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Pancreatic rat islets are encapsulated by a siliceous layer deposited on the surface of single islets upon reaction with gaseous siliceous precursors. The process preserves original islet dimensions and does not suppress viability or function. The encapsulated material is homogeneously distributed on the islet surface, and layer thickness can be controlled in the 0.1–2.0 μm interval. Dynamic perfusion experiments with glucose stimulation were carried out in both encapsulated and non-encapsulated islets. Results were treated according to a kinetic model presented here for the analysis of perfusion data; the model tested by literature data, was used to substantiate the diffusion features of the siliceous layer, which does not affect mass transfer of insulin but which modifies the texture of the islet surface tissue. The clinical potential of silica encapsulation was demonstrated by in vivo experiments using encapsulated islets transplanted into diabetic rats. Transplantation was carried out in both inbred and outbred rats and indicated prolonged restoration of normal glycaemia levels and protection from immunological attack. [Copyright &y& Elsevier]

Primary Epstein-Barr virus (EBV) infection manifests with diverse clinical symptoms, occasionally resulting in severe complications. This scoping review investigates the rare occurrence of acute acalculous cholecystitis (AAC) in the context of primary EBV infection, with a focus on understanding its prevalence, clinical features, and underlying mechanisms. The study also explores EBV infection association with Gilbert syndrome, a condition that potentially exacerbates the clinical picture. Additionally, a case report of an 18-year-old female presenting with AAC and ascites secondary to EBV infection enhances the review. A comprehensive literature review was conducted, analyzing reported cases of AAC secondary to EBV infection. This involved examining patient demographics, clinical presentations, laboratory findings, and outcomes. The search yielded 44 cases, predominantly affecting young females. Common clinical features included fever, cervical lymphadenopathy, tonsillitis/pharyngitis, and splenomegaly. Laboratory findings highlighted significant hepatic involvement. The review also noted a potential link between AAC in EBV infection and Gilbert syndrome, particularly in cases with abnormal bilirubin levels. AAC is a rare but significant complication of primary EBV infection, primarily observed in young females, and may be associated with Gilbert syndrome. This comprehensive review underscores the need for heightened clinical awareness and timely diagnosis to manage this complication effectively. [ABSTRACT FROM AUTHOR]

Biosilica, synthesized annually only by diatoms, is almost 1000 times more abundant than industrial silica. Biosilicification occurs at a high rate, although the concentration of silicic acid in natural waters is ~100 μM. It occurs in neutral aqueous solutions, at ambient temperature, and under the control of proteins that determine the formation of hierarchically organized structures. Using diatoms as an example, the fundamental differences between biosilicification and traditional sol–gel technology, which is performed with the addition of acid/alkali, organic solvents and heating, have been identified. The conditions are harsh for the biomaterial, as they cause protein denaturation and cell death. Numerous attempts are being made to bring sol–gel technology closer to biomineralization processes. Biomimetic synthesis must be conducted at physiological pH, room temperature, and without the addition of organic solvents. To date, significant progress has been made in approaching these requirements. The review presents a critical analysis of the approaches proposed to date for the silicification of biomacromolecules and cells, the formation of bionanocomposites with controlled structure, porosity, and functionality determined by the biomaterial. They demonstrated the broad capabilities and prospects of biomimetic methods for creating optical and photonic materials, adsorbents, catalysts and biocatalysts, sensors and biosensors, and biomaterials for biomedicine. [ABSTRACT FROM AUTHOR]

The interleukin (IL)-12 family consists of pro- and anti-inflammatory cytokines that are able to signal the activation of host antiviral immunity while preventing over-reactive immune reactions due to active virus replication and viral clearance. Amongst others, IL-12 and IL-23 are produced and released by innate immune cells such as monocytes and macrophages to signal the proliferation of T cells and release of effector cytokines, which subsequently activate host defence against virus infections. Interestingly, the dualities of IL-27 and -35 are evidently shown in the course of virus infections; they regulate the synthesis of cytokines and antiviral molecules, proliferation of T cells, and viral antigen presentation in order to maximize virus clearance by the host immune system. In terms of anti-inflammatory reactions, IL-27 signals the formation of regulatory T cells (Treg) which in turn secrete IL-35 to control the scale of inflammatory response that takes place during virus infections. Given the multitasking of the IL-12 family in regards to the elimination of virus infections, its potential in antiviral therapy is unequivocally important. Thus, this work aims to delve deeper into the antiviral actions of the IL-12 family and their applications in antiviral therapies. [ABSTRACT FROM AUTHOR]

