Accuracy and variability of high-dose-rate prostate brachytherapy needle tip localization using live two-dimensional and sagittally reconstructed three-dimensional ultrasound

Publication date: Available online 29 July 2017
Source:Brachytherapy
Author(s): William Thomas Hrinivich, Douglas A. Hoover, Kathleen Surry, Chandima Edirisinghe, Vikram Velker, Glenn Bauman, David D'Souza, Aaron Fenster, Eugene Wong
PurposeTo measure the accuracy and variability of manual high-dose-rate (HDR) prostate brachytherapy (BT) needle tip localization using sagittally reconstructed three-dimensional (3D) transrectal ultrasound (TRUS) augmented with live two-dimensional (2D) sagittal TRUS.Methods and MaterialsTen prostate cancer patients underwent HDR-BT during which the sagittally assisted sagittally reconstructed (SASR) segmentation technique was completed in parallel with commercially available sagittally assisted axially reconstructed (SAAR) TRUS for comparison. The SASR technique makes use of live 2D ultrasound intraoperatively and allows needle tip updates using the final 3D image in the absence of image artifacts. These updates were repeated offline twice by two separate users. Needle end-length measurements were used to calculate insertion depth errors (IDEs) for each technique.ResultsImages of 147 needles were analyzed. For the SASR technique, both users were confident in tip positions on the final 3D image within 3 mm for 52% of needles, so these tip positions were updated. For the remaining 48% of needles, the tip positions from the live 2D images were used. This SASR technique enabled the localization of all needles with IDEs within ±3 mm for 84% of needles and IDE range of [−6.2 mm, 5.9 mm], compared with 57% and [−8.1 mm, 7.7 mm] when using the commercially available SAAR technique.ConclusionsThe SASR technique mitigates the impact of 3D TRUS image artifacts on HDR-BT needle tip localization by incorporating live 2D sagittal TRUS intraoperatively and provides a statistically significant reduction in IDE variance compared with the routine SAAR technique.



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Lesion localization using the scroll bar on tomosynthesis: Why doesn't it always work?

Publication date: Available online 29 July 2017
Source:Clinical Imaging
Author(s): Sarah M. Friedewald, Victoria A. Young, Dipti Gupta
The scroll bar on digital breast tomosynthesis (DBT) is an important tool that facilitates localization of lesions on the orthogonal view. While this works well most of the time, occasionally the location of the lesion as directed by the scroll bar is seemingly inaccurate. There are five important reasons why the scroll bar indicator may suggest a contradictory lesion location. Understanding specific scenarios when this may occur will aid the reader in reconciling these differences.



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Disturbed Desmoglein-2 in the Intercalated Disc of Pediatric Patients with Dilated Cardiomyopathy

Publication date: Available online 29 July 2017
Source:Human Pathology
Author(s): Elise L Kessler, Peter GJ Nikkels, Toon AB van Veen
Dilated cardiomyopathy (DCM) leads to disturbed contraction and force transduction, and is associated with substantial mortality in all age groups. Involvement of a disrupted composition of the intercalated disc (ID) has been reported. However, in children, little is established about such subcellular changes during disease, because of the pathological mix-up with the ongoing cardiac maturation. This leaves maladaptive remodeling often undetected. We aimed at illustrating subcellular alterations in children diagnosed with DCM compared to age-matched controls, focusing on ID proteins known to be crucially stable under healthy conditions and destabilized during cardiac injury in adults. Left Ventricular or septal pediatric specimens were collected from 7 individuals diagnosed with DCM (age: 23weeks in utero - 8weeks postnatal) and age-matched controls that died of non-cardiovascular cause. We determined the amount of fibrosis and localization of ID proteins by immunohistochemistry. In pediatric DCM, most ID proteins follow similar spatio-temporal changes in localization as in controls. However, although no mutations were found, the signal of the desmosomal protein Desmoglein-2 was reduced in all pediatric DCM specimens, but not in controls or adult DCM patients. Endocardial and transmural fibrosis was increased in all pediatric DCM patients compared to age-matched controls. Composition of the ID in pediatric DCM patients is similar to controls, except for the localization of Desmoglein-2 and presence of severe fibrosis. This suggests that the architecture of desmosomes is already disturbed in the early stages of DCM. These findings contribute to the understanding of pediatric DCM.



