Sustainable Development of Magnetic Chitosan Core-Shell Network for the Removal of Organic Dyes from Aqueous Solutions

The wide use of alizarin red S (ARS), a typical anthraquinone dye, has led to its continued accumulation in the aquatic environment, which causes mutagenic and carcinogenic effects on organisms. Therefore, this study focused on the removal of ARS dye by adsorption onto a magnetic chitosan core-shell network (MCN). The successful synthesis of the MCN was confirmed by ATR-FTIR, SEM, and EDX analysis. The influence of several parameters on the removal of ARS dye by the MCN revealed that the adsorption process reached equilibrium after 60 min, pH played a major role, and electrostatic interactions dominated for the ARS dye removal under acidic conditions. The adsorption data were described well by the Langmuir isotherm and a pseudo-second order kinetic model. In addition to the preferable adsorption of hydrophobic dissolved organic matter (DOM) fractions onto the MCN, the electrostatic repulsive forces between the previously adsorbed DOM onto MCN and ARS dye resulted in lower ARS dye removal. Furthermore, the MCN could easily be regenerated and reused for up to at least five cycles with more than 70% of its original efficiency. Most importantly, the spent MCN was pyrolytically converted into N-doped magnetic carbon and used as an adsorbent for various dyes, thus establishing a waste-free adsorption process.

Enhanced photocatalytic response of ZnO embedded chitosan/β-cyclodextrin towards the detoxification of Cr(VI) under visible light

The present work focused on the assessment of heterogenous photocatalytic efficacy of ZnO@CS-β-CD towards the degradation of hexavalent chromium under visible light illumination. The prepared ZnO@CS-β-CD was extensively characterized using XRD, FTIR, SEM, EDX with mapping, TGA, DSC and UV/vis DRS techniques and the photoreduction of Cr(VI) to Cr(III) was confirmed by X-ray photoelectron spectroscopy. The DRS results revealed that the band gap of ZnO@CS-β-CD was narrowed than ZnO from 3.23 to 2.01 eV. The photocatalyst hold excellent reusability up to seven cycles and the field trail results demonstrated for the practical application for the treatment of wastewater.

Surface-Induced Silica Scaling during Brackish Water Desalination: The Role of Surface Charge and Specific Chemical Groups

Silica scaling of membranes used in reverse osmosis desalination processes is a severe problem, especially during the desalination of brackish groundwater due to high silica concentrations. This problem limits the water supply in inland arid and semiarid regions. Here, we investigated the influence of surface-exposed organic functional groups on silica precipitation and scaling. A test solution simulating the mineral content of brackish groundwater desalination brine at 75% recovery was used. The mass and chemical composition of the precipitated silica was monitored using a quartz crystal microbalance, X-ray photoelectron spectroscopy, and infrared spectroscopy, showing that surfaces with positively charged groups induced rapid silica precipitation, and the rate of silica precipitation followed the order -NH₂ ∼ -N⁺(CH₃)₃ > -NH₂/-COOH > -H₂PO₃ ∼ -OH > -COOH > -CH₃. Force vs distance AFM measurements showed that the adhesion energy between a silica colloid glued to AFM cantilever and the studied surfaces increased as the surface charge changed from negative to positive. Thus, for the first time direct measurements of molecular forces and specific chemical groups that govern silica scaling during brackish water desalination is reported here. The influence of the different functional groups and the effect of the surface charge on silica precipitation that were found here can be used to design membranes that resist silica scaling in membrane-based desalination processes.

Hexavalent chromium ion and methyl orange dye uptake via a silk protein sericin–chitosan conjugate

Sericin, a protein waste product of the silk industry, was crosslinked with chitosan, and a chitosan–sericin conjugate (CS) was prepared, characterized and used to remove hexavalent chromium (Cr(vi)) ions and methyl orange (MO) dye from aqueous solutions. The CS was shown to effectively remove Cr(vi) ions and MO dye at maximum adsorption capacities (Langmuir) of 139 mg g⁻¹ for Cr(vi) ions and 385 mg g⁻¹ for MO dye. Moreover, the adsorption of both Cr(vi) ions and MO dye was highly pH dependent and varied under different experimental conditions. Cr(vi) ion and MO dye uptake by the CS was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometry analysis. Additionally, XPS analysis of the Cr(vi)-loaded CS revealed that Cr(vi) was reduced to the less toxic Cr(iii). The CS was shown not only to be highly amenable to regeneration, but also to be able to effectively remove MO dye and Cr(vi) ions from a binary mixture.

