Synthesis of Biocompatible Hydroxyapatite Using Chitosan Oligosaccharide as a Template.
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ABSTRACT:
SUBMITTER: Wang J
PROVIDER: S-EPMC5458867 | biostudies-other | 2015 Nov
REPOSITORIES: biostudies-other
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Project description:Palladium, a near-infrared plasmonic material has been recognized for its use in photothermal therapy as an alternative to gold nanomaterials. However, its potential application has not been explored well in biomedical applications. In the present study, palladium nanoparticles were synthesized and the surface of the particles was successfully modified with chitosan oligosaccharide (COS), which improved the biocompatibility of the particles. More importantly, the particles were functionalized with RGD peptide, which improves particle accumulation in MDA-MB-231 breast cancer cells and results in enhanced photothermal therapeutic effects under an 808-nm laser. The RGD peptide-linked, COS-coated palladium nanoparticles (Pd@COS-RGD) have good biocompatibility, water dispersity, and colloidal and physiological stability. They destroy the tumor effectively under 808-nm laser illumination at 2 W cm-2 power density. Further, Pd@COS-RGD gives good amplitude of photoacoustic signals, which facilitates the imaging of tumor tissues using a non-invasive photoacoustic tomography system. Finally, the fabricated Pd@COS-RGD acts as an ideal nanotheranostic agent for enhanced imaging and therapy of tumors using a non-invasive near-infrared laser.
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Project description:Photothermal therapy (PTT) using biocompatible nanomaterials have recently attracted much attention as a novel candidate technique for cancer therapy. In this work we report the performance of newly synthesized multidentate chitosan oligosaccharide modified gold nanorods (AuNRs-LA-COS) as novel agents for PTT of cancer cells due to their excellent biocompatibility, photothermal stability, and high absorption in the near-infrared (NIR) region. The AuNRs-LA-COS exhibit a strong NIR absorption peak at 838 nm with a mean length of 26 ± 3.1 nm and diameter of 6.8 ± 1.7 nm, respectively. The temperature of AuNRs-LA-COS rapidly reached 52.6 °C for 5 min of NIR laser irradiation at 2 W/cm². The AuNRs-LA-COS had very low cytotoxicity and exhibited high efficiency for the ablation of breast cancer cells in vitro. The tumor-bearing mice were completely ablated without tumor recurrence after photothermal treatment with AuNRs-LA-COS (25 µg/mL) under laser irradiation. In summary, this study demonstrated that AuNRs-LA-COS with laser irradiation as novel agents pave an alternative way for breast cancer therapy and hold great promise for clinical trials in the near future.
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Project description:Abstract: Chemogenomic fitness assays were combined with a transcriptome analysis to understand both the mode of action and the mechanisms of resistance to Chitosan oligosaccharides (COS). COS are deacetylated chitin compounds, with antimicrobial properties, that are presumed to act by disrupting the cell membrane. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified encode membrane proteins and members of the protein degradation/ proteosome pathway. The transcriptomes of wild-type and five suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress) and furthermore, treatment with environmental stressors does not provide resistance to COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the RAS signal transduction pathway. Down-regulated transcripts included those encoding protein folding components, and respiratory chain proteins. Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane trafficking, provides protection against COS-induced cell membrane permeability and damage. We found that the ARL1 COS-resistant over-expression strain was as sensitive to amphotericin B, fluconazole and terbinafine as the wild-type (vector control). The gene targets of COS identified in this study suggest that COS’s mechanism of action is different from other commonly studied fungicides, suggesting that COS may be an effective fungicide for drug-resistant fungal pathogens. We selected the 5 overexpressing strains based on the characteristics of the genes. ARL1, encoding a GTPase and is involved in membrane trafficking, was selected since it was observed in the HIP-HOP assay as a sensitive homozygous deletion strain and in the MSP assay as multicopy suppressor. The rest of selected overexpressing strains were BCK2 and MSG5, involved in cell integrity pathways, ERG24 in ergosterol synthesis, and RBA50 in transcription. BCK2 is a Ser-Thr rich protein with protein kinase C activity that acts in signal transduction. Overexpression of BCK2 can rescue defects in yeast cwh43Δ, which displays several cell wall defects [29]. BCK2 overexpression also can suppress a cell lysis defect of mpk1Δ and pck1Δ [30]. MSG5 is also involved in signal transduction. This gene encodes a protein phosphatase involved in cell cycle control through the dephosphorylation of MAPK and is indispensable for restricting the signaling by the cell integrity pathway in yeast [31]. The inhibition of MAPK signaling leads to inhibition of cell differentiation and cell division [32]. The functions of ARL1 and ERG24 and their potential roles in chitosan resistance will be described in more detail in the Discussion. To gain a further understanding on the mode of action and mechanisms of resistance to COS, we performed a transcriptome analysis of the above mentioned five overexpressing strains known to increase resistance to COS-5.44. Each overexpressing strain and the wild type (vector control) were treated with COS-5.44 and RNAs isolated from both treated and untreated cells. The RNAs were converted to labeled cDNA and hybridized to NimbleGen expression microarrays (see Methods).
