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Technologically critical rare-earth elements are notoriously difficult to separate, owing to their subtle differences in ionic radius and coordination number1–3. The natural lanthanide-binding protein lanmodulin (LanM)4,5 is a sustainable alternative to conventional solvent-extraction-based separation6. Here we characterize a new LanM, from Hansschlegelia quercus (Hans-LanM), with an oligomeric state sensitive to rare-earth ionic radius, the lanthanum(III)-induced dimer being >100-fold tighter than the dysprosium(III)-induced dimer. X-ray crystal structures illustrate how picometre-scale differences in radius between lanthanum(III) and dysprosium(III) are propagated to Hans-LanM’s quaternary structure through a carboxylate shift that rearranges a second-sphere hydrogen-bonding network. Comparison to the prototypal LanM from Methylorubrum extorquens reveals distinct metal coordination strategies, rationalizing Hans-LanM’s greater selectivity within the rare-earth elements. Finally, structure-guided mutagenesis of a key residue at the Hans-LanM dimer interface modulates dimerization in solution and enables single-stage, column-based separation of a neodymium(III)/dysprosium(III) mixture to >98% individual element purities. This work showcases the natural diversity of selective lanthanide recognition motifs, and it reveals rare-earth-sensitive dimerization as a biological principle by which to tune the performance of biomolecule-based separation processes.

Biocement formed through microbially induced calcium carbonate precipitation (MICP) is an emerging biotechnology focused on reducing the environmental impact of concrete production. In this system, CO

Microbes are critical drivers of all ecosystems and many biogeochemical processes, yet little is known about how the three-dimensional (3D) organization of these dynamic organisms contributes to their overall function. To probe how biofilm structure affects microbial activity, we developed a technique for patterning microbes in 3D geometries using projection stereolithography to bioprint microbes within hydrogel architectures. Bacteria were printed and monitored for biomass accumulation, demonstrating postprint viability of cells using this technique. We verified our ability to integrate biological and geometric complexity by fabricating a printed biofilm with two E. coli strains expressing different fluorescence. Finally, we examined the target application of microbial absorption of metal ions to investigate geometric effects on both the metal sequestration efficiency and the uranium sensing capability of patterned engineered Caulobacter crescentus strains. This work represents the first demonstration of the stereolithographic printing of microbials and presents opportunities for future work of engineered biofilms and other complex 3D structured cultures.

Coal byproducts could be a promising feedstock to alleviate the supply risk of critical rare earth elements (REEs) due to their abundance and REE content. Herein, we investigated the economic and e...

Description, Demystifying the elusive chemistry of actinium leads to novel opportunities in radioisotope production and nuclear medicine., Actinium-based therapies could revolutionize cancer medicine but remain tantalizing due to the difficulties in studying and limited knowledge of Ac chemistry. Current efforts focus on small synthetic chelators, limiting radioisotope complexation and purification efficiencies. Here, we demonstrate a straightforward strategy to purify medically relevant radiometals, actinium(III) and yttrium(III), and probe their chemistry, using the recently discovered protein, lanmodulin. The stoichiometry, solution behavior, and formation constant of the 228Ac3+-lanmodulin complex and its 90Y3+/natY3+/natLa3+ analogs were experimentally determined, representing the first actinium-protein and strongest actinide(III)-protein complex (sub-picomolar Kd) to be characterized. Lanmodulin’s unparalleled properties enable the facile purification recovery of radiometals, even in the presence of >10+10 equivalents of competing ions and at ultratrace levels: down to 2 femtograms 90Y3+ and 40 attograms 228Ac3+. The lanmodulin-based approach charts a new course to study elusive isotopes and develop versatile chelating platforms for medical radiometals, both for high-value separations and potential in vivo applications.

Actinium-based therapies could revolutionize cancer medicine but remain tantalizing due to the difficulties in studying Ac chemistry. Current efforts focus on small synthetic chelators, limiting radioisotope complexation and purification efficiencies. Here we demonstrate how a recently discovered protein, lanmodulin, can be utilized to efficiently bind, recover, and purify medically-relevant radiometals, actinium(III) and yttrium(III), and probe their chemistry. The stoichiometry, solution behavior, and formation constant of the 228Ac-lanmodulin complex (Ac3LanM, Kd, 865 femtomolar) and its 90Y/natY/natLa analogues were experimentally determined, representing both the first actinium-protein and most stable actinide(III)-protein species to be characterized. Lanmodulin’s unparalleled properties enable the facile purification-recovery of radiometals, even in the presence of >10+10 equivalents of competing ions and at ultra-trace levels: down to 2 femtograms 90Y and 40 attograms 228Ac. The lanmodulin-based approach charts a new course to study elusive isotopes and develop versatile chelating platforms for medical radiometals, both for high-value separations and potentially in vivo applications.

