A modern scleractinian coral with a two-component calcite-aragonite skeleton.

One of the most conserved traits in the evolution of biomineralizing organisms is the taxon-specific selection of skeletal minerals. All modern scleractinian corals are thought to produce skeletons exclusively of the calcium-carbonate polymorph aragonite. Despite strong fluctuations in ocean chemistry (notably the Mg/Ca ratio), this feature is believed to be conserved throughout the coral fossil record, spanning more than 240 million years. Only one example, the Cretaceous scleractinian coral Coelosmilia (ca. 70 to 65 Ma), is thought to have produced a calcitic skeleton. Here, we report that the modern asymbiotic scleractinian coral Paraconotrochus antarcticus living in the Southern Ocean forms a two-component carbonate skeleton, with an inner structure made of high-Mg calcite and an outer structure composed of aragonite. P. antarcticus and Cretaceous Coelosmilia skeletons share a unique microstructure indicating a close phylogenetic relationship, consistent with the early divergence of P. antarcticus within the Vacatina (i.e., Robusta) clade, estimated to have occurred in the Mesozoic (ca. 116 Mya). Scleractinian corals thus join the group of marine organisms capable of forming bimineralic structures, which requires a highly controlled biomineralization mechanism; this capability dates back at least 100 My. Due to its relatively prolonged isolation, the Southern Ocean stands out as a repository for extant marine organisms with ancient traits.

A tetrahydroacridine derivative and its conjugate with gold nanoparticles: promising agents for the treatment of Alzheimer's disease.

A new tetrahydroacridine derivative (CHDA) with acetylcholinesterase inhibitory properties was synthesized. Using a range of physicochemical techniques, it was shown that the compound strongly adsorbs onto the surface of planar macroscopic or nanoparticulate gold, forming a nearly full monolayer. The adsorbed CHDA molecules reveal well-defined electrochemical behavior, being irreversibly oxidized to electroactive species. The CHDA also exhibits strong fluorescence, which is effectively quenched after adsorption onto gold via a static quenching mechanism. Both CHDA and its conjugate reveal considerable inhibitory properties against acetylcholinesterase activity, which is promising from the perspective of therapeutic application in the treatment of Alzheimer's disease. Moreover, both agents appear to be non-toxic as demonstrated using in vitro studies. On the other hand, conjugation of CHDA with nanoradiogold particles (Au-198) offers new potential diagnostic perspectives in medical imaging.

An Organofluorine Isoselenocyanate Analogue of Sulforaphane Affects Antimetabolite 5-Fluorouracil's Anticancer Activity: A Perspective for New Combinatory Therapy in Triple-Negative Breast Cancer.

Antimetabolites, especially 5-fluorouracil, are commonly used clinically to treat breast, colon, and other cancers. However, their side effects and inefficiency in monotherapy have prompted further searches for new combinations. Thus, the anticancer effect of 5-fluorouracil (5-FU) and the sulforaphane analogue, 4-isoselenocyanato-1-butyl 4'-fluorobenzyl sulfoxide (ISC), were tested in in vitro and in vivo models of triple-negative breast cancer (TNBC) as a new option for this treatment-resistant and aggressive type of breast cancer. A synergic interaction between 5-FU and ISC was observed in the TNBC in vitro model MDA-MB-231 cell line, which led to enhanced antiproliferative effects. The results of in vitro studies were confirmed by in vivo tests, which demonstrated stronger tumor growth inhibition and additive interactions between 5-FU and ISC in the murine TNBC model. Moreover, the results of the body mass and blood analysis showed the safety of the tested combination. The mechanistic study revealed that the combined treatment triggered apoptosis and necrosis, as well as inhibited cell migration.

Preparation of Surface-Supported Polylactide Spherical-Cap Particles.

Biodegradable polymer particles are of considerable importance due to their multiple applications in medical diagnostics and therapy. Spherical-cap particles have been prepared in a very general and simple method by melting a thin polymer film supported on a solid substrate that is in contact with a hydrophilic solvent. The melted polymer forms droplets which transform into solid particles attached to the surface after cooling down the sample. This approach has been demonstrated for polylactide adlayers on glass, which, when melted in glycerol, produce an array of polymer particles supported on the surface. The size of the particles depends on the experimental conditions and ranges from tens of nanometers to several micrometers. The particles can be employed to incorporate guest species, for example, drug molecules or inorganic nanoparticles. This has been confirmed herein through entrapment of an anticancer drug (doxorubicin) and radiogold (Au-198) nanoparticles. The resulting structures have been examined using a number of complementary physicochemical techniques including scanning and transmission electron microscopy, atomic force and optical microscopy as well as Raman and fluorescence spectroscopy.

