A Review of Chondroitin Sulfate's Preparation, Properties, Functions, and Applications.

Chondroitin sulfate (CS) is a natural macromolecule polysaccharide that is extensively distributed in a wide variety of organisms. CS is of great interest to researchers due to its many in vitro and in vivo functions. CS production derives from a diverse number of sources, including but not limited to extraction from various animals or fish, bio-synthesis, and fermentation, and its purity and homogeneity can vary greatly. The structural diversity of CS with respect to sulfation and saccharide content endows this molecule with distinct complexity, allowing for functional modification. These multiple functions contribute to the application of CS in medicines, biomaterials, and functional foods. In this article, we discuss the preparation of CS from different sources, the structure of various forms of CS, and its binding to other relevant molecules. Moreover, for the creation of this article, the functions and applications of CS were reviewed, with an emphasis on drug discovery, hydrogel formation, delivery systems, and food supplements. We conclude that analyzing some perspectives on structural modifications and preparation methods could potentially influence future applications of CS in medical and biomaterial research.

Microfluidic Distance Readout Sweet Hydrogel Integrated Paper-Based Analytical Device (µDiSH-PAD) for Visual Quantitative Point-of-Care Testing.

A disposable, equipment-free, versatile point-of-care testing platform, microfluidic distance readout sweet hydrogel integrated paper-based analytical device (µDiSH-PAD), was developed for portable quantitative detection of different types of targets. The platform relies on a target-responsive aptamer cross-linked hydrogel for target recognition, cascade enzymatic reactions for signal amplification, and microfluidic paper-based analytic devices (µPADs) for visual distance-based quantitative readout. A "sweet" hydrogel with trapped glucoamylase (GA) was synthesized using an aptamer as a cross-linker. When target is present in the sample, the "sweet" hydrogel collapses and releases enzyme GA into the sample, generating glucose by amylolysis. A hydrophilic channel on the µPADs is modified with glucose oxidase (GOx) and colorless 3,3'-diaminobenzidine (DAB) as the substrate. When glucose travels along the channel by capillary action, it is converted to H2O2 by GOx. In addition, DAB is converted into brown insoluble poly-3,3'-diaminobenzidine [poly(DAB)] by horseradish peroxidase, producing a visible brown bar, whose length is positively correlated to the concentration of targets. The distance-based visual quantitative platform can detect cocaine in urine with high selectivity, sensitivity, and accuracy. Because the target-induced cascade reaction is triggered by aptamer/target recognition, this method is widely suitable for different kinds of targets. With the advantages of low cost, ease of operation, general applicability, and disposability with quantitative readout, the µDiSH-PAD holds great potential for portable detection of trace targets in environmental monitoring, security inspection, personalized healthcare, and clinical diagnostics.

Surface-Enhanced Raman Scattering Active Plasmonic Nanoparticles with Ultrasmall Interior Nanogap for Multiplex Quantitative Detection and Cancer Cell Imaging.

Due to its large enhancement effect, nanostructure-based surface-enhanced Raman scattering (SERS) technology had been widely applied for bioanalysis and cell imaging. However, most SERS nanostructures suffer from poor signal reproducibility, which hinders the application of SERS nanostructures in quantitative detection. We report an etching-assisted approach to synthesize SERS-active plasmonic nanoparticles with 1 nm interior nanogap for multiplex quantitative detection and cancer cell imaging. Raman dyes and methoxy poly(ethylene glycol) thiol (mPEG-SH) were attached to gold nanoparticles (AuNPs) to prepare gold cores. Next, Ag atoms were deposited on gold cores in the presence of Pluronic F127 to form a Ag shell. HAuCl4 was used to etch the Ag shell and form an interior nanogap in Au@AgAuNPs, leading to increased Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs was found to be more uniform than that of aggregated AuNPs. Finally, Au@AgAuNPs were used for multiplex quantitative detection and cancer cell imaging. With the advantages of simple and rapid preparation of Au@AgAuNPs with highly uniform, stable, and reproducible Raman intensity, the method reported here will widen the applications of SERS-active nanoparticles in diagnostics and imaging.

Target-responsive DNA hydrogel mediated "stop-flow" microfluidic paper-based analytic device for rapid, portable and visual detection of multiple targets.

