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A dual fluorescent oligosensor was fabricated to detect kanamycin (KAN) and streptomycin (STR).

A Nd2O3@MIL(Fe)-88A composite was prepared through a hydrothermal method and used to detect dichlorvos.

A universal enzyme strand (E-DNA) recyclable L-histidine (L-His), melamine (MA), and cisplatin (CP) biosensor was fabricated on the basis of a target-specific RNA-cleaving DNAzyme with specific auramine O (AuO) dye instead of thioflavin T. In this strategy, the substrate strand (S-DNA) of the RNA-cleaving site was constructed as an intramolecular stem-loop structure, and a GT-rich sequence was imprisoned in the double-stranded stem which inhibits the formation of stable G-quadruplex (G4cpx) with AuO. The presence of L-His initiates a catalytic reaction for cleaving the RNA site of the S-DNA hydrolytically releasing the GT-rich portion, which subsequently combines with AuO and forms a G4cpx for enhanced fluorescent signal. The subsequent addition of MA uncoils the G4cpx to form T-MA-T dsDNA, or addition of CP unwound the G4cpx to form CP-DNA leading to an intensive decrease of AuO emission. Remarkably, the liberated L-His can ultimately cause several rounds of cleavage, and the liberated E-DNA can catalyze the subsequent reaction with the other S-DNA. The use of L-His and E-DNA repeatedly induces S-DNA cleavage and intensifies the emission signal. The results show that the proposed biosensor is extremely sensitive to L-His, MA, and CP with a detection limit of 0.98, 10, and 3.4 nM respectively. To the best of our knowledge, the utilization of AuO as the G4cpx inducer and stabilizer for L-His, MA, and CP detection in real milk and urine samples has never been reported.

The illegal addition of melamine to dairy products and the contamination of water with Hg2+ are serious threats to human health. This necessitates the search for new and efficient probe for detection of melamine in foods and Hg2+ in water samples.

The increased need for melamine and Pb2+ ion detection systems that are versatile, ultra-sensitive, and easy to use is highly significant.

Increased levels of toxic metal/non-metal ions cadmium (Cd2+) and sulfide (S2−) in the environment can be detrimental to human health.

Silver is often used as a water disinfectant in healthcare institutions as well as in potable water purifiers. Herein, a rapid and sensitive fluorescent biosensor for Ag+ detection was developed using a cobalt-based bi-functional metal–organic framework.

In this study, we have designed a three-fluorophore-labeled Y-shaped DNAzyme with a high catalytic cleavage activity and a three-dimensional (3D) MOF-MoS2NB (metal-organic framework fused with molybdenum disulfide nanobox), which was synthesized as an efficient quencher of the fluorescent biosensor. The synthesized porous 3D MOF-MoS2NBs and Y-shaped DNAzyme exhibited a good analytical response toward the simultaneous multiple detections of Hg2+, Ni2+, and Ag+ ions over the other coexisting metal ions. More specifically, the three kinds of enzyme aptamer and substrate aptamer (SA) were hybridized and annealed to form the Y-shaped DNAzyme structure and labeled with three different fluorophores such as FAM, TAMRA, and ROX over the 3'-end of SA. When the targets were induced, the DNAzyme was triggered to cleave the fluorophore-labeled SAs. Then, the cleaved SAs (FAM-SA, TAMRA-SA, and ROX-SA) were adsorbed on the 3D MOF-MoS2NB surface to quench the fluorescence signal due to a noncovalent interaction (van der Waals and π-π stacking interaction), which transmuted the fluorescence on-state to off-state. As a result, the fluorescence assay confiscated the high selectivity and sensitivity for the target analytes of Hg2+, Ni2+, and Ag+ ions achieved for the detection limits of 0.11 nM, 7.8 μM, and 0.25 nM, respectively. Accordingly, the sensitivity of the developed sensor was explored with a better lower detection limit than the previously reported biosensors. The utility of the designed Y-shaped DNAzyme may find a broad field of application in real water sample analysis with interfering contaminants.

Aim: To evaluate the anti-amnesia effect of Bauhinia purpurea in Scopolamine induced amnesia in rats. Materials and Methods: A total of 30 rats were divided into 5 groups 6 rats in each. Group I considered as normal control. Group II served as negative control. Group III, IV and V were treated with Donepezil (3 mg/kg), ethanolic extract of Bauhinia purpurea 200mg/kg and 400 mg/kg respectively for 14 consecutive days followed by single administration of Scopolamine (3 mg/kg) to all the groups except group I. Cognitive performance was assessed by the Morris water maze, elevated plus maze and passive avoidance paradigm. Acetyl cholinesterase enzyme level, biochemical markers such as lipid peroxidation, reduced glutathione and β amyloid 1 42 level, Neurotransmitters including dopamine and serotonin and histopathological study of rat brain were estimated. Results: Bauhinia purpurea and Donepezil rats showed significant increase in escape latency, step-through latency and decreased transfer latency in respective cognitive models of the Morris water maze, passive avoidance test and elevated plus maze. Additionally, Bauhinia purpurea extract remarkably promoted the cholinergic neurotransmission, decreasing β amyloid protein and protected against the oxidative stress damage as indicated by, increasing reduced glutathione level, lowering the level of lipid peroxidation, restored dopamine and serotonin level in the brain. Furthermore, histopathological studies revealed the reversal of neuronal damage in the treatment group compared to Scopolamine treated rats. Conclusion: Bauhinia purpurea extract showed promising antiamnesia activity against scopolamine induced amnesia in rats. This could be attributed to its brain acetyl cholinesterase level, β amyloid level inhibition, antioxidant activity and alteration in neurotransmitters level. Key words: Bauhinia purpurea, Neuroprotective, Acetylcholinesterase, β amyloid protein, Scopolamine.