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Status of Resident Attrition From Surgical Residency in the Past, Present, and Future Outlook

Publication date: Available online 29 July 2017
Source:Journal of Surgical Education
Author(s): Faris Shweikeh, Alexander C. Schwed, Chiu-Hsieh Hsu, Valentine N. Nfonsam
ObjectiveTo investigate the current rate of attrition in general surgery residency, assess the risk factors, and identify prevention strategies.DesignA literature review of the PubMed and MEDLINE databases, from January 1, 1980 to February 1, 2016, for relevant articles. The calculated attrition rate and the statistically significant influencing factors were the main measures and outcomes.SelectionAll English language articles that described attrition from a general surgery residency were included. Articles that performed an assessment of attrition rates, academic performance, reasons for resident loss, and demographics were identified and data from these studies were collected. Random-effect meta-analysis and meta-regression based on a generalized mixed-effects model was performed.ResultsA total of 26 studies were included. Reported attrition rates ranged from 2% to 30% over the course of residency training. Random-effect meta-analysis is indicative of a yearly attrition rate of 2.4% (95% CI: 1.3%-3.5%) and a cumulative 5-year attrition rate of 12.9% (95% CI: 7.9%-17.8%). Most of them leave residency during their first 2 years, and the rate significantly decreases with increasing postgraduate year (p < 0.0001). The Accreditation Council for Graduate Medical Education mandated 80-hour week is associated with a higher rate, though not significantly (3.2% [95% CI: 1.3%-5.1%] vs. 2.2% [0.9%-3.5%], p = 0.37). Pooled analysis demonstrates no statistically significant difference in the rate of attrition between males and females (2.1% [95% CI: 1.1%-3%] vs. 2.9% [95% CI: 1.6%-4.1%], p = 0.73). Most remain in graduate medical education and pursue residency training in other specialties.ConclusionAttrition in general surgery most commonly occurs within the first 2 years of training and, in contrast to previous findings, is not related to female sex. Restrictions on work hours seem to have increased the rate, whereas remediation practices can prevent it. Training programs should direct efforts towards attrition-prevention strategies.



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Physical Function after Total Knee Replacement: An observational study describing outcomes in a small group of women from China and the United States

Publication date: Available online 29 July 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Daniel K. White, Zhichang Li, Yuqing Zhang, Adam R. Marmon, Hiral Master, Joseph Zeni, Jingbo Niu, Long Jiang, Shu Zhang, Jianhao Lin
ObjectiveTo describe physical function before and six months after Total Knee Replacement (TKR) in a small sample of women from China and the United States (US).Participants60 women after TKR from China and the USDesign, Setting, Outcomes: Data was from an observational study of TKR outcomes in Newark, Delaware (US group) and a control group after TKR in Beijing (China group). Both groups followed the same Osteoarthritis Research Society International (OARSI) protocols for the six-minute walk and 30-second chair stand. We compared physical function prior to TKR and six months after using linear regression adjusted for covariates.ResultsAge and BMI were similar in the China group (n=30, 66 years and 27.0 kg/m²) as the US group (n=30, 65 years and 29.6 kg/m²). Before surgery, the China group walked 263 (95%CI [-309,-219]) less meters and had 10.2 (95%CI [-11.8, -8.5]) fewer chairs stands than the US group. At six months when compared to the US group, the China group walked 38 more meters, but this difference did not reach statistical significance (95%CI [-1.6, 77.4]), and had 3.1 (95%CI [-4.4, -1.7]) fewer chair stands. The China group had greater improvement in the six-minute walk compared with the US group, p< 0.001.ConclusionDespite having worse physical function prior to TKR, the China group had greater gains in walking endurance and similar gains in repeated chair stands compared with the US group after surgery.



