DNA Molecular Computation Using the CRISPR-Mediated Reaction and Surface Growth of Gold Nanoparticles.

DNA has emerged as a promising tool to build logic gates for biocomputing. However, prevailing methodologies predominantly rely on hybridization reactions or structural alterations to construct DNA logic gates, which are limited in simplicity and diversity. Herein, we developed simple and smart DNA-based logic gates for biocomputing through the DNA-mediated growth of gold nanomaterials without precise structure design and probe modification. Capitalizing on their excellent plasmonic properties, the surface growth of gold nanomaterials enables distinct wavelength shifts and unique shapes, which are modulated by the composition, length, and concentration of the DNA sequences. Combined with a CRISPR-mediated reaction, we constructed DNA circuits to achieve complicated biocomputing to modulate the surface growth of gold nanomaterials. By implementing logic functions controlled by input-mediated growth of gold nanomaterials, we established YES/NOT, AND/NAND, OR/NOR, XOR, and INHIBIT gates and further constructed cascade logic circuits, parity checker for natural numbers, and gray code encoder, which are promising for DNA biocomputing.

Mn2+-Mediated Modulation of PfAgo Activity for Biosensing.

Argonaute (Ago) as a powerful enzyme has provided new insights into biosensing due to its programmability, high sensitivity, and user-friendly operation. However, current strategies mainly rely on phosphorylated guide DNA to modulate the cleavage activity of Ago, which is limited in versatility and simplicity. Herein, the authors report the Mn2+-enhanced cleavage activity of Ago and employ Mn-ions with variable valence to regulate the activity of Pyrococcus furiosus Ago (PfAgo) for biosensing applications. The conversion of Mn ions with different valence states through MnO2 nanoflowers enables the sensitive detection of ascorbic acid, alkaline phosphatase, and arsenic with limits of detection of 2.5 nmol L-1, 0.009 U L-1, and 0.4 ng mL-1, respectively. A PfAgo-based immunoassay is further developed that allows for the detection of diverse targets, thus providing a promising toolbox to broaden PfAgo-based sensors into versatile bioanalytical and biomedical applications.

Tailoring the Surface and Composition of Nanozymes for Enhanced Bacterial Binding and Antibacterial Activity.

With the advantages of diverse structures, tunable enzymatic activity, and high stability, nanozymes are widely used in medicine, chemistry, food, environment, and other fields. As an alternative to traditional antibiotics, nanozymes attract more and more attention from the scientific researchers in recent years. Developing nanozymes-based antibacterial materials opens up a new avenue for the bacterial disinfection and sterilization. In this review, the classification of nanozymes and their antibacterial mechanisms are discussed. The surface and composition of nanozymes are critical for the antibacterial efficacy, which can be tailored to enhance both the bacterial binding and the antibacterial activity. On the one hand, the surface modification of nanozymes enables binding and targeting of bacteria that improves the antibacterial performance of nanozymes including the biochemical recognition, the surface charge, and the surface topography. On the other hand, the composition of nanozymes can be modulated to achieve enhanced antibacterial performance including the single nanozyme-mediated synergistic and multiple nanozymes-mediated cascade catalytic antibacterial applications. In addition, the current challenges and future prospects of tailoring nanozymes for antibacterial applications are discussed. This review can provide insights into the design of future nanozymes-based materials for the antibacterial treatments.

An ingenious turn-on ratiometric fluorescence sensor for sensitive and visual detection of tetracyclines.

To achieve facile and rapid detection of tetracyclines (TCs), herein, we fabricated an ingenious turn-on ratiometric fluorescence sensor (Ru@ZIF-8) based on embedding red-emitting Ru(bpy)32+ into zeolitic imidazolate framework-8 (ZIF-8). With the introduction of TCs, Ru@ZIF-8 system held the impervious red fluorescence, and generated green fluorescence which originated from the interaction between ZIF-8 and TCs, thereby achieving ratiometric fluorescence strategy through turn-on response signal and stable reference signal. Moreover, the ratiometric response accompanied discernible color change from red to green-yellow, which facilitated detection by naked eyes. The developed sensor exhibited prominent specificity and sensitivity, with detection limits of 2.4, 4.2, 1.6 and 7.2 nM for tetracycline, chlortetracycline, oxytetracycline and doxycycline, respectively. In addition, the satisfactory recoveries were obtained during detecting TCs in drink water, milk and beef, and the test paper-based sensor was successfully applied in real-time visual detection of TCs. All results indicated the feasibility and potential application of Ru@ZIF-8.

