Present status and application prospects of green chitin nanowhiskers: A comprehensive review.

Petrochemical resources are non-renewable, which has impeded the development of synthetic polymers. The poor degradability of synthetic polymers poses substantial environmental pressure. Additionally, the high cost of synthetic biopolymers with excellent degradation performance limits their widespread application. Thus, it is crucial to seek green, sustainable, low-cost polymers as alternatives to petrochemical-based synthetic polymers and synthetic biopolymers. Chitin is a natural and renewable biopolymer discovered in crustacean shells, insect exoskeletons, and fungal cell walls. Chitin chains consist of crystalline and amorphous regions. Note that various treatments can be employed to remove the amorphous region, enhancing the crystallinity of chitin. Chitin nanowhiskers are a high crystallinity nanoscale chitin product with a high aspect ratio, a large surface area, adjustable surface morphology, and biocompatibility. They discover widespread applications in biomedicine, environmental treatment, food packaging, and biomaterials. Various methods can be utilized for preparing chitin nanowhiskers, including chemical, ionic liquids, deacetylation, and mechanical methods. However, developing an environmentally friendly preparation process remains a big challenge for expanding their applications in different materials and large-scale production. This article comprehensively analyzes chitin nanowhiskers' preparation strategies and their drawbacks. It also highlights the extensive application in different materials and various fields, besides the potential for commercial application.

Hydrogels based on seafood chitin: From extraction to the development.

Chitin is extensively applied in vast applications due to its excellent biological properties, such as biodegradable and non-toxic. About 50 % of waste generated during seafood processing is chitin. Conventionally, chitin is extracted via chemical method. However, it has many shortcomings. Many novel extraction methods have emerged, including enzymatic hydrolysis, microbial fermentation, ultrasonic or microwave-assisted, ionic liquids, and deep eutectic solvents. Chitin and its derivatives-based hydrogels have attracted much attention due to their excellent properties. Nevertheless, they all have many limitations. Therefore, the preparation and application of chitin and its derivatives-based hydrogels are still facing great challenges. This review focuses on the challenges and prospects for sustainable chitin extraction from seafood waste and the preparation and application of chitin and its derivatives-based hydrogels. First section summarizes the mechanism and application of several methods of extracting chitin. The different extraction methods were evaluated from the aspects of yield, degree of acetylation, and protein and mineral residuals. The shortcomings of the extraction methods are also discussed. Next section summarizes the preparation and application of chitin and its derivatives-based hydrogels. Overall, we hope this mini-review can provide a practical reference for selecting chitin extraction methods from seafood and applying chitin and its derivatives-based hydrogels.

Antiproliferative Activity of Carnosic Acid is Mediated via Inhibition of Cell Migration and Invasion, and Suppression of Phosphatidylinositol 3-Kinases (PI3K)/AKT/Mammalian Target of Rapamycin (mTOR) Signaling Pathway.

BACKGROUND Lung cancer is one of the leading causes of cancer-related mortalities worldwide and majority of these deaths result from non-small cell lung cancer (NSCLC). The primary objective of this research was to determine the anticancer potential of carnosic acid, a plant derived abietane diterpene, against human lung cancer cells, as well as to determine its effects on cell migration and invasion, apoptosis, and the PI3K/AKT/m-TOR signaling pathway. MATERIAL AND METHODS Cell viability was evaluated by Cell Counting Kit-8 (CCK-8) assay; fluorescence microscopy using acridine orange/ethidium bromide stain and Comet assay were used to study cellular apoptosis. In vitro wound healing assay was used to study effects on cell migration; Transwell assay was used to study cell invasion after drug treatment. Western blot assay was used to study effects of carnosic acid on the PI3K/AKT/m-TOR signaling pathway. RESULTS It was shown that carnosic acid could inhibit the growth of A-549 human non-small cell lung carcinoma cells dose-dependently showing an IC50 value of 12.5 µM. This growth inhibition of A-549 cells was mediated via apoptotic cell death as observed by fluorescence microscopy showing nuclear fragmentation and chromatin condensation. Carnosic acid, dose-dependently, also inhibited cell migration and invasion. Finally, western blot assay revealed that carnosic acid also led to inhibition of the PI3K/AKT/m-TOR signaling pathway. CONCLUSIONS In conclusion, our results showed that Carnosic acid has the potential to inhibit cancer cell growth in A-549 lung cancer cells by activating apoptotic death, inhibiting cell migration and invasion and suppressing PI3K/AKT/m-TOR signaling pathway.

Multiplexed DNA detection using a gold nanorod-based fluorescence resonance energy transfer technique.

A fluorescence resonance energy transfer method for multiplex detection DNA based on gold nanorods had been successfully constructed. This method is simple, easy to operate, good selectivity, no requirement to label the probe molecule and can analyze simultaneously multiple targets of DNA in one sample. The limit of detection for the 18-mer, 27-mer and 30-mer targets is 0.72, 1.0 and 0.43 nM at a signal-to-noise ratio of 3. The recoveries of three targets were 96.57-98.07%, 99.12-100.04% and 97.29-99.93%, respectively. The results show that the method can be used to analyze a clinical sample or a biological sample; it also can be used to develop new probes for rapid, sensitive and highly selective multiplex detection of analytes in real samples.

A dynamic attitude measurement system based on LINS.