Sulforaphane-assisted preparation of tellurium flower-like nanoparticles.

A new method for the fabrication of flower-like tellurium nanoparticles is reported. It is based on the reduction of tellurite precursor by products generated during decomposition of sulforaphane at elevated temperature in aqueous medium. These species and other organic molecules present in the reaction mixture are being adsorbed on the surface of tellurium nuclei and govern further tellurium growth in the form of nanoflowers. The obtained particles have been characterized by a range of physicochemical techniques. It was shown that the average size of the nanoflower particles is ca. 112 nm, and they are composed of smaller domains which are ca. 30 nm in diameter. The domains are crystalline and consist of trigonal tellurium as shown by x-ray diffraction, Raman spectroscopy and high resolution transmission electron microscopy. The tellurium nanoflowers were examined from the perspective of their potential anticancer activity. The in vitro cell viability studies were conducted on breast cancer (MDA-MB-231, MCF-7) and normal cell lines (MCF-10A) employing MTT and CVS assays. It was shown, that the nanoflowers exhibit considerable cytotoxicity against cancer cells which is ca. 3-7 times higher than that observed for reference normal cells. The preliminary in vivo investigations on rats revealed that the nanoflowers accumulate predominantly in pancreas after intraperitoneal administration, without observable negative behavioral effects.

Multiwalled Carbon Nanotubes-Poly(3-octylthiophene-2,5-diyl) Nanocomposite Transducer for Ion-Selective Electrodes: Raman Spectroscopy Insight into the Transducer/Membrane Interface.

An approach to overcome drawbacks of well-established transducer materials for all-solid-state ion-selective electrodes is proposed; it is based on the formulation of the nanocomposite of multiwalled carbon nanotubes (MWCNTs) and poly(3-octylthiophene-2,5-diyl) (POT), in which the polymer is used as a dispersing agent for carbon nanotubes. Thus, the obtained material is characterized with unique properties that are important for its application as solid contact in ion-selective electrodes, including high: electronic conductivity, capacitance, and lipophilicity. Performance of the obtained all-solid-state electrodes was studied using a standard approach as well as Raman spectroscopy to allow insight into distribution of the transducer material within the sensor phases: the membrane and the transducer. Application of the composite prevents unwanted partition of POT to the membrane phase, thus eliminating the risk of alteration of the sensor performance due to uncontrolled change in the membrane composition.

Sulforaphane-conjugated selenium nanoparticles: towards a synergistic anticancer effect.

Sulforaphane-modified selenium nanoparticles can be prepared in a simple aqueous-phase redox reaction through reduction of selenite with ascorbic acid. The sulforaphane molecules present in the reaction mixture adsorb on the nanoparticle surface, forming an adlayer. The resulting conjugate was examined with several physicochemical techniques, including microscopy, spectroscopy, x-ray diffraction, dynamic light scattering and zeta potential measurements. As shown in in vivo investigations on rats, the nanomaterial administered intraperitoneally is eliminated mainly in urine (and, to a lesser extent, in feces); however, it is also retained in the body. The modified nanoparticles mainly accumulate in the liver, but the basic parameters of blood and urine remain within normal limits. The sulforaphane-conjugated nanoparticles reveal considerable anticancer action, as demonstrated on several cancer cell cultures in vitro. This finding is due to the synergistic effect of elemental selenium and sulforaphane molecules assembled in one nanostructure (conjugate). On the other hand, the cytotoxic action on normal cells is relatively low. The high antitumor activity and selectivity of the conjugate with respect to diseased and healthy cells is extremely promising from the point of view of cancer treatment.

Fate of Poly(3-octylthiophene) Transducer in Solid Contact Ion-Selective Electrodes.

