Precision pore structure optimization of additive manufacturing porous tantalum scaffolds for bone regeneration: A proof-of-concept study.

Currently, the treatment of bone defects in arthroplasty is a challenge in clinical practice. Nonetheless, commercially available orthopaedic scaffolds have shown limited therapeutic effects for large bone defects, especially for massiveand irregular defects. Additively manufactured porous tantalum, in particular, has emerged as a promising material for such scaffolds and is widely used in orthopaedics for its exceptional biocompatibility, osteoinduction, and mechanical properties. Porous tantalum has also exhibited unique advantages in personalised rapid manufacturing, which allows for the creation of customised scaffolds with complex geometric shapes for clinical applications at a low cost and high efficiency. However, studies on the effect of the pore structure of additively manufactured porous tantalum on bone regeneration have been rare. In this study, our group designed and fabricated a batch of precision porous tantalum scaffolds via laser powder bed fusion (LPBF) with pore sizes of 250 µm (Ta 250), 450 µm (Ta 450), 650 µm (Ta 650), and 850 µm (Ta 850). We then performed a series of in vitro experiments and observed that all four groups showed good biocompatibility. In particular, Ta 450 demonstrated the best osteogenic performance. Afterwards, our team used a rat bone defect model to determine the in vivo osteogenic effects. Based on micro-computed tomography and histology, we identified that Ta 450 exhibited the best bone ingrowth performance. Subsequently, sheep femur and hip defect models were used to further confirm the osteogenic effects of Ta 450 scaffolds. Finally, we verified the aforementioned in vitro and in vivo results via clinical application (seven patients waiting for revision total hip arthroplasty) of the Ta 450 scaffold. The clinical results confirmed that Ta 450 had satisfactory clinical outcomes up to the 12-month follow-up. In summary, our findings indicate that 450 µm is the suitable pore size for porous tantalum scaffolds. This study may provide a new therapeutic strategy for the treatment of massive, irreparable, and protracted bone defects in arthroplasty.

Green fabrication of hierarchical pore starch with controllable pore size and shape based on different amylose-amylopectin ratios.

Porous starch (PS) was widely prepared for its large effective surface area, pore volume, and superior hydrophilic property, but its application is limited by enzyme and chemical use. In this study, a novel method to prepare PS with controllable hierarchical pores through ultrasound-ethanol precipitation and different amylose-amylopectin ratios is proposed. As shown in porous morphology and parameters, there were macropores, mesopores and micropores in the formed PS. Moreover, we found that the content of amylose (AM) was negatively related with the total pore volume and pore diameter in PS. The different surface tensions created through ethanol evaporation and water migration during oven drying are the main mechanisms of forming pores with controllable sizes. Based on the molecular information and the long-/short-range orders reflected by crystalline pattern, lamellas, and single-/double-helices, we conclude that AM is easier to form V-type inclusion complexes with ethanol. More single helix of V-amylose was transformed from B-type polymorph after ethanol exchange, which had significantly broadened dLozentz in PS. The TG spectra proved that the novel PS has the stable thermodynamic property. Overall, the finding of an objective regular between AM and pore sizes of PS in this study may support the other work related to PS.

Highly selective removal of thallous ions from wastewater using Prussian Blue biochar composite.

Thallium, a highly toxic pollutant, shows greater toxicity to human than other common heavy metals such as mercury, lead, cadmium and its effective removal from wastewater gains great attention. The main restriction for the Tl+ removal is the interference of a high concentration of co-existing ions in wastewater. Therefore, the goal of the current work was to synthesis adsorbent with high selectivity for the Tl+ removal. Herein, the pore size sieving strategy was proposed and Prussian blue-impregnated biochar (BC@PB) particles was synthesized. More than 95% Tl+ can be removed even the concentrations of the coexistence ions (Na+, Cd2+, and Zn2+) 1,000 higher than the initial concentration of Tl+ (500 µg/L). BC@PB also showed large adsorption capacity (9365 µg/g) and more than 99% Tl+ (initial concentration, 500 µg/L) were removed in just 1 min. The BC@PB had excellent and stable Tl+ removal ability (> 99%) over a range of pH from 3 to 9, which covered the pH range of common thallium-containing wastewater. The density functional theory (DFT) calculation confirmed that not only hydrated volume but also the hydration free energy of ions, which governed the energy barrier for ions entering into narrow channels of BC@PB, played essential roles on the selectivity removal of Tl+. Overall, due to its high selectivity, high adsorption capacity and easy preparation process, the synthesized BC@PB particles based on the pore sizing sieving strategy, can be a promising candidate for the removal of thallium from wastewater.

