Medical expenditure for lung cancer in China: a multicenter, hospital-based retrospective survey.

BACKGROUND: Lung cancer is the most prevalent cancer, and the leading cause of cancer-related deaths in China. The aim of this study was to estimate the direct medical expenditure incurred for lung cancer care and analyze the trend therein for the period 2002-2011 using nationally representative data in China METHODS: This study was based on 10-year, multicenter retrospective expenditure data collected from hospital records, covering 15,437 lung cancer patients from 13 provinces diagnosed during the period 2002-2011. All expenditure data were adjusted to 2011 to eliminate the effects of inflation using China's annual consumer price index. RESULTS: The direct medical expenditure for lung cancer care (in 2011) was 39,015 CNY (US$6,041) per case, with an annual growth rate of 7.55% from 2002 to 2011. Drug costs were the highest proportionally in the total medical expenditure (54.27%), followed by treatment expenditure (14.32%) and surgical expenditure (8.10%). Medical expenditures for the disease varied based on region, hospital level, type, and stage. CONCLUSION: The medical expenditure for lung cancer care is substantial in China. Drug costs and laboratory test are the main factors increasing medical costs.

Short-term impact of breast cancer screening intervention on health-related quality of life in China: A multicentre cross-sectional survey.

OBJECTIVE: The impact of participating in breast cancer screening programmes on health-related quality of life (HRQoL)is poorly understood. METHODS: Based on a national breast cancer screening programme in China, a multicentre cross-sectional survey was conducted covering 12 provinces from September 2013 to December 2014. HRQoL of participants in the screening population and general population was evaluated by the three-levelEuroQol-five-Dimensions (EQ-5D-3L) instrument, and utility scores were generated through the Chinese value set. Univariate and multivariate regression analyses were performed to explore determinants of utility scores and anxiety/depression problems. RESULTS: For screening group and general population (n = 4756, mean age = 51.6 year old), the corresponding utility scores were 0.937 (95% CI, 0.933-0.941) and 0.953 (0.949-0.957) (P < .001). Pain/discomfort and anxiety/depression were the most common reported in both groups (51.4% and 34.3%, P < .001). Utility scores at prescreening, in-screening, and postscreening interview timings were 0.928 (0.921-0.935), 0.958 (0.948-0.969), and 0.938 (0.933-0.943), respectively (P < .001); the corresponding proportions of anxiety/depression reporting were 25.9%, 16.3%, and 21.1%, respectively (P = .004). Interview timing, geographical region, and insurance status were associated with HRQoL and anxiety/depression in women at high-risk of breast cancer. CONCLUSIONS: Utility scores of screening participants were significantly lower than that of general population in China, but the difference may be clinically insignificant. Further cohort studies using HRQoL measurements are needed.

What are the clinical symptoms and physical signs for non-small cell lung cancer before diagnosis is made? A nation-wide multicenter 10-year retrospective study in China.

BACKGROUND: Most lung cancer patients are diagnosed after the onset of symptoms. However, whether the symptoms of lung cancer were independently associated with the diagnosis of lung cancer is unknown, especially in the Chinese population. METHODS: We conducted a 10 years (2005-2014) nationwide multicenter retrospective clinical epidemiology study of lung cancer patients diagnosed in China. As such, this study focused on nonsmall cell lung cancer (NSCLC). We calculated the odds ratios (ORs) for variables associated with the symptoms and physical signs using multivariate unconditional logistic regressions. RESULTS: A total of 7184 lung cancer patients were surveyed; finally, 6398 NSCLC patients with available information about their symptoms and physical signs were included in this analysis. The most common initial symptom and physical sign was chronic cough (4156, 65.0%), followed by sputum with blood (2110, 33.0%), chest pain (1146, 17.9%), shortness of breath (1090, 17.0%), neck and supraclavicular lymphadenectasis (629, 9.8%), weight loss (529, 8.3%), metastases pain (378, 5.9%), fatigue (307, 4.8%), fever (272, 4.3%), and dyspnea (270, 4.2%). Patients with squamous carcinoma and stage III disease were more likely to present with chronic cough (P < 0.0001) and sputum with blood (P < 0.0001) than patients with other pathological types and clinical stages, respectively. Metastases pain (P < 0.0001) and neck and supraclavicular lymphadenectasis (P = 0.0006) were more likely to occur in patients with nonsquamous carcinoma than in patients with other carcinomas. Additionally, patients with stage IV disease had a higher percentage of chest pain, shortness of breath, dyspnea, weight loss, and fatigue than patients with other stages of disease. In multivariable logistic analyses, compared with patients with adenocarcinoma, patients with squamous carcinoma were more likely to experience symptoms (OR = 2.885, 95% confidence interval [CI] 2.477-3.359) but were less likely to present physical signs (OR = 0.844, 95% CI 0.721-0.989). The odds of having both symptoms and physical signs were higher in patients with late-stage disease than in those with early-stage disease (P < 0.0001). CONCLUSIONS: The symptoms and physical signs of lung cancer were associated with the stage and pathological diagnosis of NSCLC. Patients with squamous carcinoma were more likely to develop symptoms, but not signs, than patients with adenocarcinoma. The more advanced the stage at diagnosis, the more likely that symptoms or physical signs are to develop. Further prospective cohort studies are needed to explore these results.

