate both the origin of calcium carbonate inside the skeleton of this sponge and the mechanisms of biomineralization in the surface layers of chitin microfibers saturated with bromotyrosines, which have effective antimicrobial properties and are responsible for the chemical defense of this organism. The discovery of the calcified phase in the chitinous template of I. basta skeleton is expected to broaden the knowledge in biomineralization science where the calcium carbonate is regarded as a valuable material for applications in biomedicine, environmental science, and even in civil engineering.

Collagen filaments derived from the two marine demosponges Ircinia oros and Sarcotragus foetidus were for the first time isolated, biochemically characterised and tested for their potential use in regenerative medicine. SDS-PAGE of isolated filaments revealed a main collagen subunit band of 130 kDa in both of the samples under study. DSC analysis on 2D membranes produced with collagenous sponge filaments showed higher thermal stability than commercial mammalian-derived collagen membranes. Dynamic mechanical and thermal analysis attested that the membranes obtained from filaments of S. foetidus were more resistant and stable at the rising temperature, compared to the ones derived from filaments of I. oros. Moreover, the former has higher stability in saline and in collagenase solutions and evident antioxidant activity. Conversely, their water binding capacity results were lower than that of membranes obtained from I. oros. Adhesion and proliferation tests using L929 fibroblasts and HaCaT keratinocytes resulted in a remarkable biocompatibility of both developed membrane models, and gene expression analysis showed an evident up-regulation of ECM-related genes. Finally, membranes from I. oros significantly increased type I collagen gene expression and its release in the culture medium. The findings here reported strongly suggest the biotechnological potential of these collagenous structures of poriferan origin as scaffolds for wound healing.

The renewable, proteinaceous, marine biopolymer spongin is yet the focus of modern research. The preparation of a magnetic three-dimensional (3D) spongin scaffold with nano-sized Fe3O4 cores is reported here for the first time. The formation of this magnetic spongin–Fe3O4 composite was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA) (TGA-DTA), vibrating sample magnetometer (VSM), Fourier-transform infrared spectroscopy (FTIR), and zeta potential analyses. Field emission scanning electron microscopy (FE-SEM) confirmed the formation of well-dispersed spherical nanoparticles tightly bound to the spongin scaffold. The magnetic spongin–Fe3O4 composite showed significant removal efficiency for two cationic dyes (i.e., crystal violet (CV) and methylene blue (MB)). Adsorption experiments revealed that the prepared material is a fast, high-capacity (77 mg/g), yet selective adsorbent for MB. This behavior was attributed to the creation of strong electrostatic interactions between the spongin–Fe3O4 and MB or CV, which was reflected by adsorption mechanism evaluations. The adsorption of MB and CV was found to be a function of pH, with maximum removal performance being observed over a wide pH range (pH = 5.5–11). In this work, we combined Fe3O4 nanoparticles and spongin scaffold properties into one unique composite, named magnetic spongin scaffold, in our attempt to create a sustainable absorbent for organic wastewater treatment. The appropriative mechanism of adsorption of the cationic dyes on a magnetic 3D spongin scaffold is proposed. Removal of organic dyes and other contaminants is essential to ensure healthy water and prevent various diseases. On the other hand, in many cases, dyes are used as models to demonstrate the adsorption properties of nanostructures. Due to the good absorption properties of magnetic spongin, it can be proposed as a green and uncomplicated adsorbent for the removal of different organic contaminants and, furthermore, as a carrier in drug delivery applications.