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Work productivity loss after mild traumatic brain injury

Publication date: Available online 29 July 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Noah D. Silverberg, William J. Panenka, Grant L. Iverson
ObjectiveTo examine the completeness of return to work (RTW) and the degree of productivity loss in individuals who do achieve a complete RTW after mild traumatic brain injury (MTBI).DesignMulti-site prospective cohort.SettingOutpatient concussion clinics.ParticipantsSeventy-nine patients (M=41.5 years old, 55.7% female) who sustained an MTBI and were employed at the time of the injury. Participants were enrolled at their first clinic visit and assessed by telephone 6-8 months post-injury.InterventionNone.MeasuresStructured interview of RTW status, British Columbia Postconcussion Symptom Inventory (BC-PSI), Lam Employment Absence and Productivity Scale (LEAPS), MINI Neuropsychiatric Interview, brief pain questionnaire. Participants who endorsed symptoms from three or more categories with at least moderate severity on the BC-PSI were considered to meet International Classification of Diseases-10 criteria for postconcussional syndrome. RTW status was classified as complete if participants returned to their pre-injury job with the same hours and responsibilities or to a new job that was at least as demanding.ResultsOf the 46 (58.2%) patients who achieved a RTW, 33 (71.7%) had a complete RTW. Participants with complete RTW had high rates of postconcussional syndrome (44.5%) and comorbid depression (18.2%), anxiety disorder (24.2%), and bodily pain (30.3%). They also reported productivity loss on the LEAPS, such as "getting less work done" (60.6%) and "making more mistakes" (42.4%). In a regression model, productivity loss was predicted by the presence of postconcussional syndrome and a comorbid psychiatric condition, but not bodily pain.ConclusionEven in patients who RTW after MTBI, detailed assessment revealed underemployment and productivity loss associated with residual symptoms and psychiatric complications.



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Kinesiophobia and its Association with Health Related Quality of Life Across Injury Locations

Publication date: Available online 29 July 2017
Source:Archives of Physical Medicine and Rehabilitation
Author(s): Penny Goldberg, Giorgio Zeppieri, Joel Bialosky, Charlotte Bocchino, Jon van den Boogaard, Susan Tillman, Terese L. Chmielewski
ObjectiveTo compare baseline kinesiophobia levels and their association with health-related quality of life across injury locations.DesignRetrospective cross-sectional study.SettingSingle, large outpatient physical therapy clinic within an academic medical center.Participants1233 patients who underwent an initial evaluation for a diagnosis related to musculoskeletal pain and completed the TSK-11 and SF-8™ questionnaires within 7 days of their first visit were eligible for inclusion. 380 patients were excluded for missing data or because they were under 18 years of age.InterventionsNot applicable.Main Outcome MeasuresComparison of baseline kinesiophobia levels and their association with health-related quality of life across injury locations in an outpatient physical therapy setting.ResultsA total of 853 patients (range: 18-94 years, mean age = 43.55 years) were included. Separate ANOVA models compared TSK-11 scores based on involved body region and Pearson correlation coefficients were used to examine the association between TSK-11 scores the SF-8™ sub-scales at each body region. TSK-11 scores did not differ by body region (range = 23.9 to 26.1). Weak to moderate negative correlations existed between kinesiophobia and the SF-8™ subscales.ConclusionKinesiophobia levels appear elevated and negatively associated with health-related quality of life at initial physical therapy evaluation regardless of injury location. These findings suggest physical therapists in outpatient orthopaedic settings should implement routine kinesiophobia assessment and provide stratified care based on kinesiophobia levels across musculoskeletal conditions.



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A highly stable acetylcholinesterase biosensor based on chitosan-TiO2-graphene nanocomposites for detection of organophosphate pesticides

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Hui-Fang Cui, Wen-Wen Wu, Meng-Meng Li, Xiaojie Song, Yuanxu Lv, Ting-Ting Zhang
A highly stable electrochemical acetylcholinesterase (AChE) biosensor for detection of organophosphorus pesticides (OPs) was developed simply by adsorption of AChE on chitosan (CS), TiO2 sol-gel, and reduced graphene oxide (rGO) based multi-layered immobilization matrix (denoted as CS^@TiO2-CS/rGO). The biosensor fabrication conditions were optimized, and the fabrication process was probed and confirmed by scanning electron microscopy and electrochemical techniques. The matrix has a mesoporous nanostructure. Incorporation of CS and electrodeposition of a CS layer into/on the TiO2 sol-gel makes the gel become mechanically strong. The catalytic activity of the AChE immobilized CS^@TiO2-CS/rGO/glassy carbon electrode to acetylthiocholine is significantly higher than those missing any one of the component in the matrix. The detection linear range of the biosensor to dichlorvos, a model OP compound, is from 0.036μM (7.9 ppb) to 22.6μM, with a limit of detection of 29nM (6.4 ppb) and a total detection time of about 25min. The biosensor is very reproducibly and stable both in detection and in storage, and can accurately detect the dichlorvos levels in cabbage juice samples, providing an efficient platform for immobilization of AChE, and a promisingly applicable OPs biosensor with high reliability, simplicity, and rapidness.