Sericin, a protein waste product of the silk industry, was crosslinked with chitosan, and a chitosan–sericin conjugate (CS) was prepared, characterized and used to remove hexavalent chromium (Cr(vi)) ions and methyl orange dye from aqueous solutions.

Calcium phosphate scaling during wastewater desalination on oligoamide surfaces mimicking reverse osmosis and nanofiltration membranes

Desalinated domestic wastewater is an indispensable water resource in arid regions; however, its recovery can be limited by calcium phosphate scaling and fouling of the membrane. Here we investigated calcium phosphate mineralization on oligoamide surfaces that mimics reverse osmosis (RO) and nanofiltration (NF) membrane surfaces. We used a solution that simulates desalination of secondary treated domestic wastewater effluents for calcium phosphate mineralization experiments with oligoamide-coated gold surfaces. Attenuated total reflection-Fourier transform infrared spectroscopy and energy dispersive spectrometry showed that calcium phosphate and carbonate precipitated on RO mimetic surfaces. The rate of precipitation on oligoamide sensors was monitored by a quartz crystal microbalance, showing that scaling was more intense on the RO than the NF mimetic surface and that excessive carboxyl functional groups on both surfaces promoted scaling. Filtration experiments of similar solutions with commercial membranes showed that scaling was more intense on the RO membranes than on the NF membranes, which supported the results obtained with the oligoamide model surfaces. The results of this study can be implemented in developing RO and NF membranes to prevent calcium phosphate scaling and consequently lower water-treatment costs of domestic wastewater treatment.

The influence of photodynamic therapy on the wound healing process in rats

In photodynamic therapy (PDT), photosensitisers (PS) are used along with lasers for the treatment of tumors. The combined effect of photosensitisers and lasers on the wound healing process is studied using delta-aminolevulinic acid (ALA) (5 mg/kg) and hematoporphyrin derivative (HPD) (5 mg/kg) as photosensitisers in the open excision wounds of rats. The lasers used were He-Ne laser (3 J/cm2) and Nd:YAG laser (30 J/cm2). This study is important for understanding the healing process involved after PDT. Open excision wounds treated with He-Ne lasers in animals that received ALA as photosensitiser showed complete wound closure at the earliest by 13 +/- 1 days, and with results obtained for HPD and the combination of lasers with complete closing by 14 +/- 1 days. However, the control group of animals that received ALS or HPD with no laser treatment showed wound healing on the twentieth and eighteenth days with a deviation of one day and two days, respectively. ALA with the combination of Nd:YAG and He-Ne lasers and HPD with He-Ne laser alone does not show quicker wound healing effects. Histopathological results also gave similar results. Tensile strength measurements do not vary significantly from control group to the test group. ALA along with He-Ne laser of HPD along with the combination of He-Ne and low power Nd-YAG lasers are found to be ideal methods for quickening the wound healing process in rat.

Assessment of in vivo chromosomal aberrations--potency of zinc mercapto benzo thiazole

Chromosomal aberrations are microscopically visible changes in the chromosome structure. The double-stranded breaks are the ultimate DNA lesions for chromosomal aberrations. The purpose of the present study was to evaluate the induction of chromosomal aberrations by the rubber accelerator zinc mercapto benzo thiazole (ZMBT). The experiment was designed with five groups, each composed of four Swiss albino mice. The first three groups received ZMBT at 1920, 960, and 480 microg/20 g animal. The remaining two groups were the vehicle (cotton seed oil) and positive (methyl methane sulphonate) controls. Animals were given a single dose of test and control samples by IP injection. Colchicine (20 microg/animal) was administered 90 minutes before sacrificing the animals. All the animals were sacrificed at the end of 36 h by cervical dislocation. Bone marrow preparations were made, stained with Giemsa stain, and examined for chromosomal abnormalities. The results indicated a lack of incidence of chromosomal abnormalities in the test and control groups. However, significant chromosomal abnormalities such as gaps, breaks, and translocations were observed in the positive control group. Hence, the study concluded that ZMBT at different concentrations fails to induce structural chromosomal aberrations in bone marrow cells.

