Chemical Engineering Journal

Methanogenic archaea, such as Methanothermobacter marburgensis, represent a powerful biological platform for carbon capture and valorization, directly converting carbon dioxide (CO2) and molecular hydrogen (H2) into proteinogenic amino acids (AAs). In this study, we present a controlled and scalable strategy for tailoring AA production (biosynthesis and secretion) in continuous gas fermentation. By applying various Design of Experiments (DOE) techniques, we systematically identified and optimized key process parameters governing AA biosynthesis and shaping a targeted AA secretion profile. A hybrid modeling framework combining experimental data with scale-independent parameters derived from computational fluid dynamics (CFD) enabled robust performance prediction across bioreactor scales. This model-driven approach successfully translated the process from 120 mL glass bottles via 2 L to 150 L reactors, corresponding to a reaction-volume scale-up factor of 2000. These findings set the foundation for a robust and predictive platform for sustainable AA production, positioning archaea as a high-potential alternative in industrial biotechnology.

Nutrient-rich food-processing wastewaters represent valuable yet under-utilised side streams for sustainable protein production in the form of microbial biomass. Here we present an integrated dual-loop bioprocess that converts soybean-processing wastewater into microbial single-cell protein (SCP) while achieving substantial nutrient removal and product refinement. In the first loop, previously enriched microbial consortia were inoculated and cultivated in four parallel sequencing batch reactors (SBRs) for 44days at a hydraulic retention time (HRT) of 3days. This bioprocess configuration demonstrated features that support future scale-up while maintaining process stability, achieving a protein content of 33.3{+/-}3.2%, doubling the protein yield (15.32{+/-}3.49g dry weight per g soluble TKN) and quadrupling the production rate (0.29{+/-}0.06g dry weight L-1 d-1) compared to operating reactors without inoculation (HRT: 7.2days). Effluent treatment was stable, with 84% carbon and 78% nitrogen removal efficiencies, demonstrating efficient nutrient recovery. The SCP biomass was enriched in functional taxa, including Acidipropionibacterium, Lactococcus, Megasphaera, and Azospirillum, suggesting that reactor conditions and inoculum selection promoted a stable, protein-productive microbial community with potential probiotic benefits. In the second loop, bioreactor effluent was reused as aqueous matrix for heat treatment (60{degrees}C) of the SCP biomass, reducing the RNA content from 8.6% to 2.6%, with a 39% biomass loss accompanied by a 30% increase in total amino acid concentration. Hence, our valorisation approach integrates microbial biomass production, effluent reuse, and product refinement within a circular framework. The system provides a resource-efficient pathway for converting food-sector side streams into high-quality microbial community-based SCP, highlighting its potential scalability for sustainable nutrient and water management.

Accurate and decentralized quantification of serotonin, also known as 5-hydroxytryptamine (5-HT), in biological fluids is critically important for the diagnosis, prognosis, and therapeutic monitoring of neurological and psychiatric disorders. However, conventional analytical methods generally rely on centralized laboratory infrastructure, skilled personnel, and labor-intensive sample processing, which restrict their applicability in rapid near-patient and point-of-care settings. Herein, we report a portable molecularly imprinted polymer (MIP)-based electrochemical sensing platform for selective and on-site detection of serotonin using screen-printed carbon electrodes (SPCEs). The biomimetic recognition interface was fabricated through direct electropolymerization of a polydopamine recognition layer in the presence of serotonin as the template molecule, followed by template extraction to generate complementary recognition cavities for selective rebinding. The sensor fabrication parameters, including monomer concentration, electropolymerization cycles, template-to-monomer stoichiometry, and electrolyte pH, were systematically optimized to achieve improved sensitivity, selectivity, and signal stability. Under optimized conditions, the MIP/SPCE sensor exhibited a broad linear response from 10 pM -10 uM in phosphate buffer, with a correlation coefficient of R2 = 0.974 and an ultralow limit of detection of 0.16 pM. The analytical applicability of the platform was further validated in spiked artificial serum, where the sensor achieved an LOD of 0.12 pM, satisfactory recovery values of 88.66-96.02%, and acceptable precision with RSD values [≤] 8.43% (n=3), confirming its reliability in a complex biological matrix. The developed sensor demonstrated excellent selectivity toward serotonin against physiologically relevant interferents, maintaining signal retention between 99% and 101%. In addition, the platform showed high operational repeatability with an RSD of 0.45%, good inter-electrode reproducibility with an RSD of 6.3%, and long-term storage stability, retaining 90-110% of its initial response over 28 days. Importantly, cross-platform validation using a smartphone-coupled potentiostat demonstrated strong analytical agreement with laboratory-grade instrumentation, as evidenced by R2 = 0.9967 and a slope of 1.023. These findings establish the proposed MIP/SPCE platform as a simple, low-cost, portable, and smartphone-compatible electrochemical device for field-deployable serotonin monitoring in clinically relevant samples.