Biologically induced and controlled mineralization of metals promotes the development of protective structures to shield cells from thermal, chemical, and ultraviolet stresses. Metal biomineralization is widely considered to have been relevant for the survival of life in the environmental conditions of ancient terrestrial oceans. Similar behavior is seen among extremophilic biomineralizers today, which have evolved to inhabit a variety of industrial aqueous environments with elevated metal concentrations. As an example of extreme biomineralization, we introduce the category of “forced biomineralization”, which we use to refer to the biologically mediated sequestration of dissolved metals and metalloids into minerals. We discuss forced mineralization as it is known to be carried out by a variety of organisms, including polyextremophiles in a range of psychrophilic, thermophilic, anaerobic, alkaliphilic, acidophilic, and halophilic conditions, as well as in environments with very high or toxic metal ion concentrations. While much additional work lies ahead to characterize the various pathways by which these biominerals form, forced biomineralization has been shown to provide insights for the progression of extreme biomimetics, allowing for promising new forays into creating the next generation of composites using organic-templating approaches under biologically extreme laboratory conditions relevant to a wide range of industrial conditions.

The ongoing pandemic has led to an urgent need for novel drug discovery and potential therapeutics for Sars-CoV-2 infected patients. Although Remdesivir and the anti-inflammatory agent dexamethasone are currently on the market for treatment, Remdesivir lacks full efficacy and thus, more drugs are needed. This review was conducted through literature search of PubMed, MDPI, Google Scholar and Scopus. Upon review of existing literature, it is evident that marine organisms harbor numerous active metabolites with anti-viral properties that serve as potential leads for COVID-19 therapy. Inorganic polyphosphates (polyP) naturally found in marine bacteria and sponges have been shown to prevent viral entry, induce the innate immune response, and downregulate human ACE-2. Furthermore, several marine metabolites isolated from diverse sponges and algae have been shown to inhibit main protease (Mpro), a crucial protein required for the viral life cycle. Sulfated polysaccharides have also been shown to have potent anti-viral effects due to their anionic properties and high molecular weight. Likewise, select marine sponges produce bromotyrosines which have been shown to prevent viral entry, replication and protein synthesis. The numerous compounds isolated from marine resources demonstrate significant potential against COVID-19. The present review for the first time highlights marine bioactive compounds, their sources, and their anti-viral mechanisms of action, with a focus on potential COVID-19 treatment.

The growing demand for new, sophisticated, multifunctional materials has brought natural structural composites into focus, since they underwent a substantial optimization during long evolutionary selection pressure and adaptation processes. Marine biological materials are the most important sources of both inspiration for biomimetics and of raw materials for practical applications in technology and biomedicine. The use of marine natural products as multifunctional biomaterials is currently undergoing a renaissance in the modern materials science. The diversity of marine biomaterials, their forms and fields of application are highlighted in this review. We will discuss the challenges, solutions, and future directions of modern marine biomaterialogy using a thorough analysis of scientific sources over the past ten years.

The morphology, chemical, and mineralogical composition of subsurface filamentous fabrics (SFF) from the Deccan Volcanic Province (DVP) were investigated to determine the origin of these spectacular aggregates. SFF occur in a wide variety of morphologies ranging from pseudo-stalactites to irregular fabrics and are classified as SFFIr (irregular) or SFFMa (matted). The SFF samples exhibit a thread-like (or filament-like) center from which mineral precipitation starts to form the final macroscopic morphologies. Detailed investigations revealed organic material (fungal chitin) in the innermost filamentous core, which may have acted as an initial nucleus for the mineralization processes. The morphometric characteristics of certain filamentous fabrics are very similar to those of microbial filaments and the fabrics formed from them but are clearly distinct from similar types of non-biological precipitates (fibrous minerals, speleothems, and “chemical gardens”). These features indicate that the filamentous cores might be products of microbial communities that were active in the basaltic cavities. The SFF cross-sections display similar concentric layers of the mineral succession and reach thicknesses of several centimeters with spectacular lengths up to 100 cm and constant diameters. The typical mineralization sequence points to temporal variation in the chemical composition of the mineralizing fluids from Fe(Mg)-rich (Fe-oxides/-hydroxides, Fe-rich sheet silicates such as celadonite and di-/tri-smectite) to Ca-dominated (Ca-rich zeolites) and finally pure SiO2 (opal-CT, chalcedony, and macro-crystalline quartz). Assuming biological activity at least during the early mineralization processes, circumneutral pH conditions and maximum temperatures of 100–120 °C were supposed. The formation of filamentous cores including Fe-bearing phyllosilicates probably occurred near the surface after cooling of the lava, where the elements necessary for mineral formation (i.e., Si, Mg, Al, Fe) were released during alteration of the volcanic host rocks by percolating fluids.