A versatile point-of-care assay platform was developed for simultaneous detection of multiple targets based on a microfluidic paper-based analytic device (µPAD) using a target-responsive hydrogel to mediate fluidic flow and signal readout. An aptamer-cross-linked hydrogel was used as a target-responsive flow regulator in the µPAD. In the absence of a target, the hydrogel is formed in the flow channel, stopping the flow in the µPAD and preventing the colored indicator from traveling to the final observation spot, thus yielding a "signal off" readout. In contrast, in the presence of a target, no hydrogel is formed because of the preferential interaction of target and aptamer. This allows free fluidic flow in the µPAD, carrying the indicator to the observation spot and producing a "signal on" readout. The device is inexpensive to fabricate, easy to use, and disposable after detection. Testing results can be obtained within 6 min by the naked eye via a simple loading operation without the need for any auxiliary equipment. Multiple targets, including cocaine, adenosine, and Pb(2+), can be detected simultaneously, even in complex biological matrices such as urine. The reported method offers simple, low cost, rapid, user-friendly, point-of-care testing, which will be useful in many applications.

Target-responsive DNAzyme cross-linked hydrogel for visual quantitative detection of lead.

Because of the severe health risks associated with lead pollution, rapid, sensitive, and portable detection of low levels of Pb(2+) in biological and environmental samples is of great importance. In this work, a Pb(2+)-responsive hydrogel was prepared using a DNAzyme and its substrate as cross-linker for rapid, sensitive, portable, and quantitative detection of Pb(2+). Gold nanoparticles (AuNPs) were first encapsulated in the hydrogel as an indicator for colorimetric analysis. In the absence of lead, the DNAzyme is inactive, and the substrate cross-linker maintains the hydrogel in the gel form. In contrast, the presence of lead activates the DNAzyme to cleave the substrate, decreasing the cross-linking density of the hydrogel and resulting in dissolution of the hydrogel and release of AuNPs for visual detection. As low as 10 nM Pb(2+) can be detected by the naked eye. Furthermore, to realize quantitative visual detection, a volumetric bar-chart chip (V-chip) was used for quantitative readout of the hydrogel system by replacing AuNPs with gold-platinum core-shell nanoparticles (Au@PtNPs). The Au@PtNPs released from the hydrogel upon target activation can efficiently catalyze the decomposition of H2O2 to generate a large volume of O2. The gas pressure moves an ink bar in the V-chip for portable visual quantitative detection of lead with a detection limit less than 5 nM. The device was able to detect lead in digested blood with excellent accuracy. The method developed can be used for portable lead quantitation in many applications. Furthermore, the method can be further extended to portable visual quantitative detection of a variety of targets by replacing the lead-responsive DNAzyme with other DNAzymes.

Au@Pt nanoparticle encapsulated target-responsive hydrogel with volumetric bar-chart chip readout for quantitative point-of-care testing.

Point-of-care testing (POCT) with the advantages of speed, simplicity, portability, and low cost is critical for the measurement of analytes in a variety of environments where access to laboratory infrastructure is lacking. While qualitative POCTs are widely available, quantitative POCTs present significant challenges. Here we describe a novel method that integrates an Au core/Pt shell nanoparticle (Au@PtNP) encapsulated target-responsive hydrogel with a volumetric bar-chart chip (V-Chip) for quantitative POCT. Upon target introduction, the hydrogel immediately dissolves and releases Au@PtNPs, which can efficiently catalyze the decomposition of H2 O2 to generate a large volume of O2 to move of an ink bar in the V-Chip. The concentration of the target introduced can be visually quantified by reading the traveling distance of the ink bar. This method has the potential to be used for portable and quantitative detection of a wide range of targets without any external instrument.

Fabrication of carvacrol loaded cellulose acetate phthalate/shellac composite film and its application to mackerel fillets preservation.

In this research, the carvacrol (CAR) loaded cellulose acetate phthalate (CAP) /shellac (SH) films were prepared via electrostatic repulsion strategy and casting method. The CAP/SH-CAR films demonstrated excellent tensile strength, while also exhibiting good UV light barrier and thermal stability. The results showed that the addition of CAR significantly improved the barrier of the CAP film to water vapor and oxygen permeability. When the addition amount of CAR was 0.9 % (w/w) with respect to CAP content, the CAP/SH-CAR films exhibited good antibacterial activity and effectively reduced the growth of S. aureus and E. coli by approximately 47.9 % and 50.9 %, respectively. The presence of SH improved the retention rate of CAR in CAP/SH-CAR films, with the retention rate ranging from 45.2 to 56.8 %. Finally, the CAP/SH-CAR films were applied to preserve the mackerel fillets, indicating that the rate of freshness deterioration had been delayed and showing a good freshness preservation effect. Therefore, the CAP/SH-CAR films have the potential to be used as food packaging materials.