A statistical physics-based physicochemical study of L-phenylalanine adsorption on activated carbon.

CONTEXT: In this comparative study of the adsorption of L-phenylalanine (L-Phe) on two modified low-activated carbons (ACK and ACZ) at four temperatures (293-313 K), steric and energetic characteristics of adsorption were investigated. An advanced statistical physics multilayer model involving single-layer and double-layer adsorption scenarios was developed to interpret the L-Phe adsorption phenomenon. Modeling results indicate that two and three L-Phe layers were arranged depending on the tested adsorption systems. The estimated number of L-Phe molecules per leading adsorption site varied from 1.71 to 2.09 and from 1.76 to 1.86 for systems L-Phe-ACK and L-Phe-ACZ, respectively. The results show that a multimolecular adsorption mechanism might connect this amino acid molecule on ACZ and ACK surfaces in a non-parallel location. These parameters changed as follows, according to the adsorbed quantity at saturation analysis: Qasat (L-Phe-ACK) ˃ Qasat (L-Phe-ACZ). This indicates that ACK material was more efficient and valuable for L-Phe adsorption than ACZ. It was also shown that the adsorption capacity decreases as the temperature increases, proving the exothermicity of the adsorption process. This analytical substantiation is confirmed by calculating the binding energies, suggesting the occurrence of physical bonds between L-Phe amino acid molecules and ACK/ACZ binding sites and among L-Phe-L-Phe molecules. Pore size distribution was interpreted and calculated by applying the Kelvin theory to data from single adsorption isotherms. All used temperatures depicted a distribution of pores below 2 nm. The docking analysis involving L-Phe and the ACZ and ACK adsorbents reveal a significant resemblance in how receptors detect ligands. Consequently, the findings from the docking process confirm that the calculated binding affinities fall within the spectrum of adsorption energy. METHODS: This study analyzed the adsorption capacity of the L-Phe through a model proposed by statistical physics formalism. Molecular docking was used to determine the various types of interactions between the two activated carbons. Two aspects, including orientation of L-Phe on the site, number of molecules per site n, interaction energy, density of receptor site, and adsorption capacity, were discussed to elucidate the influence of activation on the two adsorbents.

Facile In Situ Building of Sulfonated SiO2 Coating on Porous Skeletons of Lithium-Ion Battery Separators.

Polyolefin separators with worse porous structures and compatibilities mismatch the internal environment and deteriorate lithium-ion battery (LIB) combination properties. In this study, a sulfonated SiO2 (SSD) composited polypropylene separator (PP@SSD) is prepared to homogenize pore sizes and in situ-built SSD coatings on porous skeletons. Imported SSD uniformizes pore sizes owing to centralized interface distributions within casting films. Meanwhile, abundant cavitations enable the in situ SSD coating to facilely fix onto porous skeleton surfaces during separator fabrications, which feature simple techniques, low cost, environmental friendliness, and the capability for continuous fabrications. A sturdy SSD coating on the porous skeleton confines thermal shrinkages and offers a superior safety guarantee for LIBs. The abundant sulfonic acid groups of SSD endow PP@SSD with excellent electrolyte affinity, which lowers Li+ transfer barriers and optimizes interfacial compatibility. Therefore, assembled LIBs give the optimal C-rate capacity and cycling stability, holding a capacity retention of 82.7% after the 400th cycle at 0.5 C.

Ligand-Insertion Strategy for Constructing 2D Conjugated Metal-Organic Framework with Large Pore Size for Electrochemical Analytics.

Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have shown great promise in various electrochemical applications due to their intrinsic electrical conductivity. A large pore aperture is a favorable feature of this type of material because it facilitates the mass transport of chemical species and electrolytes. In this work, we propose a ligand insertion strategy in which a linear ligand is inserted into the linkage between multitopic ligands, extending the metal ion into a linear unit of -M-ligand-M-, for the construction of 2D c-MOFs with large pore apertures, utilizing only small ligands. As a proof-of-concept trial of this strategy, a 2D c-MOF with mesopores of 3.2 nm was synthesized using commercially available ligands hexahydrotriphenylene and 2,5-dihydroxybenzoquinone. The facilitation of the diffusion of redox species by the large pore size of this MOF was demonstrated through a series of probes. With this feature, it showed superior performance in the electrochemical analysis of a variety of biological species.

A new strategy in bioreactor scale-up and process transfer using a dynamic initial vvm according to different aeration pore size.

Monoclonal antibody drugs have grown into a drug category with a market size of over $100 billion since the first product was launched on the market, which naturally creates a large demand for production. At the same time, the $100 billion market is distributed among more than 200 listed drugs, which indicates that the production demand for monoclonal antibody drugs is diverse. To meet this demand, major suppliers offer single-use bioreactors of all sizes. These single-use bioreactors with different specifications, especially the inconsistency of aeration pore sizes, pose great challenges for technology transfer and scale-up production, and the conventional scale-up strategies of constant Power input/volume ratio (P/V) and constant vessel volume per minute (vvm) can no longer meet the needs. This study simplified the selection of technical parameters in bioreactors based on the differences in aeration pore size. Innovatively combined the aeration pore sizes with initial aeration vvm, and comprehensively investigated the relationship between P/V, vvm and aeration pore size by designing experiments (DoE) using the orthogonal test method. The results showed a quantitative relationship between the aeration pore size and the initial aeration vvm in the P/V range of 20 ± 5 W/m3. The appropriate initial aeration was between 0.01 and 0.005 m3/min for aeration pore size ranging from 1 to 0.3 mm, which was the optimal incubation condition in the bioreactors. The choice of initial ventilation was most related to the final expression. Follow-up studies validated these findings in a 15 L glass bioreactor and a 500 L single-use bioreactor, and the results were consistent with expectations.

Microscopic and macroscopic analysis of hexavalent chromium adsorption on polypyrrole-polyaniline@rice husk ash adsorbent using statistical physics modeling.

This paper contributed with new findings to understand and characterize a heavy metal adsorption on a composite adsorbent. The synthesized polypyrrole-polyaniline@rice husk ash (PPY-PANI@RHA) was prepared and used as an adsorbent for the removal of hexavalent chromium Cr(VI). The adsorption isotherms of Cr(VI) ions on PPY-PANI@RHA were experimentally determined at pH 2, and at different adsorption temperatures (293, 303, and 313 K). Multi-layer model developed using statistical physics formalism was applied to theoretically analyze and characterize the different interactions and ion exchanges during the adsorption process for the elimination of this toxic metal from aqueous solutions, and to attribute new physicochemical interpretation of the process of adsorption. The physicochemical structures and properties of the synthesized PPY-PANI@RHA were characterized via Fourier transform infrared spectroscopy (FTIR). Fitting findings showed that the mechanism of adsorption of Cr(VI) on PPY-PANI@RHA was a multi-ionic mechanism, where one binding site may be occupied by one and two ions. It may also be noticed that the temperature augmentation generated the activation of more functional groups of the composite adsorbent, facilitating the interactions of metal ions with the binding sites and the access to smaller pore. The energetic characterization suggested that the mechanism of adsorption of the investigated systems was exothermic and Cr(VI) ions were physisorbed on PPY-PANI@RHA surface via electrostatic interaction, reduction of Cr(VI) to Cr(III), hydrogen bonding, and ion exchange. Overall, the utilization of the theory of statistical physics provided fruitful and profounder analysis of the adsorption mechanism. The estimation of the pore size distribution (PSD) of the polypyrrole-polyaniline@rice husk ash using the statistical physics approach was considered stereographic characterization of the adsorbent (here PPY-PANI@RHA was globally a meso-porous adsorbent). Lastly, the mechanism of Cr(VI) removal from wastewater using PPY-PANI@RHA as adsorbent was macroscopically investigated via the estimation of three thermodynamic functions.