Municipal wastewater constitutes a major reservoir of unutilized reactive nitrogen, representing a significant opportunity for biological valorization. The biopolymer cyanophycin is promising as a means of nitrogen capture and recovery, but current production strategies are not optimized for the physicochemical constraints of municipal wastewater systems. Here, we engineered the naturally competent soil bacterium Acinetobacter baylyi ADP1 ISx to synthesize cyanophycin from carbon and nitrogen sources prevalent in municipal wastewater and over a range of wastewater-relevant temperatures. To overcome the recurring problem of arginine availability limiting cyanophycin synthesis, we engineered an arginine-producing strain (AP1) which accumulated cyanophycin when grown on acetate and ammonium (19% CDW), nitrate (9% CDW), or urea (29% CDW) and without arginine supplementation. During this work, we observed that conditions associated with reduced cell fitness correlated with increased intracellular cyanophycin content. As temperature strongly influences cell growth but cannot be realistically modulated in wastewater contexts, we investigated the potential of induced fructose-auxotrophy to modulate cell growth independently from temperature. This intervention, accomplished with a single knockout (gap), expanded the effective range of cyanophycin accumulation from 12 C up to 30 C. Collectively, these results establish the relevance of arginine-producing strains for cyanophycin biosynthesis and position A. baylyi as a promising chassis for continued development under real-world wastewater conditions.

The development of cost-effective, serum-free media is critical for scalable cultivated meat production. This study used high-throughput screening through a Design of Experiments (DoE) approach to develop an animal-free, serum-free medium (MMM1) specifically for the C2C12 murine myoblasts model cell line with applicability in cultivated meat research including for pet food. Low cost, food-grade inputs such as methylcellulose and spirulina extract resulted in significant cell growth improvements. The optimised MMM1 formulation containing low cost, food-grade inputs, achieved cumulative population doublings comparable to 10% (v/v) fetal bovine serum over four consecutive passages. Furthermore, MMM1 supported scalable cell expansion on commercially available dextran-based microcarriers (Cytodex-3) in both static and agitated conditions in spinner flasks, matching growth rates of serum-based controls. Finally, transitioning to a food-grade DMEM/F12 basal medium maintained cell proliferation equivalent to the pharmaceutical-grade DMEM/F12, but at a significantly lower cost, thus offering a viable strategy to substantially reduce biomanufacturing costs which is a critical challenge in cultivated meat production.

Past few decades witnessed a boom in pharmaceutical and bioproduct industry with the help of bioprocess technology. Industrially important bioproducts can be produced in large scale for commercialization with the help of fermenters. Here in, pharmaceutically valuable bioproduct melanin, synthesized from Pseudomonas stutzeri strain BTC109 by using two different sized bioreactors. Under controlled conditions the bacteria were allowed to synthesis melanin nanoparticles. The important parameters to be monitored here are pH, dissolved oxygen, agitation, aeration, melanin production and cell biomass concentration. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=163 SRC="FIGDIR/small/737634v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@d92fe5org.highwire.dtl.DTLVardef@d76c07org.highwire.dtl.DTLVardef@f5516forg.highwire.dtl.DTLVardef@1b5864b_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIPharmaceutical and bioproduct development industries witnessed a shoot up due to bioprocess technology. C_LIO_LIIndustrially important bioproduct like melanin can be produced in large scale with the help of industrial fermentation technology. C_LIO_LIThe product thus obtained was found to be nano sized and it can be commercialized. C_LI