Many experimental protocols must be executed in vitro due to a lack of cell-permeable analysis probes. For instance, the cellular signaling moderator RAS proteins alternate between the active GTP-binding and the inactive GDP-binding states. Though many GTP analogs can serve as probes for RAS activity analysis, their cell impermeability renders in vivo analysis impossible. On the other hand, the lipid/calcium/phosphate (LCP) nanoparticle has enabled efficient intracellular delivery of a nucleotide analog as a chemotherapy agent. Thus, using RAS analysis and LCP nanoparticle as the prototype, we tackled the cell-impermeability issue via nanoparticle-mediated intracellular delivery of the analysis probe. Briefly, BODIPY-FT-GTP-γ-S, a GTP analog that becomes fluorescent only upon protein binding, was chosen as the analysis probe, so that GTP binding can be quantified by fluorescent activity. BODIPY-FT-GTP-γ-S-loaded LCP-nanoparticle was synthesized for efficient intracellular BODIPY-FT-GTP-γ-S delivery. Binding of the delivered BODIPY-FT-GTP-γ-S to the RAS proteins were consistent with previously reported observations; the RAS GTP binding activity was reduced in serum-starved cells; and a transient activation peak of the binding activity was observed upon subsequent serum reactivation of the cells. In a word, nanoparticle-mediated probe delivery enabled an in vivo RAS analysis method. The approach should be applicable to a wide variety of analysis protocols.

Functionalized alginate microbeads (MB) have been widely used for three-dimensional (3D) culture of cells and creating biomimetic tissue models. However, conventional methods for preparing these MB suffer from poor polydispersity, due to coalescence of droplets during the gelation process and post-aggregation. It remains an immense challenge to prepare alginate MB with narrow size distribution and uniform shape, especially when their diameters are similar to the size of cells. In this work, we developed a simple method to produce monodispersed, cell-size alginate MB through microfluidic emulsification, followed by a controlled shrinkage process and gelation in mineral oil with low concentration of calcium ion (Ca2+). During the gelation process caused by the diffusion of Ca2+ from the oil to water phase, a large amount of satellite droplets with sub-micrometer sizes was formed at the water/oil interface. As a result, each original droplet was transformed to one shrunken-MB with much smaller size and numerous submicron-size satellites. To explore the feasibility of the shrunken-MB for culturing with cells, we have successfully modified a variety of polymer nanofilms on MB surfaces using a layer-by-layer assembly approach. Finally, the nanofilm-modified MB was applied to a 3D culture of GFP-expressing fibroblast cells and demonstrated good biocompatibility.

Self-floating hollow glass microspheres (HGMS) modified with tumor-specific antibodies have been developed for capture of circulating tumor cells (CTCs), and have demonstrated effective cell isolation and good viability of isolated cancer cells. However, the capture efficiency decreases dramatically if the spiked cell concentration is low, possibly due to insufficient interactions between cancer cells and the HGMS’ surface. In order to apply the HGMS-based CTC isolation to clinically relevant samples, it is desirable to create nanostructures on the surface of HGMS to enhance cell-surface interactions. Nevertheless, current microfabrication methods cannot generate nanostructured-surface on the microspheres. The authors have developed a new HGMS with controlled nanotopographical surface structure ((NS)HGMS), and demonstrated isolation and recovery of rare cancer cells. (NS)HGMS is achieved by applying layer-by-layer (LbL) assembly of negatively charged SiO(2) nanoparticles and positively charged poly-L-arginine molecules, then sheathing the surface with an enzymatically degradable LbL film made from biotinylated alginate and poly-L-arginine, and capping with anti-EpCAM antibodies and anti-fouling PEG molecules. Compared to smooth-surfaced HGMS, (NS)HGMS showed shorter isolation time (20 min.), enhanced capture efficiency (93.6 ± 4.9 %) and lower detection limit (30 cells/mL) for commonly used cancer cell lines (MCF7, SK-BR-3, PC-3, A549 and CCRF-CEM). This (NS)HGMS-based CTC isolation method does not require specialized lab equipment or an external power source, and thus, can be used for separation of targeted cells from blood or other body fluid in a resource-limited environment.