Assessment of artificial bone materials with different structural pore sizes obtained from 3D printed polycaprolactone/ß-tricalcium phosphate (3D PCL/ß-TCP).

Artificial bone is the alternative candidate for the bone defect treatment under the circumstance that there exits enormous challenge to remedy the bone defect caused by attributes like trauma and tumors. However, the impact of pore size discrepancy for regulating new bone generation is still ambiguous. Using direct 3D printing technology, customized 3D polycaprolactone/ß-tricalcium phosphate (PCL/ß-TCP) artificial bones with different structural pore sizes (1.8, 2.0, 2.3, 2.5, and 2.8 mm) were successfully prepared, abbreviated as the 3D PCL/ß-TCP. 3D PCL/ß-TCP exhibited a 3D porous structure morphology similar to natural bone and possessed outstanding mechanical properties. Computational fluid dynamics analysis indicated that as the structural pore size increased from 1.8 to 2.8 mm, both velocity difference (from 4.64 × 10-5to 7.23 × 10-6m s-1) and depressurization (from 7.17 × 10-2to 2.25 × 10-2Pa) decreased as the medium passed through.In vitrobiomimetic mineralization experiments confirmed that 3D PCL/ß-TCP artificial bones could induce calcium-phosphate complex generation within 4 weeks. Moreover, CCK-8 and Calcein AM live cell staining experiments demonstrated that 3D PCL/ß-TCP artificial bones with different structural pore sizes exhibited advantageous cell compatibility, promoting MC3T3-E1 cell proliferation and adhesion.In vivoexperiments in rats further indicated that 3D PCL/ß-TCP artificial bones with different structural pore sizes promoted new bone formation, with the 2.5 mm group showing the most significant effect. In conclusion, 3D PCL/ß-TCP artificial bone with different structural pore sizes could promote new bone formation and 2.5 mm group was the recommended for the bone defect repair.

Precise Design of a 0.8 nm Pore Size in a Separator Interfacial Layer Inspired by a Sieving Effect toward Inhibiting Polysulfide Shuttling and Promoting Li+ Diffusion.

The incomplete blocking of small-sized polysulfides by pore size and the effect on Li+ transport are generally neglected when the size-sieving effect is employed to suppress the shuttling of polysulfides. Herein, ion-selective modified layers with pore sizes equal to, greater than, and less than 0.8 nm, respectively, on the polypropylene separator are fabricated to obtain the preferable pore size for separation of polysulfides and Li+. As a result, the modified layer with a pore size of 0.8 nm can efficiently inhibit the shuttling of polysulfides and simultaneously boost the diffusion of Li+ under the double effect of the size advantage and electrostatic shielding. Consequently, the battery using a separator with a modified layer having a pore size of 0.8 nm possesses a lower capacity attenuation of 0.047% after 1000 cycles at 2.0 C. This work serves as a vital guide for suppressing polysulfide shuttle using ion-selective sieving effects for lithium-sulfur batteries.

Study on microstructure evolution and oxidation kinetics in Coal-Oil Symbiosis.

Differences in the spontaneous combustion mechanism characteristics of Coal-Oil Symbiosis (COS) significantly affect coal mines' safety management and ecological environment maintenance. Accordingly, this study aims to investigate COS's macroscopic and microstructural characteristics with different oil mass percentage using simultaneous thermal analysis, low-temperature N2 adsorption, scanning electron microscopy (SEM), and in-situ Fourier transform infrared spectroscopy (FTIR). The results showed that with the increase of oil mass percentage, the COS displayed the weakening of oxygen absorption and the advance of some characteristic temperatures, and 11.5 °C advanced the maximum weight loss temperature on average. For the 25 % oil sample, the ignition temperature was 9.5 °C lower than that of the raw coal. Additionally, the apparent activation energy of the high oil mass percentage sample was significantly reduced in the pyrolysis and combustion stages, and when the oil mass percentage was 25 %, the activation energies of the two stages decreased by 89 % and 60.65 %, respectively. Compared to raw coal, COS exhibits fewer macropores and surface pores covered by oil, which limits oxygen adsorption. Moreover, COS with higher oil mass percentage had an increase in hydroxyl and aliphatic hydrocarbon groups, and the CH3 + CH2 content of COS increased by 69.2 % on average, providing more active groups, thereby promoting spontaneous combustion. This study provides an important reference and theoretical support for further understanding the structural evolution and oxidation kinetic behavior of COS, contributing to disaster prevention and ecological environmental protection in coal-oil coexistence mining areas.