A multimodal therapeutic approach improves the clinical outcome of auricular keloid patients.

OBJECTIVE: We retrospectively studied the efficacy of personalized therapy with surgical resection plus prophylactic management of postsurgical auricular keloids by intralesional injection of betamethasone and local pressure therapy using magnets in patients with auricular keloids. METHODS: Surgical excision was performed in all patients, and surgical techniques including fusiform excision of the keloid scar, core excision of the keloid scar followed by flap repair, and scar graft were chosen. RESULTS: A total of 85 patients with 98 auricular keloids were eligible. Seventy-two (74%) patients had primary auricular keloids, and 13 patients had recurrent keloids after surgical excision. Keloids, were located in the helix in 28 (32.9%) cases, in the earlobe in 45 (52.9%) cases, and in the entire auricle in 12 (14.1%) cases. The size of auricular keloids ranged from 10 to 35 mm. Surgical resection was uneventful in all cases. Twenty-one (21.4%) patients received fusiform excision, 47 (47.9%) patients underwent core excision and flap repair, and 30 (30.6%) patients received skin grafts. The patients were followed up for median duration of 1 year (range: 12-24 months). The cure rate was 87.2%, and the recurrence rate was 12.8%. CONCLUSION: A personalized surgical approach based on the characteristics of auricular keloids in each patient and a multimodal therapeutic regimen including surgical excision, glucocorticoid blockade, and intralesional injection of glucocorticoids and pressure therapy improve the cure rate and reduce the recurrence rate of auricular keloids.

Ordered mesoporous silica cubic particles decorated with silver nanoparticles: a highly active and recyclable heterogeneous catalyst for the reduction of 4-nitrophenol.

In this work, using a modified Stöber process, we synthesized ordered mesoporous silica cubic particles (OMS-C) and prepared a nanocatalyst (Ag-OMS-C) based on OMS-C with a high surface area via an in situ auto-reduction strategy. The as-prepared Ag-OMS-C nanocomposites demonstrated open mesopores (3.51 nm), a large specific surface area (540 m2 g-1) and a high pore volume (0.88 cm3 g-1). The catalytic reduction of 4-nitrophenol (4-NP) over the Ag-OMS-C nanocatalyst was almost complete within 150 s without stirring and the rate constant k (30 × 10-3 s-1) is much higher than those of other substrate-supported Ag nanocatalysts. Moreover, the Ag-OMS-C nanocomposites hold a stable catalytic efficiency over five reaction cycles. The results indicate that the Ag-OMS-C nanocatalyst exhibited high catalytic activity and good reusability toward the reduction of 4-NP, which might be attributed to the large specific surface area, the pore structure of the nanocatalyst, as well as the synergistic effect between OMS-C and AgNPs.

Lung cancer imaging methods in China from 2005 to 2014: A national, multicenter study.