In the present day, the increment in life expectancy has led to the necessity of developing new biomaterials for the restoration or substitution of damaged organs that have lost their functionalities. Among all the research about biomaterials, this review paper aimed to expose the main possibilities that the sol-gel synthesis method can provide for the fabrication of materials with interest in the biomedical field, more specifically, when this synthesis method is used to improve the biological properties of different magnesium alloys used as biomaterials. The sol-gel method has been widely studied and used to generate ceramic materials for a wide range of purposes during the last fifty years. Focused on biomedical research, the sol-gel synthesis method allows the generation of different kinds of biomaterials with diverse morphologies and a high potential for the biocompatibility improvement of a wide range of materials commonly used in the biomedical field such as metallic implants, as well as for the generation of drug delivery systems or interesting biomaterials for new tissue engineering therapies. [ABSTRACT FROM AUTHOR]

Perchlorate contamination in groundwater poses a serious threat to human health, owing to its interference with thyroid function. The high solubility and poor adsorption of perchlorate ions make perchlorate degradation a necessary technology in groundwater contaminant removal. Here, we demonstrate the perchlorate degradation by employing nano zero-valent iron (nZVI) embedded in biocompatible silica alginate hybrid beads fabricated using calcium chloride (1 wt%) as a crosslinker. The concentration of precursors (sodium alginate, sodium silicate) for bead formation was standardized by evaluating the thermal stability of beads prepared at different sodium silicate and alginate concentrations. Thermal degradation of silica alginate hybrid samples showed a stepwise weight loss during the thermal sweep, indicating different types of reactions that occur during the degradation process. The formation of the silica alginate hybrid structure was confirmed by FT-IR spectroscopy. Scanning electron microscopy (SEM) data revealed the surface morphology of silica alginate hybrid changes by varying sodium silicate and alginate concentrations. nZVI-loaded alginate–silicate polymer bead (nZVI-ASB) exhibited excellent perchlorate degradation efficiency by degrading 20 ppm of perchlorate within 4 h. Our study also showed the perchlorate degradation efficiency of nZVI-ASB is maximum at neutral pH conditions. [ABSTRACT FROM AUTHOR]

Despite being a promising feedstock for food, feed, chemicals, and biofuels, microalgal production processes are still uneconomical due to slow growth rates, costly media, problematic downstreaming processes, and rather low cell densities. Immobilization via entrapment constitutes a promising tool to overcome these drawbacks of microalgal production and enables continuous processes with protection against shear forces and contaminations. In contrast to biopolymer gels, inorganic silica hydrogels are highly transparent and chemically, mechanically, thermally, and biologically stable. Since the first report on entrapment of living cells in silica hydrogels in 1989, efforts were made to increase the biocompatibility by omitting organic solvents during hydrolysis, removing toxic by-products, and replacing detrimental mineral acids or bases for pH adjustment. Furthermore, methods were developed to decrease the stiffness in order to enable proliferation of entrapped cells. This review aims to provide an overview of studied entrapment methods in silica hydrogels, specifically for rather sensitive microalgae. [ABSTRACT FROM AUTHOR]

Seeding materials with living cells has been—and still is—one of the most promising approaches to reproduce the complexity and the functionality of living matter. The strategies to associate living cells with materials are limited to cell encapsulation and colonization, however, the requirements for these two approaches have been seldom discussed systematically. Here we propose a simple two-dimensional map based on materials' pore size and the cytocompatibility of their fabrication process to draw, for the first time, a guide to building cellularized materials. We believe this approach may serve as a straightforward guideline to design new, more relevant materials, able to seize the complexity and the function of biological materials. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'. [ABSTRACT FROM AUTHOR]

HBV and HCV are responsible for chronic hepatitis widespread worldwide. The study was designed for investigating the role of interleukins 27 in these two types of viral hepatitis diseases. Serum IL-27 concentration was determined in patients without treatment with HBV and HCV infections and in healthy control persons by ELISA kit, all patients were in a chronic condition, it was confirmed by many tests including (VIDAS HBs Ag Ultra confirmation, VIDAS HBs Ag Ultra IgM, Western Blot Assay Confirmation test for anti-HCV) at the Central Public Health Laboratory. There were significant differences between hepatitis patients (HBV, HCV) and control group (p=0.003) (p=0.000), respectively. According to the result of this research, it was found that HCV has the ability to stimulate the production of IL-27 more than does HBV. [ABSTRACT FROM AUTHOR]

