Tuning the fabrication of knotted reactors via 3D printing techniques and materials

4D-Printed Elution-Peak-Guided Dual-Responsive Monolithic Packing for the Solid-Phase Extraction of Metal Ions

“…Although an SPE column with a monolith packing of cuboids with small feature sizes and interstitial spaces in a fixed packing volume provides a large surface area that could extract more metal ions, based on previous reports and our experience, ,,,− vat photopolymerization 3DP usually cannot fabricate objects with enclosed channels (side length) or holes (diameter) smaller than 0.5 mm because of the inherent resolution of 3D printers and the effect of light scattering. Large void volumes among the interlacing cuboids of a monolithic packing could lead to the significant dispersion (dilution) of the eluted metal ions .…”

“…Under the optimized operating conditions [P (NIPAM) mode] for the SPE column with the 4D-printed dual-responsive monolithic packing (Table S2; sample volume: 0.5 mL; sample throughput: 17.1 h –1 ), the absolute extraction efficiencies of the metal ions ranged from 91.9 to 95.1% [ratios of the elution peak areas (10 μg L –1 ) with and without extraction; Table ], their correlation coefficients ( R ) in the working range were all greater than 0.9997 (Figure S9A,B), and the enhancement factors (EFs) ranged from 13.0 to 19.3 [ratios of H max (10 μg L –1 ) after and before extraction , ]. Compared with previously reported 3D-printed SPE devices − and commercial SPE devices − for sample pretreatment and trace-element determination (Table S3), the SPE column with the 4D-printed dual-responsive monolithic packing developed in this study provided superior analytical characteristics, including much lower MDLs (under the minimum sample volume), higher throughput, and greater extraction capacities. To validate the applicability of our analytical method for the reliable determination of metal ions in natural water and urine samples, the concentrations of the investigated metal ions in an SRM and CRMs were measured.…”

“…Figure 2B reveals that the H max / fwhm values of the metal ions increased when the number of cuboids per layer was increased from 3 to 4 mainly because of the increase in the elution peak areas (Figure S3B) but decreased thereafter because of the trade-off between the increase in the elution peak areas of the metal ions and their dispersion (larger fwhms are induced by increasing the interstitial volume among interlacing cuboids). Figures 2C and S3C indicate that the twisting angle of the interlacing cuboids is optimal at 60°, possibly because of lower shear forces, 47,66 as indicated by the H max /fwhm values and elution peak areas of the metal ions. Figure 2D shows that the H max / fwhm values of the metal ions leveled off when the number of layers of interlacing cuboids was greater than 48 because of the trade-off between the increase in the elution peak areas of the metal ions (Figure S3D) and their dispersion (H max and fwhm increased proportionally).…”

“…Three-dimensional printing (3DP) technologies are highly applicable to the customization of diverse analytical devices featuring special geometric characteristics or functionality. − The coupling of 3D-printed SPE devices with atomic spectrometric techniques has been demonstrated to allow improvements in adaptability, diversity, and analytical performance for trace-metal analysis. − Moreover, emerging four-dimensional printing (4DP) technologies based on the 3DP of stimuli-responsive materials are capable of effectively fabricating stimuli-responsive analytical devices possessing time-dependent shape programming and/or shape-memory properties. − At present, studies utilizing stimuli-responsive materials to improve the analytical performance of conventional SPE schemes are limited. It is necessary to explore the capability of 4DP technologies for advancing SPE-based analytical schemes to develop future sample-preparation techniques.…”