An experimental approach allowing visualization and quantification of the underestimated spontaneous process of partition of conducting polymer transducer material to the ion-selective membrane phase is proposed. The approach proposed is based on optical properties of the transducer material applied, using polythiophene as a model system. It is shown that this process occurs not only during the sensor preparation step but also during pretreatment of the sensor before use. As shown, this uncontrolled partition of the transducer to the receptor leads to conducting polymer contents in the membrane phase reaching 0.5% w/w; this process is accompanied by a partial spontaneous change of the oxidation state of polythiophene. The conducting polymer present in the membrane participates to some extent in the overall response of the sensor, which can be observed as a change in the polythiophene optical emission spectra. Fluorescence microscopic images obtained clearly show that the conducting polymer is distributed throughout the membrane thickness, being present also at the membrane/solution interface. The experimental results presented were obtained for K+-selective sensors using poly(3-octylthiophene) as a model transducer; however, the proposed approach is also applicable for other systems.

Colloidal carbon soot templated TiO2/Ag surface functionalized 3D printed metal brushes as new generation surface enhanced Raman scattering substrates.

This present work demonstrated the functional transformation of 3D printed metal substrates into a new family of Surface-enhanced Raman Scattering substrates, a promising approach in developing SERS-based Point-of-care (PoC) analytical platforms. l-Powder Bed Fusion (l-PBF, Additive manufacturing or 3D printing technique) printed metal substrates have rough surfaces, and exhibit high thermal stability and intrinsic chemical inertness, necessitating a suitable surface functionalization approach. This present work demonstrated a unique multi-stage approach to transform l-PBF printed metal structures as recyclable SERS substrates by colloidal carbon templating, chemical vapor deposition, and electroless plating methods sequentially. The surface of the printed metal structures was functionalized using the colloidal carbon soot particles, that were formed by the eucalyptus oil flame deposition method. These carbon particles were shown to interact with the metals present in the printed structures by forming metal carbides and function as an adlayer on the surface. Subsequent deposition of TiO2 onto these templates led to strong grafting of TiO2 and retaining the fractal structure of the soot template onto the metal surface. Electroless deposition of silver nanoparticles resulted in the formation of fractally structured TiO2/Ag nanostructures and these functionalized printed metal structures were shown as excellent SERS substrates in enhancing the vibrational spectral features of Rhodamine B (RhB). The presence of TiO2 photocatalyst on the surface was shown to remove the RhB analyte from the surface under photochemical conditions, which enables the regeneration of SERS activity, and the substrate can be recycled. The migration of metals from the printed metal structures into the fractally ordered TiO2/Ag nanostructures was found to enhance the photocatalytic activity and increase the recyclability of these substrates. This study demonstrates the potential of 3D-printed Inconel metal substrates as next-generation recyclable SERS platforms, offering a substantial advancement over traditional colloidal, thin-film, flexible, and hard SERS substrates.

Post-mortem recrystallization of biogenic amorphous calcium carbonate guided by the inherited macromolecular framework.

In contrast to abiotically formed carbonates, biogenetic carbonates have been observed to be nanocomposite, organo-mineral structures, the basic build-blocks of which are particles of quasi-uniform size (10-100 nm) organized into complex higher-order hierarchical structures, typically with highly controlled crystal-axis alignments. Some of these characteristics serve as criteria for inferring a biological origin and the state of preservation of fossil carbonate materials, and to determine whether the biomineralization process was biologically induced or controlled. Here we show that a calcium storage structure formed by the American lobster, a gastrolith initially consisting of amorphous calcium carbonate (ACC) and amorphous calcium phosphate (ACP), post-mortem can crystallize into (thus secondary) calcite with structural properties strongly influenced by the inherited organic matrix. This secondary calcite meets many structural criteria for biominerals (thus called the biomorphic calcite), but differs in trace element distributions (e.g., P and Mg). Such observations refine the capability to determine whether a fossil carbonates can be attributed to biogenic processes, with implications for the record of life on Earth and other terrestrial planets.

Preclinical evaluation of [18F]SYN1 and [18F]SYN2, novel radiotracers for PET myocardial perfusion imaging.

