Component Of Microparticles Research Articles

Engineered bacteria that self-assemble bioglass polysilicate coatings display enhanced light focusing

Cutting-edge photonic devices frequently rely on microparticle components to focus and manipulate light. Conventional methods used to produce these microparticle components frequently offer limited control of their structural properties or require low-throughput nanofabrication of more complex structures. Here, we employ a synthetic biology approach to produce environmentally friendly, living microlenses with tunable structural properties. We engineered Escherichia coli bacteria to display the silica biomineralization enzyme silicatein from aquatic sea sponges. Our silicatein-expressing bacteria can self-assemble a shell of polysilicate "bioglass" around themselves. Remarkably, the polysilicate-encapsulated bacteria can focus light into intense nanojets that are nearly an order of magnitude brighter than unmodified bacteria. Polysilicate-encapsulated bacteria are metabolically active for up to 4 mo, potentially allowing them to sense and respond to stimuli over time. Our data demonstrate that synthetic biology offers a pathway for producing inexpensive and durable photonic components that exhibit unique optical properties.

ENVIRONMENTAL POLLUTION AND IMPACT OF HIGHWAYS DURING OPERATION

The current state and rapid development of road construction and transport infrastructure are the reasons for the increase in environmental pollution, especially in the immediate vicinity of highways. Roadside areas accumulate a large amount of pollutants which leads to changes in soil properties and comprehensive degradation of landscapes. Together with the road runoff, pollutants enter the lakes and the rivers and cause significant damage to aquatic flora and fauna. During the operation of highways, a large amount of exhaust gases, oil products, heavy metals, and dust enters the natural environment. Currently, in Ukraine, most studies are aimed at reducing the negative impact of exhaust gases on the atmosphere, oil pollution of soils and the aquatic environment. Unlike in the European countries, the research on the formation of microparticles which, together with dust and surface runoff contaminate soils, surface and groundwater of roadside areas has not been conducted at all. This paper analyzes the European research experience on the negative impact of microparticles on the environment. The components of microparticles - micropollutants formed as a result of the interaction of vehicles with the road surface (tire wear products, road dust, road markings, etc.) are presented. The paper also presents the sources of formation, qualitative and quantitative characteristics of the main micropollutants and their pathways in the roadside area. This will allow further developing the effective measures to reduce the formation and spread of micr

Implementation of Novel Autochthonous Microencapsulated Strains of Lactiplantibacillus plantarum, Lactococcus lactis, and Lamb’s Rennet in the Production of Traditional “Paški Sir” Cheese

This study aimed to implement a microencapsulated form of selected autochthonous lactic-acid bacteria (LAB) isolated from the cheese-production chain and natural rennet obtained from suckling lambs in the traditional production of hard sheep cheese, “Paški sir”, from the island of Pag, Croatia. Two different formulations of microparticles were prepared: (i) microparticles containing the strain of both Lactiplantibacillus plantarum and Lactococcus lactis (S2) and (ii) microparticles containing both strains and natural rennet (S3). These formulations were used in the production of Paški sir cheese simultaneously with standard production using non-encapsulated commercial starter cultures and commercial rennet (S1). The number of Lc. lactis isolates decreased at day 30 and were not isolated during the remaining ripening process, whereas the number of L. plantarum remained stable throughout the ripening process. The level of LAB and the release of the rennet from microsphere formulations at the end allowed for the production of cheese with the same characteristics as the commercial product, indicating no negative interactions of natural rennet, bacterial culture, and chemical components of microparticles. To our knowledge, this is the first report of a microencapsulated L. plantarum (isolated from the abomasum of lambs) coupled with natural lamb’s rennet used in the production of hard sheep cheese. This pilot study showed the great potential for maintaining authenticity in cheese production by combining traditional and sustainable innovative technologies.

Clinical Value Screening, Prognostic Significance, and Key Gene Identification of TrkB in Laryngeal Carcinoma.

