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1. Decoding Fine API Agglomeration as a Key Indicator of Powder Flowability and Dissolution: Impact of Particle Engineering

   https://doi.org/10.1007/s11095-022-03293-z  

   Kim, Sangah ; Cheikhali, Mirna ; Davé, Rajesh N. ( October 2022 , Pharmaceutical Research)

   Purpose: Fine API agglomeration and its mitigation via particle engineering, i.e., dry coating, remains underexplored. The purpose was to investigate agglomeration before and after dry coating of fine cohesive APIs and impact on powder processability, i.e., flowability (FFC), bulk density (BD), and dissolution of BCS Class II drugs. Method: Ibuprofen (three sizes), fenofibrate, and griseofulvin (5-20 µm), before and after dry coating with varying amounts of hydrophobic (R972P) or hydrophilic (A200) nano- silica, were assessed for agglomeration, FFC, BD, surface energy, wettability, and dissolution. The granular Bond number (Bog), a dimensionless parameter, evaluated through material-sparing particle-scale measures and particle-contact models, was used to express relative powder cohesion. Results: Significant powder processability improvements after dry coating were observed: FFC increased by multiple flow regimes, BD increased by 25-100 %, agglomerate ratio (AR) reduction by over an order of magnitude, and greatly enhanced API dissolution rate even with hydrophobic (R972P) silica coating. Scrutiny of particle-contact models revealed non-triviality in estimating API surface roughness, which was managed through the assessment of measured bulk properties. A power-law correlation was identified between AR and Bog and subsequently, between AR and FFC & bulk density; AR below 5 ensured improved processability and dissolution. Conclusion: Agglomeration, an overlooked material-sparing measure for powder cohesiveness, was a key indicator of powder processability and dissolution. The significant agglomerate reduction was possible via dry coating with either silica type at adequate surface area coverage. Reduced agglomeration after dry coating also countered the adverse impact of increased surface hydrophobicity on dissolution. 

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2. Copper oxide nanoparticle dissolution at alkaline pH is controlled by dissolved organic matter: influence of soil-derived organic matter, wheat, bacteria, and nanoparticle coating

   https://doi.org/10.1039/d0en00574f  

   Hortin, J. M. ; Anderson, A. J. ; Britt, D. W. ; Jacobson, A. R. ; McLean, J. E. ( January 2020 , Environmental Science: Nano)

   Dissolution of CuO nanoparticles, releasing Cu ions, is a primary mechanism of Cu interaction in the rooting zone of plants. CuO dissolution is sometimes incorrectly considered negligible at high pH, since complexation of Cu with dissolved organic matter may enhance nanoparticle dissolution. Therefore data on the effects of plant-microbial-soil interactions on nanoparticle dissolution, particularly in alkaline soils, are needed. Dissolution of CuO nanoparticles (100 mg kg −1 Cu) was studied in sand supplemented with factorial combinations of wheat growth, a root-colonizing bacterium, and saturated paste extracts (SPEs) from three alkaline, calcareous soils. In control sand systems with 3.34 mM Ca(NO 3 ) 2 solution, dissolved Cu was low (266 μg L −1 Cu). Addition of dissolved organic matter via wheat root metabolites and/or soil SPEs increased dissolved Cu to 795–6250 μg L −1 Cu. Dissolution was correlated with dissolved organic carbon ( R = 0.916, p < 0.0001). Ligands >3 kDa, presumably fulvic acid from the SPEs, complexed Cu driving solubility; the addition of plant exudates further increased solubility 1.5–3.5×. The root-colonizing bacterium decreased dissolved Cu in sand pore waters from planted systems due to metabolism of root exudates. Batch solubility studies (10 mg L −1 Cu) with the soil SPEs and defined solutions containing bicarbonate or fulvic acid confirmed elevated CuO nanoparticle solubility at >7.5 pH. Nanoparticle dissolution was suppressed in batch experiments compared to sand, via nanoparticle organic matter coating or homoconjugation of dissolved organic matter. Alterations of CuO nanoparticles by soil organic matter, plant exudates, and bacteria will affect dissolution and bioavailability of the CuO nanoparticles in alkaline soils. 

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3. Fluorination promotes lithium salt dissolution in borate esters for lithium metal batteries

   https://doi.org/10.1039/D3TA06228G  

   Ma, Peiyuan ; Kumar, Ritesh ; Vu, Minh Canh ; Wang, Ke-Hsin ; Mirmira, Priyadarshini ; Amanchukwu, Chibueze V. ( January 2024 , Journal of Materials Chemistry A)

   Lithium metal batteries promise higher energy densities than current lithium-ion batteries but require novel electrolytes to extend their cycle life. Fluorinated solvents help stabilize the solid electrolyte interphase (SEI) with lithium metal, but are believed to have weaker solvation ability compared to their nonfluorinated counterparts and are deemed ‘poorer electrolytes’. In this work, we synthesize tris(2-fluoroethyl) borate (TFEB) as a new fluorinated borate ester solvent and show that TFEB unexpectedly has higher lithium salt solubility than its nonfluorinated counterpart (triethyl borate). Through experiments and simulations, we show that the partially fluorinated –CH2F group acts as the primary coordination site that promotes lithium salt dissolution. TFEB electrolyte has a higher lithium transference number and better rate capability compared to methoxy polyethyleneglycol borate esters reported in the literature. In addition, TFEB supports compact lithium deposition morphology, high lithium metal Coulombic efficiency, and stable cycling of lithium metal/LiFePO4 cells. This work ushers in a new electrolyte design paradigm where partially fluorinated moieties enable salt dissolution and can serve as primary ion coordination sites for next-generation electrolytes. 

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4. Novel Quasi-Emulsion Solvent Diffusion-Based Spherical Cocrystallization Strategy for Simultaneously Improving the Manufacturability and Dissolution of Indomethacin

   https://doi.org/10.1021/acs.cgd.0c00876  

   Chen, Hongbo ; Xu, Hongyun ; Wang, Chenguang ; Kang, Hyunho ; Haynes, Christy L. ; Mahanthappa, Mahesh K. ; Sun, Changquan Calvin ( October 2020 , Crystal Growth & Design)

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5. Reductive dissolution of pyrite by methanogenic archaea

   https://doi.org/10.1038/s41396-021-01028-3  

   Payne, Devon ; Spietz, Rachel L. ; Boyd, Eric S. ( December 2021 , The ISME Journal)

   Abstract The formation and fate of pyrite (FeS 2 ) modulates global iron, sulfur, carbon, and oxygen biogeochemical cycles and has done so since early in Earth’s geological history. A longstanding paradigm is that FeS 2 is stable at low temperature and is unavailable to microorganisms in the absence of oxygen and oxidative weathering. Here, we show that methanogens can catalyze the reductive dissolution of FeS 2 at low temperature (≤38 °C) and utilize dissolution products to meet cellular iron and sulfur demands associated with the biosynthesis of simple and complex co-factors. Direct access to FeS 2 is required to catalyze its reduction and/or to assimilate iron monosulfide that likely forms through coupled reductive dissolution and precipitation, consistent with close associations observed between cells and FeS 2 . These findings demonstrate that FeS 2 is bioavailable to anaerobic methanogens and can be mobilized in low temperature anoxic environments. Given that methanogens evolved at least 3.46 Gya, these data indicate that the microbial contribution to the iron and sulfur cycles in ancient and contemporary anoxic environments may be more complex and robust than previously recognized, with impacts on the sources and sinks of iron and sulfur and other bio-essential and thiophilic elements such as nickel and cobalt. 

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