Prediction of response to promising first-line chemotherapy in ovarian cancer patients with residual peritoneal tumors: practical biomarkers and robust multiplex models.

BACKGROUND: Platinum/taxane (TC) chemotherapy with debulking surgery stays the mainstay of the treatment in ovarian cancer patients with peritoneal metastasis, and recently its novel modality, intraperitoneal carboplatin with dose-dense paclitaxel (ddTCip), was shown to have greater therapeutic impact. Nevertheless, the response varies among patients and consequent recurrence, or relapse often occurs. Discovery of therapeutic response predictor to ddTCip and/or TC therapy is eagerly awaited to improve the treatment outcome. METHODS: Using datasets in 76 participants in our ddTCip study and published databases on patients received TC therapy, we first validated a total of 75 previously suggested markers, sought out more active biomarkers through the association analyses of genome-wide transcriptome and genotyping data with progression-free survival (PFS) and adverse events, and then developed multiplex statistical prediction models for PFS and toxicity by mainly using multiple regression analysis and the classification and regression tree (CART) algorithm. RESULTS: The association analyses revealed that SPINK1 could be a possible biomarker of ddTCip efficacy, while ABCB1 rs1045642 and ERCC1 rs11615 would be a predictor of hematologic toxicity and peripheral neuropathy, respectively. Multiple regression analyses and CART algorithm finally provided a potent efficacy prediction model using 5 gene expression data and robust multiplex toxicity prediction models-CART models using a total of 4 genotype combinations and multiple regression models using 15 polymorphisms on 12 genes. CONCLUSION: Biomarkers and multiplex models composed here could work well in the response prediction of ddTCip and/or TC therapy, which might contribute to realize optimal selection of the key therapy.

Synthesis of 2,8-Dioxabicyclo[3.3.1]nonane Derivatives and Their Neuroprotective Activities.

Twenty natural-product-like 2,8-dioxabicyclo[3.3.1]nonane derivatives were synthesized and their neuroprotective activities were tested using human monoamine oxidases (MAO) A and B and acetyl and butyryl cholinesterases (ChE). Compound 1s showed inhibitory activity for MAO-A, MAO-B and acetylcholinesterase (AChE) (IC50 values 34.0, 2.3 and 11.0 µM, respectively). The inhibition mode of (-)-1s for MAO-B was investigated. Chiral HPLC of (±)-1s separated the enantiomers and (-)-1s showed MAO-B inhibitory activity. Molecular docking simulation of (-)-1s and MAO-B revealed the binding mode.

A Tricyclic Aromatic Polyketide Isolated from the Marine-Derived Fungus Curvularia aeria.

A novel tricyclic polyketide, curvulanone (1), was isolated from the marine-derived fungus Curvularia aeria. The structure of 1 was determined by NMR and single-crystal X-ray crystallography. 1 had a cyclopentabenzopyranone with 3-acetic acid structure that is rarely found in natural compounds. Monoamine oxidase and sirtuin 1 inhibitory test was exhibited and 1 showed their inhibitory activity.

Stepwise Functionalization of Single-Walled Carbon Nanotubes with Subsequent Molecular Conversion to Control Photoluminescence Properties.

Functionalization of single-walled carbon nanotubes (SWCNTs) has attracted interest because it alters the near-infrared (NIR) photoluminescence (PL) wavelength and emission efficiency. These modifications depend on the binding configuration and degree of functionalization. Excessive functionalization reduces the emission efficiency as the integrity of the conjugated π system decreases; thus, controlling the degree of functionalization is essential. Because the binding configurations and degree of functionalization are affected by the reagent structure, a stepwise approach combining SWCNTs functionalization and subsequent reactions to introduce functional groups into the addenda could effectively control their PL properties and functionalities. We studied this approach by implementing the reductive alkylation of SWCNTs by using bromoalkanes with t-butyl carbamate (Boc)-protected amino groups and subsequent deprotection and amidation reactions. The reaction products were analyzed based on absorption, PL, and Raman spectroscopy and the Kaiser test. Depending on the structure of the reagent, deprotection and amidation reactions competed with the elimination reaction of addenda, altering the PL properties of the SWCNTs. Furthermore, the elimination reaction was inhibited in the adducts functionalized using dibromoalkane with Boc-protected amino groups, demonstrating that the use of appropriate reagents enables the molecular conversion of the functional groups of SWCNT adducts without affecting their PL properties.

Synthesis and Conformational Analysis of Fullerene Torsion Balances for Assessing the Contribution of Dispersion and Anionic Character in Non-Covalent Arene-Fullerene Interactions.