Purpose Using human gene chip expression profiling technology to screen out downstream genes related to TrkB regulation in laryngeal cancer cells. Methods Using the Hep-2 TrkB shRNA cell line, divide it into an experimental group (shNTRK2) and a control group (PLKO1), and use the human gene expression microarray to screen out the differential genes. Then, select 10 upregulated genes and 10 downregulated genes from the differential genes, and use RT-PCR to verify whether the screening results of human gene expression microarray profiles are reliable. Use GO, KEGG, and miRNA enrichment analyses, PPI network diagram, etc., to analyze the differential genes and further screen out the key genes. Results A total of 318 differential genes (87 upregulated genes and 231 downregulated genes) were screened in laryngeal cancer cells. Use RT-PCR for the 10 upregulated differential genes (DMKN, FHL1, FOXN4, GGNBP1, HOXB9, ABCB1, TNFAI, RGS2, LINC01133, and FGG) and 10 downregulated differential genes (CHI3L1, FMOD, IGFBP1, IRF5, SPARC, NPAS4, TRPS1, TRAP, COL8A1, and DNER), and the results are consistent with the chip results, confirming the accuracy of the chip results; GO analysis results show that the downstream differential genes (DEGs) regulated by TrkB are mainly involved in biological processes such as retinol metabolic process, diterpenoid metabolic process, and regulation of cell-substrate adhesion. DEGs mainly affect cytoskeletal protein binding, serotonin-activated cation-selective channel activity, and sphingosine molecular functions. DEGs are mainly enriched in the cell periphery, secretory granule, cytoplasmic membrane-bounded vesicle lumen, blood microparticle, and other molecular components. The results of disease enrichment analysis show that the downstream differential genes regulated by TrkB are mainly involved in atypical hemolytic uremic syndrome, hematologic disease, meningococcal disease, lung cancer, susceptibility, asthma, and other diseases. The PPI network diagram results showed 7 hub genes, and then, we used GO analysis and KEGG enrichment analysis to see the biological process, cell component, molecular functions, and biological pathways. Conclusion Gene chip technology was used to screen out the differential genes of TrkB epigenetic modification in the Hep-2 cell line, and seven key genes (ALDH1A1, SDR16C5, PIK3R1, PLCG2, IL2RG, PIK3CD, and SPARC) were further screened using bioinformatics technology.

Expert Design and Optimization of Ethyl Cellulose-Poly (ε-caprolactone) Blend Microparticles For Gastro-Retentive Floating Delivery of Metformin Hydrochloride.

Metformin Hydrochloride (MH) is an oral anti-hyperglycemic agent belonging to the biguanide class of drugs. The present study involves the formulation and evaluation of gastro-retentive floating microparticles containing MH as a model drug for the prolongation of absorption time. Three levels of a three-factor, Box-Behnken design were used to evaluate the critical formulation variables. Microparticles were prepared using a water-in-oil-in-water double-emulsion solvent evaporation method and examined in terms of production yield, particle size, entrapment efficiency, floating ability, morphology, FTIR (Fourier transform infrared spectroscopy), and in vitro drug release. The optimum conditions for preparing MH microparticles were predicted to be the content of ethyl cellulose content (150 mg),poly (ε-caprolactone) (150 mg), and polyvinyl alcohol (1%w/v).The optimized MH microparticles were found to be spherical with a mean size of 350.2 µm. Entrapment efficiency was 58.62% for microparticles. 63.94% of microparticles showed floating properties. The FTIR analysis confirmed no chemical linkage between microparticle components. in vitro release study showed a controlled release for up to 8h. These results demonstrated that MH microparticles, as a drug delivery system, may be useful to achieve a controlled drug release profile suitable for oral administration and may help to reduce the dose of the drug and to improve patient compliance.

Evaluation of the In Vitro Stability of Stimuli-Sensitive Fatty Acid-Based Microparticles for the Treatment of Lung Cancer.