Magnetic Co3O4 nanoparticles (NPs) have great potential for applications in biomedicine, as contrast enhancement agents for magnetic resonance imaging, or for drug delivery. Although these NPs are so attractive, their potential toxicity raises serious questions about decreasing cellular viability. In this context, Co3O4 NPs were prepared via sol–gel method and encapsulated with a layer of TiO2, a biocompatible oxide, and subjected to structural, magnetic and toxicity characterization. X‐ray diffractograms of the samples demonstrate the successful synthesis of the spinel and Raman spectroscopy confirms the coating of the Co3O4 spinel with TiO2. The Co3O4 cores showed a very intense superparamagnetic character; however, this behavior is strongly suppressed when the material is covered with TiO2. According to the neutral red uptake assay, the coating of the cores with TiO2 significantly decreases the cytotoxic character of the Co3O4 particles and, as it can be observed with the zeta (ξ) potential measurements, they form a stable colloidal dispersion at cytoplasmic pH. The effect of the thermal treatment enhances the biocompatibility even further, with no statistically significant effect on cell viability even at the highest analyzed concentration. The proposed pathway presents a successful sol–gel method for the preparation of Co3O4@TiO2 core‐shell nanoparticles. This work opens up possibilities for future application of these materials not only for magnetic resonance imaging but also in catalysis and hyperthermia. [ABSTRACT FROM AUTHOR]

Designing biocompatible materials to encapsulate xenogeneic insulin-releasing β-cells for transplantation has been considered as a promising alternative to avoid the immunosuppression and drawbacks of the treatment of Type 1 diabetes mellitus (T1D) by direct islet transplantation. The current work for the first time studied a hybrid alginate@TiO2 microcapsule as a reservoir for rat insulinoma-derived INS-1E cells, as a β-cell surrogate, towards the treatment of T1D. The hybrid microcapsule is composed of an alginate core as a biocompatible matrix for cell encapsulation and a crack-free TiO2 shell as a semipermeable membrane to prevent cell leakage, protect encapsulated cells from immune attacks, as well as allow the diffusion of nutrients and the secretion of insulin. Compared to most-commonly used pure alginate microcapsules, the insulin-secreting INS-1E cells encapsulated in our alginate@TiO2 microcapsules revealed higher metabolic activity and maintained the insulin secretion over more than 6 weeks. This study highlights that our designed alginate@TiO2 hybrid microcapsules can serve as an ideal reservoir for cell encapsulation towards the treatment of T1D, thus further promoting the development of artificial organs for cell therapy. [ABSTRACT FROM AUTHOR]

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The organic–inorganic hybrid materials have been used in different fields to immobilize biomolecules since they offer many advantages. The aim of this study was to optimize and characterize the alginate‐silica hybrid hydrogel as a stable and injectable form for microfluidic systems using internal gelation method and increase the stability and activity of immobilized enzyme for biocatalytic conversions as well. Characterization was carried out by scanning electron microscopy, energy dispersive spectroscopy/mapping, Brunauer–Emmett–Teller, Barrett–Joyner–Halenda, and Fourier‐transform infrared spectroscopy analyses, and the shrinkages of monoliths were evaluated. Subsequent to optimizing the enzyme concentration (40 μg), hydrolytic conversion of 4‐nitrophenyl β‐d‐glucopyranoside (pNPG) was performed to understand the behavior of the bioconversion in the microfluidic system. The yield was 94% which reached the equilibrium at 24 h indicating that the alginate‐silica gel derived microsystem overcome some drawbacks of monolithic systems. Additionally, bioconversion of Ruscus aculeatus saponins was carried out at the same setup in order to obtain aglycon part, which has pharmaceutical significance. Although pure aglycon could not be achieved, an intermediate compound was obtained based on the HPLC analysis. The developed formulation can be utilized for various life science applications. [ABSTRACT FROM AUTHOR]

In recent years, the potential use of silica nanoparticles (SiNPs) among different biomedical fields has grown. A deep understanding of the physicochemical properties of nanoparticles (NPs) and their regulation of specific biological responses is crucial for the successful application of NPs. Exposure to NP physicochemical properties (size, shape, porosity, etc.) could result in deleterious effects on cellular functions, including a pro-inflammatory response mediated via activation of the NLRP3 inflammasome. The aim of this study was to evaluate the potential in vitro immunomodulatory effect of 12-nm and 200-nm SiNPs on the expression of pro-inflammatory cytokines and NLRP3 inflammasome components in human primary neutrophils and PBMCs. This study demonstrates that regardless of the size of the nanoparticles, SiNPs induce the production of pro-inflammatory cytokines in a dose-dependent manner. Induced IL-1β production after exposure to SiNPs suggests the involvement of NLRP3 inflammasome components participation in this process. In conclusion, SiNPs induce the production of pro-inflammatory cytokines in a dose-dependent manner. Furthermore, our data suggest that the production and release of IL-1β possibly occurs through the formation of the NLRP3 inflammasome. [ABSTRACT FROM AUTHOR]