Characterization of effective moisture diffusivity based on pore structure of concrete.

Concrete durability is greatly influenced by the transport rate of aggressive chemicals. Moisture diffusion plays a key role in the long-term performance of cementitious materials, as it facilitates the entry of aggressive chemicals into concrete. The pore size distribution plays a critical role in determining moisture diffusivity. However, the characteristics of the concrete pore structure have not been included comprehensively in the material models so far. In this paper, a theoretical model was developed to obtain the pore size volume fractions for each diffusion mechanism including Molecular, Knudsen and Surface diffusions. An effective moisture diffusivity in concrete was then obtained using the weighted average based on the diffusion mechanisms and pore size volume fractions. The model's validity was demonstrated by comparing model predictions with available experimental data. The findings of this study provide valuable insights into the behavior of the concrete pore structure and its impact on moisture diffusivity.

Improving Active Site Local Proton Transfer in Porous Organic Polymers for Boosted Oxygen Electrocatalysis.

Improving proton transfer is vital for electrocatalysis with porous materials. Although several strategies are reported to assist proton transfer in channels, few studies are dedicated to improving proton transfer at the local environments of active sites in porous materials. Herein, we report on new Co-corrole-based porous organic polymers (POPs) with improved proton transfer for electrocatalytic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). By tuning the pore sizes and installing proton relays at Co corrole sites, we designed and synthesized POP-2-OH with improved proton transfer both in channels and at local Co active sites. This POP shows remarkable activity for both electrocatalytic ORR with E1/2 = 0.91 V vs RHE and OER with h10 = 255 mV. Therefore, this work is significant to present a strategy to improve active site local proton transfer in porous materials and highlight the key role of such structural functionalization in boosting oxygen electrocatalysis.

AI-assisted deep learning segmentation and quantitative analysis of X-ray microtomography data from biomass ashes.

X-ray microtomography is a non-destructive method that allows for detailed three-dimensional visualisation of the internal microstructure of materials. In the context of using phosphorus-rich residual streams in combustion for further ash recycling, physical properties of ash particles can play a crucial role in ensuring effective nutrient return and sustainable practices. In previous work, parameters such as surface area, porosity, and pore size distribution, were determined for ash particles. However, the image analysis involved binary segmentation followed by time-consuming manual corrections. The current work presents a method to implement deep learning segmentation and an approach for quantitative analysis of morphology, porosity, and internal microstructure. Deep learning segmentation was applied to microtomography data. The model, with U-Net architecture, was trained using manual input and algorithm prediction.•The trained and validated deep learning model could accurately segment material (ash) and air (pores and background) for these heterogeneous particles.•Quantitative analysis was performed for the segmented data on porosity, open pore volume, pore size distribution, sphericity, particle wall thickness and specific surface area.•Material features with similar intensities but different patterns, intensity variations in the background and artefacts could not be separated by manual segmentation - this challenge was resolved using the deep learning approach.

Microfiber/Nanofiber/Attapulgite Multilayer Separator with a Pore-Size Gradient for High-Performance and Safe Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) have an extremely diverse application nowadays as an environmentally friendly and renewable new energy storage technology. The porous structure of the separator, one essential component of LIBs, provides an ion transport channel for the migration of ions and directly affects the overall performance of the battery. In this work, we fabricated a composite separator (GOP-PH-ATP) via simply laminating an electrospun polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) nanofibrous membrane coated with attapulgite (ATP) nanoparticles onto a PP nonwoven microfibrous fabric, which exhibits a unique porous structure with a pore-size gradient along the thickness direction that ranges from tens of microns to hundreds of nanometers. As a result, besides the enhanced thermal stability given by the chosen materials, the GOP-PH-ATP separator was endowed with a superhigh porosity of ~95%, strong affinity with electrolyte, and great electrolyte uptake of ~760%, thus effectively enabling an ionic conductivity of 2.38 mS cm-1 and a lithium-ion transference number of 0.62. Furthermore, the cell with the GOP-PH-ATP separator shows an excellent cycling performance with a capacity retention of 91.2% after 150 cycles at 1 C, suggesting that the composite separator with a pore-size gradient structure has great potential to be applied in LIBs.