The fatty acid-based microparticles containing iron oxide nanoparticles and paclitaxel (PAX) are a viable proposition for the treatment of lung cancer. The microparticles inhaled as a dry powder can be guided to selected locations using an external magnetic field, and when accumulated there, the active compound release can be triggered by local hyperthermia. However, this general strategy requires that the active compound is released from microparticles and can reach the targeted cells before microparticles are removed. Isothermal titration calorimetry was used to demonstrate that the components of microparticles were released and transferred to albumins and lipid bilayers. The morphology of the measured particulates was studied with scanning electron microscopy and dynamic light scattering. To determine the cytotoxicity of microparticles, cell culture studies were done. It has been shown that the transfer efficiency depends predominantly on the fatty acid composition of microparticles, which, together with the active ingredient, accumulate predominantly in membrane structures after being released from microparticles and before entering the cytoplasm. The release process is sufficient; hence, paclitaxel-loaded microparticles effectively suppressed the proliferation of A549 human lung epithelial cells of malignant origin (IC50 values for both lauric acid-based and myristic/palmitic-based microparticles containing paclitaxel were below 0.375 μg/mL), while reference microparticles were noncytotoxic.

A Stability-Indicating HPLC-DAD Method for Determination of Ferulic Acid into Microparticles: Development, Validation, Forced Degradation, and Encapsulation Efficiency.

A simple stability-indicating HPLC-DAD method was validated for the determination of ferulic acid (FA) in polymeric microparticles. Chromatographic conditions consisted of a RP C18 column (250 mm × 4.60 mm, 5 μm, 110 Å) using a mixture of methanol and water pH 3.0 (48 : 52 v/v) as mobile phase at a flow rate of 1.0 mL/min with UV detection at 320 nm. The developed method was validated as per ICH guidelines with respect to specificity, linearity, limit of quantification, limit of detection, accuracy, precision, and robustness provided suitable results regarding all parameters investigated. The calibration curve was linear in the concentration range of 10.0–70.0 μg/mL with a correlation coefficient >0.999. Precision (intraday and interday) was demonstrated by a relative standard deviation lower than 2.0%. Accuracy was assessed by the recovery test of FA from polymeric microparticles (99.02% to 100.73%). Specificity showed no interference from the components of polymeric microparticles or from the degradation products derived from acidic, basic, and photolytic conditions. In conclusion, the method is suitable to be applied to assay FA as bulk drug and into polymeric microparticles and can be used for studying its stability and degradation kinetics.

Procoagulant Actions of Circulating Microparticles in Sickle Cell Anemia and Sepsis Associated Coagulopathy and Their Modulation By a Triblock Polymer MST 188