Facile fabricate sandwich-structured molecularly imprinted dopamine polymer for simultaneously specific capture of Low-density lipoprotein and eliminate "bad cholesterol".

A simplified approach for preparation of sandwich type molecularly imprinted polymers (PPDA-MIPs) is proposed for simultaneously identify Low-density lipoprotein (LDL) and dispose "bad cholesterol". Porous polydopamine nanosphere (PPDA) is applied as a matrix for immobilization of LDL, and the imprinted layer is formed by dopamine acting as a functional monomer. Since imprinted cavities exhibit shape memory effects in terms of recognizing selectivity, the PPDA-MIPs exhibit excellent selectivity toward LDL and a substantial binding capacity of 550.3 µg mg-1. Meanwhile, six adsorption/desorption cycles later, the adsorption efficiency of 83.09 % is still achieved, indicating the adequate stability and reusability of PPDA-MIPs. Additionally, over 80 % of cholesterol is recovered, indicating the completeness of "bad cholesterol" removal in LDL. Lastly, as demonstrated by gel electrophoresis, PPDA-MIPs performed satisfactory behavior for the removal of LDL from the goat serum sample.

Recent studies on proteins and polysaccharides-based pH-responsive fluorescent materials.

Polymer-based pH-responsive fluorescent materials have the characteristics of fast response, real-time monitoring, visualisation, and easy forming. Consequently, they have attracted widespread attention in wound healing, sweat monitoring, security and anti-counterfeiting, freshness detection of aquatic products, metal-ion sensing and bioimaging. This paper analyses the preparation principles and characteristics of pH-responsive fluorescent materials based on cellulose, chitosan and proteins. It then outlines the fluorescence properties, environmental response mechanisms and applications of various luminescent materials. Next, the research indicates that amines, N-heterocyclic rings, carboxyl groups and amino plasmonic groups on the fluorescent molecule structure and polymer skeleton appear to change the degree of ionisation under acid or alkali stimulation, which affects the light absorption ability of chromophore electrons, thus producing fluorescence changes in fluorescent materials under different pH stimuli. On this basis, the challenges and growth encountered in the development of proteins and polysaccharides-based pH-responsive fluorescent materials were prospected to provide theoretical references and technical support for constructing pH-responsive fluorescent materials with high stability, high sensitivity, long-lasting pH-response and wide detection range.

[Comparative study on pharmacokinetics and tissue distribution of a novel microemulsion based on the paclitaxel/L-OH lipid complex and paclitaxel injection in cremophor].

The pharmacokinetics and tissue distributions of the novel paclitaxel microemulsion based on the L-OH lipid complex made in our laboratory were studied in this article with the commercial paclitaxel injection in cremophor as reference preparation by injected intravenously with single dose of 5 mg x kg(-1) in rats. LC-MS/MS method was used to determine the drug concentration in plasma and calculate the pharmacokinetic parameters. [3H]-paclitaxel was used to reveal the tissue distributions of different organs in 0.5 h, 3 h, 24 h and 120 h. The results indicated that the AUC of the emulsion group descended to 42.55%, with the CLz and Vz increased by 2.27 times and 3.81 times respectively. Tissue distribution results revealed that the emulsion showed a significantly increase in liver and spleen with a peak concentration up to 5 times; a slightly increase was observed in lung with no statistical differences; a significantly decrease in heart, kidney, gastrointestinal tract, bone marrow, aorta, thymus, pancreas, fat, muscle, skin, seminal vesicle, reproductive organs and brain with a drop of 40%-80%. These results indicated that paclitaxel microemulsion based on L-OH lipid complexes can remarkably reduced the blood exposure, accelerate plasma clearance rate and increase distribution volume. The fact that paclitaxel microemulsion tended to be uptake by reticuloendothelial system (RES) contributed to the target in liver, spleen and lung, and help to reduce the toxicity in blood, heart, kidney and gastrointestinal tract.

Simple lignin-based, light-driven shape memory polymers with excellent mechanical properties and wide range of glass transition temperatures.