A dynamic attitude measurement system (DAMS) is developed based on a laser inertial navigation system (LINS). Three factors of the dynamic attitude measurement error using LINS are analyzed: dynamic error, time synchronization and phase lag. An optimal coning errors compensation algorithm is used to reduce coning errors, and two-axis wobbling verification experiments are presented in the paper. The tests indicate that the attitude accuracy is improved 2-fold by the algorithm. In order to decrease coning errors further, the attitude updating frequency is improved from 200 Hz to 2000 Hz. At the same time, a novel finite impulse response (FIR) filter with three notches is designed to filter the dither frequency of the ring laser gyro (RLG). The comparison tests suggest that the new filter is five times more effective than the old one. The paper indicates that phase-frequency characteristics of FIR filter and first-order holder of navigation computer constitute the main sources of phase lag in LINS. A formula to calculate the LINS attitude phase lag is introduced in the paper. The expressions of dynamic attitude errors induced by phase lag are derived. The paper proposes a novel synchronization mechanism that is able to simultaneously solve the problems of dynamic test synchronization and phase compensation. A single-axis turntable and a laser interferometer are applied to verify the synchronization mechanism. The experiments results show that the theoretically calculated values of phase lag and attitude error induced by phase lag can both match perfectly with testing data. The block diagram of DAMS and physical photos are presented in the paper. The final experiments demonstrate that the real-time attitude measurement accuracy of DAMS can reach up to 20″ (1σ) and the synchronization error is less than 0.2 ms on the condition of three axes wobbling for 10 min.

A K(+)-mediated G-quadruplex formation enhancement fluorescence polarization system based on quantum dots for detection of Hg2+ and biothiols.

A fluorescence polarization homogenous system based on CdTe/CdS QDs that employed a K(+)-mediated G-quadruplex as an enhancer was identified for sensitive and selective detection of Hg(2+) and biothiols in complex samples.

DNAzyme self-assembled gold nanorods-based FRET or polarization assay for ultrasensitive and selective detection of copper(II) ion.

In the paper, we have constructed a very simple, sensitive and promising assay for fluorescence biosensor detection of Cu(2+) in aqueous solutions based on FRET between gold nanorods (AuNRs) and the 3'-TAMRA-labeled substrate strand (Sub) of DNAzyme. The fluorescence of the Sub is quenched when the substrate strand-DNAzyme strand (Sub-Enz) duplex is adsorbed on AuNRs surface through electrostatic interaction. In the presence of Cu(2+), the fluorescence is restored due to the decrease of FRET efficiency caused by the specific cleavage of the Sub by the DNAzyme (Enz), which weakens the electrostatic interaction between the AuNRs and short 3'-TAMRA-labeled DNA fragment. This method shows a high sensitivity for Cu(2+) with a detection limit of 9.83 pM (S/N=3) and a linear range from 0.016 nM to 40 nM. At the same time, Cu(2+) can be detected sensitively based on the significantly decreased Fluorescent polarization (FP). The detection limit of 8.40 pM is experimentally achieved for Cu(2+).

An ultrasensitive quantum dots fluorescent polarization immunoassay based on the antibody modified Au nanoparticles amplifying for the detection of adenosine triphosphate.

In this work, an ultrasensitive fluorescent polarization immunoassay (FPIA) method based on the quantum dot/aptamer/antibody/gold nanoparticles ensemble has been developed for the detection of adenosine triphosphate (ATP). DNA hybridization is formed when ATP is present in the PBS solution containing the DNA-conjugated quantum dots (QDs) and antibody-AuNPs. The substantial sensitivity improvement of the antibody-AuNPs-enhanced method is mainly attributed to the slower rotation of fluorescent unit when QDs-labeled oligonucleotides hybridize with antibody modified the gold nanoparticle. As a result, the fluorescent polarization (FP) values of the system increase significantly. Under the optimal conditions, a linear response with ATP concentration is ranged from 8×10(-12) M to 2.40×10(-4) M. The detection limit reached as low as 1.8 pM. The developed work provides a sensitive and selective immunoassay protocol for ATP detection, which could be applied in more bioanalytical systems.

Protein-binding aptamer assisted signal amplification for the detection of influenza A (H1N1) DNA sequences based on quantum dot fluorescence polarization analysis.

We report a fluorescence polarization platform for H1N1 detection based on the construction of a DNA functional QD fluorescence polarization probe and a bi-functional protein binding aptamer (Apt-DNA). The assay has a linear range from 10 nM to 100 nM with a detection limit of 3.45 nM and is selective over the mismatched bases.

A one-step selective fluorescence turn-on detection of cysteine and homocysteine based on a facile CdTe/CdS quantum dots-phenanthroline system.

In this paper, we report a simple, selective, sensitive and low-cost turn-on photoluminescent sensor for cysteine and homocysteine based on the fluorescence recovery of the CdTe/CdS quantum dots (QDs)-phenanthroline (Phen) system. In the presence of Phen, the fluorescence of QDs could be quenched effectively due to the formation of the non-fluorescent complexes between water-soluble thioglycolic acid (TGA)-capped QDs and Phen. Subsequently, upon addition of cysteine and homocysteine, the strong affinity of cysteine and homocysteine to QDs enables Phen to be dissociated from the surface of QDs and to form stable and luminescent complexes with cysteine and homocysteine in solution. Thus, the fluorescence of CdTe/CdS QDs was recovered gradually. A good linear relationship was obtained from 1.0 to 70.0 µM for cysteine and from 1.0 to 90.0 µM for homocysteine, respectively. The detection limits of cysteine and homocysteine were 0.78 and 0.67 µM, respectively. In addition, the method exhibited a high selectivity for cysteine and homocysteine over the other substances, such as amino acids, thiols, proteins, carbohydrates, etc. More importantly, the sensing system can not only achieve quantitative detection of cysteine and homocysteine but also could be applied in semiquantitative cysteine and homocysteine determination by digital visualization. Therefore, as a proof-of-concept, the proposed method has potential application for the selective detection of cysteine and homocysteine in biological fluids.