Introduction:Circulating microparticles (MPs) represent vesicles and cellular fragments of less than 1um which are generated in microvascular angiopathic conditions in both sickle cell anemia (SCA) and sepsis associated coagulopathy (SAC). MPs mediate pro-coagulant actions via the expression of their surface phospholipids and tissue factor. In SCA, MPS are mainly of erythrocytic origin generated during hemolysis and contribute to thrombin generation. In SAC, MPs are generated through the fragmentation of both blood and endothelial cells and contribute to thrombogenic and inflammatory responses. MST-188 is a triblock polymer with affinity to hydrophobic surfaces which are generated in microangiopathic conditions and may also interact with the phospholipid component of MPs. To test the hypothesis that MST-188 may decrease the pro-coagulant effects of MPs, a functional method to access MPs levels and a thrombin generation assay was used.Materials & Methods:Citrated and EDTA anticoagulated whole blood samples (N =10 -15) were collected from healthy normal individuals, SCA patients and confirmed SAC patients. Individual aliquots of these samples were supplemented with saline and MST 188 at a concentration range of 0.1-10mg/ml. After 30mins of incubation these mixtures were centrifuged at 2,500g and plasma was retrieved and frozen. These samples were analyzed for functional microparticle levels using an annexin binding/chromogenic substrate based method for microparticle mediated thrombin generation (Hyphen Biomedical Paris France). The results are expressed in terms of nM of microparticles present. The same samples were also evaluated for thrombin generation using a commercially available flurometric method (Technoclone Vienna Austria). The results are compiled in the total amount thrombin generated and thrombokinetic profile.Results:In comparison to normal (16.3 ±4.2 nm), the MPs levels were significantly higher in the SCA (34.2±8.4 nm) and SAC patients (22.6±9.1 nm). The functional level of MPs was markedly reduced in the MST 1-88 supplemented normal (9.3 ± 1.6 nm), SCA (18.1± 4.6 nm) and SAC (14.6 ± 3.1 nm). This decrease ranged from 36-48%. In the thrombin generation assays in contrast to normal (250±38 nm) SCA patients (348±58 nM) and is SAC patient’s plasma (368±71 nm) generated higher levels of thrombin. Supplementation of MST 1-88 resulted in significant decrease in thrombin generation in normal (110±14 nm), SCA patient’s plasma (160±21 nm) and SAC patient’s (168±26 nm) groups. The decrease in thrombin generation ranged from 24-55%. These results show that both the microparticle facilitated and tissue factor mediated generation of thrombin is decreased by supplementing MST 1-88.Discussion:Both SCA and SAC are associated with vaso-occlusive complications due to the deposition of fibrin in the microvasculture resulting in the generation of microparticles from cellular deformation and damage. The microparticles further augment thrombogenesis and contribute to vascular complications in SCA and SAC. In this study, both SCA and SAC groups exhibited higher levels of microparticles compared to normals. Supplementation of MST 188 to both groups of blood samples resulted in a marked decrease of functioning microparticles and thrombin generation. This may be due to the interaction of MST 188 with hydrophobic moieties of the microparticles. . DisclosuresEmanuele:Mast Therapeutics: Employment.

Procoagulant Phospholipid Activity, Whole Blood Thromboelastography and Thrombin Generation Assay to Detect Hypercoagulability in Thalassemic Children

INTRODUCTIONLife expectancy of thalassemia patients has markedly increased over the last few decades. Nevertheless patients suffer from many complications of this congenital chronic disease.The presence of a highincidence of thrombotic events has led to the identification of a hypercoagulable state in these patients.The thrombotic risk is higher in β-thalassemia intermedia and splenectomized patients. The mechanisms responsible for the increased thrombotic risk are still unclear. Several factors that contribute to the hypercoagulable state in patients with thalassemia have been identified: chronic platelet activation, abnormal red blood cells, microparticles,iron overload, endothelial damage, splenectomy, decreased levels of anticoagulant factors and presence of prothrombotic mutations. We aimed to assess hypercoagulability in children with β-thalassemia. DESIGN AND METHODSSixty eight thalassemia major and 42 thalassemia intermedia patients included our study. The control group consisted of 41 age and sex matched healthy children. Demographic data of patients were recorded from their medical records. None of the thalassemic patients have thrombosis before. To evaluate the relative role of microparticles, blood cells and plasma: coagulation tests (prothrombin time, activated prothrombin time, fibrinogen and d-dimer), serum coagulation factor levels (factor II, V, VII, VIII, IX, X, von willebrand factor, protein C, protein S, antithrombin III), procoagulant phospholipid activity and thrombin generation assay were studied from plasma, thromboelastography from whole blood.The main component of microparticles are negative anionic phospholipids.Procoagulant phospholipid activity is a functional analyse to detect microparticles.Thromboelastography measures indices of the viscoelastic properties of whole blood after activation of coagulation and the thrombin generation assay measures the actual thrombin concentrations before and after the clot is formed. RESULTSThe median age is 144 months ( 11-236 months)in thalassemia major and 142 months (72-202 months) in thalassemia intermedia patients. Plasma factor II, factor V, factor IX, factor X and protein C levels were significantly lower in thalassemia major and intermedia patients than control subjects. Plasma phospholipid activity and whole blood thromboelastography parameters were all consistent with hypercoagulability in thalassemic patients, especially in splenectomized patients. Endogenous thrombin potential (area under the curve in thrombin generation assay) was significantly lower in thalassemic patients than control subjects and in non-splenectomized patients than splenectomized patients contrary to expectations. CONCLUSIONSThe hypercoagulability in thalassemic patients especially in splenectomized patients can be determined with procoagulant microparticle activity and whole blood thromboelastography but not with thrombin generation assay in platelet poor plasma. These findings showthat blood cells and/or platelets may be more important determinants of thrombotic risk rather than plasma abnormalities in thalassemic patients. DisclosuresNo relevant conflicts of interest to declare.