Chitin, as one of nature’s most abundant structural polysaccharides, possesses worldwide, high industrial potential and a functionality that is topically pertinent. Nowadays, the metallization of naturally predesigned, 3D chitinous scaffolds originating from marine sponges is drawing focused attention. These invertebrates represent a unique, renewable source of specialized chitin due to their ability to grow under marine farming conditions. In this study, the development of composite material in the form of 3D chitin-based skeletal scaffolds covered with silver nanoparticles (AgNPs) and Ag-bromide is described for the first time. Additionally, the antibacterial properties of the obtained materials and their possible applications as a water filtration system are also investigated.

The development of novel and effective methods for the isolation of chitin, which remains one of the fundamental aminopolysaccharides within skeletal structures of diverse marine invertebrates, is still relevant. In contrast to numerous studies on chitin extraction from crustaceans, mollusks and sponges, there are only a few reports concerning its isolation from corals, and especially black corals (Antipatharia). In this work, we report the stepwise isolation and identification of chitin from Cirrhipathes sp. (Antipatharia, Antipathidae) for the first time. The proposed method, aiming at the extraction of the chitinous scaffold from the skeleton of black coral species, combined a well-known chemical treatment with in situ electrolysis, using a concentrated Na2SO4 aqueous solution as the electrolyte. This novel method allows the isolation of α-chitin in the form of a microporous membrane-like material. Moreover, the extracted chitinous scaffold, with a well-preserved, unique pore distribution, has been extracted in an astoundingly short time (12 h) compared to the earlier reported attempts at chitin isolation from Antipatharia corals.

Novel strategies to treat cancer effectively without adverse effects on the surrounding normal tissue are urgently needed. Marine sponges provide a natural and renewable source of promising anti-tumor agents. Here, we investigated the anti-tumor activity of Aerothionin and Homoaerothionin, two bromotyrosines isolated from the marine demosponge Aplysina cavernicola, on two mouse pheochromocytoma cells, MPC and MTT. To determine the therapeutic window of these metabolites, we furthermore explored their cytotoxicity on cells of the normal tissue. Both metabolites diminished the viability of the pheochromocytoma cell lines significantly from a concentration of 25 µM under normoxic and hypoxic conditions. Treatment of MPC cells leads moreover to a reduction in the number of proliferating cells. To confirm the anti-tumor activity of these bromotyrosines, 3D-pheochromocytoma cell spheroids were treated with 10 µM of either Aerothionin or Homoaerothionin, resulting in a significant reduction or even complete inhibition of the spheroid growth. Both metabolites reduced viability of normal endothelial cells to a comparable extent at higher micromolar concentration, while the viability of fibroblasts was increased. Our in vitro results show promise for the application of Aerothionin and Homoaerothionin as anti-tumor agents against pheochromocytomas and suggest acceptable toxicity on normal tissue cells.

For the first time, 3D chitin scaffolds from the marine demosponge Aplysina archeri were used for adsorption and immobilization of laccase from Trametes versicolor. The resulting chitin–enzyme biocatalytic systems were applied in the removal of tetracycline. Effective enzyme immobilization was confirmed by scanning electron microscopy. Immobilization yield and kinetic parameters were investigated in detail, in addition to the activity of the enzyme after immobilization. The designed systems were further used for the removal of tetracycline under various process conditions. Optimum process conditions, enabling total removal of tetracycline from solutions at concentrations up to 1 mg/L, were found to be pH 5, temperature between 25 and 35 °C, and 1 h process duration. Due to the protective effect of the chitinous scaffolds and stabilization of the enzyme by multipoint attachment, the storage stability and thermal stability of the immobilized biomolecules were significantly improved as compared to the free enzyme. The produced biocatalytic systems also exhibited good reusability, as after 10 repeated uses they removed over 90% of tetracycline from solution. Finally, the immobilized laccase was used in a packed bed reactor for continuous removal of tetracycline, and enabled the removal of over 80% of the antibiotic after 24 h of continuous use.