BACKGROUND: The study was conducted to examine changes in diagnostic and staging imaging methods for lung cancer in China over a 10-year period and to determine the relationships between such changes and socioeconomic development. METHODS: This was a hospital-based, nationwide, multicenter retrospective study of primary lung cancer cases. The data were extracted from the 10-year primary lung cancer databases at eight tertiary hospitals from various geographic areas in China. The chi-squared test was used to assess the differences and the Cochran-Armitage trend test was used to estimate the trends of changes. RESULTS: A total of 7184 lung cancer cases were analyzed. Over the 10-year period, the utilization ratio of diagnostic imaging methods, such as chest computed tomography (CT) and chest magnetic resonance imaging (MRI), increased from 65.79% to 81.42% and from 0.73% to 1.96%, respectively, while the utilization ratio of chest X-ray declined from 50.15% to 30.93%. Staging imaging methods, such as positron emission tomography-CT, neck ultrasound, brain MRI, bone scintigraphy, and bone MRI increased from 0.73% to 9.29%, 22.95% to 47.92%, 8.77% to 40.71%, 42.40% to 62.22%, and 0.88% to 4.65%, respectively; abdominal ultrasound declined from 83.33% to 59.9%. These trends were more notable in less developed areas than in areas with substantial economic development. CONCLUSION: Overall, chest CT was the most common radiological diagnostic method for lung cancer in China. Imaging methods for lung cancer tend to be used in a diverse, rational, and regionally balanced manner.

Clinical characteristics and medical service utilization of lung cancer in China, 2005-2014: Overall design and results from a multicenter retrospective epidemiologic survey.

OBJECTIVES: This study aimed to explore the clinical profile and its trajectory of lung cancer on clinicopathological characteristics and medical service utilization in China. METHODS: Patients diagnosed with primary lung cancer in tertiary hospitals during 2005-14 were selected from seven geographic regions of China. Data on clinical characteristics and medical service utilization was extracted from medical record, and the ten-year trends were explored. RESULTS: A total of 7184 patients were included, the mean age was 58.3 years and the male-to-female-ratio was 2.7. From 2005 to 2014, the proportion of ≥60 year-old patients increased from 41.2% to 56.2% (p < 0.001). The smoking rate decreased from 62.9% to 51.1% (p < 0.001) and the proportion of females increased from 23.5% to 31.9% (p < 0.001). The proportion of advanced stage increased from 41.9% to 47.4% (p < 0.001). Adenocarcinoma's proportion increased from 36.4% to 53.5% (p < 0.001) while that of squamous carcinoma decreased from 45.4% to 34.4% (p < 0.001). The application of chest X-ray dropped from 50.2% to 31.0% (p < 0.001) but that of chest CT increased from 65.8% to 81.4% (p < 0.001). As two main treatment options, chemotherapy (p = 0.290) and surgery (p = 0.497) remained stable. The medical expenditure per patient increased from 40,508 to 66,020 Chinese Yuan (p < 0.001). CONCLUSIONS: The sustaining high smoking exposure, increasing proportion of female patients, advancing clinical stage, shifting of predominant pathology and increasing medical expenditure demonstrate potential challenges and directions on lung cancer prevention and control in China. Despite substantial changes of clinical characteristics, main treatment options remained unchanged, which needs further investigation.

Medical expenses of urban Chinese patients with stomach cancer during 2002-2011: a hospital-based multicenter retrospective study.

BACKGROUND: In China, stomach cancer is the third most common cancer and the third leading cause of cancer death. Few studies have examined Chinese stomach cancer patients' medical expenses and their associated trends. The Cancer Screening Program in Urban China (CanSPUC) is a Major Public Health Project funded by the central government. Through this project, we have extracted patients' medical expenses from hospital billing data to examine the costs of the first course treatments (which refers to 2 months before and 10 months after the date of cancer diagnosis) in Chinese patients with stomach cancer and the associated trends. METHODS: The expense data of 14,692 urban Chinese patients with stomach cancer were collected from 40 hospitals in 13 provinces. We estimated the inflation-adjusted medical expenses per patient during 2002-2011. We described the time trends of medical expenses at the country-level, and those trends by subgroup, and analyzed the compositions of medical expenses. We constructed the Generalized Linear Mixed (GLM) regression model with Poisson distribution to examine the factors that were associated with medical expenses per patient. RESULTS: The average medical expenses of the first course treatments were about 43,249 CNY (6851 USD) in 2011, more than twice of that in 2002. The expenses increased by an average annual rate of 7.4%. Longer stay during hospitalization and an increased number of episodes of care are the two main contributors to the expense increase. The upward trend of medical expenses was observed in almost all patient subgroups. Drug expenses accounted for over half of the medical expenses. CONCLUSIONS: The average medical expenses of the first course (2 months before and 10 months after the date of cancer diagnosis) treatments per stomach cancer patient in urban China in 2011 were doubled during the previous 10 years, and about twice as high as the per capita disposable income of urban households in the same year. Such high expenses indicate that it makes economic sense to invest in cancer prevention and control in China.