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Highly efficient electrochemical sensing platform for sensitive detection DNA methylation, and methyltransferase activity based on Ag NPs decorated carbon nanocubes

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Fenglei Gao, Taotao Fan, Shanshan Ou, Jing Wu, Xing Zhang, Jianjun Luo, Na Li, Yao Yao, Yingfeng Mou, Xianjiu Liao, Deqin Geng
In this paper, we reported a sensitive and selective electrochemical method for quantify DNA methylation, analyzing DNA MTase activity and screening of MTase inhibitor based on silver nanoparticles (Ag NPs) decorated carbon nanocubes (CNCs) as signal tag. The Ag NPs/CNCs was prepared by in situ growth of nanosilver on carboxylated CNCs and used as a tracing tag to label antibody. The sensor was prepared by immobilizing the double DNA helix structure on the surface of gold electrode. When DNA MTase was introduced, the probe was methylated. Successively, anti-5-methylcytosine antibody labeled Ag NPs/CNCs was specifically conjugated on the CpG methylation site. The electrochemical stripping signal of the Ag NPs was used to monitor the activity of MTase. The electrochemical signal has a linear relationship with M.SssI activities ranging from 0.05 to 120U/mL with a detection limit of 0.03U/mL. In addition, we also demonstrated the method could be used for rapid evaluation and screening of the inhibitors of MTase. The newly designed strategy avoid the requirement of deoxygenation for electrochemical assay, and thus provide a promising potential in clinical application.



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A high-sensitivity electrochemical aptasensor of carcinoembryonic antigen based on graphene quantum dots-ionic liquid-nafion nanomatrix and DNAzyme-assisted signal amplification strategy

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Jing-Yi Huang, Lang Zhao, Wan Lei, Wei Wen, Yi-Jia Wang, Ting Bao, Hua-Yu Xiong, Xiu-Hua Zhang, Sheng-Fu Wang
In this work, we have developed an electrochemical aptasensor for high-sensitivity determination of carcinoembryonic antigen (CEA) based on lead ion (Pb²⁺)-dependent DNAzyme-assisted signal amplification and graphene quantum dot-ionic liquid-nafion (GQDs-IL-NF) composite film. We designed hairpin DNA containing CEA-specific aptamers and DNAzyme chains. In the presence of CEA, hairpin DNA recognized the target and performed a DNAzyme-assisted signal amplification reaction to yield a large number of single-stranded DNA. The GQDs-IL-NF composite film was immobilized on the glassy carbon electrode for the interaction with single-stranded DNA through noncovalent π-π stacking interaction. Therefore, the methylene blue-labeled substrate DNA (MB-substrate) was fixed on the electrode and exhibited an initial electrochemical signal. Under optimal conditions, the response current change was proportional to the concentration of CEA, demonstrating a wide linear range from 0.5fgmL⁻¹ to 0.5ngmL⁻¹, with a low detection limit of 0.34fgmL⁻¹. Furthermore, the proposed aptasensor was successfully applied in determining CEA in serum samples, showing its superior prospects in clinical diagnosis.



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Analytical, thermodynamical and kinetic characteristics of photoluminescence immunosensor for the determination of Ochratoxin A

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Roman Viter, Maryna Savchuk, Igor Iatsunskyi, Zuzanna Pietralik, Nikolay Starodub, Nelya Shpyrka, Almira Ramanaviciene, Arunas Ramanavicius
Ochratoxin A (OTA) is one of the most widespread and dangerous food contaminants. Therefore, rapid, label-free and precise detection of low OTA concentrations requires novel sensing elements with advanced bio-analytical properties. In the present paper we report photoluminescence (PL) based immunosensor for the detection of OTA. During the development of immunosensor photoluminescent ZnO nanorods (ZnO-NRs) were deposited on glass substrate. Then the ZnO-NRs were silanized and covalently modified by Protein-A (Glass/ZnO-NRs/Protein-A). The latest structure was modified by antibodies against OTA (Anti-OTA) in order to form OTA-selective layer (Glass/ZnO-NRs/Protein-A/Anti-OTA). In order to improve immunosensors selectivity the surface of Glass/ZnO-NRs/Protein-A/Anti-OTA was additionally blocked by BSA. Formed Glass/ZnO-NRs/Protein-A/BSA&Anti-OTA structures were integrated within portable fiber optic detection system, what is important for the development of low cost and portable immunosensors. The immunosensor has been tested in a wide range of OTA concentrations from 10⁻⁴ng/ml until 20ng/ml. Interaction isotherms were derived from analytical signals of immunosensor. Association constant and Gibbs free energy for the interaction of Glass/ZnO-NRs/Protein-A/Anti-OTA with OTA were calculated, analyzed and compared with some other related results. Sensitivity range and limit of detection were determined as 0.1–1ng/ml and 10⁻²ng/ml, respectively. Interaction kinetics of ZnO-NRs with OTA was evaluated. Response time of the immunosensor toward OTA was in the range of 500–800s. Some insights related to the mechanism of PL-signal generation are proposed and discussed.