Microtox system, a new approach to the safety evaluation of medical devices

Medical devices of both intra- and extra-corporeal applications may contain leachable toxicants that warrant routine testing using internationally recognized/practiced protocols. An in vitro Microtox system comprising a selected bioluminescence strain of bacteria-Photobacterium phosphorium which emits light as an end product of its respiration, is used to screen out toxicants from biomaterials/devices. A Microtox system was standardized and validated in our laboratory conditions. Our experiences with extract of pyrogenic cardiotomy reservoir, blood filter and systemically toxic (in mice) Barium methacrylate (monomer), and CIBA epoxy polymer materials established a positive correlation with Microtox system. Hence, the Microtox system gives adequate evidence as an alternative in vitro method to evaluate the toxicity of biomaterials and medical devices.

Effect of bone wax extract on the frequency of bone marrow erythrocyte micronuclei in mice

The present study evaluated the induction of micronuclear potency of indigenously developed bone wax saline extract. The experiment was designed with 2 batches, each consisting of 8 groups with 3 male Swiss albino mice each. In each batch, the first 3 groups received Chitra's bone wax saline extract and the second 3 groups received Johnson & Johnson bone wax saline extract at 12.5, 25.0 or 50.0 ml/kg body weight ip for 2 d. The remaining 2 groups were vehicle (saline) and positive (cyclophosphamide) controls. Animals were sacrificed 24 and 36 h after the second dosing and bone marrow smears were prepared and evaluated for micronuclei. The Chitra's and Johnson & Johnson's bone wax extracts failed to induce micronuclei in bone marrow erythrocytes of mice.

Lack of micronucleus induction by 'Sobatum' in bone marrow erythrocytes of Swiss mice

The plant Solanum trilobatum is mainly used for asthma, chronic febrile affections and difficult parturition. The active principle (Sobatum) obtained from the petroleum ether extract of the plant was proved as an anticancer agent by in vitro and in vivo experiments. Here, an effort was made to evaluate the induction of micronucleus by the Sobatum in the bone marrow of swiss mice. The micronucleus assay was conducted after 24 and 72 h of second administration of the Sobatum. The first set of experiments (24 h after second administration) consisted of 4 groups with 3 male Swiss albino mice each. The first group (as control) received only dimethyl sulfoxide, the second, third and fourth groups received different doses of the Sobatum (100, 200, 400 mg/kg body weight), and the fifth group (as positive control) received cyclophosphamide (100 mg/kg body weight) by i.p. injection. In the second set of experiment (72 h after the second administration) consisting of 5 groups, the first, as control, received dimethyl sulfoxide, the second, third and fourth groups received different concentrations of the Sobatum (100, 200, 400 mg/kg body weight), and the fifth group as positive control received cyclophosphamide (100 mg/kg body weight). All the animals of the first and second sets of experiment were killed 24 and 72 h after the second medication (2 consecutive days), and bone marrow smears were prepared, stained with May-Grunwald and Giemsa stain, and evaluated for the evidence of micronucleus. The study concluded that the Sobatum fails to influence the induction of micronuclei in bone marrow erythrocytes of mice 24 and 72 h after the second administration, thereby proving that Sobatum to has no cytogenetic toxic potential.

Levels of cerium in the tissues of rats fed a magnesium-restricted and cerium-adulterated diet

Cerium, a lanthanide, is the most abundant rare earth element present in monazite and is biologically active. It has been postulated that cerium toxicity in conjunction with magnesium deficiency causes tropical endomyocardial fibrosis, a restrictive human cardiomyopathy (Valiathan et al. 1989; Valiathan and Kartha 1990). Generally, lanthanides are known to be poorly absorbed (Durbin et al. 1956; Evans 1990). The present study was carried out to ascertain whether magnesium deficiency promotes accumulation of cerium in various organs of rats.