We employ a molecular torsion balance displaying bifurcated conformational isomerism to quantitatively evaluate the non-covalent interactions between the fullerene surface and substituted arene moieties containing elements with high atomic numbers, as well as the thermodynamic processes involved in the folding equilibrium using nuclear magnetic resonance spectroscopy. The interaction between fullerene and haloaryl groups was stronger in cases where the introduced halogen had a higher atomic number, indicating that dispersion forces play a significant role in the interaction between fullerenes and 4-haloaryl groups. The dispersion term also significantly contributed to the interaction between fullerene and the 4-mercaptophenyl group. Moreover, the addition of an appropriate base to the 4-mercaptophenyl-appended torsion balance formed the corresponding thiophenolate anion, resulting in a large negative change in the folding free energy in CDCl3 . Detailed analysis suggested that the observed attractive anionic arene-fullerene interactions predominantly originated from solvation effects.

Neoadjuvant chemotherapy followed by interval debulking surgery for advanced epithelial ovarian cancer: GOTIC-019 study.

INTRODUCTION: Three randomized controlled trials have resulted in extremely extensive application of the strategy of using neoadjuvant chemotherapy (NAC) followed by interval debulking surgery (IDS) for patients with advanced epithelial ovarian cancer in Japan. This study aimed to evaluate the status and effectiveness of treatment strategies using NAC followed by IDS in Japanese clinical practice. PATIENTS AND METHODS: We conducted a multi-institutional observational study of 940 women with Federation of Gynecology and Obstetrics (FIGO) stages III-IV epithelial ovarian cancer treated at one of nine centers between 2010 and 2015. Progression-free survival (PFS) and overall survival (OS) were compared between 486 propensity-score matched participants who underwent NAC followed by IDS and primary debulking surgery (PDS) followed by adjuvant chemotherapy. RESULTS: Patients with FIGO stage IIIC receiving NAC had a shorter OS (median OS: 48.1 vs. 68.2 months, hazard ratio [HR]: 1.34; 95% confidence interval [CI] 0.99-1.82, p = 0.06) but not PFS (median PFS: 19.7 vs. 19.4 months, HR: 1.02; 95% CI: 0.80-1.31, p = 0.88). However, patients with FIGO stage IV receiving NAC and PDS had comparable PFS (median PFS: 16.6 vs. 14.7 months, HR: 1.07 95% CI: 0.74-1.53, p = 0.73) and OS (median PFS: 45.2 vs. 35.7 months, HR: 0.98; 95% CI: 0.65-1.47, p = 0.93). CONCLUSIONS: NAC followed by IDS did not improve survival. In patients with FIGO stage IIIC, NAC may be associated with a shorter OS.

Evaluation of the feasibility of human papillomavirus sponge-type self-sampling device at Japanese colposcopy clinics.

AIM: Self-sampling human papillomavirus (HPV) testing has been introduced for cervical cancer screening worldwide. In Japan, there are two types (brush and sponge) of HPV self-sampling devices. However, the recommended type for cervical cancer screening remains unclear. This study aimed to evaluate the feasibility of the HPV self-sampling device-sponge type (HSD-ST). Additionally, we aimed to examine the positive rate (sensitivity) for cervical intraepithelial neoplasia (CIN) 2 or worse using the HSD-ST. Finally, we aimed to perform a questionnaire survey regarding the usability of the HSD-ST. METHODS: We included 165 women who underwent HPV testing at one of three gynecologic clinics. First, the women used the HSD-ST and completed a questionnaire regarding its usability. Subsequently, they underwent physician-sampling HPV testing and cytology. We examined the agreement rate of HPV positivity between self- and physician-sampling HPV testing. RESULTS: The HPV-positive rates of self- and physician-collected samples were 59.4% and 62.4%, respectively, with an overall concordance rate of 88.5% and a calculated kappa coefficient of 0.76, indicating high concordance. Moreover, the positive (sensitivity) rates for CIN2 or worse were 81.4% and 89.8% in the self- and physician-collected samples, respectively. CONCLUSIONS: Our findings demonstrated the feasibility and usability of the HSD-ST.

Controlling the reactivity of La@C82 by reduction: reaction of the La@C82 anion with alkyl halide with high regioselectivity.