Structure-based tissue engineering requires large-scale 3D cell/tissue manufacture technologies, to produce biologically active scaffolds. Special attention is currently paid to naturally pre-designed scaffolds found in skeletons of marine sponges, which represent a renewable resource of biomaterials. Here, an innovative approach to the production of mineralized scaffolds of natural origin is proposed. For the first time, a method to obtain calcium carbonate deposition ex vivo, using living mollusks hemolymph and a marine-sponge-derived template, is specifically described. For this purpose, the marine sponge Aplysin aarcheri and the terrestrial snail Cornu aspersum were selected as appropriate 3D chitinous scaffold and as hemolymph donor, respectively. The formation of calcium-based phase on the surface of chitinous matrix after its immersion into hemolymph was confirmed by Alizarin Red staining. A direct role of mollusks hemocytes is proposed in the creation of fine-tuned microenvironment necessary for calcification ex vivo. The X-ray diffraction pattern of the sample showed a high CaCO3 amorphous content. Raman spectroscopy evidenced also a crystalline component, with spectra corresponding to biogenic calcite. This study resulted in the development of a new biomimetic product based on ex vivo synthetized ACC and calcite tightly bound to the surface of 3D sponge chitin structure.

Marine demosponges (Porifera: Demospongiae) are recognized as first metazoans which have developed over millions of years of evolution effective survival strategies based on unique metabolic pathways to produce both biologically active secondary metabolites and biopolymer-based stiff skeletons with 3D architecture. Up to date, among marine demosponges, only representatives of the Verongiida order have been known to synthetize biologically active substances as well as skeletons made of structural polysaccharide chitin. This work, to our knowledge, demonstrates for the first time that chitin is an important structural component within skeletons of non-verongiid demosponges Acarnus wolffgangi and Echinoclathria gibbosa collected in the Red Sea. Calcofluor white staining, FTIR and Raman analysis, ESI-MS, SEM, and fluorescence microscopy as well as a chitinase digestion assay were applied in order to confirm, with strong evidence, the finding of α-chitin in the skeleton of both species. We suggest that, the finding of chitin within these representatives of Poecilosclerida order is a promising step in the evaluation of these sponges as novel renewable sources for both biologically active metabolites and chitin, which are of prospective application for pharmacology and biomedicine.

Innovative materials were made via the combination of chitin and lignin, and the immobilization of lipase from Aspergillus niger. Analysis by techniques including FTIR, XPS and 13C CP MAS NMR confirmed the effective immobilization of the enzyme on the surface of the composite support. The electrokinetic properties of the resulting systems were also determined. Results obtained from elemental analysis and by the Bradford method enabled the determination of optimum parameters for the immobilization process. Based on the hydrolysis reaction of para-nitrophenyl palmitate, a determination was made of the catalytic activity, thermal and pH stability, and reusability. The systems with immobilized enzymes were found to have a hydrolytic activity of 5.72 mU, and increased thermal and pH stability compared with the native lipase. The products were also shown to retain approximately 80% of their initial catalytic activity, even after 20 reaction cycles. The immobilization process, using a cheap, non-toxic matrix of natural origin, leads to systems with potential applications in wastewater remediation processes and in biosensors.