Background and Aims Beginning and completion of malolactic fermentation (MLF) are complicated because of the harsh environment of wine. Encapsulation of lactic acid bacteria could be an attractive strategy to improve their activity and stability. This work evaluates the fermentative capacity of Oenococcus oeni encapsulated into silica-alginate (Si-Al) and alginate capsules under adverse winemaking conditions (high alcohol concentration, low pH and low temperature). Mechanical and chemical stability of capsules was also monitored. Methods and Results Silica-alginate capsules showed higher malolactic activity and better mechanical and chemical stability than untreated alginate capsules. Their capacity for bacteria retention was similar to that of alginate capsules. Ethanol, pH and fermentation temperature had great influence on fermentative behaviour of free and encapsulated bacteria. Under extreme winemaking conditions, such as high ethanol concentration (13-16%), low pH (3.0-3.3) and low fermentation temperature (13-15°C), the highest consumption of malic acid was achieved using Si-Al capsules. Free and encapsulated bacteria showed similar fermentative profiles in the presence of variable concentration of malic acid and nitrogen in wine. Conclusions Encapsulated O. oeni in Si-Al gels enhanced MLF in wines with a high concentration of ethanol and low pH and at low fermentation temperature. Moreover, inclusion of an inorganic network of silicates significantly improved the mechanical robustness and chemical stability of alginate capsules. Significance of the Study The application of Si-Al-encapsulated bacteria is an interesting strategy to improve MLF in warm climates where wines have higher ethanol concentration and in cool climates with higher acidity and low fermentation temperature. [ABSTRACT FROM AUTHOR]

There are some reports regarding hepatitis B virus (HBV) reactivation in patients with myeloma who are HBV carriers or who have had a resolved HBV infection, and there is no standard prophylaxis strategy for these patients. We performed a retrospective multicenter study to determine the incidence and characteristics of HBV reactivation in patients with multiple myeloma. We identified 641 patients with multiple myeloma who had been treated using novel agents and/or autologous stem cell transplantation with high-dose chemotherapy between January 2006 and June 2014 at nine Japanese hospitals. The patients' characteristics, laboratory data, and clinical courses were retrieved and statistically analyzed. During a median follow-up of 101 weeks, one of eight (12.5 %) HBV carriers developed hepatitis and 9 of 99 (9.1 %) patients with resolved HBV infection experienced HBV reactivation; the cumulative incidences of HBV reactivation at 2 years (104 weeks) and 5 years (260 weeks) were 8 and 14 %, respectively. The nine cases of reactivation after resolved HBV infection had received entecavir as preemptive therapy or were carefully observed by monitoring their HBV DNA levels, and none of these cases developed hepatitis. Among patients with multiple myeloma, HBV reactivation was not rare. Therefore, long-term monitoring of HBV DNA levels is needed to prevent hepatitis that is related to HBV reactivation in these patients. [ABSTRACT FROM AUTHOR]

Yeast cells were encapsulated into alginate microparticles of a few hundred micrometers diameter using a centrifuge-based droplet shooting device. We demonstrate the first experimental results of glycolytic oscillations in individual yeast cells immobilized in this way. We investigated both the individual and collective oscillatory behaviors at different cell densities. As the cell density increased, the amplitude of the individual oscillations increased while their period decreased, and the collective oscillations became more synchronized, with an order parameter close to 1 (indicating high synchrony). We also synthesized biphasic-Janus microparticles encapsulating yeast cells of different densities in each hemisphere. The cellular oscillations between the two hemispheres were entrained at both the individual and population levels. Such systems of cells encapsulated into microparticles are useful for investigating how cell-to-cell communication depends on the density and spatial distribution of cells. [ABSTRACT FROM AUTHOR]