Rare earth elements (REEs) are critical components of green technologies, but current mining and purification methods remain environmentally unsustainable due to their high energy consumption and intensive chemical requirements. Bio-hydrometallurgical processes have the potential to concentrate and recover REEs at a circumneutral pH. Work presented here uses bacteria at neutral pH to concentrate REEs from solution and subsequently recover those REEs using sodium citrate. Shewanella oneidensis MR-1 was incubated anaerobically in a culture media solution spiked with 14 REEs and yttrium for one to six days. REE concentrations remaining in solution were then compared to REE concentrations on cell pellets. For these same timepoints, the loosely bound extracellular polymeric substance (LB-EPS) was removed from cells prior to quantifying REEs on pellets to narrow down the location of REE binding. Moreover, cell pellets collected after 5 days in REE spiked solution were subjected to a time series desorption assay using sodium citrate. Shewanella oneidensis at a starting OD600 of 0.6 adsorbed 1.18mg/g of REE after 3 days. 80% of these REEs were located in the LB-EPS. In 10 minutes, 0.5 M sodium citrate desorbed about 75% of REEs from cells and over 95% after 24 hours. This method was also applied to Alaskan coal and showed that 68-86% of REEs were desorbed form S. oneidensis. This study elucidates the REE binding location and capacity of S. oneidensi, REE removal efficiency of sodium citrate overtime, and the application of this sustainable biotechnology for REE recovery at a circumneutral pH from Alaskan coal.

Underwater adhesion research increasingly draws on bioinspired systems to uncover the molecular mechanisms that enable strong interfacial binding in aqueous environments. The biofilm adhesin Bap1 from Vibrio cholerae contains a short peptide motif, SYWFFGWHTK (CP), which exhibits exceptional adhesive performance, surpassing mussel foot protein mfp5 under comparable conditions. Despite its promise, the roles of ionic environments and aggregation behavior in governing CP adhesion remain unclear. In this study, we investigate how ion identity influences CP aggregation, film formation, and interfacial properties. Using dynamic light scattering, we identify the formation of micron-scale assemblies of aggregated molecular clusters (AAMCs), with size distributions modulated by salt type. Quartz crystal microbalance with dissipation and liquid atomic force microscopy reveal that CP film formation is both surface- and ion-dependent. On gold substrates, AAMCs preferentially adsorb and collapse into rigid, smooth nanofilms, consistent with hydrophobic-driven compaction. In contrast, silicate surfaces inhibit such collapse, yielding distinct morphologies and interfacial energetics. These findings demonstrate that surface chemistry and ionic conditions jointly regulate peptide aggregation and adhesion. This work provides mechanistic insight into hydrophobic-rich peptide systems and informs the rational design of next-generation wet adhesives, with broader implications for biomaterials and peptide-based formulations. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/733527v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1bd012aorg.highwire.dtl.DTLVardef@1977892org.highwire.dtl.DTLVardef@16cf79borg.highwire.dtl.DTLVardef@f405bf_HPS_FORMAT_FIGEXP M_FIG C_FIG

Most antimicrobial drug candidates currently in development are derivatives of established antibiotic classes. In contrast, antimicrobial heteroatom-doped carbon quantum dot (CQD) nanoparticles vastly differ from their chemical antibiotic counterparts and exhibit potent antibacterial activity and favourable biocompatibility, representing a promising alternative strategy, particularly for topical applications. Here, we report the incorporation of cobalt-doped carbon quantum dots (Co-CQDs) into injectable, biocompatible hydrogels capable of both sensing pH and eliminating bacteria. Ultrasmall Co-CQDs demonstrated broad-spectrum activity against gram-positive Methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative Pseudomonas aeruginosa (PAO1), mediated by membrane hyperpolarisation and reactive oxygen species (ROS) induced membrane damage. The particles showed negligible effect on primary fibroblast and endothelial cell viability at concentrations that were bactericidal to MRSA. Polymeric hydrogels were fabricated via electrospinning of chitosan, polyvinylpyrrolidone (PVP), and polyvinyl alcohol (PVA) polymer blends incorporating Co-CQD and pH-responsive HPTS particles. This approach provided accurate measurement of environmental pH within the physiological range observed across healthy and chronic wounds. In vivo, the injectable hydrogels exhibited robust antimicrobial efficacy against MRSA without impairing wound closure relative to untreated controls, while also reducing inflammatory immune responses in infected tissues. Collectively, these findings demonstrate the potential of ultrasmall metal-doped CQDs for infection control and their integration into 3D matrices as multifunctional theragnostic platforms.