Medical expenditure for liver cancer in urban China: A 10-year multicenter retrospective survey (2002-2011).

OBJECTIVE: This study aims to understand the medical expenditure for liver cancer during 2002-2011 in urban areas of China. MATERIALS AND METHODS: This is a retrospective study. Based on a stratified cluster sampling method, a medical expenditure survey collected basic personal information from related medical records. Two-tailed independent sample t-test, variance analysis, and Student-Newman-Keuls Tests were used in cost analysis for the corresponding data types. RESULTS: A total of 12,342 liver cancer patients were included in the analysis. Overall average medical expenditure per case for liver cancer diagnosis and treatment in China has increased from ¥21, 950 to ¥40, 386 over the study period. For each liver cancer patient diagnosed between 2009 and 2011, the average expenditures were 29,332 CNY for stage I, 35,754 CNY for stage II, 34,288 CNY for stage III, and 30,275 CNY for stage IV diseases (P < 0.001). Pharmaceuticals accounted for the biggest part of the medical expenditure and it rose from 48.01% to 52.96% during these ten years, and the share of nursing fee expenses was the lowest (around 1%). Over the entire 10-year data period, the per capita expenditure of the east region (32,983 CNY) was higher than that of the west region (26,219 CNY) and slightly higher than the central region (31,018 CNY, P < 0.001). DISCUSSION: As a major cancer in China, liver cancer accounts for a large portion of health economic burden and its medical expenditure is heavy for families. Early diagnosis and treatment for liver cancer will save medical expenditure. CONCLUSION: The economic burden of liver cancer is high in China and related medical expenditure has increased.

Health-related quality of life and utility scores of patients with breast neoplasms in China: A multicenter cross-sectional survey.

BACKGROUND: Health-related quality of life and utility scores of patients with breast cancer and precancerous lesions are sparse in China. This study aimed to derive utility scores of patients with breast cancer and precancer in China. MATERIAL AND METHODS: An interviewer-administered cross-sectional survey was conducted in 12 provinces across China from 2013 to 2014. The three-level EuroQol-5-Dimension instrument was used to evaluate quality of life, and utility scores were generated using the Chinese value set. Univariate and multivariate analyses were performed to explore the determinants of utility scores. RESULTS: In total, 2626 breast cancer and 471 precancer patients were included. Mean age was 49.1 for breast cancer and 41.4 years for precancer (p < 0.001). Among the five dimensions, pain/discomfort was the most reported problem, 53.9% in breast cancer and 29.3% in precancer patients. Mean (95% CI) utility scores for breast cancer and precancer patients were estimated as 0.887 (0.875-0.899) and 0.781 (0.774-0.788), and the scores of breast cancer at stage-I, stage-II, stage-III and stage-IV were 0.789 (0.774-0.805), 0.793 (0.783-0.802), 0.774 (0.759-0.788) and 0.686 (0.654-0.717), respectively. Mean (95% CI) visual analogue scale scores for breast cancer and precancer were 75.6 (74.0-77.3) and 72.8 (72.3-73.3). Multiple regression showed advanced clinical stage, lower educational level, lower household income, surgery treatment, and undergoing treatment were independently associated with lower utility scores for breast cancer patients. CONCLUSION: The utility scores deteriorate with the severity of breast neoplasms. Detailed utility scores of breast cancer and precancer are fundamental for further cost-utility analysis in China.

Medical expenditure for esophageal cancer in China: a 10-year multicenter retrospective survey (2002-2011).