Ex vivo cell aggregates must overcome significant limitations in the transport of nutrients, drugs, and signaling proteins compared to vascularized native tissue. Further, engineered extracellular environments often fail to sufficiently replicate tethered signaling cues and the complex architecture of native tissue. Co-cultures of cells with microparticles (MPs) is a growing field directed towards overcoming many of these challenges by providing local and controlled presentation of both soluble and tethered proteins and small molecules. Further, co-cultured MPs offer a mechanism to better control aggregate architecture and even to report key characteristics of the local microenvironment such as pH or oxygen levels. Herein, we provide a brief introduction to established and developing strategies for MP production including the choice of MP materials, fabrication techniques, and techniques for incorporating additional functionality. In all cases, we emphasize the specific utility of each approach to form MPs useful for applications in cell aggregate co-culture. We review established techniques to integrate cells and MPs. We highlight those strategies that promote targeted heterogeneity or homogeneity, and we describe approaches to engineer cell-particle and particle–particle interactions that enhance aggregate stability and biological response. Finally, we review advances in key application areas of MP aggregates and future areas of development. Statement of Significant Cell-scaled polymer microparticles (MPs) integrated into cellular aggregates have been shown to be a powerful tool to direct cell response. MPs have supported the development of healthy cartilage, islets, nerves, and vasculature by the maintenance of soluble gradients as well as by the local presentation of tethered cues and diffusing proteins and small molecules. MPs integrated with pluripotent stem cells have directed in vivo expansion and differentiation. Looking forward, MPs are expected to support both the characterization and development of in vitro tissue systems for applications such as drug testing platforms. However, useful co-cultures must be designed keeping in mind the limitations and attributes of each material strategy within the context of the overall tissue biology. The present review integrates prospectives from materials development, drug delivery, and tissue engineering to provide a toolbox for the development and application of MPs useful for long-term co-culture within cell aggregates.

In this work, ceramic hollow fiber supported polydimethylsiloxane (PDMS) composite membranes were developed by dip-coating PDMS layer on the surface of macroporous ceramic hollow fiber support. By controlling the properties of polymer solution and ceramic hollow fiber, high-quality ceramic hollow fiber supported PDMS composite membranes were fabricated for pervaporation (PV) recovery of bio-butanol. It was found both the viscosity of PDMS dip-coating solution and pore size and structure of ceramic support played critical roles in determining the microstructures, the mass transport and the PV performance of PDMS composite membrane. The optimized composite membrane with defect-free PDMS layer and low transport resistance of support showed a total flux of 1282 g/m2 h and separation factor of 42.9 for 1 wt% n-butanol–water mixtures at temperature of 40 °C during 200 h continuous operation. In addition, the membrane PV performance and stability in acetone–butanol–ethanol (ABE) fermentation broth were investigated. The results showed the PDMS composite membrane exhibited high and stable performance for butanol recovery from ABE systems. Compared with literatures, our work demonstrated that the ceramic hollow fiber supported PDMS composite membrane could be a competitive PV membrane for recovering organic compounds from fermentation broth to produce renewable biofuels.

A ceramic hollow fiber membrane distributor was proposed for the micro-scale distribution of reactants in heterogeneous catalytic reaction. To evaluate the feasibility and the performance of the ceramic hollow fiber membrane based reactant distribution, phenol hydroxylation with hydrogen peroxide (H2O2) over TS-1 solid catalysts was selected as a model reaction. The effects of membrane structural parameters of ceramic hollow fiber membrane on the micro-scale distribution and the reaction selectivity were studied in detail. The influence of operation conditions such as hydrogen peroxide flow rate, stirring rate and phenol/H2O2 molar ratio on the membrane distribution process was discussed. The ceramic hollow fiber membrane with small pore size and proper gradient in the pore structure was demonstrated to have a promotion effect on the reaction selectivity, which indicated its ability to generate uniform droplets in micro-scale. In addition, the increase of H2O2 flow rate and/or stirring rate can result in an improvement of reaction selectivity. Because of its controllable structure, high chemical stability and high packing density, the ceramic hollow fiber membrane distributor has potential for widespread applications in heterogenous catalysis.