Lignin is the most abundant biomass source of aromatic hydrocarbons but, at present, is not effectively utilized. The development of simple and efficient methods for producing lignin-based polymers to replace petroleum-based products is an important strategy for promoting environmentally friendly and sustainable materials and controlling carbon emissions. In this work, lignin-based, light-driven shape memory polymers (ELIDs) with improved mechanical properties have been prepared from enzymatic hydrolysis lignin, itaconic acid and 1,12-dodecanediol, without any chemical modification of the lignin. The polymers contain large proportions of lignin (20-40 wt%, designated ELID20 to ELID40) and their mechanical properties are dependent on the lignin content. Maximum tensile strength (46.9 MPa) was achieved with ELID30, maximum elongation at break (93.7 %) was achieved with ELID20 and highest fracture energy (10.75 J cm-3) was achieved with ELID25. These excellent mechanical properties are accompanied by good thermal stability and a wide range of glass transition temperatures (21.2-157.3 °C), supporting a broad range of applications. The shape fixation rate (Rf) and shape recovery rate (Rr) were highest for ELID30 (98.7 % and 97.4 %, respectively). Under 1 sun simulated solar irradiation, ELID20 reached a temperature exceeding the glass transition temperature in 15 s and, under 3 sun simulated solar irradiation, ELID30 reached a temperature of 130 °C and shape recovered in 60 s. The excellent mechanical properties and good light-driven shape memory of ELIDs provide inspiration for the development and utilization of lignin-based polymers.

High lignin, light-driven shape memory polymers with excellent mechanical performance.

With the gradual global standardization of carbon emission policies, the development of renewable resources to replace traditional fossil resources is assuming increasing importance. Lignin is the most abundant natural source of aromatic compounds and has the potential to replace petroleum-based aromatic hydrocarbons. In this work, the rigid benzene ring structure and excellent photothermal properties of lignin were exploited to produce light-driven lignin-based shape memory polymers (ELEPs) that contain high proportions of lignin and have good mechanical properties. Enzymatically hydrolyzed lignin (EL), epoxy soybean oil (ESO) and polyethylene glycol (PEG 400) were copolymerized and cured to form ELEPs, which have a disordered three-dimensional network. An increase in the proportion of EL from 40 to 60 wt% enhanced the mechanical properties, as reflected by an increase in tensile strength from 11.3 to 30.8 MPa and in the glass transition temperature (Tg) from 93 to 115.7 °C. Under simulated solar irradiation (2000 W m-2), ELEP50, which contains 50 wt% lignin and has a Tg of 105 °C, reached a surface temperature as high as 105 °C and achieved shape memory within 20 s. The shape fixation ratio (Rf) and shape recovery ratio (Rr) were stably >98 % and >97 %, respectively, over eight cycles in a bending-recovery experiment. The unique light-driven shape memory properties of ELEPs provide a method for high value utilization of EL, and the design strategy offers new ideas for producing novel intelligent materials.

Integrating Target-Responsive Hydrogel with Pressuremeter Readout Enables Simple, Sensitive, User-Friendly, Quantitative Point-of-Care Testing.

Point-of-care testing (POCT) with the advantages of speed, simplicity, and low cost, as well as no need for instrumentation, is critical for the measurement of analytes in a variety of environments lacking access to laboratory infrastructure. In the present study, a hydrogel pressure-based assay for quantitative POCT was developed by integrating a target-responsive hydrogel with pressuremeter readout. The target-responsive hydrogels were constructed with DNA grafted linear polyacrylamide and the cross-linking DNA for selective target recognition. The hydrogel response to the target substance allows release of the preloaded Pt nanoparticles, which have good stability and excellent catalytic ability for decomposing H2O2 to O2. Then, the generated O2 in a sealed environment leads to significant pressure increase, which can be easily read out by a handheld pressuremeter. Using this target-responsive hydrogel pressure-based assay, portable and highly sensitive detection of cocaine, ochratoxin A, and lead ion were achieved with excellent accuracy and selectivity. With the advantages of portability, high sensitivity, and simple sample processing, the hydrogel pressure-based assay shows great potential for quantitative POCT of a broad range of targets in resource-limited settings.

A portable visual detection method based on a target-responsive DNA hydrogel and color change of gold nanorods.

A new method based on a functional DNA crosslinked hydrogel as a target-responsive unit and gold nanorods (AuNRs) as a multicolor signal readout circuit was developed for the sensitive and visual detection of different targets. The color variation of the AuNR solution was correlated with the concentration of the target. This system can be extended to detect various targets by designing the corresponding target-responsive DNA hydrogels.

Swelling behaviors of porous lignin based poly (acrylic acid).