Graphical abstract

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Fluorinated tripodal receptors for potentiometric chloride detection in biological fluids

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Nadezda Pankratova, Maria Cuartero, Laura A. Jowett, Ethan N.W. Howe, Philip A. Gale, Eric Bakker, Gastón A. Crespo
Fluorinated tripodal compounds were recently reported to be efficient transmembrane transporters for a series of inorganic anions. In particular, this class of receptors has been shown to be suitable for the effective complexation of chloride, nitrate, bicarbonate and sulfate anions via hydrogen bonding. The potentiometric properties of urea and thiourea-based fluorinated tripodal receptors are explored here for the first time, in light of the need for reliable sensors for chloride monitoring in undiluted biological fluids. The ion selective electrode (ISE) membranes with tren-based tris-urea bis(CF3) tripodal compound (ionophore I) were found to exhibit the best selectivity for chloride over major lipophilic anions such as salicylate (logKCl−/Sal−pot=+1.0) and thiocyanate (logKCl−/SCN−pot=+0.1). Ionophore I-based ISEs were successfully applied for chloride determination in undiluted human serum as well as artificial serum sample, the slope of the linear calibration at the relevant background of interfering ions being close to Nernstian (49.8±1.7mV). The results of potentiometric measurements were confirmed by argentometric titration. Moreover, the ionophore I-based ISE membrane was shown to exhibit a very good long-term stability of potentiometric performance over the period of 10 weeks. Nuclear magnetic resonance (NMR) titrations, potentiometric sandwich membrane experiments and density functional theory (DFT) computational studies were performed to determine the binding constants and suggest 1:1 complexation stoichiometry for the ionophore I with chloride as well as salicylate.



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Sliding-strip microfluidic device enables ELISA on paper

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Mohit S. Verma, Maria-Nefeli Tsaloglou, Tyler Sisley, Dionysios Christodouleas, Austin Chen, Jonathan Milette, George M. Whitesides
This article describes a 3D microfluidic paper-based analytical device that can be used to conduct an enzyme-linked immunosorbent assay (ELISA). The device comprises two parts: a sliding strip (which contains the active sensing area) and a structure surrounding the sliding strip (which holds stored reagents—buffers, antibodies, and enzymatic substrate—and distributes fluid). Running an ELISA involves adding sample (e.g. blood) and water, moving the sliding strip at scheduled times, and analyzing the resulting color in the sensing area visually or using a flatbed scanner. We demonstrate that this device can be used to detect C-reactive protein (CRP)—a biomarker for neonatal sepsis, pelvic inflammatory disease, and inflammatory bowel diseases—at a concentration range of 1–100ng/mL in 1000-fold diluted blood (1–100µg/mL in undiluted blood). The accuracy of the device (as characterized by the area under the receiver operator characteristics curve) is 89% and 83% for cut-offs of 10ng/mL (for neonatal sepsis and pelvic inflammatory disease) and 30ng/mL (for inflammatory bowel diseases) CRP in 1000-fold diluted blood respectively. In resource-limited settings, the device can be used as a part of a kit (containing the device, a fixed-volume capillary, a pre-filled tube, a syringe, and a dropper); this kit would cost ~ $0.50 when produced in large scale (>100,000 devices/week). This kit has the technical characteristics to be employed as a pre-screening tool, when combined with other data such as patient history and clinical signs.