2012-12-22 | GSE32888 | GEO
Project description:Abstract: Chemogenomic fitness assays were combined with a transcriptome analysis to understand both the mode of action and the mechanisms of resistance to Chitosan oligosaccharides (COS). COS are deacetylated chitin compounds, with antimicrobial properties, that are presumed to act by disrupting the cell membrane. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified encode membrane proteins and members of the protein degradation/ proteosome pathway. The transcriptomes of wild-type and five suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress) and furthermore, treatment with environmental stressors does not provide resistance to COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the RAS signal transduction pathway. Down-regulated transcripts included those encoding protein folding components, and respiratory chain proteins. Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane trafficking, provides protection against COS-induced cell membrane permeability and damage. We found that the ARL1 COS-resistant over-expression strain was as sensitive to amphotericin B, fluconazole and terbinafine as the wild-type (vector control). The gene targets of COS identified in this study suggest that COSM-bM-^@M-^Ys mechanism of action is different from other commonly studied fungicides, suggesting that COS may be an effective fungicide for drug-resistant fungal pathogens. We selected the 5 overexpressing strains based on the characteristics of the genes. ARL1, encoding a GTPase and is involved in membrane trafficking, was selected since it was observed in the HIP-HOP assay as a sensitive homozygous deletion strain and in the MSP assay as multicopy suppressor. The rest of selected overexpressing strains were BCK2 and MSG5, involved in cell integrity pathways, ERG24 in ergosterol synthesis, and RBA50 in transcription. BCK2 is a Ser-Thr rich protein with protein kinase C activity that acts in signal transduction. Overexpression of BCK2 can rescue defects in yeast cwh43M-NM-^T, which displays several cell wall defects [29]. BCK2 overexpression also can suppress a cell lysis defect of mpk1M-NM-^T and pck1M-NM-^T [30]. MSG5 is also involved in signal transduction. This gene encodes a protein phosphatase involved in cell cycle control through the dephosphorylation of MAPK and is indispensable for restricting the signaling by the cell integrity pathway in yeast [31]. The inhibition of MAPK signaling leads to inhibition of cell differentiation and cell division [32]. The functions of ARL1 and ERG24 and their potential roles in chitosan resistance will be described in more detail in the Discussion. To gain a further understanding on the mode of action and mechanisms of resistance to COS, we performed a transcriptome analysis of the above mentioned five overexpressing strains known to increase resistance to COS-5.44. Each overexpressing strain and the wild type (vector control) were treated with COS-5.44 and RNAs isolated from both treated and untreated cells. The RNAs were converted to labeled cDNA and hybridized to NimbleGen expression microarrays (see Methods). Three cDNA biological replicates either with or without a 60 minutes exposure to COS-5.44 for each of the five overexpressing strains as well as an untransformed wild type BY4743 cells (vector control; for a total of 36 samples) were hybridized to NimbleGen 4X72k microarrays (Roche NimbleGen, Inc. Design ID A6186-00-01, TI4932 60mer expr X4).
2012-12-22 | E-GEOD-32888 | biostudies-arrayexpress
Project description:Fabrication of scaffolds from biomaterials for restoration of defected mandible bone has attained increased attention due to limited accessibility of natural bone for grafting. Hydroxyapatite (Ha), collagen type 1 (Col1) and chitosan (Cs) are widely used biomaterials which could be fabricated as a scaffold to overcome the paucity of bone substitutes. Here, rabbit Col1, shrimp Cs and bovine Ha were extracted and characterized with respect to physicochemical properties. Following the biocompatibility, degradability and cytotoxicity tests for Ha, Col1 and Cs a hydroxyapatite/collagen/chitosan (Ha·Col1·Cs) scaffold was fabricated using thermally induced phase separation technique. This scaffold was cross-linked with (1) either glutaraldehyde (GTA), (2) de-hydrothermal treatment (DTH), (3) irradiation (IR) and (4) 2-hydroxyethyl methacrylate (HEMA), resulting in four independent types (Ha·Col1·Cs-GTA, Ha·Col1·Cs-IR, Ha·Col1·Cs-DTH and Ha·Col1·Cs-HEMA). The developed composite scaffolds were porous with 3D interconnected fiber microstructure. However, Ha·Col1·Cs-IR and Ha·Col1·Cs-GTA showed better hydrophilicity and biodegradability. All four scaffolds showed desirable blood biocompatibility without cytotoxicity for brine shrimp. In vitro studies in the presence of human amniotic fluid-derived mesenchymal stem cells revealed that Ha·Col1·Cs-IR and Ha·Col1·Cs-DHT scaffolds were non-cytotoxic and compatible for cell attachment, growth and mineralization. Further, grafting of Ha·Col1·Cs-IR and Ha·Col1·Cs-DHT was performed in a surgically created non-load-bearing rabbit maxillofacial mandible defect model. Histological and radiological observations indicated the restoration of defected bone. Ha·Col1·Cs-IR and Ha·Col1·Cs-DHT could be used as an alternative treatment in bone defects and may contribute to further development of scaffolds for bone tissue engineering.