BACKGROUND: Positron emission tomography (PET) is now an established diagnostic method for myocardial perfusion imaging (MPI) in coronary artery disease, which is the main cause of death globally. The available tracers show several limitations, therefore, the 18F-labelled tracer is in high demand nowadays. The preclinical studies on normal Wistar rats aimed to characterise two potential, novel radiotracers, [18F]SYN1 and [18F]SYN2, to evaluate which is a better candidate for PET MPI cardiotracer. RESULTS: The dynamic microPET images showed rapid myocardial uptake for both tracers. However, the uptake was higher and also stable for [18F]SYN2, with an average standardized uptake value of 3.8. The biodistribution studies confirmed that [18F]SYN2 uptake in the cardiac muscle was high and stable (3.02%ID/g at 15 min and 2.79%ID/g at 6 h) compared to [18F]SYN1 (1.84%ID/g at 15 min and 0.32%ID/g at 6 h). The critical organs determined in dosimetry studies were the small intestine and the kidneys. The estimated effective dose for humans was 0.00714 mSv/MBq for [18F]SYN1 and 0.0109 mSv/MBq for [18F]SYN2. The tested dose level of 2 mg/kg was considered to be the No Observed Adverse Effect Level (NOAEL) for both candidates. The better results were achieved for [18F]SYN2, therefore, further preclinical studies were conducted only for this tracer. Radioligand binding assays showed significant responses in 3 from 68 assays: muscarinic acetylcholine M1 and M2 receptors and potassium channel hERG. The compound was mostly metabolised via an oxidative N-dealkylation, while the fluor substituent was not separated from the molecule. CONCLUSION: [18F]SYN2 showed a favourable pharmacodynamic and pharmacokinetic profile, which enabled a clear visualization of the heart in microPET. The compound was well-tolerated in studies in normal rats with moderate radiation exposure. The results encourage further exploration of [18F]SYN2 in clinical studies.

Magnetic-nanoparticle-decorated polypyrrole microvessels: toward encapsulation of mRNA cap analogues.

Many phosphorylated nucleoside derivatives have therapeutic potential, but their application is limited by problems with membrane permeability and with intracellular delivery. Here, we prepared polypyrrole microvessel structures modified with superparamagnetic nanoparticles for use as potential carriers of nucleotides. The microvessels were prepared via the photochemical polymerization of the monomer onto the surface of aqueous ferrofluidic droplets. A complementary physicochemical analysis revealed that a fraction of the nanoparticles was embedded in the microvessel walls, while the other nanoparticles were in the core of the vessel. SQUID (superconducting quantum interference device) measurements indicated that the incorporated nanoparticles retained their superparamagnetic properties; thus, the resulting nanoparticle-modified microvessels can be directed by an external magnetic field. As a result of these features, these microvessels may be useful as drug carriers in biomedical applications. To demonstrate the encapsulation of drug molecules, two labeled mRNA cap analogues, nucleotide-derived potential anticancer agents, were used. It was shown that the cap analogues are located in the aqueous core of the microvessels and can be released to the external solution by spontaneous permeation through the polymer walls. Mass spectrometry analysis confirmed that the cap analogues were preserved during encapsulation, storage, and release. This finding provides a foundation for the future development of anticancer therapies and for the delivery of nucleotide-based therapeutics.

Anticancer effect and safety of doxorubicin and nutraceutical sulforaphane liposomal formulation in triple-negative breast cancer (TNBC) animal model.

Female breast cancer is the most deadly cancer in women worldwide. The triple-negative breast cancer subtype therapies, due to the lack of specific drug targets, are still based on systemic chemotherapy with doxorubicin, which is burdened with severe adverse effects. To enhance therapeutic success and protect against systemic toxicity, drug carriers or combination therapy are being developed. Thus, an innovative liposomal formulation containing doxorubicin and the main nutraceutical, sulforaphane, has been developed. The anticancer efficacy and safety of the proposed liposomal formulation was evaluated in vivo, in a 4T1 mouse model of triple-negative breast cancer, and the mechanism of action was determined in vitro, using triple-negative breast cancer MDA-MB-231 and non-tumorigenic breast MCF-10A cell line. The elaborated drug carriers were shown to efficiently deliver both compounds into the cancer cell and direct doxorubicin to the cell nucleus. Incorporation of sulforaphane resulted in a twofold inhibition of tumor growth and the potential of up to a fourfold reduction in doxorubicin concentration due to the synergistic interaction between the two compounds. Sulforaphane was shown to increase the accumulation of doxorubicin in the nuclei of cancer cells, accompanied by inhibition of mitosis, without affecting the reactive oxygen species status of the cell. In normal cells, an antagonistic effect resulting in less cytotoxicity was observed. In vivo results showed that sulforaphane incorporation yielded not only cardioprotective, but also nephro- and hepatoprotective effects. The results of the research revealed the prospects of applying sulforaphane as a component of liposomal doxorubicin in triple-negative breast cancer chemotherapy.

