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1.
Autoimmunity ; 57(1): 2347379, 2024 Apr 27.
Article En | MEDLINE | ID: mdl-38723105

Thymoma is closely associated with myasthenia gravis (MG). However, due to the heterogeneity of thymoma and the intricate pathogenesis of MG, it remains unclear why some patients with thymoma develop MG and others do not. In this study, we conducted a comparative phenotype analysis of thymocytes in type B thymomas in patients with MG (MG (+) thymomas) and without MG (MG (-) thymomas) via fluorescence-activated cell sorting (FACS). Our results show that the developmental stages defined by the expression of CD3, CD4, and CD8 were largely maintained in both MG (+) and MG (-) thymomas, with CD4+CD8+ cells constituting the majority of thymocytes in type B thymoma, and no significant difference between this cell population was observed in MG (+) and MG (-) thymomas.We discovered that CD4+CD8+ thymocytes in MG (+) thymomas expressed low levels of αß TCR and high levels of IL-7 receptor α (IL-7Rα), whereas in MG (-) thymomas, CD4+CD8+ thymocytes exhibited the opposite pattern of αß TCR and IL-7Rα expression. These results suggest that the positive and negative selection processes of CD4+CD8+ thymocytes might differ between MG (+) thymomas and MG (-) thymomas. The expression of the Helios transcription factor is induced during negative selection and marks a group of T cells that have undergone negative selection and are likely to be deleted due to strong TCR binding with self-peptides/MHC ligands. We observed that the percentage of Helios-positive CD4SP T cells was greater in MG (-) than in MG (+) thymomas. Thus, the differentially regulated selection process of CD4+CD8+ thymocytes, which involves TCR and IL-7/IL-7Rα signaling, is associated with the presence of MG in type B thymomas.


Myasthenia Gravis , Receptors, Antigen, T-Cell, alpha-beta , Thymocytes , Thymoma , Humans , Thymoma/immunology , Thymoma/pathology , Thymoma/metabolism , Myasthenia Gravis/immunology , Myasthenia Gravis/pathology , Myasthenia Gravis/metabolism , Receptors, Antigen, T-Cell, alpha-beta/metabolism , Male , Thymocytes/immunology , Thymocytes/metabolism , Female , Middle Aged , Receptors, Interleukin-7/metabolism , Receptors, Interleukin-7/immunology , Adult , Aged , Thymus Neoplasms/immunology , Thymus Neoplasms/pathology , Thymus Neoplasms/metabolism , CD4-Positive T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/metabolism , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/metabolism , Immunophenotyping
2.
BMC Surg ; 23(1): 367, 2023 Dec 08.
Article En | MEDLINE | ID: mdl-38066463

BACKGROUND: The object was to compare changes in patients undergoing lung surgery before and after COVID-19 outbreak, and to explore the impact of COVID-19 on lung surgery and its coping strategies. METHOD: A retrospective review of patients undergoing thoracic surgery at a single institution was conducted. Group A included patients treated between January 23, 2019, and January 23, 2020, while Group B included patients treated between June 1, 2020, and June 1, 2021, at our center. We compared the reasons of seeking medical treatment, the general characteristics of patients, imaging features, pathological features, surgical methods and postoperative recovery. RESULT: Compared to Group A, the number of patients with pulmonary nodules screened by routine check-up increased in Group B (57.6% vs 46.9%, p < 0.05). Female patient increased (55.2%vs 44.7%). Patient without smoking history or with family history of lung cancer increased (70.7% vs 60.7%) (10.1%vs 7.8%). Early stage lung cancer increased. Lobectomy decreased (53.4% vs 64.1%). Segmental resection increased (33.3% vs 12.7%). Patients without postoperative comorbidities increased (96.1%vs 85.7%). In the case of patients with Ground Glass Opacity(GGO), their age was comparatively lower (52 ± 9.9 vs. 55 ± 10.7), the female patients increased, patient without smoking history, tumor history, family history of tumor increased, small GGO increased. Lobectomy decreased (35.2% vs 49.7%). Segmental resection increased (49.6% vs 21.2%). Patients without postoperative comorbidities increased (96.5% vs 87.4%). CONCLUSION: Since COVID-19 outbreak, more young, non-smoking, female lung cancers, more Ground Glass Opacity, none high risk patients have been detected through screening, suggesting that our current screening criteria for lung cancer may need to be revised. Higher requirements, including the selection of the timing of nodular surgery, surgical methods were put forward for thoracic surgeons' skills.