Yeast cells were encapsulated into alginate microparticles of a few hundred micrometers diameter using a centrifuge-based droplet shooting device. We demonstrate the first experimental results of glycolytic oscillations in individual yeast cells immobilized in this way. We investigated both the individual and collective oscillatory behaviors at different cell densities. As the cell density increased, the amplitude of the individual oscillations increased while their period decreased, and the collective oscillations became more synchronized, with an order parameter close to 1 (indicating high synchrony). We also synthesized biphasic-Janus microparticles encapsulating yeast cells of different densities in each hemisphere. The cellular oscillations between the two hemispheres were entrained at both the individual and population levels. Such systems of cells encapsulated into microparticles are useful for investigating how cell-to-cell communication depends on the density and spatial distribution of cells. [ABSTRACT FROM AUTHOR]

Colloidal carriers based on silica (Si) matrices are an innovative approach within the context of therapeutic drug delivery systems. These carriers are emerging as a great promise for diagnosis and treatment of a wide range of injuries, particularly in cancer and infectious diseases. In addition, bioencapsulation for biosensing and cell therapy in silica sol-gel allows the survival of enzymes and cells for a long period of time. Owing to their porosity, large surface area, and high capability of functionalization, silica nanoparticles (SiNP) have been considered as an attractive option for several bioanalysis applications, such as selective bioseparation, imaging, and drug and gene delivery. However, although great advances are achieved in the biomedical fields, some toxicity effects can be associated with the use of SiNP. This article aims to present a comprehensive review of recent technological advances for silica matrices in biomedical applications, as well as the potential impact of silica-based materials on human health and environment. [ABSTRACT FROM AUTHOR]

The impact of interleukin 28B (IL-28B) on the results of interferon (IFN)-based therapy in patients chronically infected with hepatitis B virus (HBV) is poorly understood. The aim of this study was to evaluate the relationship between IL-28B markers and the response to IFN monotherapy in Polish patients with anti-hepatitis B e (HBe)-positive chronic hepatitis B (CHB). We determined three single-nucleotide polymorphisms (SNPs) of IL-28B (rs12979860, rs12980275, and rs8099917) in 86 patients who were treated with pegylated interferon (PEG-IFN) for 48 weeks. The effectiveness of the therapy was evaluated based on the virological and biochemical response. The primary efficacy parameters were the HBV DNA viral load below 400 IU/ml and 2,000 IU/ml in combination with alanine aminotransferase (ALT) normalization (<40 IU/l), measured 24 weeks after the treatment. Viral load below 400 IU/ml or 2,000 IU/ml with ALT normalization was achieved by 37 % and 46 % of patients, respectively. It has been shown that the distribution of IL-28B genotypes in the dominant genetic model in patients with different therapeutic success differ significantly only for rs12979860. The IL-28B rs12979860 CC genotype was associated with lower treatment success [odds ratio (OR), 0.31; p = 0.025 and OR, 0.37; p = 0.044 for <400 IU/ml HBV DNA with <40 IU/l ALT, and <2,000 IU/ml HBV DNA with <40 IU/l ALT, respectively]. However, in the conditional logistic regression analysis adjusted by factors associated with combined response, rs12979860 was significantly associated only with <400 IU/ml HBV DNA with <40 IU/l ALT (OR, 0.24; p = 0.026). IL-28B polymorphisms have prognostic significance in assessing the treatment effectiveness based on the virological and biochemical response of patients with anti-HBe-positive CHB. [ABSTRACT FROM AUTHOR]

In nature, a few living organisms such as diatoms, magnetotactic bacteria, and eggs have developed specific mineral structures, which can provide extensive protection or unique functions. However, most organisms do not have such structured materials due to their lack of biomineralization ability. The artificial introduction of biomimetic-constructed nanominerals is challenging but holds great promise. In this overview, we highlight two typical types of mineral-living complex systems. One involves biological surface-induced nanomaterials, which produces artificial living-mineral core-shell structures such as the mineralencapsulated yeast, cyanobacteria, bacteria and viruses. The other involves internal nanominerals that could endow organisms with unique structures and properties. The applications of these biomimetic generated nanominerals are further discussed, mainly in four potential areas: storage, protection, 'stealth' and delivery. Since biomineralization combines chemical, nano and biological technologies, we suggest that nanobiomimetic mineralization may open up another window for interdisciplinary research. Specifically, this is a novel material-based biological regulation strategy and the integration of living organisms with functional nanomaterials can create 'super' or intelligent nanoscale living complexes for biotechnological practices. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Fluorescein-loaded magnetic nanoparticles (FMNPs) have been increasingly utilized in nanomedicine due to their unique properties. In this study, polyamidoamine (PAMAM) dendrimer was used to modify the FMNPs through bifunctional polyethylene glycol linker. The obtained PAMAM modified magnetic nanoparticles (PFMNPs) were characterized by transmission electron microscope, thermogravimetric analysis, zeta potential titration, and fourier transform infrared spectroscopy. The effect of PAMAM conjugation on the biodistribution of FMNPs and PFMNPs were investigated by confocal laser scanning microscopy and inductively coupled plasma atomic emission spectrometry, respectively. It was revealed that PAMAM conjugation resulted in a lower uptake of FMNPs in the lung and less aggregation in the liver, whereas a higher uptake in brain and testis. Furthermore, the serum biochemical and the hematological analysis indicated the PFMNPs caused no significant changes in enzymes reflective of inflammatory response or organ toxicity. [ABSTRACT FROM AUTHOR]