Isoporous Membranes by the Symmetric Triblock Copolymer: A Strategy to Improve the Mechanical Strength without Sharply Changing the Pore Size and Permselectivity.

Isoporous membranes produced from diblock copolymers commonly display a poor mechanical property that shows many negative impacts on their separation application. It is theoretically predicted that dense films produced from symmetric triblock copolymers show much stronger mechanical properties than those of homologous diblock copolymers. However, to the best of our knowledge, symmetric triblock copolymers have rarely been fabricated into isoporous membranes before, and a full understanding of separation as well as mechanical properties of membranes prepared from triblock copolymers and homologous diblock copolymers has not been conducted, either. In this work, a cleavable symmetric triblock copolymer with polystyrene as the side block and poly(4-vinylpyridine) (P4VP) as the middle block was synthesized and designed by the RAFT polymerization using the symmetric chain transfer agent, which located at the center of polymer chains and could be removed to produce homologous diblock copolymers with half-length while having the same composition as that found in triblock copolymers. The self-assembly of these two copolymers in thin films and casting solutions was first investigated, observing that they displayed similar self-organized structures under these two conditions. When fabricated into isoporous membranes, they showed similar pore sizes (5-7% difference) and comparable rejection performance (∼10% difference). However, isoporous membranes produced from triblock copolymers showed significantly improved mechanical strength and higher toughness (2-10 times larger) as evidenced by the compacting resistance, strain-stress determination, and nanoindentation testing, suggesting the unique and novel structure-performance relationship in the isoporous membranes produced from symmetric triblock copolymers. The above finding will guide the way to fabricate mechanically robust isoporous membranes without notably changing the separation performance from rarely used symmetric triblock copolymers, which can be synthesized by the controlled polymerization as facilely as that found for diblock copolymers.

Adsorption in Pyrene-Based Metal-Organic Frameworks: The Role of Pore Structure and Topology.

Pore topology and chemistry play crucial roles in the adsorption characteristics of metal-organic frameworks (MOFs). To deepen our understanding of the interactions between MOFs and CO2 during this process, we systematically investigate the adsorption properties of a group of pyrene-based MOFs. These MOFs feature Zn(II) as the metal ion and employ a pyrene-based ligand, specifically 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy). Including different additional ligands leads to frameworks with distinctive structural and chemical features. By comparing these structures, we could isolate the role that pore size, the presence of open-metal sites (OMS), metal-oxygen bridges, and framework charges play in the CO2 adsorption of these MOFs. Frameworks with constricted pore structures display a phenomenon known as the confinement effect, fostering stronger MOF-CO2 interactions and higher uptakes at low pressures. In contrast, entropic effects dominate at elevated pressures, and the MOF's pore volume becomes the driving factor. Through analysis of the CO2 uptakes of the benchmark materials ─some with narrower pores and others with larger pore volumes─it becomes evident that structures with narrower pores and high binding energies excel at low pressures. In contrast, those with larger volumes perform better at elevated pressures. Moreover, this research highlights that open-metal sites and inherent charges within the frameworks of ionic MOFs stand out as CO2-philic characteristics.

Adsorption performance and mechanism of a starch-stabilized ferromanganese binary oxide for the removal of phosphate.