Development of silastic polyurethane (Angioflex) materials with antibacterial agent

Bioimplants incorporated with antimicrobial agents are needed to control Foreign Body Associated Infection (FBAI) in clinical settings. Attempts are made here to develop five different types of polyurethane (Angioflex), viz., (1) bare polymer, (2) bare polymer glow discharged, (3) bare polymer coated with chlorhexidine, (4) chlorhexidine coated polymer glow discharged, and (5) material (4) recoated with another layer of chlorhexidine digluconate. These materials are tested for their in vitro antibacterial effects using disc diffusion technique against five different standard clinical staphylococcus strains, viz., Wood 46 (Staph. aureus), A 182 (Staph. epidermidis), A 313 (Staph. epidermidis), A 61 (Staph. epidermidis), and A 72 (Staph. epidermidis). Maximum antibacterial effects (zone of inhibition) are observed with polyurethanes incorporated with chlorhexidine digluconate (3) and chlorhexidine incorporated and glow discharged (4). Findings of this study indicate that glow discharge does not seem to produce either additive 8r synergistic antibacterial effects with chlorhexidine digluconate coated Angioflex material.

Cerium stimulates protein biosynthesis in rat heart in vivo

The aim of the study was to ascertain whether Ce, a lanthanide that has been implicated in the pathogenesis of tropical endomyocardial fibrosis, interferes with the biosynthetic repertoire of the cardiac muscle in vivo. Female Sprague-Dawley rats received Ce chloride iv at 1.3 mg/kg body wt.; controls received an equal volume of physiological saline. Rates of protein synthesis and transcription in cardiac muscle, measured in terms of incorporation of (3H)-phenylalanine and (3H)-uridine, respectively, into trichloroacetic acid-insoluble material were found to be significantly higher in Ce-treated animals. As low levels of Ce were earlier shown to stimulate collagen as well as noncollagen protein synthesis in cardiac fibroblasts in vitro, the stimulatory effect of the element in vivo reported here supports the speculation that it may influence the expression of proteins like collagen in the heart and contribute to their accumulation as in endomyocardial fibrosis.

Development of artificial skin (Template) and influence of different types of sterilization procedures on wound healing pattern in rabbits and guinea pigs

Different types of sterilization procedures have been applied onto artificial skin (Template) developed in our laboratory from polyether urethane, chitosan and polyvinyl alcohol, etc. Studies have been performed to investigate the differences in the wound healing pattern. It appears that quickened wound healing takes place in the rabbit model despite different types of samples and sterilization methods.

Casein as a carrier matrix for 5-fluorouracil: drug release from microspheres, drug-protein conjugates and in-vivo degradation of microspheres in rat muscle

Glutaraldehyde cross-linked casein microspheres were loaded with 5-fluorouracil (5-FU) from concentrated aqueous solutions of the drug after the microspheres were synthesized and cleaned. In-vitro release of the drug was examined in phosphate buffer in the absence and in the presence of protease at 37 degrees C. Drug release data showed that only about 20% of the drug is released in the absence of protease even after 5 days, while digestion of the matrix with protease released the entrapped drug completely in about 24 h. A protein-drug conjugate was synthesized via carbamoyl linkage using 6-(5-FU-1-yl)hexyl isocyanate and the drug release was examined in phosphate buffer at 37 degrees C. Release from the protein-5-FU conjugate was slower compared with the release from microspheres in the presence of protease. Implantation of placebo microspheres of different cross-linking densities in the gluteal muscle of rats showed no adverse tissue reactions over a one-year period. Histopathological examination of the tissues containing injected microspheres suggested that the biological life of casein microspheres in muscle is about 6 months, which is three times that of cross-linked albumin microspheres.