BACKGROUND: Esophageal cancer is associated with substantial disease burden in China, and data on the economic burden are fundamental for setting priorities in cancer interventions. The medical expenditure for the diagnosis and treatment of esophageal cancer in China has not been fully quantified. This study aimed to examine the medical expenditure of Chinese patients with esophageal cancer and the associated trends. METHODS: From 2012 to 2014, a hospital-based multicenter retrospective survey was conducted in 37 hospitals in 13 provinces/municipalities across China as a part of the Cancer Screening Program of Urban China. For each esophageal cancer patient diagnosed between 2002 and 2011, clinical information and expense data were extracted by using structured questionnaires. All expense data were reported in Chinese Yuan (CNY; 1 CNY = 0.155 USD) based on the 2011 value and inflated using the year-specific health care consumer price index for China. RESULTS: A total of 14,967 esophageal cancer patients were included in the analysis. It was estimated that the overall average expenditure per patient was 38,666 CNY, and an average annual increase of 6.27% was observed from 2002 (25,111 CNY) to 2011 (46,124 CNY). The average expenditures were 34,460 CNY for stage I, 39,302 CNY for stage II, 40,353 CNY for stage III, and 37,432 CNY for stage IV diseases (P < 0.01). The expenditure also differed by the therapy type, which was 38,492 CNY for surgery, 27,933 CNY for radiotherapy, and 27,805 CNY for chemotherapy (P < 0.05). Drugs contributed to 45.02% of the overall expenditure. CONCLUSIONS: These conservative estimates suggested that medical expenditures for esophageal cancer in China substantially increased in the last 10 years, treatment for early-stage esophageal cancer costs less than that for advanced cases, and spending on drugs continued to account for a considerable proportion of the overall expenditure.

DNA-stabilized silver nanoclusters and carbon nanoparticles oxide: A sensitive platform for label-free fluorescence turn-on detection of HIV-DNA sequences.

Based on the remarkable difference between the interactions of carbon nanoparticles (CNPs) oxide with single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA), and the fact that fluorescence of DNA-stabilized silver nanoclusters (AgNCs) can be quenched by CNPs oxide, DNA-functionalized AgNCs were applied as label-free fluorescence probes and a novel fluorescence resonance energy transfer (FRET) sensor was successfully constructed for the detection of human immunodeficiency virus (HIV) DNA sequences. CNPs oxide were prepared with the oxidation of candle soot, hence it is simple, time-saving and low-cost. The strategy of dual AgNCs probes was applied to improve the detection sensitivity by using dual- probe capturing the same target DNA in a sandwich mode and as the fluorescence donor, and using CNPs oxide as the acceptor. In the presence of target DNA, a dsDNA hybrid forms, leading to the desorption of the ssDNA-AgNCs probes from CNPs oxide, and the recovering of fluorescence of the AgNCs in a HIV-DNA concentration-dependent manner. The results show that HIV-DNA can be detected in the range of 1-50nM with a detection limit of 0.40nM in aqueous buffer. The method is simple, rapid and sensitive with no need of labeled fluorescent probes, and moreover, the design of fluorescent dual-probe makes full use of the excellent fluorescence property of AgNCs and further improves the detection sensitivity.

Fluorescent assay for alkaline phosphatase activity based on graphene oxide integrating with λ exonuclease.

A novel fluorescence turn-on strategy for the alkaline phosphatase (ALP) assay is developed based on the preferential binding of graphene oxide (GO) to single-stranded DNA (ssDNA) over double-stranded DNA (dsDNA) coupled with λ exonuclease (λ exo) cleavage. Specifically, in the absence of ALP, the substrate-dsDNA constructed by one oligonucleotide with a fluorophore at the 3'-end (F-DNA) and its complementary sequence modified with a 5'-phosphoryl termini (p-DNA), is promptly cleaved by λ exo, and the resulting F-DNA is adsorbed on GO surface, allowing fluorescence quenching. Whereas the introduction of ALP leads to the hydrolysis of the P-DNA, and the yielding 5'-hydroxyl end product hampers the λ exo cleavage, inducing significant fluorescence enhancement due to the weak binding of dsDNA with GO. Under the optimized conditions, the approach exhibits high sensitivity and specificity to ALP with a detection limit of 0.19 U/L, and the determination of ALP in spiked human serum samples has also been realized. Notably, this new approach not only provides a novel and sensitive platform for the ALP activity detection but also promotes the exploitation of the GO-based biosensing for the detection of the protein with no specific binding element, and thus extending the GO-based sensing applications into a new field.

A fluorescent aptasensor using double-stranded DNA/graphene oxide as the indicator probe.