In this work, we fabricated a metal-organic framework derived magnetic porous carbon (MPC) composite using a one-pot solid state template method. The formation of the synthesized composite was confirmed with various spectroscopic techniques, and it was proved that the composite can effectively quench the fluorescence of ssDNA. This property was utilized in the specific and efficient recognition of harmful arsenate ions. FAM-labelled single strand DNA (FAM-ssDNA) was adsorbed on the surface of the MPC composite and immobilized viaπ-π stacking interactions, which resulted in the fluorescence emission being quenched. A fluorescence quenching efficiency of 96% was achieved, due to the huge surface area of the MPC composite. Upon the addition of As(v) ions into our sensing system, the fluorescence emission dramatically increased, due to the strong affinity for As(v) of the surface of the MPC composite. Consequently, the adsorbed FAM-ssDNA was spontaneously displaced from the surface of the MPC composite, and so the fluorescence intensity was regained. Based on this mechanism, the fabricated biosensor exhibited a highly sensitive fluorescence response to As(v) in the range from 0 to 15 nM, with a detection limit as low as 630 pM. Furthermore, the sensing system is suitable for diverse biological and environmental samples.

The research outlines a novel ultrasensitive oligosensor which was designed by FRET-based selective simultaneous detection of multiple organic pollutant (chloramphenicol (CP) and 17β-estradiol (17E)) utilizing the MOF-MoS2 nanomaterial with Exo I signal amplification and target recycling strategy. In this oligosensor, the specific oligomers of 17E (ROX-SSO) and CP (TAMRA-SSO) are used as the recognition parts and the ROX and TAMRA as the fluorescent probes. The cubic-MOF incorporated by a few layered MoS2 sheets (MOF-MoS2) is used as oligomer adsorbing material and an efficient fluorescent nanoquencher for reducing the background signal. In this detection approach, the ROX-SSO and TAMRA-SSO probes could be adsorbed on the surface of the MOF-MoS2 through π-stacking and Vander Waals interactions. At the same time, the fluorescence of the ROX and TAMRA could be efficiently quenched due to the energy transfer between fluorophores and MOF-MoS2. In the addition of 17E & CP, the specific oligomers can be preferentially bound with the 17E & CP, and the newly formed ROX-SSO-17E &TAMRA-SSO-CP complex can be released from the MOF-MoS2 surface and the partial recovery of fluorescence signal. Subsequently, the addition of Exo I is to trigger and digest the ROX-SSO-17E &TAMRA-SSO-CP complex, resulted in the remarkable recovery of fluorescence emission. At the same time, the liberated targets mediate a new cycle of digestion, resulting in the ultra-trace detection of targets. Thus, with the aid of the helper MOF-MoS2 the turn-on detection of 17E and CP may be easily accomplished by observing the fluorescence signal of the respective fluorophores from “off” to “on”. Under optimal circumstances, the oligosensor has an excellent accuracy of 17E and CP, with detection limits of 180 and 200 pM, respectively. Furthermore, for the first time, the research successfully utilized this oligosensor to detect 17E and CP in milk, honey and water samples.

Alzheimer’s disease (AD) is a primary degenerative disease of the central nervous system. The progression of Alzheimer’s disease will ultimately lead to dementia, behavioral and cognitive impairments. Increased level of the enzyme acetylcholinesterase AChE plays a key role in hydrolysis of the neurotransmitter Acetylcholine (ACh) which worsen the condition of cognitive dysfunction. Several drug of natural origin are known to possess AChE inhibition and antioxidant activity .The main objective of the present study is to evaluate AChE inhibition and antioxidant activity of the plant Ipomoea Aquatica Forsk .Leaves of Ipomoea Aquatica Forsk was extracted with Chloroform, n-Hexane, Ethanol and mixture of Ethanol: water (6:4) (hydro-alcoholic extract) using soxhlet extraction. All the four extracts were examined for In-Vitro anti-cholinesterase by Ellman’s method and antioxidant activity by DPPH and Hydrogen peroxide radical scavenging assay. Results obtained from the study clearly demonstrates that all four extract has shown promising acetylcholinesterase inhibition activity in hydro alcoholic extract reveals the best inhibition potential with IC50 49.03 μg /ml .Similarly all the extracts projects significant antioxidant activity in DPPH assay with IC50 value ranging from 19.64 to 88.63 μg /ml and in Hydrogen peroxide assay with IC50 value ranging from 56.79 to 137.3 μg /ml.