The role of antigen specificity in the binding of murine monoclonal anti-DNA antibodies to microparticles from apoptotic cells

Antibodies to DNA (anti-DNA) are the serological hallmark of systemic lupus erythematosus and markers of underlying immune system disturbances. These antibodies bind to both single-stranded and double-stranded DNA, mediating pathogenesis by forming immune complexes. As shown recently, DNA in blood exists in both free and particulate forms, with DNA representing an important component of microparticles. Microparticles are membrane-bound vesicles containing nuclear molecules, released by membrane blebbing during cell death and activation. A panel of monoclonal NZB/NZW F1 anti-DNA antibodies was tested for binding to microparticles generated from apoptotic THP-1 and Jurkat cells. These studies showed that only certain anti-DNA antibodies in the panel, specific for double-stranded DNA, bound to microparticles. Binding to particles was reduced by soluble DNA or DNase treatment. Together, these results indicate that particle binding is a feature of only certain anti-DNA antibodies, reflecting immunochemical properties of the antibodies and the nature of the exposed DNA antigens.

The Expression of HMGB1 on Microparticles Released during Cell Activation and Cell Death In Vitro and In Vivo

High mobility group box protein 1 (HMGB1) is a nonhistone nuclear protein that is a prototypic alarmin that can stimulate innate immunity and drive the pathogenesis of a wide range of inflammatory diseases. While HMGB1 can be released from both activated and dying cells, its biochemical and immunological properties differ depending on the release mechanism, resulting from redox changes and posttranslational modifications including acetylation. In addition to release of HMGB1, cell death is associated with the release of microparticles. Microparticles are small membrane-bound vesicles that contain cytoplasmic, nuclear and membrane components. Like HMGB1, microparticles display immunological activity and levels are elevated in diseases characterized by inflammation and vasculopathy. While studies have addressed the immunological effects of HMGB1 and microparticles independently, HMGB1, like other nuclear molecules, is a component of microparticles. Evidence for the physical association of HMGB1 comes from Western blot analysis of microparticles derived from RAW 264.7 macrophage cells stimulated by lipopolysaccharide (LPS) or induced to undergo apoptosis by treatment with etoposide or staurosporine in vitro. Analysis of microparticles in the blood of healthy volunteers receiving LPS shows the presence of HMGB1 as assessed by flow cytometry. Together, these findings indicate that HMGB1 can be a component of microparticles and may contribute to their activities. Furthermore, particle HMGB1 may represent a useful biomarker for in vivo events that may not be reflected by measurement of the total amount of HMGB1 in the blood.

Reduction in microparticle adsorption using a lateral interconnection method in a PDMS‐based microfluidic device

Microparticle adsorption on microchannel walls occurs frequently due to nonspecific interactions, decreasing operational performance in pressure-driven microfluidic systems. However, it is essential for delicate manipulation of microparticles or cells to maintain smooth fluid traffic. Here, we report a novel microparticle injection technique, which prevents particle loss, assisted by sample injection along the direction of fluid flow. Sample fluids, including microparticles, mammalian (U937), and green algae (Chlorella vulgaris) cells, were injected directly via a through hole drilled in the lateral direction, resulting in a significant reduction in microparticle attachment. For digital microfluidic application, the proposed regime achieved a twofold enhancement of single-cell encapsulation compared to the conventional encapsulation rate, based on a Poisson distribution, by reducing the number of empty droplets. This novel interconnection method can be straightforwardly integrated as a microparticle or cell injection component in integrated microfluidic systems.