In this mini-review, we shall first cover a short history of the discovery of chitin isolated from sponges; as well as its evolutionarily ancient roots. Next, we will delve into the unique structural, mechanical, and thermal properties of this naturally occurring polymer to illuminate how its physicochemical properties may find uses in diverse areas of the material sciences. We show how the unique properties and morphology of sponge chitin renders it quite useful for the new route of “Extreme Biomimetics”; where high temperatures and pressures allow a range of interesting bioinorganic composite materials to be made. These new biomaterials have electrical, chemical, and material properties that have applications in water filtration, medicine, catalysis, and biosensing.

C.I. Natural Red 4 dye, also known as carmine or cochineal, was adsorbed onto the surface of spongin-based fibrous skeleton of Hippospongia communis marine demosponge for the first time. The influence of the initial concentration of dye, the contact time, and the pH of the solution on the adsorption process was investigated. The results presented here confirm the effectiveness of the proposed method for developing a novel dye/biopolymer hybrid material. The kinetics of the adsorption of carmine onto a marine sponge were also determined. The experimental data correspond directly to a pseudo-second-order model for adsorption kinetics (r2 = 0.979–0.999). The hybrid product was subjected to various types of analysis (FT-IR, Raman, 13C CP/MAS NMR, XPS) to investigate the nature of the interactions between the spongin (adsorbent) and the dye (the adsorbate). The dominant interactions between the dye and spongin were found to be hydrogen bonds and electrostatic effects. Combining the dye with a spongin support resulted with a novel hybrid material that is potentially attractive for bioactive applications and drug delivery systems.

Marine sponges remain representative of a unique source of renewable biological materials. The demosponges of the family Ianthellidae possess chitin-based skeletons with high biomimetic potential. These three-dimensional (3D) constructs can potentially be used in tissue engineering and regenerative medicine. In this study, we focus our attention, for the first time, on the marine sponge Ianthella labyrinthus Bergquist & Kelly-Borges, 1995 (Demospongiae: Verongida: Ianthellidae) as a novel potential source of naturally prestructured bandage-like 3D scaffolds which can be isolated simultaneously with biologically active bromotyrosines. Specifically, translucent and elastic flat chitinous scaffolds have been obtained after bromotyrosine extraction and chemical treatments of the sponge skeleton with alternate alkaline and acidic solutions. For the first time, cardiomyocytes differentiated from human induced pluripotent stem cells (iPSC-CMs) have been used to test the suitability of I. labyrinthus chitinous skeleton as ready-to-use scaffold for their cell culture. Results reveal a comparable attachment and growth on isolated chitin-skeleton, compared to scaffolds coated with extracellular matrix mimetic Geltrex®. Thus, the natural, unmodified I. labyrinthus cleaned sponge skeleton can be used to culture iPSC-CMs and 3D tissue engineering. In addition, I. labyrinthus chitin-based scaffolds demonstrate strong and efficient capability to absorb blood deep into the microtubes due to their excellent capillary effect. These findings are suggestive of the future development of new sponge chitin-based absorbable hemostats as alternatives to already well recognized cellulose-based fabrics.

Chitin, as a fundamental polysaccharide in invertebrate skeletons, continues to be actively investigated, especially with respect to new sources and the development of effective methods for its extraction. Recent attention has been focused on marine crustaceans and sponges; however, the potential of spiders (order Araneae) as an alternative source of tubular chitin has been overlooked. In this work, we focused our attention on chitin from up to 12 cm-large Theraphosidae spiders, popularly known as tarantulas or bird-eating spiders. These organisms “lose” large quantities of cuticles during their molting cycle. Here, we present for the first time a highly effective method for the isolation of chitin from Caribena versicolor spider molt cuticle, as well as its identification and characterization using modern analytical methods. We suggest that the tube-like molt cuticle of this spider can serve as a naturally prefabricated and renewable source of tubular chitin with high potential for application in technology and biomedicine.