COVID-19 , Lung Neoplasms , Female , Humans , China/epidemiology , COVID-19/epidemiology , Early Detection of Cancer/methods , Lung Neoplasms/diagnosis , Lung Neoplasms/epidemiology , Lung Neoplasms/surgery , Retrospective Studies , Tomography, X-Ray Computed/methods , Male , Adult , Middle Aged , Aged
3.
Curr Med Chem ; 2023 May 25.
Article En | MEDLINE | ID: mdl-37231753

INTRODUCTION: SETD1A is upregulated in non-small cell lung cancer (NSCLC) tissues. This study investigated the molecular mechanism of the SETD1A/WTAPP1/WTAP axis in NSCLC. METHODS: Ferroptosis is a unique cell death mode driven by iron-reliant phospholipid peroxidation, which is regulated by multiple cellular metabolic pathways, including REDOX homeostasis, iron metabolism, mitochondrial activity and metabolism of amino acids, lipids and sugars. Thus, the levels of ferroptosis markers (MDA, SOD, GSH) were measured in vitro, and NSCLC cell behaviors were assessed. SETD1A-mediated H3K4me3 methylation was analyzed. SETD1A-exerted effects on ferroptosis and tumor growth in vivo were verified in nude mouse models. RESULTS: SETD1A was highly expressed in NSCLC cells. Silencing SETD1A suppressed NSCLC cell proliferation and migration, inhibited MDA, and enhanced GPX4, SOD, and GSH levels. SETD1A elevated WTAP expression through WTAPP1 upregulation by mediating H3K4me3 methylation in the WTAPP1 promoter region. WTAPP1 overexpression partly averted the promotional effect of silencing SETD1A on NSCLC cell ferroptosis. WTAP interference abrogated the inhibitory effects of WTAPP1 on NSCLC cell ferroptosis. Silencing SETD1A facilitated ferroptosis and accelerated tumor growth in nude mice through the WTAPP1/WTAP axis. CONCLUSION: SETD1A amplified WTAP expression through WTAPP1 upregulation by mediating H3K4me3 modification in the WTAPP1 promoter region, thus promoting NSCLC cell proliferation and migration and inhibiting ferroptosis.

4.
Cancer Gene Ther ; 29(11): 1761-1772, 2022 11.
Article En | MEDLINE | ID: mdl-35821283

GSK3B is the mRNA form of glycogen synthase kinase 3 beta (GSK-3ß), which is a critical repressor of Wnt/ß-catenin signaling pathway and generally inhibited in cancer cells. Plenty of researches have disclosed that circular RNAs, namely circRNAs exert important functions in the progression of various human malignancies including lung adenocarcinoma (LUAD). Therefore, we attempted to explore whether there existed certain circRNAs that could mediate LUAD development by regulating GSK3B expression and Wnt/ß-catenin pathway. In the present research, circ-GSK3B (hsa_circ_0066903) was found to be significantly down-regulated in LUAD tissues and cells and it suppressed the proliferation, migration and stemness of LUAD cells. Furthermore, it was discovered that circ-GSK3B competitively sponged miR-3681-3p and miR-3909 to elevate GSK3B expression. Circ-GSK3B could impair the binding ability of FKBP51 to GSK-3ß to inhibit the phosphorylation of GSK-3ßS9, resulting in the inactivation of Wnt/ß-catenin signaling. In addition, the regulatory effect of circ-GSK3B on LUAD tumorigenesis and cell progression was testified through in vitro and in vivo rescue experiments. In conclusion, circ-GSK3B suppressed LUAD development through up-regulating and activating GSK3B.