Endohedral metallofullerenes have excellent redox properties, which can be used to vary their reactivity to certain classes of molecules, such as alkyl halides. In this study, the thermal reaction of the La@C2v-C82 anion with benzyl bromide derivatives 1 at 110 °C afforded single-bonded adducts 2-5 with high regioselectivity. The products were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and visible-near infrared spectroscopy. The reaction of La@C2v-C82 with alkyl halides using the same conditions showed no consumption of La@C2v-C82, indicating that the reactivity of La@C2v-C82 toward alkyl halides was effectively increased by one-electron reduction. Single-crystal X-ray diffraction analysis of the single-bonded adduct 3a revealed the addition site of the p-methoxybenzyl group on La@C2v-C82. Theoretical calculations indicated that the addition site carbons in neutral La@C2v-C82 have high spin density, whereas those in the La@C2v-C82 anion do not have high charge densities. Thus, the reaction is believed to occur via electron transfer, followed by the radical coupling of La@C2v-C82 and benzyl radicals, rather than by bimolecular nucleophilic substitution reaction of La@C2v-C82 anion with 1.

Understanding the Nature and Strength of Noncovalent Face-to-Face Arene-Fullerene Interactions.

Face-to-face noncovalent arene-fullerene interactions are important in several research fields such as synthetic chemistry, materials chemistry, and medicinal chemistry; however, their nature and strength are still poorly understood. In this study, we prepare a fullerene-based torsion balance containing thioanisole, phenol, naphthalene, azulene, and pyrene moieties as a unimolecular model system. Moreover, we compare the folding free energies between the folded and the unfolded conformers of a series of the molecular torsion balances to quantify noncovalent interactions between arenes and the fullerene surface. This work demonstrates that the contributions of polarizabilities, anionic charges, electronic dipole moments, and the number of arene rings to the interactions can be experimentally measured by analyzing the folding equilibrium of the molecular torsion balances.

Visible-Light-Induced Synthesis of 1,2,3,4-Tetrahydroquinolines through Formal [4+2] Cycloaddition of Acyclic α,ß-Unsaturated Amides and Imides with N,N-Dialkylanilines.

1,2,3,4-Tetrahydroquinolines should be applicable to the development of new pharmaceutical agents. A facile synthesis of 1,2,3,4-tetrahydroquinolines that is achieved by a photoinduced formal [4+2] cycloaddition reaction of acyclic α,ß-unsaturated amides and imides with N,N-dialkylanilines under visible-light irradiation, in which a new IrIII complex photosensitizer, a thiourea, and an oxidant act cooperatively in promoting the reaction, is reported. The photoreaction enables the synthesis of a wide variety of 1,2,3,4-tetrahydroquinolines, while controlling the trans/cis diastereoselectivity (>99:1) and constructing contiguous stereogenic centers. A chemoselective cleavage of an acyclic imide auxiliary is demonstrated.

Synthesis and antifungal activity of polycyclic pyridone derivatives with anti-hyphal and biofilm formation activity against Candida albicans.

Thirty-five pyridone derivatives were synthesized, with derivatization conducted on polycyclic pyridone scaffolds, including cis- or trans-oxydecalin and other cyclic structures, by domino-Knoevenagel-electrocyclic reactions. The anti-fungal activities of the synthesized compounds were tested against Candida albicans. Ten compounds inhibited hyphal formation without inhibiting growth. Pyridones with anti-hyphal formation activity (4c, 6d, 12a and 12c) were tested for their ability to inhibit biofilm formation. Compound 6d showed both anti-hyphal and biofilm inhibition activity.

Treatment-related leukemia after taxane and platinum therapy in gynecological cancer patients (Gynecologic Oncology Trial and Investigation Consortium 011).

AIM: To clarify incidence and clinical features of treatment-related leukemia (TRL) due to taxane/platinum therapy in gynecological cancer patients. METHODS: We conducted a retrospective study of gynecological cancer patients who were diagnosed at facilities participating in the Gynecologic Oncology Trial and Investigation Consortium and started only taxane/platinum therapy as chemotherapy between 2002 and 2006. RESULTS: The site of the primary lesion was the ovary in 124, endometrium in 37, and uterine cervix in 4. The regimen of chemotherapy was paclitaxel (T) + carboplatin (C) therapy in 134 and others in 31 patients. The cumulative incidence was 2.4% (4/165), and the incidence was 2.9/1,000 person-years. All four cases were acute myeloid leukemia. The average total doses of T and C in patients without TRL were 1,693 (SD 1,050) and 4,170 (SD 2,423) mg. For TRL patients, the total T and C doses were, respectively, 1,555 and 3,540 mg, 1,620 and 4,200 mg, 2,130 and 4,700 mg, 3,220 mg and 8,310 mg. The fourth patient received additional 2,415 mg of docetaxel and 2,155 mg of nedaplatin. The intervals from the primary chemotherapy to the onset of TRL were 27, 34, 67, and 114 months. Three patients had no evidence of ovarian cancer. Three patients died of TRL at 4 days, 5 months, and 11 months, one patient remained in remission at 25 months after diagnosis of TRL. CONCLUSION: Patients receiving taxane/platinum therapy should undergo long-term follow-up with attention to the development of TRL, even if the gynecologic malignant cancer is in remission.