The teratogenic potential of bone wax extract in rats

This study evaluated the teratogenic defects of rat brain, eye, heart, urogenital and skeletal systems after po administration of bone wax saline extract on days 9-13 of gestation. The experiment involved 5 groups of 6 pregnant wistar rats each. The vehicle control group received only 50.0 ml distilled water/kg; 3 test groups received 12.5, 25.0 or 50.0 ml of bone wax saline extract/kg; and the last group received 100 mg caffeine/kg as positive control. On the 21st day of gestation all the animals were sacrificed under ether anesthesia and fetuses were collected for routine teratological evaluations. There was no significant change in maternal body weight or food consumption and no external, visceral, skeletal and histological abnormalities in the vehicle control and bone wax dosed groups. Abnormalities were observed in the positive control group.

Evaluation of bone-wax extract on the frequency of chromosomal aberrations in the bone marrow of Swiss mice

Indigenously developed bone wax was evaluated for cytogenetic effects of a saline extract of the bone wax. Swiss mice were assigned to 5 groups of 6 animals each. Groups I, II, III were given non-lethal doses of 2.5, 5.0 or 10.0 ml bone-wax saline extract/kg body wt and Groups IV and V received sterile 0.9% saline vehicle or cyclophosphamide ip as controls. After 24 h the mice were sacrificed by cervical dislocation. Bone marrow preparations were stained with Giemsa's stain and examined by light microscopy. Abnormalities such as numbers of chromosome gaps, breaks and translocations were noted. The bone-wax saline extract did not induce chromosomal aberrations in the bone marrow of Swiss mice under our laboratory conditions.

Skin sensitization study of a new BIS-GMA based dental restorative material

One of the criteria for the Dental Restorative Material is to not to evoke sensitization reaction when used clinically. The newly synthesized BIS-GMA based Chitra's Dental Material intended for such application was tested for skin sensitization as per the international protocol of test i.e. skin Maximization test in G.Pig. Result of this test showed conclusively that the material is devoid of sensitization potential and fit for clinical application.

Mandatory biological testing of Spictra Cardiotomy Reservoir

Disposable rigid Spictra Cardiotomy Reservoir is one of the units used in the extracorporeal techniques during open-heart surgery. It was designed, developed, and tested by different groups of our Institute as an indigenous product to offset the prohibitive cost of the imported one. The finished device was subjected to mandatory biological tests, such as pyrogen (in vivo rabbits and in vitro Limulus Amebocyte Lysate test) and sterility tests. It can be concluded from the case study that the device deemed to have passed the test for apyrogenicity and sterility.

Studies on the effect of degree of hydrophilicity on tissue response of polyurethane interpenetrating polymer networks

Interpenetrating polymer networks of polyurethane and vinyl monomers such as polyacrylamide, polyvinyl pyrrolidone, poly(hydroxyethyl methacrylate) and poly(methyl methacrylate) were implanted intramuscularly in rabbits. Attempts were made to correlate the morphological aspects of the interpenetrating polymer networks to their histological response. A relatively increased hydrophilicity of hydrophobicity of the interpenetrating polymer networks as in the case of polyurethane-polyvinyl pyrrolidone and polyurethane-poly(methyl methacrylate) interpenetrating polymer networks, respectively, could elicit an inert response whilst degradation of materials promoted reactivity.

Effects of biostability and morphology on host response of polyurethane-based soft tissue implants

Polyurethane has been found to be one of the most successful polymers for soft tissue applications. We have investigated the effect of material biostability and morphology on the host response of polyurethane-based soft tissue implants in rabbits. The polyurethane containing allophanate linkage was prepared by using hexamethylene diisocyanate, polypropylene glycol (400) and 1,4-butane diol. Biuret-based biostable polyurethanes were prepared by using hexamethylene diisocyanate, polytetramethylene glycol and trimethylol propane and water. Samples of circular button and rectangular specimens were implanted subcutaneously in rabbits in the paravertebral region for a post-implantation period of 9 months. Relatively larger polyurethane samples with different morphology elicit a varied tissue response with our candidate polyurethane materials. A favorable tissue response was observed with rectangularly shaped thin polyurethane. Giant cell reaction, absence of fibrous tissue encapsulation and degradation were noticed for the rectangular smooth samples at the end of post-implantation period of 9 months. No malignant changes were noticed in any of these samples.