Wastewater surveillance (WS) has been widely adopted as a cost-effective and population-representative infectious disease monitoring tool and is increasingly being applied to bacterial and antimicrobial resistance gene (ARG) targets. However, some of these targets may persist in pipe biofilms and detach into wastewater, complicating accurate WS interpretation. To investigate biofilm contributions to wastewater pathogen and ARG signals, paired sink-drain biofilm, branch-drain-plumbing biofilm (sewer biofilm), and wastewater were collected from five hospital sites over a four-month period and analyzed using 16S rRNA gene amplicon sequencing and probe-capture metagenomics. Overall, sewer biofilm bacterial communities were as diverse as wastewater. Across sites, a mean of 9% (0.9 to 23.3%) of wastewater bacterial communities could be attributed to sewer biofilm communities. Many clinically relevant pathogens were consistently detected both in sewer biofilm and wastewater, including environmentally persistent and/or biofilm-associated taxa (e.g., Pseudomonas aeruginosa, Klebsiella pneumoniae). While many ARGs overlapped between wastewater and biofilms (e.g., tetA, sul1, blaCTX-M, vanA), others were significantly enriched in sewer biofilms (e.g., qacL, van-operon and OXA genes). Together, these findings confirm that wastewater pathogen and resistome profiles integrate inputs from both human shedding and pipe-resident communities and therefore need to be considered when selecting WS targets and interpreting signal.

While defined synthetic substrates can replace Matrigel for human induced pluripotent stem cell (hiPSC) culture and hiPSC-derived cardiomyocyte (hiPSC-CM) production, existing approaches culture cells on two-dimensional surfaces and yield structurally immature cardiomyocytes, limiting their use in disease modeling and regenerative medicine. Here, we developed a xeno-free, fully-defined cyclic RGD (cRGD)-functionalized alginate platform in which we encapsulated hiPSCs to support their expansion and in situ cardiac differentiation. cRGD functionalization was essential for hiPSC survival and pluripotency, with maximal support achieved at a low ligand density (25 M). In the presence of cRGD, hiPSC encapsulation into softer gels made from lower molecular weight alginates led to enhanced hiPSC expansion and improved cardiogenesis. Strikingly, differentiation in situ with 3D gels led to hiPSC-CM with higher structural maturity, including a markedly increased proportion of Desmin positive cardiomyocytes. Finally, after enzymatic retrieval from hydrogels, cardiomyocytes derived from softer gels formed tissue-engineered myocardium with superior contractile force compared to tissue fashioned from hiPSC-CM derived from more rigid gels. Together, these results demonstrate the promise of this defined, tunable platform for biomanufacturing of structurally mature cardiomyocytes from hiPSC.

Engineered epithelial models require three-dimensional extracellular matrix environments that support organized cell growth and allow independent access to luminal and basal compartments. However, many organ-on-chip (OoC) fabrication strategies rely on planar geometries, non-native materials, or multi-step assembly workflows that limit architectural complexity and experimental control. Here, we report a direct in-chip volumetric printing strategy for fabricating stretchable and perfusable collagen-I scaffolds inside custom OoC devices. A vitamin C-regulated ruthenium/sodium persulfate photocrosslinking system enabled high-fidelity printing of collagen-I into open-lumen architectures with ductal- and alveolar-inspired features. By generating scaffolds directly within the final culture device, this workflow eliminates post-print transfer and integrates defined collagen architectures with compartmentalized fluidic access and a mechanically actuable chip format. To support chip-based culture, printed collagen constructs were stabilized after fabrication using EDC/NHS chemistry, which limited thermally induced collagen densification, improved shape retention, and maintained scaffold anchorage during perfusion. The chip design provided separate access to the printed lumen and surrounding basal compartment, which enabled compartment-specific fluid handling while preserving scaffold integrity during inflation, stretching, and perfusion of the printed construct. On the collagen-I scaffolds, human milk-derived mammary epithelial cells formed epithelial layers with tight junctions and lactation associated markers. The platform further supported perfusion culture, in situ staining, and whole-chip volumetric imaging. Together, this work establishes direct in-chip collagen-I volumetric printing as a biofabrication strategy for creating perfusable epithelial tissue chips with native matrix architecture and compartmentalized fluidic control.