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Shell-encoded Au nanoparticles with tunable electroactivity for specific dual disease biomarkers detection

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Yuan Zhao, Yaxin Yang, Yali Sun, Linyan Cui, Fangjie Zheng, Jiru Zhang, Qijun Song, Chuanlai Xu
The exploration of electroactive labelling with tailorable and strong differential pulse voltammetry (DPV) responses is of great importance in accurate and sensitive screening of a panel of biomarkers related to cancer. Herein, shell-encoded gold nanoparticles (Au NPs) are fabricated and give rise to shell species-dominated DPV peak potentials. Two independent DPV peaks appear at −0.08V for Au@Cu2O core-shell NPs and 0.26V for Au@Ag core-shell NPs. Shell-encoded Au NPs drastically exhibit shell thickness-tunable amplified peak currents. The non-interfering and amplified DPV responses enable shell-encoded Au NPs to be an alternative electrochemical signal amplifier for dual screening of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP). The limits of detection (LODs) are calculated to be 1.8pg/mL for CEA and 0.3pg/mL for AFP. In comparison to the parallel single-analyte assays, shell-encoded Au NPs engineered electrochemical aptasensors offer multiplexing capability and show significant prospects in biomedical research and early diagnosis of diseases.



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Hall effect biosensors with ultraclean graphene film for improved sensitivity of label-free DNA detection

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Phan Thi Kim Loan, Dongqin Wu, Chen Ye, Xiaoqing Li, Vu Thanh Tra, Qiuping Wei, Li Fu, Aimin Yu, Lain-Jong Li, Cheng-Te Lin
The quality of graphene strongly affects the performance of graphene-based biosensors which are highly demanded for the sensitive and selective detection of biomolecules, such as DNA. This work reported a novel transfer process for preparing a residue-free graphene film using a thin gold supporting layer. A Hall effect device made of this gold-transferred graphene was demonstrated to significantly enhance the sensitivity (≈ 5 times) for hybridization detection, with a linear detection range of 1pM to 100nM for DNA target. Our findings provide an efficient method to boost the sensitivity of graphene-based biosensors for DNA recognition.

Graphical abstract

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DNA origami nanorobot fiber optic genosensor to TMV

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Emanuela Torelli, Marisa Manzano, Sachin K. Srivastava, Robert S. Marks
In the quest of greater sensitivity and specificity of diagnostic systems, one continually searches for alternative DNA hybridization methods, enabling greater versatility and where possible field-enabled detection of target analytes. We present, herein, a hybrid molecular self-assembled scaffolded DNA origami entity, intimately immobilized via capture probes linked to aminopropyltriethoxysilane, onto a glass optical fiber end-face transducer, thus producing a novel biosensor. Immobilized DNA nanorobots with a switchable flap can then be actuated by a specific target DNA present in a sample, by exposing a hemin/G-quadruplex DNAzyme, which then catalyzes the generation of chemiluminescence, once the specific fiber probes are immersed in a luminol-based solution. Integrating organic nanorobots to inorganic fiber optics creates a hybrid system that we demonstrate as a proof-of-principle can be utilized in specific DNA sequence detection. This system has potential applications in a wide range of fields, including point-of-care diagnostics or cellular in vivo biosensing when using ultrathin fiber optic probes for research purposes.



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Graphene oxide@gold nanorods-based multiple-assisted electrochemiluminescence signal amplification strategy for sensitive detection of prostate specific antigen

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Jun-Tao Cao, Jiu-Jun Yang, Li-Zhen Zhao, Yu-Ling Wang, Hui Wang, Yan-Ming Liu, Shu-Hui Ma
A novel and competitive electrochemiluminescence (ECL) aptasensor for prostate specific antigen (PSA) assay was constructed using gold nanorods functionalized graphene oxide (GO@AuNRs) multilabeled with glucose oxidase (GOD) and streptavidin (SA) toward luminol-based ECL system. A strong initial ECL signal was achieved by electrodeposited gold (DpAu) on the electrode because of gold nanoparticles (AuNPs) motivating the luminol ECL signal. The signal probes prepared by loading GOD and SA-biotin-DNA on GO@AuNRs were used for achieving multiple signal amplification. In the absence of PSA, the signal probes can be attached on the electrode by hybridization reaction between PSA aptamer and biotin-DNA. In this state, the GOD loaded on the probe could catalyze glucose to in situ produce H2O2 and then AuNRs catalyze H2O2 to generate abundant reactive oxygen species (ROSs) in luminol ECL reaction. Both the high-content GOD and AuNRs in the signal probe amplified the ECL signal in the ECL system. Moreover, the combination of SA with biotin-DNA further expands ECL intensity. The integration of such amplifying effects in this protocol endows the aptasensor with high sensitivity and good selectivity for PSA detection. This aptasensor exhibits a linear relation in the range of 0.5pgmL⁻¹ to 5.0ngmL⁻¹ with the detection limit of 0.17pgmL⁻¹ (S/N = 3). Besides, the strategy was successfully applied in determination of human serum samples with recovery of 81.4–116.0%.