A review of the article "Mouse and human islets survive and function after coating by biosilicification" related to bioencapsulation for cell transplantation by D. B. Jaroch and colleague published in the September 3, 2013 issue of the journal is presented.

Different divalent metal ions (Ba, Sr, Ca, Zn) were selected as crosslinkers. The mechanical properties, cytocompatibility, histocompatibility, cell proliferation and long-term cultivation were investigated. The resulting microcapsules had good sphericity, smooth surface and particle size distribution of 300-400 μm. Sr microcapsules exhibited a better mechanical strength. The molecular weights cut-off of all membranes were between 24 and 67 kDa. All microcapsules had no cytotoxicity. After intraperitoneal transplantation, the recovered microcapsules still maintained good mechanical strength and morphology with no fibrosis or macrophage aggregation phenomena. The microencapsulated PC12 cells showed no significant variation after recultivation following microcapsule breaking. The cell activity sequence of different microcapsules after 72 h was as follows: bare control cell >Sr > Ca> Ba> Zn. After 9 weeks' in vitro culture, the cell survival rate was higher than 80 %. This paper will be of scientific interests for the basic research and clinical application of alginate/chitosan microcapsules embedded with drugs or cells. [ABSTRACT FROM AUTHOR]

Several baseline predictors that are associated with high response rates to PEG-IFN in CHB have been determined. Nonetheless, even patients with a high chance of achieving a response, are still at risk of non-response. Recently, a lot of effort has been made in discovering on-treatment predictors of response in order to provide solid stopping rules. In HBeAg positive patients the absence of a decline in HBsAg at week 12 provided the best stopping rule for HBV genotype A and D patients, whereas an HBsAg level > 20.000 IU/mL at week 12 was best for genotype B and C patients. For HBeAg negative patients, no HBsAg decline and less than 2 log HBV DNA decline at week 12 provided the best stopping rule, through all major HBV genotypes. Besides these stopping rules based on efficacy, pros and cons, including costs and side-effects of PEG-IFN based treatment, should always be weighed on an individual basis. [ABSTRACT FROM AUTHOR]

Cyanobacteria inhabit nearly every ecosystem on earth, play a vital role in nutrient cycling, and are useful as model organisms for fundamental research in photosynthesis and carbon and nitrogen fixation. In addition, they are important for several established biotechnologies for producing food additives, nutritional and pharmaceutical compounds, and pigments, as well as emerging biotechnologies for biofuels and other products. Encapsulation of living cyanobacteria into a porous silica gel matrix is a recent approach that may dramatically improve the efficiency of certain production processes by retaining the biomass within the reactor and modifying cellular metabolism in helpful ways. Although encapsulation has been explored empirically in the last two decades for a variety of cell types, many challenges remain to achieving optimal encapsulation of cyanobacteria in silica gel. Recent evidence with Synechocystis sp. PCC 6803, for example, suggests that several unknown or uncharacterized proteins are dramatically upregulated as a result of encapsulation. Also, additives commonly used to ease stresses of encapsulating living cells, such as glycerol, have detrimental impacts on photosynthesis in cyanobacteria. This mini-review is intended to address the current status of research on silica sol-gel encapsulation of cyanobacteria and research areas that may further the development of this approach for biotechnology applications. [ABSTRACT FROM AUTHOR]