Fluorescence and Colorimetric Dual-Mode Ratiometric Sensor Based on Zr-Tetraphenylporphyrin Tetrasulfonic Acid Hydrate Metal-Organic Frameworks for Visual Detection of Copper Ions.

As a special heavy metal ion, copper ions (Cu2+) play an indispensable role in the fields of environmental protection and safety. Their excessive intake not only easily leads to diseases but also affects human health. Therefore, it is particularly important to construct a facile, effective, and highly selective Cu2+ probe. Herein, a novel Zr-tetraphenylporphyrin tetrasulfonic acid hydrate (TPPS) metal-organic framework (ZTM) was fabricated using TPPS as the ligand and exhibited strong red fluorescence with a high quantum yield of 12.22%. In addition, we designed a ratiometric fluorescent probe by introducing green fluorescein isothiocyanate (FITC), which was not subject to environmental interference and had high accuracy. When exposed to different amounts of Cu2+, the fluorescence emission at 667 nm from ZTMs is remarkably quenched, while that at 515 nm from FITC is enhanced, accompanied by a change in the solutions' fluorescence color from red to green under a UV lamp. Besides, the ZTMs solutions display an excellent ratiometric colorimetric response for Cu2+ and produce an obvious color change (from green to colorless) that is visible to the naked eye. The fabricated ZTMs@FITC fluorescent probe exhibits distinguished performance for Cu2+ detection with linear ranges of 0.1 to 5 µM and 5 to 50 µM, as well as a low detection limit of 5.61 nM. Moreover, a colorimetric sensor based on ZTMs exhibits a good linear range from 0.1 to 20 µM for Cu2+ with the detection limit of 4.96 nM. Furthermore, the dual-signal ratiometric sensor has significant specificity for Cu2+ and is successfully applied for monitoring Cu2+ in water samples, which proves its practical application value in the environment and biological systems.

Innovative ratiometric optical strategy: Nonconjugated polymer dots based fluorescence-scattering dual signal output for sensing mercury ions.

A new ratiometric platform was developed for sensing Hg2+, which combined fluorescence and scattering simultaneously. This ratiometric strategy reflected superiorities over conventional methods, since the two independent signals at irrelevant categories meet the requirements of sufficient wavelength separation, stimulation under one excitation, and collection on single instrument. Herein, nonconjugated polymer dots (N-PDs) were served as the recognition unit for Hg2+ with turn-off fluorescence and turn-on scattering. Additionally, two signal collection tactics were proposed to achieve fluorescence and scattering in a window: one was to record down-conversion fluorescence and second-order scattering spectra (FL@SOS), and the other was to gather the fluorescence excited by second-order diffraction light and first-order scattering (SODL-FL@FOS). This ratiometric sensor exhibited outstanding performance toward Hg2+ in the range of 0.1-50 µM with the detection limit of 27 nM. By contrast, the present proposal provided a more ingenious and scalable way to construct ratiometric sensor than traditional approach.

Electrocardiographic localization of peripherally inserted central catheter tip position in critically ill patients with advanced cancer: An application study.

BACKGROUND: We compared the methods of electrocardiogram (ECG) and X-ray localization of the peripherally inserted central catheter (PICC) tip position, in order to find a more convenient, practical, and safe method. OBJECTIVE: To investigate the value of applying electrocardiographic localization of the PICC tip position in critically ill patients with advanced cancer in Hebei Province, China. METHOD: Enrolled 137 advanced cancers requiring PICC placement. The position of the catheter tip was localized with the bedside electrocardiogram in real time. Then, the localization was performed using a chest X-ray (the gold standard). The accuracy of electrocardiographic location was checked. RESULTS: Specific P waves were observed in 130 patients. No change in the P waves was observed for the remaining seven patients. The age of the latter group of patients was more advanced (87.29 [5.15] years), a significant difference to that of the 130 patients with specific P waves (71.58 [14.84] years) (t = -6.704, p < .001). Specific P waves not only involve ascendance in P waves but also ascendance in QRS waves. CONCLUSIONS: The use of an ECG to localize the PICC tip in critically ill patients with advanced cancer may replace the unnecessary use of chest X-rays. Specific P waves not only involve an increase in P waves but also an increase in QRS waves. If there is no change in the P wave, a chest X-ray film must be obtained. In elderly patients, because there is a possibility of catheter tip malposition, a comprehensive evaluation should be performed before surgery.

On-off-on fluorescent sensor for glutathione based on bifunctional vanadium oxide quantum dots induced spontaneous formation of MnO2 nanosheets.