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Molecular imprinting coupled with electrochemical analysis for plasma samples classification in acute myocardial infarction diagnostic

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Victoria V. Shumyantseva, Tatiana V. Bulko, Larisa V. Sigolaeva, Alexey V. Kuzikov, Pavel V. Pogodin, Alexander I. Archakov
Electroanalysis of myoglobin (Mb) in 10 plasma samples of healthy donors (HDs) and 14 plasma samples of patients with acute myocardial infarction (AMI) was carried out with screen-printed electrodes modified first with multi-walled carbon nanotubes (MWCNT) and then with a molecularly imprinted polymer film (MIP), viz., myoglobin-imprinted electropolymerized poly(o-phenylenediamine). The differential pulse voltammetry (DPV) parameters, such as a maximum amplitude of reduction peak current (A, nA), a reduction peak area (S, nA × V), and a peak potential (P, V), were measured for the MWCNT/MIP-sensors after their incubation with non-diluted plasma. The relevance of the multi-parameter electrochemical data for accurate discrimination between HDs and patients with AMI was assessed on the basis of electrochemical threshold values (this requires the reference standard method (RAMP® immunoassay)) or alternatively on the basis of the computational cluster assay (this does not require any reference standard method). The multi-parameter electrochemical analysis of biosamples combined with computational cluster assay was found to provide better accuracy in classification of plasma samples to the groups of HDs or AMI patients.



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Liposome-amplified photoelectrochemical immunoassay for highly sensitive monitoring of disease biomarkers based on a split-type strategy

Publication date: 15 January 2018
Source:Biosensors and Bioelectronics, Volume 99
Author(s): Junyang Zhuang, Bin Han, Wenchao Liu, Jinfei Zhou, Kewei Liu, Dapeng Yang, Dianping Tang
Liposomes are an excellent candidate component for biosensors to transduce and amplify detection signals due to their outstanding ability in encapsulating signal marker compounds. However, the use of liposomes for photoelectrochemical (PEC) signal transduction has not yet been achieved due the lack of appropriate sensing strategy. Herein, we report on a novel liposomes-amplified PEC immunoassay (LAPIA) method for sensitive HIV-p24 antigen (p24) detection based on a split-type strategy. Initially, liposomes were encapsulated with alkaline phosphatase (ALP) in their hydrophilic chamber and conjugated with secondary antibody on the surface to form the ALP-encapsulated liposomes (ALP-Ls) based PEC signal label. Sandwiched immunoassay based on the ALP-Ls label was then carried out in microwell plate. Upon addition of tween 20, the ALP molecules were released and catalyzed the hydrolysis of ascorbic acid 2-phosphate (AA-p) to produce ascorbic acid (AA). The latter then donated electron to the graphene/g-C3N4 nanohybrids based photoelectrode, arousing an increased photocurrent signal. The separation of immunoreaction step and PEC signal excitation (i.e. split-type) not only enabled the realization of liposomes based amplification strategy, but also could eliminate the PEC-caused biomolecules damage. The developed PEC method possessed a wide calibration range from 1.0pgmL⁻¹ to 50ngmL⁻¹ and a low detection limit of 0.63pgmL⁻¹. Its practicability was demonstrated by assaying human serum samples. Moreover, the universality of the liposomes-amplified PEC sensing strategy was also demonstrated by developing it into a sensitive microRNA detection method.



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Angiogenesis Inhibition in the Second-Line Treatment of Metastatic Colorectal Cancer. A Definite Conclusion?

Publication date: Available online 29 July 2017
Source:Seminars in Oncology
Author(s): M. Ducreux, P. Österlund, J.P. Pignon




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