Inclusion Complexes of Daidzein with Cyclodextrin-Based Metal-Organic Framework-1 Enhance Its Solubility and Antioxidant Capacity.

Daidzein, an aglycone-type isoflavone, is useful in the prevention of atherosclerotic cardiovascular diseases. However, the solubility of daidzein remains relatively low even with pharmaceutical interventions (e.g., γ-cyclodextrin inclusion complex). In the present study, daidzein-cyclodextrin-metal organic framework solid dispersion complexes were prepared by the solvent evaporation method. The physicochemical properties of the complex and its effect on the solubility of daidzein were evaluated. The enhancement effect of a cyclodextrin-metal organic framework on the antioxidant properties of daidzein was verified using a diphenyl-picrylhydrazyl radical scavenging test. Powder X-ray diffraction results showed that the characteristic diffraction peaks of daidzein and cyclodextrin-metal organic framework disappeared and new peaks (2θ = 7.1°, 16.5°) were observed. FT-IR measurements showed that the peak derived from the carbonyl group of daidzein shifted to the lower wavenumber. NOESY 1H-1H NMR showed cross peaks at the proton on the resorcinol side of daidzein and the proton (H-5, H-6) in a cyclodextrin-metal organic framework. Dissolution rate of daidzein at 5 min in distilled water was 0.06% for daidzein alone while the daidzein inclusion complex was about 100%. When fasted state simulated intestinal fluid was used, the dissolution rate of the daidzein complex was about 71% compared with that of daidzein alone (~ 3.0%) at 5 min. The daidzein inclusion complex improved the antioxidant capacity to ~ 1.3 times (17.8 µg/mL) compared to the IC50 of daidzein alone (22.9 µg/mL). Preparations of cyclodextrin-metal organic framework inclusion complexes will be a platform in developing pharmaceutical formulations to enhance the bioavailability and activity of drugs.

A phase 2 study of intraperitoneal carboplatin plus intravenous dose-dense paclitaxel in front-line treatment of suboptimal residual ovarian cancer.

BACKGROUND: We evaluated the efficacy of intraperitoneal (IP) carboplatin in combination with dose-dense paclitaxel (ddTCip) for suboptimal residual ovarian cancer. METHODS: This was a phase 2 study to evaluate ddTCip. Patients with stage II-IV ovarian carcinoma, who underwent primary cytoreductive surgery and had radiologically evaluable disease after surgery, were eligible to participate in this study. IP carboplatin (AUC = 6) was administered on day 1, and intravenous paclitaxel (80 mg/m2) was administered on days 1, 8 and 15. The primary endpoint was response rate. Secondary endpoints included progression-free survival (PFS), overall survival (OS) and safety. Interval- debulking surgery followed by the same regimen was allowed when indicated. RESULTS: A total of 117 patients were considered eligible for this study prior to surgery and temporarily registered. Of the 117 patients, 76 patients met the inclusion criteria and were enrolled in this study. Fifty-nine (83.1%) patients had objective clinical responses. Median PFS and OS were 18.3 and 55.5 months, respectively. Sixty-four (84.2%) patients had grade 3/4 neutropenia, 43 (56.5%) patients had anaemia and 17 (22.4%) patients had thrombocytopenia. Port-related adverse events occurred in nine (11.8%) patients. CONCLUSIONS: Front-line chemotherapy with ddTCip therapy appears safe and effective, even for patients with suboptimal residual ovarian cancer. TRIAL REGISTRATION: UMIN Clinical Trials Registry (ID: UMIN000001713) on February 16th, 2009.

A comparison of liquid-based and conventional cytology using data for cervical cancer screening from the Japan Cancer Society.

