Adsorption isotherms of La³⁺ and Ce³⁺ on SA-PGA gel particles.

<p>Adsorption isotherms of La³⁺ and Ce³⁺ on SA-PGA gel particles.</p

Digital photographs of SA gels (a, b, c, d) and SA-PGA gels (e, f, h, i).

<p>Digital photographs of SA gels (a, b, c, d) and SA-PGA gels (e, f, h, i).</p

Adsorption of Rare Earths(Ⅲ) Using an Efficient Sodium Alginate Hydrogel Cross-Linked with Poly-γ-Glutamate

<div><p>With the exploitation of rare earth ore, more and more REEs came into groundwater. This was a waste of resources and could be harmful to the organisms. This study aimed to find an efficient adsorption material to mitigate the above issue. Through doping sodium alginate (SA) with poly-γ-glutamate (PGA), an immobilized gel particle material was produced. The composite exhibited excellent capacity for adsorbing rare earth elements (REEs). The amount of La³⁺ adsorbed on the SA-PGA gel particles reached approximately 163.93 mg/g compared to the 81.97 mg/g adsorbed on SA alone. The factors that potentially affected the adsorption efficiency of the SA-PGA composite, including the initial concentration of REEs, the adsorbent dosage, and the pH of the solution, were investigated. 15 types of REEs in single and mixed aqueous solutions were used to explore the selective adsorption of REEs on gel particles. Scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy analyses of the SA and SA-PGA gel beads suggested that the carboxyl groups in the composite might play a key role in the adsorption process and the morphology of SA-PGA changed from the compact structure of SA to a porous structure after doping PGA. The kinetics and thermodynamics of the adsorption of REEs were well fit with the pseudo-second-order equation and the Langmuir adsorption isotherm model, respectively. It appears that SA-PGA is useful for recycling REEs from wastewater.</p></div

Assignment of the main vibrational modes.(C_HCl:0.1mol/L,50mL).

<p>Assignment of the main vibrational modes.(C_HCl:0.1mol/L,50mL).</p

Selective adsorption experiments of REEs: (a) single solution, (b) mixed solution.

<p>Selective adsorption experiments of REEs: (a) single solution, (b) mixed solution.</p

Effects of the initial concentration of REEs, adsorbent dosage, and pH of solution on the adsorption by gel particles (Adsorption conditions: temperature 30°C; 150 rpm; and 3h adsorption time).

<p>Effects of the initial concentration of REEs, adsorbent dosage, and pH of solution on the adsorption by gel particles (Adsorption conditions: temperature 30°C; 150 rpm; and 3h adsorption time).</p

Adsorption kinetic curves (a) and pseudo-second-order plots (b) for the adsorption by gel particles.

<p>Adsorption kinetic curves (a) and pseudo-second-order plots (b) for the adsorption by gel particles.</p

Regeneration of these two gel particles (Adsorption conditions: 30 ml of 0.05 M hydrochloric acid solution, 30 min, 150 rpm, 30°C).

<p>Regeneration of these two gel particles (Adsorption conditions: 30 ml of 0.05 M hydrochloric acid solution, 30 min, 150 rpm, 30°C).</p

FT-IR spectra of SA, PGA, SA-PGA, SA-PAG-La, and SA-PGA-La-HCl gels.

<p>FT-IR spectra of SA, PGA, SA-PGA, SA-PAG-La, and SA-PGA-La-HCl gels.</p

Improving the Signal-to-Background Ratio during Catalytic Hairpin Assembly through Both-End-Blocked DNAzyme

Catalyzed hairpin assembly (CHA) is an important DNA engineering tool for a variety of applications such as DNA nanotechnology and biosensing. Here we report a hairpin-type of both-end-blocked DNAzyme to improve the signal-to-background ratio during the CHA process. In the design, the DNAzyme activity can be blocked efficiently via locking both ends of the G-rich DNAzyme sequence in the loop and stem (blocking efficiency = 96%) and can be easily recovered during the CHA process (activation efficiency = 94%). The both-end-blocked DNAzyme is by far the most sensitive optical detection mode for monitoring the CHA process that can be used for determination of 0.05 fmol miRNA-21. The fabricated CHA-DNAzyme sensing system was also able to discriminate miRNA-21 from single-/three-base mismatch miRNA-21. The feasibility of real application was also tested via detection of miRNA-21 levels in tumor cell samples. Therefore, the sensing system with the advantages of convenience, high sensitivity, and selectivity is an appealing strategy for miRNA detection