In vivo biocompatibility of an aliphatic crosslinked polyurethane in rabbit

A cage implantation technique has been adopted in a rabbit animal model to investigate the biocompatibility of an aliphatic crosslinked polyurethane based on hexamethylene diisocyanate (HDI). In this study, four cages are represented; the cage containing the candidate polyurethane material, biomedical grade polyurethane (Tecoflex), the commercial grade polyvinylchloride (PVC), and an empty cage which were implanted subcutaneously in rabbits. Exudates were aspirated from these cages at 4, 7, 14, and 21 days postimplantation. Exudates were analyzed for variations in proteins, cell counts, and extracellular enzymes. Results with the four types of cage implants showed that the candidate polyurethane caused an inflammatory response comparable to that caused by medical-grade Tecoflex and the empty cage control.

Preparation and evaluation of radiopaque hydrogel microspheres based on PHEMA/iothalamic acid and PHEMA/iopanoic acid as particulate emboli

Highly porous poly(2-hydroxyethyl methacrylate) (PHEMA) microspheres prepared by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) in presence of polymeric diluents such as poly(methyl methacrylate) (PMMA) in toluene and poly(tetramethylene glycol) (PTMG) were made radiopaque by esterification of the reactive hydroxyl groups with iothalamic acid and iopanoic acid, two radiopaque substances clinically used. Of the various solvents and catalysts examined, tetrahydrofuran (THF) and N,N'-dimethyl paratoluidine (DMPT) were found to be best for obtaining a high degree of conversion. More than 30 wt% iodine could be bound to the microspheres which made them sufficiently radiopaque to be imaged radiographically. Microspheres retained their porosity, swelling ability, hydrophilicity, and surface morphology to a significant extent after iodination. Preliminary implantation studies of such microspheres subcutaneously in rats have shown no adverse tissue reactions over a 6-month period. It is suggested that these microspheres would prove to be useful as particulate emboli in endovascular embolization.

Hepatic studies of intraperitoneally administered tris(2-ethyl hexyl)trimellitate (TOTM) and di(2-ethyl hexyl)phthalate in rats

Adult male rats receiving tris(2-ethyl hexyl)trimellitate (TOTM) intraperitoneally for seven days exhibited no significant changes in the activities of hepatic aminopyrine-N-demethylase, aryl hydrocarbon hydroxylase or glutathione-S-transferase, or in the glutathione contents. However, except for the glutathione level, the di(2-ethyl hexyl)phthalate (DEHP)-treated group showed significant increases in the activities of these enzymes. Changes in the body weight and the absolute and relative liver weights were also observed among the DHEP-treated group.

Pulmonary vasospasm in rabbits infused with stroma free haemoglobin solution

Effect of infusion of stroma free haemoglobin solution into mice and rabbits was studied. Though no abnormalities were noted in mice, pulmonary vasospasm and hepatocytic necrosis were seen in all rabbits. In addition to reports that low adenosine deaminase levels in the solution could be a cause of vasoconstriction, it is proposed on the basis of present results that either denaturation of haemoglobin molecule itself or release of super oxide anion during oxygenation of haemoglobin, could cause cellular damage leading to toxicity.

The occurrence of phthalic acid esters in various samples of commercially available sodium chloride injections (Indian Pharmacopoeia)

Conclusive evidence for the presence of di(2-ethylhexyl) phthalate (DEHP) in 15 out of 17 commercially available sodium chloride injection (Indian Pharmacopoeia) samples was obtained and concentration levels as high as 11.0 mg/500 ml of saline were detected. The presence of such contaminants in i.v. fluids, avoidable by the institution of appropriate quality control measures before manufacturing and marketing, is a matter of serious concern. Stipulated specifications in different pharmacopoeias are meant only to ensure sterility and pyrogenicity, and it is advisable that cognisance be taken of the presence of toxic contaminants e.g. di(2-ethylhexyl) phthalate.