Naturally occurring three-dimensional (3D) biopolymer-based matrices that can be used in different biomedical applications are sustainable alternatives to various artificial 3D materials. For this purpose, chitin-based structures from marine sponges are very promising substitutes. Marine sponges from the order Verongiida (class Demospongiae) are typical examples of demosponges with well-developed chitinous skeletons. In particular, species belonging to the family Ianthellidae possess chitinous, flat, fan-like fibrous skeletons with a unique, microporous 3D architecture that makes them particularly interesting for applications. In this work, we focus our attention on the demosponge Ianthella flabelliformis (Linnaeus, 1759) for simultaneous extraction of both naturally occurring (“ready-to-use”) chitin scaffolds, and biologically active bromotyrosines which are recognized as potential antibiotic, antitumor, and marine antifouling substances. We show that selected bromotyrosines are located within pigmental cells which, however, are localized within chitinous skeletal fibers of I. flabelliformis. A two-step reaction provides two products: treatment with methanol extracts the bromotyrosine compounds bastadin 25 and araplysillin-I N20 sulfamate, and a subsequent treatment with acetic acid and sodium hydroxide exposes the 3D chitinous scaffold. This scaffold is a mesh-like structure, which retains its capillary network, and its use as a potential drug delivery biomaterial was examined for the first time. The results demonstrate that sponge-derived chitin scaffolds, impregnated with decamethoxine, effectively inhibit growth of the human pathogen Staphylococcus aureus in an agar diffusion assay.

Sponges are a valuable source of natural compounds and biomaterials for many biotechnological applications. Marine sponges belonging to the order Verongiida are known to contain both chitin and biologically active bromotyrosines. Aplysina archeri (Aplysineidae: Verongiida) is well known to contain bromotyrosines with relevant bioactivity against human and animal diseases. The aim of this study was to develop an express method for the production of naturally prefabricated 3D chitin and bromotyrosine-containing extracts simultaneously. This new method is based on microwave irradiation (MWI) together with stepwise treatment using 1% sodium hydroxide, 20% acetic acid, and 30% hydrogen peroxide. This approach, which takes up to 1 h, made it possible to isolate chitin from the tube-like skeleton of A. archeri and to demonstrate the presence of this biopolymer in this sponge for the first time. Additionally, this procedure does not deacetylate chitin to chitosan and enables the recovery of ready-to-use 3D chitin scaffolds without destruction of the unique tube-like fibrous interconnected structure of the isolated biomaterial. Furthermore, these mechanically stressed fibers still have the capacity for saturation with water, methylene blue dye, crude oil, and blood, which is necessary for the application of such renewable 3D chitinous centimeter-sized scaffolds in diverse technological and biomedical fields.

The bioactive bromotyrosine-derived alkaloids and unique morphologically-defined fibrous skeleton of chitin origin have been found recently in marine demosponges of the order Verongiida. The sophisticated three-dimensional (3D) structure of skeletal chitinous scaffolds supported their use in biomedicine, tissue engineering as well as in diverse modern technologies. The goal of this study was the screening of new species of the order Verongiida to find another renewable source of naturally prefabricated 3D chitinous scaffolds. Special attention was paid to demosponge species, which could be farmed on large scale using marine aquaculture methods. In this study, the demosponge Pseudoceratina arabica collected in the coastal waters of the Egyptian Red Sea was examined as a potential source of chitin for the first time. Various bioanalytical tools including scanning electron microscopy (SEM), fluorescence microscopy, FTIR analysis, Calcofluor white staining, electrospray ionization mass spectrometry (ESI-MS), as well as a chitinase digestion assay were successfully used to confirm the discovery of α-chitin within the skeleton of P. arabica. The current finding should make an important contribution to the field of application of this verongiid sponge as a novel renewable source of biologically-active metabolites and chitin, which are important for development of the blue biotechnology especially in marine oriented biomedicine.