Adenocarcinoma of Lung , Lung Neoplasms , MicroRNAs , Humans , RNA, Circular/genetics , beta Catenin/genetics , Glycogen Synthase Kinase 3 beta/genetics , Glycogen Synthase Kinase 3 beta/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Gene Expression Regulation, Neoplastic , Cell Proliferation/genetics , Cell Line, Tumor , Adenocarcinoma of Lung/genetics , Adenocarcinoma of Lung/metabolism , Adenocarcinoma of Lung/pathology , Lung Neoplasms/pathology
5.
Biosci Rep ; 40(6)2020 06 26.
Article En | MEDLINE | ID: mdl-32530032

A homogeneous polysaccharide (GLP), with an average molecular weight of 4.44 × 104 Da, was isolated and purified from the fruiting bodies of Ganoderma lucidum. In this work, we examined the antitumor activities of GLP using a mouse Lewis lung cancer (LLC) model and explored possible molecular pathways involved in its immunomodulatory mechanism on tumor-host interaction. GLP administration (25 and 100 mg/kg) significantly inhibited tumor growth, as evidenced by the decreased tumor volume and tumor weight, as well as histological features of tumor tissues with concomitant down-regulation of proliferating cell nuclear antigen (PCNA) proliferative marker. Less myeloid-derived suppressor cells (MDSCs) were accumulated in both spleen and tumor tissues from GLP-treated mice. In contrast, the percentage of CD4+ and CD8+ T cells together with the production of Th1-type cytokines (IFN-γ and IL-12) was increased in the spleen of LLC-bearing mice following GLP administration. Furthermore, GLP administration reversed the attenuated expression of CARD9, p-Syk and p-p65, and increased indoleamine 2,3-dioxygenase (IDO) protein expression in MDSCs of LLC-bearing mice. Collectively, our data demonstrated the first time that GLP induced the differentiation of MDSCs and inhibited the accumulation of MDSCs via CARD9-NF-κB-IDO pathway, thus prevented lung cancer development.


Antineoplastic Agents/pharmacology , CARD Signaling Adaptor Proteins/metabolism , Carcinoma, Lewis Lung/drug therapy , Cell Differentiation/drug effects , Fungal Polysaccharides/pharmacology , Indoleamine-Pyrrole 2,3,-Dioxygenase/metabolism , Myeloid-Derived Suppressor Cells/drug effects , Reishi , Animals , Antineoplastic Agents/isolation & purification , Carcinoma, Lewis Lung/enzymology , Carcinoma, Lewis Lung/immunology , Carcinoma, Lewis Lung/pathology , Cell Line, Tumor , Fruiting Bodies, Fungal , Fungal Polysaccharides/isolation & purification , Male , Mice, Inbred C57BL , Myeloid-Derived Suppressor Cells/enzymology , Myeloid-Derived Suppressor Cells/immunology , NF-kappa B/metabolism , Reishi/chemistry , Signal Transduction , Tumor Burden/drug effects , Tumor Microenvironment
6.
J BUON ; 24(1): 273-279, 2019.
Article En | MEDLINE | ID: mdl-30941980

PURPOSE: To investigate the role of microRNA-122-5p in the pathogenesis of non-small cell lung cancer (NSCLC) and its underlying mechanism. METHODS: A total of 72 pairs of NSCLC tissues and paracancerous tissues were collected. The expression level of microRNA-122-5p in NSCLC tissues and paracancerous tissues were detected by qRT-PCR (quantitative real-time polymerase chain reaction). The relationship between microRNA-122-5p expression and the clinical prognosis of NSCLC patients was then analyzed. Bioinformatics prediction and luciferase activity assay were performed to validate the direct binding of microRNA-122-5p and p53. Cell cycle, proliferation, and apoptosis were detected after microRNA-122-5p knockdown in NSCLC cells. The regulatory effect of microRNA-122-5p on promoting NSCLC development was detected by Western blot. RESULTS: MicroRNA-122-5p was more overexpressed in NSCLC tissues than in paracancerous tissues. MicroRNA-122-5p expression was negatively correlated with survival rate of NSCLC patients. Besides, microRNA-122-5p knockdown remarkably inhibited the proliferation and cell cycle advancement and increased apoptosis of NSCLC cells. Luciferase reporter gene assay and Western blot results indicated that microRNA-122-5p downregulated p53 and activated PI3K-AKT pathway, thereby promoting NSCLC development. CONCLUSION: MicroRNA-122-5p is overexpressed in NSCLC. Overexpression of microRNA-122-5p promotes NSCLC development by downregulating p53 and activating PI3K-AKT pathway.