We developed a fluorescent aptasensor based on the making use of double-stranded DNA (dsDNA)/graphene oxide (GO) as the signal probe and the activities of exonuclease I (Exo I). This method takes advantage of the stronger affinity of the aptamer to its target rather than to its complementary sequence (competitor), and the different interaction intensity of dsDNA, mononucleotides with GO. Specifically, in the absence of target, the competitor hybridizes with the aptamer, preventing the digestion of the competitor by Exo I, and thus the formed dsDNA is adsorbed on GO surface, allowing fluorescence quenching. When the target is introduced, the aptamer preferentially binds with its target. Thereby, the corresponding nuclease reaction takes place, and slight fluorescence change is obtained after the introduction of GO due to the weak affinity of the generated mononucleotides to GO. Adenosine (AD) was chosen as a model system and tested in detail. Under the optimized conditions, smaller dissociation constant (Kd, 311.0 µM) and lower detection limit (LOD, 3.1 µM) were obtained in contrast with traditional dye-labeled aptamer/GO based platform (Kd=688.8 µM, LOD=21.2 µM). Satisfying results were still obtained in the evaluation of the specificity and the detection of AD in human serum, making it a promising tool for the diagnosis of AD-relevant diseases. Moreover, we demonstrated the effect of the competitor on the LOD, and the results reveal that the sensitivity could be enhanced by using the rational competitor. The present design not only constructs a label-free aptamer based platform but also extends the application of dsDNA/GO complex in biochemical and biomedical studies.

A gold nanoparticle-based label free colorimetric aptasensor for adenosine deaminase detection and inhibition assay.

A novel strategy for the fabrication of a colorimetric aptasensor using label free gold nanoparticles (AuNPs) is proposed in this work, and the strategy has been employed for the assay of adenosine deaminase (ADA) activity. The aptasensor consists of adenosine (AD) aptamer, AD and AuNPs. The design of the biosensor takes advantage of the special optical properties of AuNPs and the interaction between AuNPs and single-strand DNA. In the absence of ADA, the AuNPs are aggregated and are blue in color under appropriate salt concentration because of the grid structure of an AD aptamer when binding to AD, while in the presence of the analyte, AuNPs remain dispersed with red color under the same concentration of salt owing to ADA converting AD into inosine which has no affinity with the AD aptamer, thus allowing quantitative investigation of ADA activity. The present strategy is simple, cost-effective, selective and sensitive for ADA with a detection limit of 1.526 U L(-1), which is about one order of magnitude lower than that previously reported. In addition, a very low concentration of the inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA) could generate a distinguishable response. Therefore, the AuNP-based colorimetric biosensor has great potential in the diagnosis of ADA-relevant diseases and drug screening.

Relationship of serum MMP-7 levels for colorectal cancer: a meta-analysis.

This meta-analysis aimed to identify the value of serum matrix metalloproteinase-7 (MMP-7) levels for the diagnosis of colorectal cancer (CRC). Through searching the following electronic databases: Cochrane Library (Issue 12, 2014), Web of Science (1945∼2014), PubMed (1966∼2014), CINAHL (1982∼2014), EMBASE (1980∼2014), and CBM (1982∼2014), related articles were determined without any language restrictions. Stata statistical software (Version 12.0, Stata Corporation, College Station, TX, USA) was chosen to deal with statistical data. Standard mean difference (SMD) and its corresponding 95 % confidence interval (95 % CI) were calculated to clarify the correlation between serum MMP-7 levels and CRC. Seven clinical case-control studies which recruited 430 CRC patients and 357 healthy subjects were selected for statistical analysis. The main findings of our meta-analysis showed that the serum MMP-7 level in CRC patients was significantly higher than that in control subjects (SMD = 2.15, 95 % CI = 1.46∼2.84, P < 0.001). Ethnicity-stratified analysis indicated a higher serum MMP-7 level in CRC patients than that of control subjects among the Asians and the Caucasians (Asians: SMD = 2.83, 95 % CI = 1.76∼3.91, P < 0.001; Caucasians: SMD = 1.06, 95 % CI = 0.46∼1.66, P = 0.001; respectively). The present meta-analysis indicated that the increased serum level of MMP-7 may be connected with the development of CRC; thus, serum levels of MMP-7 could be an independent biomarker for CRC patients.

Influence of three anionic gemini surfactants with different chain lengths on the optical properties of a cationic polyfluorene.