OBJECTIVE: Liquid-based cytology has replaced conventional cytology in cervical cancer screening in many countries. However, a detailed comparison of liquid-based cytology with conventional cytology has not been reported in Japan. Therefore, the aim of the study is to evaluate efficacy of liquid-based cytology in Japan. METHODS: We first evaluated the prevalence of use of liquid-based cytology and then examined the efficacy of liquid-based cytology and conventional cytology for detecting CIN and the rate of unsatisfactory specimens using data from cancer screening collected by the Japanese Cancer Society from FY2011 to FY2014. A Poisson regression model with random effects analyses was used to classify histological outcomes and unsatisfactory specimens using liquid-based cytology compared to conventional cytology. RESULTS: A total of 3 815 131 women were analyzed in the study. The rate of liquid-based cytology increased from approximately 8% in FY2011 to 37% in FY2014. Compared to conventional cytology, the detection rates with liquid-based cytology were significantly higher (1.42 times) for CIN1+ [detection rate ratio (DRR) = 1.42, 95% confidence interval (CI) 1.35-1.48, P < 0.001] and CIN2+ (DRR = 1.16, 95% CI 1.08-1.25, P < 0.001). Positive predictive value ratios of CIN1+ and CIN2+ were also significantly higher for liquid-based cytology than for conventional cytology. However, there was no significant difference between liquid-based cytology and conventional cytology for detection rates and positive predictive values of CIN3+ and cancer. The rate of unsatisfactory specimens was significantly lower with liquid-based cytology compared to conventional cytology (DRR = 0.07, 95% CI 0.05-0.09, P < 0.001). CONCLUSIONS: In order to avoid the unsatisfactory specimens in cervical cancer screening, the results of this study did indicate that liquid-based cytology was more useful than conventional cytology in practical standpoints.

Synthesis of Fullerene-Fluorene Dyads through the Platinum-Catalyzed Reactions of [60]Fullerene with 9-Ethynyl-9H-fluoren-9-yl Carboxylates.

The single-step regio- and stereoselective platinum-catalyzed reactions of [60]fullerene with a series of 9-ethynyl-9H-fluoren-9-yl carboxylates afforded fullerene-fluorene dyads in their [2 + 2] cycloaddition forms. The presented reactions represent the first examples of the use of easily accessible fluorenyl carboxylates as fluorenylideneallene precursors. In addition, the single-crystal X-ray structure of one of the dyads reveals a distorted cyclobutane ring. Furthermore, the dyad forms a layered structure with close-packed arrays of C60 spheres in its crystals.

New criteria for the omission of lymphadenectomy in endometrioid carcinoma.

OBJECTIVE: To establish new criteria for the omission of lymphadenectomy in patients with endometrioid carcinoma. METHODS: We retrospectively reviewed 185 cases of histologically confirmed endometrioid carcinoma by hysterectomy at Jichi Medical University Hospital between January 2006 and December 2011. We reviewed patient medical records to detect risk factors for lymph node metastasis to identify the optimum criteria for lymphadenectomy omission. RESULTS: Univariate analysis revealed risk factors for lymph node metastasis to be a large tumor size (volume index ≥40 cm³) (p<0.0001), tumor diameter >2 cm (p=0.0003), myometrial invasion ≥50% based on pre-operative MRI (p=0.0366), elevated serum CA125 (pre-menopausal value ≥70 U/mL, post-menopausal value ≥25 U/mL) (p=0.0004), and lymphadenopathy on pre-operative CT scans (p=0.0002). Multivariate analysis indicated that tumor volume index, tumor diameter, elevated serum CA125, and CT scans positive for lymphadenopathy were independent risk factors for lymph node metastasis. Thus, we set tumor diameter >2 cm, elevated serum CA125, and CT scans positive for lymphadenopathy as risk factors. In cases with no risk factors, the rate of lymph node metastasis was 2.1%, which rose to 8.9%, 30.4%, and 58.3% for those with one, two, and three risk factors, respectively. The rate of para-aortic lymph node metastasis rose from 0% to 2.5%, 10.9%, and 41.7% among those with zero, one, two, and three risk factors, respectively. CONCLUSIONS: We propose that lymphadenectomy can be omitted in cases of endometrioid carcinoma that do not have any of the following risk factors: tumor diameter >2 cm, elevated serum CA125, and a CT scan positive for lymphadenopathy. We believe that these new criteria will limit inter-institutional differences as they are all objective factors. Further, they are useful in predicting lymph node metastasis, including para-aortic lymph node metastasis, based on the number of risk factors present.

A phase II randomized controlled study of pegylated liposomal doxorubicin and carboplatin vs. gemcitabine and carboplatin for platinum-sensitive recurrent ovarian cancer (GOTIC003/intergroup study).