Carcinoma, Non-Small-Cell Lung/pathology , Gene Expression Regulation, Neoplastic , Lung Neoplasms/pathology , MicroRNAs/genetics , Phosphatidylinositol 3-Kinases/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Tumor Suppressor Protein p53/metabolism , Apoptosis , Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/metabolism , Case-Control Studies , Cell Movement , Cell Proliferation , Female , Humans , Lung Neoplasms/genetics , Lung Neoplasms/metabolism , Male , Middle Aged , Phosphatidylinositol 3-Kinases/genetics , Prognosis , Proto-Oncogene Proteins c-akt/genetics , Signal Transduction , Tumor Cells, Cultured , Tumor Suppressor Protein p53/genetics
7.
Saudi J Biol Sci ; 26(8): 2037-2042, 2019 Dec.
Article En | MEDLINE | ID: mdl-31889790

The purpose of this study was to explore the internal mechanism of lung cancer under the action of caspase recruitment domain-containing protein 9 (CARD9) and immunosuppressive cells myeloid-derived suppressor cells (MDSCs) in the Lewis lung cancer mice model. In this research, mice were selected as research objects, and the mechanism of CARD9 and immunosuppressive cells MDSCs in lung cancer was studied by experimental methods such as mRNA expression level, HE staining of tumor cells, and electron microscopy. The results showed that CARD9 regulated lung cancer by controlling the working state of immunosuppressive cells MDSCs and its downstream product indoleamine 2, 3-dioxygenase (IDO). The study confirmed the tumor regulatory mechanism of CARD9-MDSCs-NF-KB-IDO in MDSCs under tumor environment. In summary, the mechanism of CARD9 and immunosuppressive cells MDSCs in lung cancer was to achieve the goal of tumor control through the control of downstream product IDO. There are still some shortcomings in the research process, but the research results still provide some guidance for future research. Therefore, it is a research topic with practical significance.

8.
Biochem Biophys Res Commun ; 495(4): 2482-2489, 2018 01 22.
Article En | MEDLINE | ID: mdl-29269300

Tyrosine kinase inhibitors (TKIs) exert potent therapeutic efficacy in non-small cell lung cancers (NSCLC) harboring epidermal growth factor receptor (EGFR) activating mutations. However, a major impediment for the effective treatment is the development of drug resistance. Some evidence supports a role for miRNAs in modulating NSCLC TKIs resistance. Here we show that miR-181a is significantly up-regulated in gefitinib-resistant cells compared with gefitinib-sensitive cells. Upregulation of miR-181a caused resistance of gefitinib, whereas downregulation of miR-181a sensitized NSCLC cells to gefitinib. Furthermore, the miR-181a plasma levels were significantly increased in acquired gefitinib resistant NSCLC patients compared with the plasma levels prior to gefitinib treatment in each patient. Bioinformatics analysis and luciferase reporter assay showed that growth arrest-specific 7 (GAS7) was a direct target gene of miR-181a. A significant inverse correlation between the expression of miR-181a and GAS7 was identified in NSCLC tissues. Downregulation of GAS7 expression could antagonize gefitinib re-sensitivity in PC9GR mediated by knockdown of miR-181a via AKT/ERK pathways and epithelial-to-mesenchymal transition markers. Additionally, GAS7 expression was downregulated in a large cohort of NSCLC patients, and a high mRNA level of GAS7 was associated with improved overall survival. Collectively, our findings provide a novel basis for using miR-181a/GAS7-based therapeutic strategies to reverse gefitinib resistance in NSCLC.