The effects of three sulfonate gemini surfactants with different hydrophobic chain lengths (8, 10, and 12 carbon atoms) on the optical properties of a fluorene-based conjugated cationic polymer poly{[9,9-bis(6'-N,N,N-trimethylammonium)hexyl]-fluorene-phenylene} bromide (PFP) dissolved in DMSO-water solutions (4% v/v) or water were investigated, respectively. When surfactants with PFP dissolved in DMSO-water solutions (4% v/v) are incubated, a decrease in photoluminescence (PL) intensity and a red shift of emission maxima are obtained at low surfactant concentrations. Intriguingly, two different Stern-Volmer constants (KSV1 and KSV2) are obtained and analyzed in detail for the first time. Further increase in the surfactant concentration enhanced PL intensity, and distinct blue shifts of both absorption and emission maxima are observed. Importantly, the turning point between the emission quenching and enhancement is closely related to the hydrophobic chain length: the longer the chain length, the earlier the turning point appears. Simulation studies provide strong evidence to explain these phenomena. Surface tension measurements show more insight on the interactions between PFP and surfactant. On the contrary, no emission quenching is obtained at low surfactant concentrations for PFP dissolved in water.

Amplified fluorescent assay of potassium ions using graphene oxide and a conjugated cationic polymer.

We present a low background, highly selective and amplified fluorescent sensor for potassium ions using graphene oxide (GO) and a cationic conjugated polymer (CCP). This method takes advantage of the phenomenon that the addition of CCP cannot release the dye labeled guanine-rich DNA from the GO surface, and the conformational switch of the guanine-rich DNA from random coil to G-quadruplex induced by the target.

An ultra-high sensitive platform for fluorescence detection of micrococcal nuclease based on graphene oxide.

Micrococcal nuclease (MNase) is the extracellular nuclease of Staphylococcus aureus (S. aureus). It preferentially digests single-stranded nucleic acids. The existence of MNase can be the standard to identify S. aureus and the content of MNase can be used to evaluate the pathogenicity of S. aureus. Herein, an ultra-high sensitive and selective fluorescent sensing platform for MNase is developed based on MNase-induced DNA strand scission and the difference in affinity of graphene oxide (GO) for single-stranded DNA containing different numbers of bases in length. In the absence of MNase, the adsorption of the dye-labeled ssDNA on GO makes the dyes close proximity to GO surface resulting in high efficiency quenching of fluorescence of the dyes. Conversely, and very importantly, in the presence of MNase, it cleaves the dye-labeled ssDNA into small fragments. The introduction of GO into the sensing solution results in weak quenching of the fluorescence of the dyes due to the weak affinity of the short dye-labeled oligonuleotide fragment to GO, and the fluorescence intensity gradually increases with increasing concentration of MNase. MNase can be detected in a range of 8×10⁻5 to 1.6×10⁻³ unit/mL with a detection limit of 2.7×10⁻5 unit/mL and good selectivity. The detection limit is of two orders of magnitude lower than those reported fluorescence MNase assays. Moreover, when the GO-based biosensor is used in S. aureus sample assays, preeminent fluorescence signals are obtained, thus the platform of the GO-based biosensor can be used to detect MNase in real-world samples.

Amplified fluorescent sensing of DNA using graphene oxide and a conjugated cationic polymer.

We explore the interactions between a fluorescein (FAM)-labeled single-stranded DNA (P), graphene oxide (GO), and a cationic conjugated polymer, poly [(9,9-bis(6'-N,N,N-trimethylammonium)hexyl)-fluorenylene phenylene dibromide] (PFP). It is found that the fluorescence change of P-GO-PFP system is dependent on the addition order of P and PFP. When adding PFP into P/GO complex, the fluorescence resonance energy transfer (FRET) from PFP to P is inefficient. If P is added to PFP/GO complex, efficient FRET is obtained. This may be attributed to the equal binding ability for P and PFP to GO. The results of time-resolved fluorescence and fluorescence anisotropy support the different fluorescent response under different addition order of P and PFP to GO. Based on the above phenomenon, we demonstrate a method to reduce the high background signal of a traditional PFP-based DNA sensor by introducing GO. In comparison to the use of single PFP, the combination of PFP with GO-based method shows enhanced sensitivity with a detection limit as low as 40 pM for target DNA detection.