Background: The design of new technologies for treatment of human disorders such as protein deficiencies is a complex and difficult task. Particularly, the construction of artificial organs, based on the immunoisolation of protein-secreting cells, requires the use of suitable materials which have to be biocompatible with the immunoisolated cells and avoid any inappropriate host response. Methodology/Principal Findings: This work investigates the in vivo behavior of mechanically resistant hybrid beads which can be considered as a model for artificial organ for cell therapy. This hybrid system was designed and fabricated via the encapsulation of living cells (HepG2) within alginate-silica composites. Two types of beads (alginate-silica hybrid (AS) or alginate/silica hybrid subsequently covered by an external layer of pure alginate (ASA)), with or without HepG2 cells, were implanted into several female Wistar rats. After four weeks, the potential inflammatory local response that might be due to the presence of materials was studied by histochemistry. The results showed that the performance of ASA beads was quite promising compared to AS beads, where less abnormal rat behaviour and less inflammatory cells in histological sections were observed in the case of ASA beads. Conclusions/Significance: The current study highlights that alginate-silica composite materials coated with an extra-alginate shell offer much promise in the development of robust implantation devices and artificial organs. [ABSTRACT FROM AUTHOR]

A new biosensor was designed for the assessment of aquatic environment quality. Three microalgae were used as toxicity bioindicators: Chlorella vulgaris, Pseudokirchneriella subcapitata and Chlamydomonas reinhardtii. These microalgae were immobilized in alginate and silica hydrogels in a two step procedure. After studying the growth rate of entrapped cells, chlorophyll fluorescence was measured after exposure to (3-(3,4-dichlorophenyl)-1,1-dimethylurea) (DCMU) and various concentrations of the common herbicide atrazine. Microalgae are very sensitive to herbicides and detection of fluorescence enhancement with very good efficiency was realized. The best detection limit was 0.1 µM, obtained with the strain C. reinhardtii after 40 minutes of exposure. [ABSTRACT FROM AUTHOR]

We report a droplet-based microfluidic synthetic technique to generate disk-like hydrogel beads for cell encapsulation and manipulation. Utilizing this microfluidic synthetic technique, the size of the disk-like calcium alginate (CA) hydrogel beads and the number of cells encapsulated in the disk-like CA hydrogel beads could be well controlled by individually adjusting the flow rates of reagents. As a proof-of-concept, we demonstrated that single cell (yeast cell or mammalian cell) could be successfully encapsulated into disk-like CA hydrogel beads with high cell viability. Taking advantage of the flat top/bottom surfaces of disk-like CA hydrogel beads, cell division processes in culture media were clearly observed and recorded at a desired position without rolling and moving. This facile microfluidic chip provides a feasible method for size-controlled disk-like hydrogel beads generation and cell encapsulation. It could be a promising candidate for cell division observation and quantitative biological study in lab-on-a-chip applications. [ABSTRACT FROM AUTHOR]

Global gene expression of Synechocystis sp. PCC 6803 encapsulated in silica gel was examined by microarray analysis. Cultures were encapsulated in gels derived from aqueous precursors or from alkoxide precursors and incubated under constant light for 24 h prior to RNA extraction. Cultures suspended in liquid media were exposed to 500 mM salt stress and incubated under identical conditions for comparison purposes. The expression of 414 genes was significantly altered by encapsulation in aqueous-derived gels (fold change ≥1.5 and P value < 0.01), the expression of 1,143 genes was significantly altered by encapsulation in alkoxide-derived gels, and only 243 genes were common to both encapsulation chemistries. Additional qRT-PCR analyses of four selected genes, ggpS, cpcG2, slr5055, and sll5057, confirmed microarray results for those genes. These results illustrate that encapsulation stress is quite different than salt stress in terms of gene expression response. Furthermore, a number of hypothetical and unknown proteins associated with encapsulation and alcohol stress have been identified with implications for improving encapsulation protocols and rationally engineering microorganisms for direct biofuel production. [ABSTRACT FROM AUTHOR]

The exploitation of organo-silica immobilized lactic acid bacteria (LAB) to perform malolactic fermentation (MLF) in wine is described. The immobilization of a large amount of Oenococcus oeni cell culture was achieved by a two-step process in an original pilot plant. Cells are entrapped in Ca-alginate microbeads, coated with an organo-silica membrane obtained by two treatments: the first a sol suspension of tetraetoxysilane, the second using methyltriethoxysilane in gas phase. The resulting material improves the physico-chemical features of alginate, avoids cell leakage during fermentation, and protects the cells from antimicrobial compounds. In MLFs carried out at the microvinification scale, the activity of immobilized cells did not differ from that of free cells, and no differences were found in the chemical composition of the wines obtained. The use of immobilized bacteria allowed: (1) simultaneous alcoholic and malolactic fermentations in must inoculated with free yeast and immobilized bacteria; (2) the sequential MLF of three wine lots with the same biomass of immobilized bacteria; (3) the achievement of MLF in a wine with lysozyme added to suppress wild LAB and their potential spoilage. [ABSTRACT FROM AUTHOR]