Drug Resistance, Neoplasm , Lung Neoplasms/drug therapy , Lung Neoplasms/metabolism , MicroRNAs/metabolism , Nerve Tissue Proteins/metabolism , Quinazolines/therapeutic use , Biomarkers, Tumor/metabolism , China/epidemiology , Female , Gefitinib , Humans , Lung Neoplasms/mortality , Male , Protein Kinase Inhibitors/toxicity , Risk Factors , Survival Rate
9.
Chem Commun (Camb) ; 52(92): 13452-13455, 2016 Nov 10.
Article En | MEDLINE | ID: mdl-27757456

Vitamin B9 gels were found to be pH-switchable by adding triethylamine or acetic acid. Such recyclable gels can be used as novel co-crystallization media, resulting in four stoichiometric vitamin C co-crystals. Under highly supersaturated conditions, uniform microspheres of (VC)·(NA) with different particle sizes were obtained through a spherical crystallization process.

10.
Interact Cardiovasc Thorac Surg ; 19(4): 644-9, 2014 Oct.
Article En | MEDLINE | ID: mdl-25009308

OBJECTIVES: Lung-preserving surgery was proved to be effective and safe to treat patients with benign bronchial strictures. However, this surgical treatment has been rarely reported in patients with complete occlusion in the left main bronchus. The aim of this study was to assess the value of this procedure and report our experience in the treatment of these patients with left atelectasis caused by inflammatory bronchial occlusion. METHODS: We reviewed and analysed the medical records of 8 patients who had undergone left main bronchus sleeve resection for symptomatic left atelectasis caused by inflammatory bronchial occlusion from May 2007 to April 2011. RESULTS: Eight patients (3 men and 5 women) with a medical history of active pulmonary tuberculosis were involved in this study. The median age was 23 years. Parenchyma-sparing left main bronchus resection was performed in 4 patients, 1 of whom received partial wedge resection in the lingual lobe. Left main bronchus sleeve resection plus superior lobectomy was performed in 2 patients and left main bronchus sleeve resection plus left inferior lobectomy in 2 patients, 1 of whom received additional partial wedge resection of the lingual lobe. The procedure was completed successfully in all 8 patients without postoperative deaths. The mean follow-up time was 49.3 months, ranging from 23 to 69 months. No major complications, including stenosis and atelectasis, were observed during the follow-up period. The symptoms of pulmonary atelectasis disappeared and pulmonary ventilation function improved significantly. CONCLUSIONS: In symptomatic patients with left atelectasis caused by inflammatory bronchial occlusion, lung-preserving surgery is an effective and safe surgical treatment.


Airway Obstruction/surgery , Bronchitis/complications , Organ Sparing Treatments/methods , Pneumonectomy/methods , Pulmonary Atelectasis/surgery , Adolescent , Adult , Airway Obstruction/diagnosis , Airway Obstruction/etiology , Airway Obstruction/physiopathology , Bronchitis/diagnosis , Bronchitis/physiopathology , Bronchoscopy , Constriction, Pathologic , Female , Forced Expiratory Volume , Humans , Male , Pulmonary Atelectasis/diagnosis , Pulmonary Atelectasis/etiology , Pulmonary Atelectasis/physiopathology , Pulmonary Ventilation , Recovery of Function , Retrospective Studies , Time Factors , Tomography, X-Ray Computed , Total Lung Capacity , Treatment Outcome , Young Adult
11.
PLoS One ; 9(5): e97607, 2014.
Article En | MEDLINE | ID: mdl-24836450