Effective removal of phosphate from water is essential for preventing the eutrophication and worsening of water quality. This study aims to enhance phosphate removal by synthesizing starch-stabilized ferromanganese binary oxide (FMBO-S), discover the factors, and investigate adsorption mechanisms. FMBO and FMBO-S properties were studied using Scanning Electron Microscopy, BET analysis, Polydispersity Index (PDI), Fourier Transform Infrared Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). After starch loading, the average pore diameter increased from 14.89 Å to 25.16 Å, and significantly increased the pore volume in the mesopore region. FMBO-S showed a PDI value below 0.5 indicating homogeneous size dispersity and demonstrated faster and higher adsorption capacity: 61.24 mg g-1 > 28.57 mg g-1. Both FMBO and FMBO-S adsorption data fit well with the pseudo-second-order and Freundlich models, indicating a chemisorption and multilayered adsorption process. The phosphate adsorption by FMBO was pH-dependent, suggesting electrostatic attraction as the dominant mechanism. For the FMBO-S, phosphate adsorption was favored in a wide pH range, despite the weaker electrostatic attraction as evident from the point of zero charge and zeta potential values, indicating ligand exchange as a main mechanism. Moreover, the XPS analysis shows a significant change in the proportion of Fe species for FMBO-S than FMBO after phosphate adsorption, indicating significant involvement of Fe. Meanwhile, phosphate adsorption was almost unaffected by the presence of Cl-, NO3-, and SO42- anions, whereas CO32- significantly reduced the adsorption capacity. This study revealed that FMBO-S could be a promising, low-cost adsorbent for phosphate removal and recovery from water.

Coordination-Driven Templated Synthesis of Hierarchically Porous Zeolitic Imidazolate Frameworks for Cascade Enzyme Cycle Amplification Coupled Immunoassay.

Although hierarchically porous zeolitic imidazolate frameworks (HPZIFs) not only inherit the intrinsic architectural and chemical stabilities of their microporous counterparts but also afford open space for the efficient mass diffusion of the macromolecules involved, their rational design and construction are still challenging. Herein, HPZIFs with tailorable pore sizes ranging from 18 to 54 nm were successfully fabricated by using a newly developed soft-template-directed strategy. Our success rooted in the fact that the screened PS81-PVP44-PEO113 triblock copolymer could effectively coordinate with the metal precursor for the directed crystallization of ZIFs along surfactant assemblies. The advantages of continuous large pores and open structures in such HPZIFs were fully taken into account to serve as a bioreactor for the efficient immunoassay. The expanded large pores provided not only a significantly vast surface area to enhance the density of capture antibodies but also enough space for accommodating multiple conjugated biomolecules in one pore channel. In combination with a cascade enzyme cycle amplification strategy, a model biomarker of prostate-specific antigen (PSA) at the femtomolar level was checked with a limit of detection of 92 fM using the developed immunosensor. Specific screening on patients with prostate cancer or even benign prostatic hyperplasia was exemplified through accurately quantifying small changes of PSA concentration in clinical serum samples, prefiguring the great potential of the developed HPZIF-8 immunosensor platform for the early monitoring and diagnostics of diseases.

Misleading Pore Size Measurements in Gelatin and Alginate Hydrogels Revealed by Confocal Microscopy.

It is a well-documented phenomenon that the porous structure of hydrogels observed with vacuum-based imaging techniques is generated during the freezing and drying process employed prior to observation. Nevertheless, vacuum-based techniques, such as scanning electron microscopy (SEM), are still being commonly used to measure pore sizes in hydrogels, which is often not representative of the actual pore size in hydrated conditions. The frequent underestimation of the impact of freezing and drying on hydrogel structures could stem from a lack of cross-fertilization between materials science and biomedical or food science communities, or from the simplicity and visually appealing nature of SEM imaging, which may lead to an overemphasis on its use. Our study provides a straightforward and impactful way of pinpointing this phenomenon exploiting two hydrogels ubiquitously applied in tissue engineering, including gelatin methacryloyl and alginate as proof-of-concept hydrogels. By comparing images of the samples in the native hydrated state, followed by freezing, freeze-drying, and rehydration using SEM and confocal microscopy, we highlight discrepancies between hydrogel pore sizes in the hydrated versus the dry state. To conclude, our study offers recommendations for researchers seeking insight in hydrogel properties and emphasizes key factors that require careful control when using SEM as a characterization tool.