Supramolecular cross-linked porous lignin based poly (acrylic acid) [LBPAA] was lab-synthesized by copolymerizing lignin grafted N, N'-methylene-bisacrylamide (LM) and acrylic acid. LBPAA successfully acted as a water retention agent with salt resistance and biodegradation for agricultural applications. Lignin was found to improve its swelling behaviors with higher water retention, fast swelling and de-swelling rates. The salt tolerance was stronger in the case of LBPAA (60 PAA/40 LM) [60 wt% PAA/40 wt% LM], i.e., 145.79 g·g(-1) higher than PAA at 0.09 mM KCl solution. The effect of ion charges on the LBPAA swelling ratio was greater than that of ionic radius. The weight loss of LBPAA (60 PAA/40 LM) was 5.47%, 4.96%, and 4.56% in the soil of Tangshan, Harbin, and Sian, respectively. The soil moisture content and clay content were observed to decrease gradually with increasing the burial time. The biodegradation test of LBPAA (60 PAA/40 LM) composite exhibited different bacterial colony forming units (CFU), the soil of Tangshan was 2.0 × 10(3) CFU·g(-1) soil, 7.0 × 10(3) CFU·g(-1) soil for Harbin, and 6.10 × 10(4) CFU·g(-1) soil for Sian. However, the organic matter contents in the soils did not have significant changes (Tangshan 6.21 mg·g(-1), Harbin 0.61 mg·g(-1), and Sian 0.405 mg·g(-1)).

Design and synthesis of target-responsive hydrogel for portable visual quantitative detection of uranium with a microfluidic distance-based readout device.

Due to uranium's increasing exploitation in nuclear energy and its toxicity to human health, it is of great significance to detect uranium contamination. In particular, development of a rapid, sensitive and portable method is important for personal health care for those who frequently come into contact with uranium ore mining or who investigate leaks at nuclear power plants. The most stable form of uranium in water is uranyl ion (UO2(2+)). In this work, a UO2(2+) responsive smart hydrogel was designed and synthesized for rapid, portable, sensitive detection of UO2(2+). A UO2(2+) dependent DNAzyme complex composed of substrate strand and enzyme strand was utilized to crosslink DNA-grafted polyacrylamide chains to form a DNA hydrogel. Colorimetric analysis was achieved by encapsulating gold nanoparticles (AuNPs) in the DNAzyme-crosslinked hydrogel to indicate the concentration of UO2(2+). Without UO2(2+), the enzyme strand is not active. The presence of UO2(2+) in the sample activates the enzyme strand and triggers the cleavage of the substrate strand from the enzyme strand, thereby decreasing the density of crosslinkers and destabilizing the hydrogel, which then releases the encapsulated AuNPs. As low as 100nM UO2(2+) was visually detected by the naked eye. The target-responsive hydrogel was also demonstrated to be applicable in natural water spiked with UO2(2+). Furthermore, to avoid the visual errors caused by naked eye observation, a previously developed volumetric bar-chart chip (V-Chip) was used to quantitatively detect UO2(2+) concentrations in water by encapsulating Au-Pt nanoparticles in the hydrogel. The UO2(2+) concentrations were visually quantified from the travelling distance of ink-bar on the V-Chip. The method can be used for portable and quantitative detection of uranium in field applications without skilled operators and sophisticated instruments.

Design and synthesis of target-responsive aptamer-cross-linked hydrogel for visual quantitative detection of ochratoxin A.

A target-responsive aptamer-cross-linked hydrogel was designed and synthesized for portable and visual quantitative detection of the toxin Ochratoxin A (OTA), which occurs in food and beverages. The hydrogel network forms by hybridization between one designed DNA strand containing the OTA aptamer and two complementary DNA strands grafting on linear polyacrylamide chains. Upon the introduction of OTA, the aptamer binds with OTA, leading to the dissociation of the hydrogel, followed by release of the preloaded gold nanoparticles (AuNPs), which can be observed by the naked eye. To enable sensitive visual and quantitative detection, we encapsulated Au@Pt core-shell nanoparticles (Au@PtNPs) in the hydrogel to generate quantitative readout in a volumetric bar-chart chip (V-Chip). In the V-Chip, Au@PtNPs catalyzes the oxidation of H2O2 to generate O2, which induces movement of an ink bar to a concentration-dependent distance for visual quantitative readout. Furthermore, to improve the detection limit in complex real samples, we introduced an immunoaffinity column (IAC) of OTA to enrich OTA from beer. After the enrichment, as low as 1.27 nM (0.51 ppb) OTA can be detected by the V-Chip, which satisfies the test requirement (2.0 ppb) by the European Commission. The integration of a target-responsive hydrogel with portable enrichment by IAC, as well as signal amplification and quantitative readout by a simple microfluidic device, offers a new method for portable detection of food safety hazard toxin OTA.