The State of the Art in Machining Additively Manufactured Titanium Alloy Ti-6Al-4V.

Titanium alloys are extensively used in various industries due to their excellent corrosion resistance and outstanding mechanical properties. However, titanium alloys are difficult to machine due to their low thermal conductivity and high chemical reactivity with tool materials. In recent years, there has been increasing interest in the use of titanium components produced by additive manufacturing (AM) for a range of high-value applications in aerospace, biomedical, and automotive industries. The machining of additively manufactured titanium alloys presents additional machining challenges as the alloys exhibit unique properties compared to their wrought counterparts, including increased anisotropy, strength, and hardness. The associated higher cutting forces, higher temperatures, accelerated tool wear, and decreased machinability lead to an expensive and unsustainable machining process. The challenges in machining additively manufactured titanium alloys are not comprehensively documented in the literature, and this paper aims to address this limitation. A review is presented on the machining characteristics of titanium alloys produced by different AM techniques, focusing on the effects of anisotropy, porosity, and post-processing treatment of additively manufactured Ti-6Al-4V, the most commonly used AM titanium alloy. The mechanisms resulting in different machining performance and quality are analysed, including the influence of a hybrid manufacturing approach combining AM with conventional methods. Based on the review of the latest developments, a future outlook for machining additively manufactured titanium alloys is presented.

First paleoproteome study of fossil fish otoliths and the pristine preservation of the biomineral crystal host.

Otoliths are calcium carbonate components of the stato-acoustical organ responsible for hearing and maintenance of the body balance in teleost fish. During their formation, control over, e.g., morphology and carbonate polymorph is influenced by complex insoluble collagen-like protein and soluble non-collagenous protein assemblages; many of these proteins are incorporated into their aragonite crystal structure. However, in the fossil record these proteins are considered lost through diagenetic processes, hampering studies of past biomineralization mechanisms. Here we report the presence of 11 fish-specific proteins (and several isoforms) in Miocene (ca. 14.8-14.6 Ma) phycid hake otoliths. These fossil otoliths were preserved in water-impermeable clays and exhibit microscopic and crystallographic features indistinguishable from modern representatives, consistent with an exceptionally pristine state of preservation. Indeed, these fossil otoliths retain ca. 10% of the proteins sequenced from modern counterparts, including proteins specific to inner ear development, such as otolin-1-like proteins involved in the arrangement of the otoliths into the sensory epithelium and otogelin/otogelin-like proteins that are located in the acellular membranes of the inner ear in modern fish. The specificity of these proteins excludes the possibility of external contamination. Identification of a fraction of identical proteins in modern and fossil phycid hake otoliths implies a highly conserved inner ear biomineralization process through time.

Earthworm granules: A model of non-classical biogenic calcium carbonate phase transformations.

Different non-classical crystallization mechanisms have been invoked to explain structural and compositional properties of biocrystals. The identification of precursor amorphous nanoparticle aggregation as an onset process in the formation of numerous biominerals (crystallization via particle attachment) constituted a most important breakthrough for understanding biologically mediated mineralization. A comprehensive understanding about how the attached amorphous particles transform into more stable, crystalline grains has yet to be elucidated. Here, we document structural, biogeochemical, and crystallographic aspects of the formation as well as the further phase transformations of the amorphous calcium carbonate particles formed by cultured specimens of earthworm Lumbricus terrestris. In-situ observations evidence the formation of proto-vaterite after dehydration of earthworm-produced ACC, which is subsequently followed by proto-vaterite transformation into calcite through nanoparticle attachment within the organic framework. In culture medium spiked with trace amounts of Mn2+, the cauliflower-like proto-vaterite structures become longer-lived than in the absence of Mn2+. We propose that the formation of calcite crystals takes place through a non-classical recrystallization path that involves migration of proto-vaterite nanoparticles to the crystallization site, and then, their transformation into calcite via a dissolution-recrystallization reaction. The latter is complemented by ion-by-ion crystal growth and associated with impurity release. These observations are integrated into a new model of the biocrystallization of earthworm-produced carbonate granules which highlights the sensibility of this process to environmental chemical changes, its potential impact on the bioavailability of contaminants as well as the threat that chemical pollution poses to the normal development of its early stages. STATEMENT OF SIGNIFICANCE: Understanding the mechanisms of nucleation, stabilization and aggregation of amorphous calcium carbonate (ACC) and factors controlling its further transformation into crystalline phases is fundamental for elucidation of biogenic mineralization. Some species of earthworms are natural workbench to understand the biogenic ACC, stabilization and the transformation mechanisms, because they create millimeter-sized calcareous granules from amorphous calcium carbonate, which crystallize to a more stable mineral phase (mostly calcite). This study undergoes into the mechanisms of ACC stabilization by the incorporation of trace elements, as manganese, and the ulterior precipitation of calcareous granules by a coupled process of amorphous particle attachment and ion-by-ion growth. The study points to sensibility of this process to environmental chemical changes.