Demosponges possess a skeleton made of a composite material with various organic constituents and/or siliceous spicules. Chitin is an integral part of the skeleton of different sponges of the order Verongida. Moreover, sponges of the order Verongida, such as Aplysina cavernicola or Ianthella basta, are well-known for the biosynthesis of brominated tyrosine derivates, characteristic bioactive natural products. It has been unknown so far whether these compounds are exclusively present in the cellular matrix or whether they may also be incorporated into the chitin-based skeletons. In the present study, we therefore examined the skeletons of A. cavernicola and I. basta with respect to the presence of bromotyrosine metabolites. The chitin-based-skeletons isolated from these sponges indeed contain significant amounts of brominated compounds, which are not easily extractable from the skeletons by common solvents, such as MeOH, as shown by HPLC analyses in combination with NMR and IR spectroscopic measurements. Quantitative potentiometric analyses confirm that the skeleton-associated bromine mainly withstands the MeOH-based extraction. This observation suggests that the respective, but yet unidentified, brominated compounds are strongly bound to the sponge skeletons, possibly by covalent bonding. Moreover, gene fragments of halogenases suggested to be responsible for the incorporation of bromine into organic molecules could be amplified from DNA isolated from sponge samples enriched for sponge-associated bacteria.

The biosynthesis, chemistry, structural features and functionality of spongin as a halogenated scleroprotein of keratosan demosponges are still paradigms. This review has the principal goal of providing thorough and comprehensive coverage of spongin as a naturally prefabricated 3D biomaterial with multifaceted applications. The history of spongin’s discovery and use in the form of commercial sponges, including their marine farming strategies, have been analyzed and are discussed here. Physicochemical and material properties of spongin-based scaffolds are also presented. The review also focuses on prospects and trends in applications of spongin for technology, materials science and biomedicine. Special attention is paid to applications in tissue engineering, adsorption of dyes and extreme biomimetics.

The biosynthesis, structural diversity, and functionality of collagens of sponge origin are still paradigms and causes of scientific controversy. This review has the ambitious goal of providing thorough and comprehensive coverage of poriferan collagens as a multifaceted topic with intriguing hypotheses and numerous challenging open questions. The structural diversity, chemistry, and biochemistry of collagens in sponges are analyzed and discussed here. Special attention is paid to spongins, collagen IV-related proteins, fibrillar collagens from demosponges, and collagens from glass sponge skeletal structures. The review also focuses on prospects and trends in applications of sponge collagens for technology, materials science and biomedicine.

Sponges (Porifera) are recognized as aquatic multicellular organisms which developed an effective biochemical pathway over millions of years of evolution to produce both biologically active secondary metabolites and biopolymer-based skeletal structures. Among marine demosponges, only representatives of the Verongiida order are known to synthetize biologically active substances as well as skeletons made of structural polysaccharide chitin. The unique three-dimensional (3D) architecture of such chitinous skeletons opens the widow for their recent applications as adsorbents, as well as scaffolds for tissue engineering and biomimetics. This study has the ambitious goal of monitoring other orders beyond Verongiida demosponges and finding alternative sources of naturally prestructured chitinous scaffolds; especially in those demosponge species which can be cultivated at large scales using marine farming conditions. Special attention has been paid to the demosponge Mycale euplectellioides (Heteroscleromorpha: Poecilosclerida: Mycalidae) collected in the Red Sea. For the first time, we present here a detailed study of the isolation of chitin from the skeleton of this sponge, as well as its identification using diverse bioanalytical tools. Calcofluor white staining, Fourier-transform Infrared Spcetcroscopy (FTIR), electrospray ionization mass spectrometry (ESI-MS), scanning electron microscopy (SEM), and fluorescence microscopy, as well as a chitinase digestion assay were applied in order to confirm with strong evidence the finding of a-chitin in the skeleton of M. euplectellioides. We suggest that the discovery of chitin within representatives of the Mycale genus is a promising step in their evaluation of these globally distributed sponges as new renewable sources for both biologically active metabolites and chitin, which are of prospective use for pharmacology and biomaterials oriented biomedicine, respectively.