PURPOSE: To compare the efficacy, safety, and tolerability profiles of pegylated liposomal doxorubicin and carboplatin (PLDC) with those of gemcitabine and carboplatin (GC) for the treatment of patients with platinum-sensitive recurrent ovarian cancer. METHODS: Ovarian cancer patients with recurrence > 6 months after first-line platinum and taxane-based therapies were randomly assigned to PLDC [pegylated liposomal doxorubicin 30 mg/m2 plus carboplatin area under the curve (AUC) 5 mg/mL/min on day 1] every 4 weeks or GC (gemcitabine 1000 mg/m2 on days 1 and 8 plus carboplatin AUC 4 mg/mL/min on day 1) every 3 weeks for at least 6 cycles. The primary endpoint was progression-free survival, and overall response rate, overall survival, toxicity, and dose administration were secondary endpoints. RESULTS: One-hundred patients (49 PLDC; 51 GC) were randomly assigned. Over a median follow-up of 24 months, the median progression-free survival was 12.0 months (95% CI 9.2-15.0) for PLDC and 9.8 months (8.9-12.3) for GC [HR 0.69 (0.455-1.047)] with a difference of 2.2 months. The response rate was 57.1% (41.0-72.3) for PLDC and 56.4% (39.6-72.2) for GC. No obvious differences in toxicity (G3/4) were noted between arms. The median relative dose intensity of planned dose per week was 88.9% for pegylated liposomal doxorubicin and 53.1% for gemcitabine (p < 0.0001). CONCLUSIONS: PLDC and GC are both good treatment candidates for platinum-sensitive recurrent ovarian cancer patients; however, the dose intensity was lower for GC than for PLDC. PLDC had a more favorable risk-benefit profile than that of GC for patients.

Liquid-based endometrial cytology using SurePath™ is not inferior to suction endometrial tissue biopsy for detecting endometrial malignancies: Midterm report of a multicentre study advocated by Japan Association of Obstetricians and Gynecologists.

OBJECTIVE: We conducted a prospective, multicentre study to compare the clinical performance of liquid-based endometrial cytology (LBEC) using SurePath™ with that of suction endometrial tissue biopsy (SETB). This study is officially advocated and reported by the Japan Association of Obstetricians and Gynecologists. By publishing our midterm data, we intend to disseminate the benefits of LBEC system, using the descriptive reporting format and algorithmic interpretational approach. METHODS: From April 2014 to December 2015, we consecutively assessed 1116 LBEC specimens and 1044 SETB specimens in our five outpatient clinics. RESULTS: The sensitivity of suction tissue biopsies was 85.2%, whereas the sensitivity of LBEC was 92.2%. The specificity of suction tissue biopsies was 98.9% and that of LBEC was 98.5%. The negative predictive value of LBEC (99.1%) was higher than that of SETB (98.1%), although the difference between these values was not significant. CONCLUSIONS: The clinical performance of LBEC for detecting endometrial malignancies was almost identical to the performance of SETB. This indicates that LBEC was not inferior to SETB for the detection of endometrial cancer. The LBEC is appropriate for various clinical situations as the first-step detecting tool. In addition, it could be used for cancer surveillance for women with signs highly suggestive of endometrial malignancies and in Lynch syndrome patients, on a larger scale.

Effect of Substituents and Initial Degree of Functionalization of Alkylated Single-Walled Carbon Nanotubes on Their Thermal Stability and Photoluminescence Properties.

Alkylated single-walled carbon nanotubes (SWNTs) have been thermally treated to determine the influence of substituents and the degree of functionalization on their thermal stability and photoluminescence (PL) properties. Alkylated SWNTs were prepared by treating SWNTs with sodium naphthalenide and alkyl bromide. The defunctionalization of the alkylated SWNTs was monitored by absorption and Raman spectra. Selective recovery of the characteristic absorption and radial breathing mode peaks was observed during the thermal treatment, which indicates that the thermal stability of the alkylated SWNTs decreases with increases in SWNT diameter and degree of functionalization. n-Butylated and phenethylated SWNTs showed higher thermal stability than sec-butylated and benzylated SWNTs for a similar degree of functionalization, respectively. The diameter selectivity and effect of substituents on the thermal elimination reaction were confirmed by density functional theory. In addition, it was shown that the initial degree of functionalization of the alkylated SWNTs, with the alkyl group and degree of functionalization being kept constant after thermal treatment, strongly affects their PL properties; Stokes shift, and PL peak intensity.