Mono-(2-ethylhexyl) phthalate (MEHP), the active metabolite of di-(2-ethylhexyl) phthalate (DEHP), is a widespread environmental contaminant and has been proved to have potential adverse effects on the reproductive system, carcinogenicity, liver, kidney and developmental toxicities. However, the effect of MEHP on vascular system remains unclear. The main purpose of this study was to evaluate the cytotoxic effects of MEHP on human umbilical endothelial cells (HUVEC) and its possible molecular mechanism. HUVEC cells were treated with MEHP (0, 6.25, 12.5, 25,50 and 100 µM), and the cellular apoptosis and mitochondrial membrane potential as well as intracellular reactive oxygen species were determined. In present study, MEHP induced a dose-dependent cell injury in HUVEC cell via an apoptosis pathway as characterized by increased percentage of sub-G1, activation of caspase-3, -8 and -9, and increased ratio of Bax/bcl-2 mRNA and protein expression as well as cytochrome C releasing. In addition, there was obvious oxidative stress, represented by decreased glutathione level, increased malondialdehyde level and superoxide dismutase activity. N-Acetylcysteine, as an antioxidant that is a direct reactive oxygen species scavenger, could effectively block MEHP-induced reactive oxygen species generation, mitochondrial membrane potential loss and cell apoptosis. These data indicated that MEHP induced apoptosis in HUVEC cells through a reactive oxygen species-mediated mitochondria-dependent pathway.


Diethylhexyl Phthalate/analogs & derivatives , Environmental Pollutants/toxicity , Human Umbilical Vein Endothelial Cells/drug effects , Acetylcysteine/pharmacology , Antioxidants/pharmacology , Apoptosis/drug effects , Apoptosis Regulatory Proteins/metabolism , Caspases/metabolism , Cell Survival/drug effects , Cells, Cultured , Cytochromes c/biosynthesis , Diethylhexyl Phthalate/toxicity , Glutathione/metabolism , Humans , Malondialdehyde/metabolism , Membrane Potential, Mitochondrial/drug effects , Reactive Oxygen Species/metabolism , Signal Transduction/drug effects , Superoxide Dismutase/metabolism
12.
Biochem Biophys Res Commun ; 446(1): 179-86, 2014 Mar 28.
Article En | MEDLINE | ID: mdl-24582749

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR TKIs) such as gefitinib are clinically effective treatments for non-small cell lung cancer (NSCLC) patients with EGFR activating mutations. However, therapeutic effect is ultimately limited by the development of acquired TKI resistance. MicroRNAs (miRNAs) represent a category of small non-coding RNAs commonly deregulated in human malignancies. The aim of this study was to investigate the role of miRNAs in gefitinib resistance. We established a gefitinib-resistant cell model (PC9GR) by continually exposing PC9 NSCLC cells to gefitinib for 6 months. MiRNA microarray screening revealed miR-138-5p showed the greatest downregulation in PC9GR cells. Re-expression of miR-138-5p was sufficient to sensitize PC9GR cells and another gefitinib-resistant NSCLC cell line, H1975, to gefitinib. Bioinformatics analysis and luciferase reporter assay showed that G protein-coupled receptor124 (GPR124) was a direct target of miR-138-5p. Experimental validation demonstrated that expression of GPR124 was suppressed by miR-138-5p on protein and mRNA levels in NSCLC cells. Furthermore, we observed an inverse correlation between the expression of miR-138-5p and GPR124 in lung adenocarcinoma specimens. Knockdown of GPR124 mimicked the effects of miR-138-5p on the sensitivity to gefitinib. Collectively, our results suggest that downregulation of miR-138-5p contributes to gefitinib resistance and that restoration of miR-138-5p or inhibition GPR124 might serve as potential therapeutic approach for overcoming NSCLC gefitinib resistance.


Carcinoma, Non-Small-Cell Lung/genetics , Carcinoma, Non-Small-Cell Lung/metabolism , Lung Neoplasms/genetics , Lung Neoplasms/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Quinazolines/pharmacology , Receptors, G-Protein-Coupled/genetics , Receptors, G-Protein-Coupled/metabolism , Adenocarcinoma/drug therapy , Adenocarcinoma/genetics , Adenocarcinoma/metabolism , Adenocarcinoma of Lung , Antineoplastic Agents/pharmacology , Carcinoma, Non-Small-Cell Lung/drug therapy , Cell Line, Tumor , Down-Regulation , Drug Resistance, Neoplasm/genetics , Drug Resistance, Neoplasm/physiology , Gefitinib , Gene Knockdown Techniques , Humans , Lung Neoplasms/drug therapy , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism , Receptors, G-Protein-Coupled/antagonists & inhibitors
13.
Biomacromolecules ; 7(8): 2443-8, 2006 Aug.
Article En | MEDLINE | ID: mdl-16903694