Surface functionalized 3D printed metal structures as next generation recyclable SERS substrates.

Combining the design flexibility and rapid prototyping capabilities of additive manufacturing with photocatalytic and plasmonic functionalities is promising for the development of next-generation SERS applications such as point of care diagnostics and in situ monitoring of chemical reactions in fuels and chemical processing. Laser powder bed fusion (LPBF) is a well-matured additive manufacturing technique which generates metallic structures through localised melting and joining of metal powders using a laser. LPBF reduces material wastage during manufacturing, is applicable to a wide range of metals and alloys, and allows printing of complex internal structures. This feature article elaborates the use of soot templating, chemical vapour deposition and electroless plating techniques for grafting plasmonic and semiconductor nanoparticles on the surface of LPBF manufactured metallic substrates. The capability to fabricate different types of intricate metallic lattices using additive manufacturing is demonstrated and technical challenges in their adequate functionalization are elaborated. The developed methodology allows tailoring of the substrate structure, composition, morphology, plasmonic and photocatalytic activities and thus unveils a new class of recyclable SERS substrates.

Photopolymerized polypyrrole microvessels.

We report on the preparation of water-filled polymer microvessels through the photopolymerization of pyrrole in a water/chloroform emulsion. The resulting structures were characterized by complementary spectroscopic and microscopic techniques, including Raman spectroscopy, XPS, SEM, and TEM. The encapsulation of fluorescent, magnetic, and ionic species within the microvessels has been demonstrated. Confocal microscopy and fluorescence anisotropy measurements revealed that the encapsulated chromophore (Rhodamine 6G) resides within voids in the capsules; however, strong interaction of the dye with polypyrrole results in a measurable decrease in its rotational dynamics. Microvessels loaded with ferrofluid exhibit magnetic properties, and their structures can be directed with an external magnetic field. TEM measurements allowed imaging of individual nanoparticles entrapped within the vessels. The application of Cu(2+)-loaded microvessels as a transducer layer in all-solid-state ion-selective electrodes was also demonstrated.

Evaluation of Strong Cation Ion-Exchange Resin Cost Efficiency in Manufacturing Applications-A Case Study.

The effective ionic capacities of strong cation ion-exchange resins were investigated and compared using conditions similar to those found in white goods, in order to establish behavioral differences between commercial products and evaluate their capacity in a broader business context. Nine different products of equivalent TDS (Technical Data Sheet) capacity were observed to examine their differences in approximately real-life conditions. For a broader context of applicability analysis, besides the absolute ionic operating capacity, the following additional factors were included in the evaluation: the standard deviation in the resins' performances and their relative prices. A complete method for material applicability evaluation was hereby proposed and shown to offer cost factor benefits of up to 21.1% within the range of products examined, in comparison to a cost-only evaluation for equivalent materials.

Medical Adhesives and Their Role in Laparoscopic Surgery-A Review of Literature.

Laparoscopic surgery is undergoing rapid development. Replacing the traditional method of joining cut tissues with sutures or staples could greatly simplify and speed up laparoscopic procedures. This alternative could undoubtedly be adhesives. For decades, scientists have been working on a material to bond tissues together to create the best possible conditions for tissue regeneration. The results of research on tissue adhesives achieved over the past years show comparable treatment effects to traditional methods. Tissue adhesives are a good alternative to surgical sutures in wound closure. This article is a review of the most important groups of tissue adhesives including their properties and possible applications. Recent reports on the development of biological adhesives are also discussed.