Fluorescence sensing of glutathione by tailor-made chemical sensors is a prospective technique, which could provide simple, fast, and visual detection. Herein, a fluorescence sensor based on vanadium oxide quantum dots (VOx QDs) and permanganate (MnO4-) has been designed for monitoring glutathione. The bifunctional VOx QDs, possessing rich redox chemistry and robust fluorescence (exhibiting fluorescence near 505 nm upon excitation at 450 nm), were synthesized via cryogenic-mediated liquid-phase exfoliation. In the presence of MnO4-, VOx QDs induced the spontaneous formation of MnO2 nanosheets which caused the fluorescence quenching. However, the subsequent introduction of glutathione could trigger MnO2 reduction to Mn2+, and the fluorescence was recovered. Based on this phenomenon, an "on-off-on" fluorescence sensor for glutathione detection was established. Under the optimal conditions, this sensor allowed detection of glutathione in the linear range of 0.5-100 µM with a detection limit of 0.254 µM. Additionally, the proposed strategy revealed the selectivity toward glutathione and the potential of practical application in the analysis of human serum, vegetable, and fruit samples.

Ingenious dual-emitting Ru@UiO-66-NH2 composite as ratiometric fluorescence sensor for detection of mercury in aqueous.

The increasing deterioration of ecosystem derived from heavy metals residues brings about the environmental and food contamination, which presses the exploration of facile platform for monitoring heavy metals. Herein, a ratiometric fluorescence sensor was designed for Hg2+ detection based on the compound of UiO-66-NH2 and Ru(bpy)32+ (Ru@UiO-66-NH2) which was synthesized by situ encapsulation. The innovative composite displayed two emission peaks at 437 and 604 nm, and the addition of Hg2+ could only quench the blue fluorescence due to static quenching and photo-induced electron transfer mechanism, providing an internal standard to promote the precision. Under optimal conditions, the ratiometric Ru@UiO-66-NH2 probe revealed outstanding anti-interference capability and performed with a great limit of detection (LOD) of 0.053 µM for Hg2+, which was 2-fold lower than that of single-color UiO-66-NH2. By merit of Ru@UiO-66-NH2, test hydrogels were fabricated to provide a tactics for visual, rapid and on-site detection of Hg2+. Additionally, the dual-emitting sensing platform presented satisfactory recoveries and reliabilities in lake water, tap water, and drink water, demonstrating the application potential of this proposed ratiometric fluorescence sensor for monitoring Hg2+.

Effect of hypoglycemic anti-deafness capsules in diabetic patients with deafness and toxicological assessment in rats.

OBJECTIVE: Through experiment on animals and clinical trials to explore the safety and efficacy of hypoglycemic anti-deafness capsules on diabetic patients with deafness. METHODS: Total 296 patients with non-insulin dependent diabetes mellitus (NIDDM) were randomly divided into two groups. A treatment group of 164 patients (208 ears) was treated with hypoglycemic anti-deafness capsules based on TCM syndrome differentiation. A control group of 132 patients (184 ears) was treated with glibenclamide and conventional drug treatment for deafness. The following were observed: hearing, fasting plasma glucose (FPG), 2 h postprandial plasma glucose (2hPG), 24 h urine glucose (24hUG), improvement of main symptoms, platelet function, and changes in superoxide dismutase (SOD) and lipid peroxide (LPO) levels. In animal studies, Kunming mice, weighing 18-22 g were used. Half of the mice were males and half were females. Wistar rats, weighing 80-120 g were used. Half of the rats were males and half were females. Male Wistar rats, weighing 200-220 g, were also used. Their acute and chronic toxicity was studied. RESULTS: The hearing improvement was 56.7% in the treatment group and 26.6% in the control group. FPG, 2hPG, and 24hUG were improved significantly (P < 0.05, P < 0.01, P < 0.01, respectively) in the treatment group and 2hPG and 24hUG improved significantly in the control group (P < 0.05, P < 0.05). The improvement in 2hPG and 24hUG in the treatment group was significantly greater than that in the control group P < 0.01).There was no significant difference in FPG between the two groups (P < 0.05). Main symptoms in the treatment group were significantly more improved than those in the control group (P < 0.05, P < 0.01). In the treatment group, platelet adhesion and aggregation, SOD, and LPO were all significantly improved from before treatment (P < 0.05, P < 0.01). However, in the control group, except LOP (P < 0.05), there were no significant differences from before treatment to after (P < 0.05). In animal studies, no obvious acute or long-term toxicity was observed from capsule administration. CONCLUSION: Through experiment on animals and clinical trials, we can found that hypoglycemic anti-deafness capsules could decrease blood glucose and serum triglycerides of alloxan-induced diabetic rats. This herbal capsule is effective for safely treating diabetic patients with deafness.