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Project description:Simultaneous integration of photon emission and biocompatibility into nanoparticles is an interesting strategy to develop applications of advanced optical materials. In this work, we present the synthesis of biocompatible optical nanocomposites from the combination of near-infrared luminescent lanthanide nanoparticles and water-soluble chitosan. NaYF4:Yb,Er upconverting nanocrystal guests and water-soluble chitosan hosts are prepared and integrated together into biofunctional optical composites. The control of aqueous dissolution, gelation, assembly, and drying of NaYF4:Yb,Er nanocolloids and chitosan liquids allowed us to design novel optical structures of spongelike aerogels and beadlike microspheres. Well-defined shape and near-infrared response lead upconverting nanocrystals to serve as photon converters to couple with plasmonic gold (Au) nanoparticles. Biocompatible chitosan-stabilized Au/NaYF4:Yb,Er nanocomposites are prepared to show their potential use in biomedicine as we find them exhibiting a half-maximal effective concentration (EC50) of 0.58 mg mL-1 for chitosan-stabilized Au/NaYF4:Yb,Er nanorods versus 0.24 mg mL-1 for chitosan-stabilized NaYF4:Yb,Er after 24 h. As a result of their low cytotoxicity and upconverting response, these novel materials hold promise to be interesting for biomedicine, analytical sensing, and other applications.
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Project description:Microbial biofilms are considerably more resistant to antibiotics than planktonic cells. It has been reported that chitosan coupling with the aminoglycoside antibiotic streptomycin dramatically disrupted biofilms of several Gram-positive bacteria. This finding suggested the application of the covalent conjugate of antimicrobial natural polysaccharides and antibiotics on anti-infection therapy. However, the underlying molecular mechanism of the chitosan-streptomycin conjugate (CS-Strep) remains unclear and the poor water-solubility of the conjugate might restrict its applications for anti-infection therapy. In this study, we conjugated streptomycin with water-soluble chitosan oligosaccharides (COS). Unlike CS-Strep, the COS-streptomycin conjugate (COS-Strep) barely affected biofilms of tested Gram-positive bacteria. However, COS-Strep efficiently eradicated established biofilms of the Gram-negative pathogen Pseudomonas aeruginosa. This activity of COS-Strep was influenced by the degree of polymerization of chitosan oligosaccharide. The increased susceptibility of P. aeruginosa biofilms to antibiotics after conjugating might be related to the following: Suppression of the activation of MexX-MexY drug efflux pump system induced by streptomycin treatment; and down-regulation of the biosynthesis of biofilm exopolysaccharides. Thus, this work indicated that covalently linking antibiotics to chitosan oligosaccharides was a possible approach for the development of antimicrobial drugs against biofilm-related infections.
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Project description:Chitosan oligosaccharide (COS), a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS.Three different chemogenomic fitness assays, haploinsufficiency (HIP), homozygous deletion (HOP), and multicopy suppression (MSP) profiling were combined with a transcriptomic analysis to gain insight in to the mode of action and mechanisms of resistance to chitosan oligosaccharides. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified are involved in processes such as RNA biology (transcription, translation and regulatory mechanisms), membrane functions (e.g. signalling, transport and targeting), membrane structural components, cell division, and proteasome processes. The transcriptomes of control wild type and 5 suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the Ras signal transduction pathway. Down-regulated transcripts included those encoding protein folding components and respiratory chain proteins. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress) and pre-treatment with these well characterized environmental stressors provided little or any resistance to COS.Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane trafficking, provides protection against COS-induced cell membrane permeability and damage. We found that the ARL1 COS-resistant over-expression strain was as sensitive to Amphotericin B, Fluconazole and Terbinafine as the wild type cells and that when COS and Fluconazole are used in combination they act in a synergistic fashion. The gene targets of COS identified in this study indicate that COS's mechanism of action is different from other commonly studied fungicides that target membranes, suggesting that COS may be an effective fungicide for drug-resistant fungal pathogens.
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