This paper presents a comparative study on the antifouling properties of poly(ethylene glycol) (PEG)-based polymer coatings prepared by surface-initiated polymerization (SIP). Three types of poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMEMA) polymer thin films of approximate 100 nm thickness were grafted from a catechol initiator that was immobilized on a Ti substrate. OEGMEMA monomers containing side chains of 4, 9, and 23 EG units were used in surface-initiated atom transfer radical polymerization (SI-ATRP) to form POEGMEMA-4, -9, and -23 polymer brushes. The chemical composition, thickness, and wettability of the polymer brushes were characterized by X-ray photoelectron spectroscopy (XPS), ellipsometry, and static water contact angle measurements, respectively. The dependence of antifouling performance on EG side chain length was systemically tested and compared by 3T3 fibroblast cell adhesion assays. Results from 4-h cell culture experiments revealed the complete absence of cell attachment on all the grafted Ti substrates. Excellent cell fouling resistance continued with little dependence on EG side chain length up to three weeks, after which long-term antifouling performance depended on the EG chain length as the grafted samples reached confluent cell coverage in 7, 10, and 11 weeks for POEGMEMA-4, -9, and -23, respectively.


Coated Materials, Biocompatible/chemistry , Materials Testing , Polyethylene Glycols/chemistry , Polymethacrylic Acids/chemistry , Titanium/chemistry , 3T3 Cells , Animals , Cell Adhesion , Mice , Time Factors
14.
J Am Chem Soc ; 127(45): 15843-7, 2005 Nov 16.
Article En | MEDLINE | ID: mdl-16277527

In this paper, we demonstrate the first use of a catecholic initiator for surface-initiated polymerization (SIP) from metal surfaces to create antifouling polymer coatings. A new bifunctional initiator inspired by mussel adhesive proteins was synthesized, which strongly adsorbs to Ti and 316L stainless steel (SS) substrates, providing an anchor for surface immobilization of grafted polymers. Surface-initiated atom transfer radical polymerization (SI-ATRP) was performed through the adsorbed biomimetic initiator to polymerize methyl methacrylate macromonomers with oligo(ethylene glycol) (OEG) side chains. X-ray photoelectron spectroscopy, surface FT-IR, and contact angle analysis confirmed the sequential grafting of initiator and polymer, and ellipsometry indicated the formation of polymer coatings of up to 100 nm thickness. Cell adhesion experiments performed with 3T3-Swiss albino fibroblasts showed substantially reduced cell adhesion onto polymer grafted Ti and 316L SS substrates as compared to the unmodified metals. Moreover, micropatterning of grafted polymer coatings on Ti surfaces was demonstrated by combining SI-ATRP and molecular assembly patterning by lift-off (MAPL), creating cell-adhesive and cell-resistant regions for potential use as cell arrays. Due to the ability of catechols to bind to a large variety of inorganic surfaces, this biomimetic anchoring strategy is expected to be a highly versatile tool for polymer thin film surface modification for biomedical and other applications.


Biomimetic Materials/chemistry , Catechols/chemistry , Metals/chemistry , Oxides/chemistry , Polymers/chemistry , Animals , Cell Adhesion , Mice , Spectroscopy, Fourier Transform Infrared , Surface Properties , Swiss 3T3 Cells , Titanium/chemistry
15.
Langmuir ; 21(6): 2537-44, 2005 Mar 15.
Article En | MEDLINE | ID: mdl-15752050

Various free radical surface initiated polymerization (SIP) conditions were investigated on clay nanoparticles coated with monocationic 2,2'-azobisisobutyronitrile (AIBN) type free radical initiators. Interesting differences in the mechanism of polymer nanocomposite product formation and the role of nanoparticle surface bound AIBN initiators were observed on three types of poly(methyl methacrylate) (PMMA) polymerization conditions: bulk, suspension, and solution. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) measurements confirmed the attachment of the initiator on the clay particles without decomposition of the azo group. XRD and transmission electron microscopy (TEM) showed that a well-dispersed structure was accomplished only by bulk and solution SIP. The suspension SIP product consisted of a partially exfoliated structure as shown by XRD and clay particle aggregate formation as shown by TEM. In general, the molecular weights (MWs) of the surface bound polymers were found to be lower than those of the free polymer. Using the same clay loading and initiator concentrations, we observed that relatively higher MW polymers were obtained from suspension and bulk polymerizations in contrast to solution method. However, the most interesting observation is that the surface bound polymers (on all three conditions) showed much narrower polydispersity compared to that of a typical AIBN type free radical polymerization.

