Simultaneous fluorometric determination of the DNAs of Salmonella enterica, Listeria monocytogenes and Vibrio parahemolyticus by using an ultrathin metal-organic framework (type Cu-TCPP).

Ultrathin (<10 nm) nanosheets of a metal-organic framework (MOF-NSs) were prepared in high-yield and scalable production by a surfactant-assisted one-step method. The MOF-NSs possess distinguished affinity for ssDNA but not for dsDNA. This causes the fluorescence of the labeled DNA to be quenched. On binding to the target DNA (shown here for Salmonella enterica, Listeria monocytogenes and Vibrio parahemolyticus), the labeled duplex is released and the fluorescence of the label is restored. The labels Texas Red, Cy3 and FAM were used and give red, red or green fluorescence depending on the kind of pathogen. The detection limits are 28 pM, 35 pM and 15 pM for the gene segments of Salmonella enterica, Listeria monocytogenes and Vibrio parahemolyticus, respectively. Graphical abstract Schematic of an ultrasensitive fluorescent biosensor for multiplex detection of pathogenic DNAs based on ultrathin MOF nanosheets (type Cu-TCPP).

Eye-Readable and Wearable Colorimetric Sensor Arrays for In Situ Monitoring of Volatile Organic Compounds.

Wearable sensors utilize changes in color as a response to physiological stimuli, making them easily recognizable by the naked eye. These colorimetric wearable sensors offer benefits such as easy readability, rapid responsiveness, cost-effectiveness, and straightforward manufacturing techniques. However, their applications in detecting volatile organic compounds (VOCs) in situ have been limited due to the low concentration of complex VOCs and complicated external interferences. Aiming to address these challenges, we introduced readable and wearable colorimetric sensing arrays with a microchannel structure and highly gas-sensitive materials for in situ detection of complex VOCs. The highly gas-sensitive materials were designed by loading gas-sensitive dyes into the porous metal-organic frameworks and further depositing the composites on the electrospun nanofiber membrane. The colorimetric sensor arrays were fabricated using various gas-sensitive composites, including eight dye/MOF composites that respond to various VOCs and two Pd2+/dye/MOF composites that respond to ethylene. This enables the specific recognition of multiple characteristic VOCs. A microfluidic channel made of polydimethylsiloxane (PDMS) was integrated with different colorimetric elements to create a wearable sensor array. It was attached to the surface of fruits to collect and monitor VOCs using the DenseNet classification method. As a proof of concept, we demonstrated the feasibility of the wearable sensing system in monitoring the ripening process of fruits by continuously measuring the VOC emissions from the skin of the fruit.

Integrated Fruit Ripeness Assessment System Based on an Artificial Olfactory Sensor and Deep Learning.

Artificial scent screening systems, inspired by the mammalian olfactory system, hold promise for fruit ripeness detection, but their commercialization is limited by low sensitivity or pattern recognition inaccuracy. This study presents a portable fruit ripeness prediction system based on colorimetric sensing combinatorics and deep convolutional neural networks (DCNN) to accurately identify fruit ripeness. Using the gas chromatography-mass spectrometry (GC-MS) method, the study discerned the distinctive gases emitted by mango, peach, and banana across various ripening stages. The colorimetric sensing combinatorics utilized 25 dyes sensitive to fruit volatile gases, generating a distinct scent fingerprint through cross-reactivity to diverse concentrations and varieties of gases. The unique scent fingerprints can be identified using DCNN. After capturing colorimetric sensor image data, the densely connected convolutional network (DenseNet) was employed, achieving an impressive accuracy rate of 97.39% on the validation set and 82.20% on the test set in assessing fruit ripeness. This fruit ripeness prediction system, coupled with a DCNN, successfully addresses the issues of complex pattern recognition and low identification accuracy. Overall, this innovative tool exhibits high accuracy, non-destructiveness, practical applicability, convenience, and low cost, making it worth considering and developing for fruit ripeness detection.

Shear Exfoliated Metal-Organic Framework Nanosheet-Enabled Flexible Sensor for Real-Time Monitoring of Superoxide Anion.

Recently, two-dimensional metal-organic framework (2D MOF) nanosheets have drawn a lot of attention on account of their various advantages, like ultrathin thickness, ultralarge specific surface area, abundant accessible active sites, favorable solution dispersion properties, and ease of designability. However, until now, it is still difficult to produce 2D MOF nanosheets in large scale, which hinders the practical applications of 2D MOF nanosheets. Here, for the first time, we introduced a novel shear exfoliation method to prepare scalable 2D MOF nanosheets by using a commercial blender. As a proof of concept, we used two kinds of layer-structured MOFs (ELM-12, Cu(bpy)2(OTf)2, bpy = 4,4-bipyridine, OTf = trifluoromethanesulfonate and Zn2(bim)4, bim = benzimidazole) as samples to prepare MOF nanosheets. The thickness of the two kinds of MOF nanosheets obtained is 3-5 nm. Notably, the exfoliated MOF nanosheet (ELM-12) shows improved electrochemical catalytic activity compared with its bulk counterpart. Based on this, an ELM-12 nanosheet-based flexible sensor was developed for detecting superoxide anions (O2•-) released from cancer cells. The fabricated flexible sensor displays excellent sensitivity, selectivity, flexibility, stability, and reproducibility.

Laser-induced noble metal nanoparticle-graphene composites enabled flexible biosensor for pathogen detection.

Noble metal nanoparticle-3D graphene hybrid nanocomposites possess the advantage of nanoparticles and graphene, which have attracted extensive interest. Here we developed a one-step laser induction method to prepare various noble metal nanoparticle-3D graphene nanocomposites. The nanocomposites were converted from polyimide film coated with the corresponding metal precursor-chitosan hydrogel ink. These nanoparticles including gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), and platinum nanoparticles (PtNPs), were evenly distributed on the surface of porous 3D graphene. Furthermore, we prepared an AuNPs-3D graphene interdigitated array electrode using the one-step laser induction method, which was used to fabricate a flexible impedimetric immunosensor for the detection of Escherichia coli O157:H7. The immunosensor shows excellent performance including low detection limit, high selectivity, and great flexibility.

Transumbilical Single-Site Laparoscopic Inguinal Hernia Inversion and Ligation in Girls.

OBJECTIVES: The combination of transumbilical single-site laparoscopic inguinal hernia inversion and ligation is a new approach for girls. We have done 13 cases in our hospital since May 2013. MATERIALS AND METHODS: Thirteen girls with inguinal hernia, from 6 months to 10 years of age, were treated with transumbilical single-site laparoscopy. RESULTS: None of the patients underwent conversion from single-site laparoscopy to the open approach or conventional laparoscopic surgery. The average operation time was 35.15±6.68 minutes. Four cases were found to have a contralateral inguinal hernia. The patients were discharged the day after operation. Follow-up of 7 months to a year with all cases showed no recurrence and no incision complication. CONCLUSIONS: The combination of transumbilical single-site laparoscopic inguinal hernia inversion and ligation is a reliable, safe, and cosmetic herniorrhaphy for girls with inguinal hernia.