Microparticles are novel effectors of immunity

Microparticles represent an intercellular communication and delivery mechanism for the efficient and effective transfer of biological information. These cargo vectors contain packages of material selectively assimilated from their parental cell, which includes bioactive lipids, integrins, cytokines, enzymes, mRNA and micro-RNA that can reprogramme recipient cells. Elevated levels of circulating microparticles are associated with a number of cardiovascular and inflammatory pathologies making them useful biomarkers for disease activity. Yet their full contribution to disease pathogenesis and its timely resolution remains to be elucidated. An emerging notion is that microparticles originating from different cell types or because of differential stimuli can exert deleterious or protective immunomodulatory actions. Herein, we discuss the bioactions of various microparticle components including genetic material, proteins and lipids and how they influence cellular behavior and ultimately host immunity.

Composites of Enteric Polymer/Magnetite: Preparation and Application in Release Processes

The controlled release of drugs represents an interesting procedure applied in the minimization of side effects and in the therapeutic action of pharmacological molecules. With the aim of measuring the kinetics of release of aspirin dispersed in composite of an enteric polymer (Eudragit L-100) in the presence/absence of magnetic particles, we have considered the measurement of fluorescence as a convenient tool. The results indicate that rate of release and amount of dispersed drug in solution varies directly with the concentration of magnetite in the composite, as a consequence of strong interaction between components of microparticles.

Synthesis of novel pyrrolyl-indomethacin derivatives

In the present work, we report the synthesis of the novel esters of indomethacin (IDMC) and an ester of reduced IDMC. For this purpose, IDMC is covalently bound by using a spacer chain to the pyrrole (Py) in the 3-position. The innovative pyrrole-indomethacin (3-Py-IDMC) derivates show no cytotoxic effects in primary calvarial osteoblasts. The designed IDMC derivates have been studied because they could be injected locally as a component of polymeric micro-particles. In fact, the new 3-Py-IDMC derivatives will assure their further polymerization since the 2- and 5-monomer positions are free.

Delaminated sodium titanate nanobelts in synergy with cationic polyacrylamide to induce flocculation on kaolin clay

Nanoparticle with higher aspect ratio and greater surface area renders higher micro-bridging ability in flocculating paper furnishes adsorbed with cationic polymers. Sodium titanate nanobelt is a typical one-dimensional nano-material with extremely high aspect ratios. In this paper, the nanobelt was synthesized hydrothermally and successfully peeled with tetramethylammonium hydroxide (TMAOH). The peeled nanobelt was characterized by XRD, TEM, BET surface area and surface charge measurement, and employed as a microparticle component partnered with cationic polyacrylamide (CPAM) to constitute a retention system. The flocculation behavior of kaolin clay by CPAM/nanobelt system was investigated using a photometric dispersion analyzer connected with a dynamic drainage jar. The morphology of flocculated kaolin was characterized by TEM and optical microscope. The results showed that the peeling treatment reduced both the length and the width of nanobelt, increased the charge density and sorption capacity to CPAM but did not significantly alter its structure and zeta potential in aqueous dispersion. The peeled nanobelts partnered with CPAM offered the biggest synergistic flocculating effect at a very low dosage, especially the ones that were peeled for 6–10 days. The kaolin flocs induced by CPAM/peeled nanobelt were larger and denser than those induced by CPAM alone, and become even denser but smaller with increased peeling time.