16.
Colloids Surf B Biointerfaces ; 42(1): 29-43, 2005 Apr 25.
Article En | MEDLINE | ID: mdl-15784324

Biological events occurring at the implant-host interface, including protein adsorption are mainly influenced by surface properties of the implant. Titanium alloys, one of the most widely used implants, has shown good biocompatibility primarily through its surface oxide. In this study, a surface sol-gel process based on the surface reaction of metal alkoxides with a hydroxylated surface was used to prepare ultrathin titanium oxide (TiOx) coatings on silicon wafers. The oxide deposited on the surface was then modified by self-assembled monolayers (SAMs) of silanes with different functional groups. Interesting surface morphology trends and protein adhesion properties of the modified titanium oxide surfaces were observed as studied by non-specific protein binding of serum albumin. The surface properties were investigated systematically using water contact angle, ellipsometry, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) measurements. Results showed that the surface sol-gel process predominantly formed homogeneous, but rough and porous titanium oxide layers. The protein adsorption was dependent primarily on the silane chemistry, packing of the alkyl chains (extent of van der Waals interaction), morphology (porosity and roughness), and wettability of the sol-gel oxide. Comparison was made with a thermally evaporated TiOx-Ti/Si-wafer substrate (control). This method further extends the functionalization of surface sol-gel derived TiOx layers for possible titanium alloy bioimplant surface modification.


Biocompatible Materials/chemistry , Phase Transition , Proteins/chemistry , Titanium/chemistry , Adsorption , Alloys , Binding Sites , Implants, Experimental , Microscopy, Atomic Force , Refractometry , Spectrometry, X-Ray Emission , Surface Properties , Water/chemistry
17.
J Am Chem Soc ; 126(28): 8735-43, 2004 Jul 21.
Article En | MEDLINE | ID: mdl-15250726

We report the synthesis and characterization of dendritic thiophene derivatives with their unique supramolecular assembly into 2-D crystals, nanowires, and nanoparticle aggregates. The structure and size of the dendrons and dendrimers have been confirmed with various techniques, such as NMR, SEC, and MALDI-TOF-MS. The mass values were consistent with the mass observed by MALDI-TOF-MS, whereas SEC measurements also gave useful information on the hydrodynamic volume of the individual dendrimers. The interesting electrooptical properties were highlighted by very broad absorption spectra and narrower fluorescence consistent with their electrochemical behavior. The self-organization of the dendrimers on the solid substrate is dependent on the nature of the substrate, preparation methods, and the molecule-molecule and molecule-substrate interactions. Thus, 14T-1 and 30T both formed globular aggregates on mica surface, while 14T-1 also formed nanowires on graphite surface. On the other hand, the larger 30T was observed to form 2-D crystalline structures. By varying the alkyl chain length attached to 14T-1, we were also able to obtain 2-D crystals on graphite. This showed that the different symmetry of packing for 30T and 14T-1 is also dependent on several factors, such as the molecular shape, size, and the presence of noncovalent intermolecular interactions. The results demonstrated the unique ability of thiophene dendrimers to form nanostructures on surfaces.

18.
Org Lett ; 4(12): 2067-70, 2002 Jun 13.
Article En | MEDLINE | ID: mdl-12049519

[structure: see text] Thiophene dendrons and dendrimers were designed and synthesized using a convergent approach. Metal-mediated coupling reactions were used in the synthesis. A rational approach allowed the formation of alphaalpha, betabeta, and alphabeta linkages between the dendrons and thiophene units.

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