Epidemiological studies demonstrated an association between increased levels of ambient air pollution particles and human morbidity and mortality. Production of oxidants, either directly by the air pollution particles or by the host response to the particles, appears to be fundamental in the biological effects seen after exposure to particulate matter (PM). However, the precise components and mechanisms responsible for oxidative stress following PM exposure are yet to be defined. Direct oxidant generation by air pollution particles is attributed to organic and metal components. Organic compounds generate an oxidative stress through redox cycling of quinone-based radicals, by complexing of metal resulting in electron transport, and by depletion of antioxidants by reactions between quinones and thiol-containing compounds. Metals directly support electron transport to generate oxidants and also diminish levels of antioxidants. In addition to direct generation of oxidants by organic and metal components, cellular responses contribute to oxidative stress after PM exposure. Reactive oxygen species (ROS) production occurs in the mitochondria, cell membranes, phagosomes, and the endoplasmic reticulum. Oxidative stress following PM exposure initiates a series of cellular reactions that includes activation of kinase cascades and transcription factors and release of inflammatory mediators, which ultimately lead to cell injury or apoptosis. Consequently, oxidative stress in cells and tissues is a central mechanism by which PM exposure leads to injury, disease, and mortality. [ABSTRACT FROM AUTHOR]

The implication of hemochromatosis ( HFE) gene mutations in chronic viral hepatitis remains controversial. The aim of the present study was to measure the frequencies of the common HFE gene mutations in Moroccan subjects with chronic viral hepatitis B and C and to assess their influence on the progression of liver disease. H63D and C282Y mutations were screened by the polymerase chain reaction followed by restriction fragment length polymorphism analysis in 170 chronic hepatitis B patients, 168 chronic hepatitis C patients, and 200 healthy controls. A very small proportion of patients infected with hepatitis B virus (HBV) or hepatitis C virus (HCV; 1.8% and none, respectively) were heterozygous for the C282Y mutation, that is, rates not statistically different from those observed in healthy control (2%, P > 0.05). Similarly, the frequency of the H63D allele was not significantly different between HBV (13.8%) or HCV (14.3%) patients and controls (13.5%, P > 0.05). Multivariate analysis showed that carriers of the H63D mutation infected with HBV are at higher risk to progress towards an advanced liver disease when compared with patients infected with HBV with wild-type (OR = 2.45, 95% CI = 1.07-5.58). In contrast, no association between HFE mutated HCV-infected patients and an increased risk of disease progression was found (OR = 1.24, 95% CI = 0.61-2.50, P = 0.547). In conclusion, in Morocco the frequency of the HFE C282Y allele is very low and H63D mutation carriage occurs in almost 14% of the patients, a rate similar in chronic hepatitis patients and healthy controls. In the case of chronic hepatitis B, the carriage of the H63D variant represents a risk factor of evolution towards a more active disease. J. Med. Virol. 83:2096-2102, 2011. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Stresses imposed on the cyanobacterium Synechocystis sp. PCC 6803 by various compounds present during silica sol-gel encapsulation, including salt, ethanol (EtOH), polyethylene glycol (PEG), glycerol, and glycine betaine, were investigated. Viability of encapsulated cells and photosynthetic activity of cells stressed by immediate (2 min) and 24-h exposure to the five stress-inducing compounds were monitored by pulse amplitude modulated fluorometry. Cells of Synechocystis sp. PCC 6803 readily survive encapsulation in both alkoxide-derived gels and gels from aqueous precursors and can remain active at least 8 weeks with slight degradation in PSII efficiency. Post-encapsulation survival was improved in gels containing no additive when compared with gels containing PEG or glycerol. Glycerol was shown to have a detrimental effect on Synechocystis sp. PCC 6803, reducing ϕPSII and F′/ F′ by as much as 75%, possibly a result of disrupting excitation transfer between the phycobilisomes and photosystems. PEG was similarly deleterious, dramatically reducing the ability to carry out a state transition and adequately manage excitation energy distribution. EtOH stress also hindered state transitions, although less severely than PEG, and the cells were able to recover nearly all photosynthetic efficiency within 24 h after an initial drop. Betaine did not interfere with state transitions but did reduce quantum yield and photochemical quenching. Finally, Synechocystis sp. PCC 6803 was shown to recover from salt stress. [ABSTRACT FROM AUTHOR]