In this study, Hippospongia communis marine demosponge skeleton was used as an adsorbent for sodium copper chlorophyllin (SCC). Obtained results indicate the high sorption capacity of this biomaterial with respect to SCC. Batch experiments were performed under different conditions and kinetic and isotherms properties were investigated. Acidic pH and the addition of sodium chloride increased SCC adsorption. The experimental data were well described by a pseudo-second order kinetic model. Equilibrium adsorption isotherms were determined and the experimental data were analyzed using both Langmuir and Freundlich isotherms. The effectiveness of the process was confirmed by 13C Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance (13C CP/MAS NMR), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TG). This novel SCC-sponge-based functional hybrid material was found to exhibit antimicrobial activity against the gram-positive bacterium Staphylococcus aureus.

A new method is proposed for the production of a novel chitin-polyhedral oligomeric silsesquioxanes (POSS) enzyme support. Analysis by such techniques as X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy confirmed the effective functionalization of the chitin surface. The resulting hybrid carriers were used in the process of immobilization of the lipase type b from Candida antarctica (CALB). Fourier transform infrared spectroscopy (FTIR) confirmed the effective immobilization of the enzyme. The tests of the catalytic activity showed that the resulting support-biocatalyst systems remain hydrolytically active (retention of the hydrolytic activity up to 87% for the chitin + Methacryl POSS® cage mixture (MPOSS) + CALB after 24 h of the immobilization), as well as represents good thermal and operational stability, and retain over 80% of its activity in a wide range of temperatures (30–60 °C) and pH (6–9). Chitin-POSS-lipase systems were used in the transesterification processes of rapeseed oil at various reaction conditions. Produced systems allowed the total conversion of the oil to fatty acid methyl esters (FAME) and glycerol after 24 h of the process at pH 10 and a temperature 40 °C, while the Methacryl POSS® cage mixture (MPOSS) was used as a chitin-modifying agent.

Integrative taxonomy provides a major approximation to species delimitation based on integration of different perspectives (e.g. morphology, biochemistry and DNA sequences). The aim of this study was to assess the relationships and boundaries among Eastern Pacific Aplysina species using morphological, biochemical and molecular data. For this, a collection of sponges of the genus Aplysina from the Mexican Pacific was studied on the basis of their morphological, chemical (chitin composition), and molecular markers (mitochondrial COI and nuclear ribosomal rDNA: ITS1-5.8-ITS2). Three morphological species were identified, two of which are new to science. A. clathrata sp. nov. is a yellow to yellow-reddish or -brownish sponge, characterized by external clathrate-like morphology; A. revillagigedi sp. nov. is a lemon yellow to green, cushion-shaped sometimes lobate sponge, characterized by conspicuous oscules, which are slightly elevated and usually linearly distributed on rims; and A. gerardogreeni a known species distributed along the Mexican Pacific coast. Chitin was identified as the main structural component within skeletons of the three species using FTIR, confirming that it is shared among Verongida sponges. Morphological differences were confirmed by DNA sequences from nuclear ITS1-5.8-ITS2. Mitochondrial COI sequences showed extremely low but diagnostic variability for Aplysina revillagigedi sp. nov., thus our results corroborate that COI has limited power for DNA-barcoding of sponges and should be complemented with other markers (e.g. rDNA). Phylogenetic analyses of Aplysina sequences from the Eastern Pacific and Caribbean, resolved two allopatric and reciprocally monophyletic groups for each region. Eastern Pacific species were grouped in general accordance with the taxonomic hypothesis based on morphological characters. An identification key of Eastern Pacific Aplysina species is presented. Our results constitute one of the first approximations to integrative taxonomy, phylogeny and evolutionary biogeography of Eastern Pacific marine sponges; an approach that will significantly contribute to our better understanding of their diversity and evolutionary history.