Plasma diagnostics for complex plasmas under microgravity and on ground

AbstractComplex plasmas are low-temperature plasmas containing micron-sized particles (microparticles) such as dust grains. These are present in astrophysical systems (comets, molecular clouds, et al.) and in technological applications (microchip production by plasma etching, deposition of solar cells, et al.). Complex plasmas are also of interest in basic science because these are often used as models for many other strongly coupled many-body systems in solid state, fluid, or plasma physics. Since gravity has a strong influence on the microparticle component, experiments under microgravity (parabolic flights, sounding rockets, International Space Station (ISS)) are performed. Interaction between microparticles depends on plasma parameters such as ion density or ion temperature. Also, the presence of microparticles may change the properties of background plasma. Therefore, the background plasma needs to be characterized to provide adequate interpretation of the microgravity experiments. For this purpose a dedicated high-speed diagnostic system has been set up.

Application of tomographic particle image velocimetry to studies of transport in complex (dusty) plasma

Over the past twelve years, two-dimensional and stereoscopic particle image velocimetry (PIV) techniques have been used to obtain detailed measurements of the thermal and transport properties of the microparticle component of dusty plasma systems. This letter reports on an extension of these techniques to obtain a volumetric, three-dimensional velocity vector measurement using tomographic PIV. Initial measurements using the tomographic PIV diagnostic are presented.

Microparticles

Microparticles represent a heterogeneous population of vesicles with a diameter of 100 to 1000 nm that are released by budding of the plasma membrane and express antigens specific of their parental cells. Although microparticle formation represents a physiological phenomenon, a multitude of pathologies are associated with a considerable increase in circulating microparticles, including inflammatory and autoimmune diseases, atherosclerosis, and malignancies. Microparticles display an broad spectrum of bioactive substances and receptors on their surface and harbor a concentrated set of cytokines, signaling proteins, mRNA, and microRNA. Recent studies provided evidence for the concept of microparticles as veritable vectors for the intercellular exchange of biological signals and information. Indeed, microparticles may transfer part of their components and content to selected target cells, thus mediating cell activation, phenotypic modification, and reprogramming of cell function. Because microparticles readily circulate in the vasculature, they may serve as shuttle modules and signaling transducers not only in their local environment but also at remarkable distance from their site of origin. Altogether, this transcellular delivery system may extend the confines of the limited transcriptome and proteome of recipient cells and establishes a communication network in which specific properties and information among cells can be efficiently shared. At least in same cases, the sequential steps of the transfer process underlie complex regulatory mechanisms, including selective sorting ("packaging") of microparticle components and content, specificity of interactions with target cells determined by surface receptors, and ultimately finely tuned and signal-dependent release and delivery of microparticle content.

Degradation of carbon tetrachloride in the presence of zero-valent iron

Efforts to achieve the decomposition of carbon tetrachloride through anaerobic and aerobic bioremediation and chemical transformation have met with limited success because of the conditions required and the formation of hazardous intermediates. Recently, particles of zero-valent iron (ZVI) have been used with limited success for in situ remediation of carbon tetrachloride. We studied a modified microparticulate product that combines controlled-release carbon with ZVI for stimulation of in situ chemical reduction of persistent organic compounds in groundwater. With this product, a number of physical, chemical, and microbiological processes were combined to create very strongly reducing conditions that stimulate rapid, complete dechlorination of organic solvents. In principle, the organic component of ZVI microparticles is nutrient rich and hydrophilic and has high surface area capable of supporting the growth of bacteria in the groundwater environment. In our experiments, we found that as the bacteria grew, oxygen was consumed, and the redox potential decreased to values reaching -600 mV. The small modified ZVI particles provide substantial reactive surface area that, in these conditions, directly stimulates chemical dechlorination and cleanup of the contaminated area without accumulation of undesirable breakdown products. The objective of this work was to evaluate the effectiveness of ZVI microparticles in reducing carbon tetrachloride under laboratory and field conditions. Changes in concentrations and in chemical and physical parameters were monitored to determine the role of the organic products in the reductive dechlorination reaction. Laboratory and field studies are presented.