Granular extracellular matrix (gECM)-based biomaterials commonly contain polymer components to improve scaffold cohesion and handling during fabrication and use. However, these polymer hydrogel components may dilute ECM content and increase fabrication and regulatory complexity. This study evaluated whether particle-only gECM wafers could serve as a simplified alternative to hydrogel-based gECM scaffolds while maintaining structural, mechanical, and biological performance. Decellularized human cartilage and skin tissues were processed and fabricated into three scaffold formats: gECM hydrogels, freeze-dried gECM hydrogel wafers, and freeze-dried particle-only gECM wafers. Across fabrication methods, scaffold swelling, volume fraction, and stiffness were strongly influenced by both tissue type and fabrication approach. gECM hydrogels exhibited the greatest swelling and lowest stiffness, while gECM wafers displayed higher volume fractions and greater mechanical stiffness. Notably, gECM particle-only wafers achieved performance comparable to gECM hydrogel wafers despite the absence of a secondary polymer network. Particle-only wafers also maintained swelling behavior and structural properties over 3 months of dry storage at room temperature, with only modest decreases in stiffness. In vitro studies showed sustained cell viability over 14 days on particle-only wafers, with chondrocytes infiltrating cartilage wafers and fibroblasts remaining primarily surface-localized on skin wafers. In addition, particle-only wafers remained cohesive during implantation into a bovine cartilage defect model. These findings demonstrate that particle-only gECM wafers can achieve structural integrity, mechanical performance, and cytocompatibility without the need for an additional polymer network, highlighting a simplified and ECM-rich biomaterial platform. By eliminating polymer carriers and enabling dry storage with preserved function, this approach supports the development of off-the-shelf, translationally accessible gECM particle-only wafers for tissue engineering applications.

Avascular meniscus tears exhibit minimal intrinsic healing and often progress to joint degeneration due to restricted biological repair capacity and inadequate restoration of tissue-level structure and function. Here, we report a hydrophilic polydopamine (hPDA) fueled bioglue platform that overcomes the solubility limitations of conventional polydopamine (PDA) and enables functional repair of avascular meniscus injuries. Water-soluble hPDA was synthesized via controlled depolymerization and recrystallization, yielding monomeric and oligomeric species rich in catechol, amine, and hydroxyl functionalities. Incorporation of hPDA into fibrin bioglues markedly enhanced mechanical performance, producing 520-525% increases in lap-shear modulus, 165-190% increases in adhesive strength, and a 160% increase in compressive modulus relative to fibrin controls, while degradation was markedly attenuated over 14 days. hPDA exhibited excellent cytocompatibility in both 2D and 3D cultures. In a bovine avascular meniscus explant model, hPDA fueled bioglues promoted tissue integration and aligned collagen remodeling, restoring interfacial mechanics with a 488% increase in tensile modulus and up to 150% higher pull-out strength after 6 weeks. These findings establish hPDA as a versatile bioadhesive building block with strong potential for repairing avascular meniscus tears and other mechanically demanding connective tissues. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=110 SRC="FIGDIR/small/738365v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1f376dborg.highwire.dtl.DTLVardef@10029feorg.highwire.dtl.DTLVardef@1c4f191org.highwire.dtl.DTLVardef@cfa2fe_HPS_FORMAT_FIGEXP M_FIG C_FIG

Tissue engineered skin models are important tools for the in vitro study of physiological and pathophysiological processes as well as the valuation of therapeutic strategies and the efficacy of pharmaceutical and cosmetic compounds. Replicating the functional anatomy of cutaneous tissue is a crucial aspect in ensuring that observations made using these models are translatable to the actual situation in native skin. However, most contemporary full-thickness skin models neglect the reconstruction of the undulated microtopography of the dermal-epidermal junction (DEJ), which not only contributes to the biological functionality of the skin (e.g. stem cell niches), but also affects tissue mechanics and drug diffusion. Herein, we fabricated bilayer skin models with DEJ-like microtopographies introduced by interfacial wrinkling between a hydrogel and a nanofibrous membrane through a controllable swelling-deswelling approach. The interfacial wrinkles contributed to the structural integrity of the bilayer models. Their formation could be induced in the presence of living cells through mechanical stress-driven buckling instabilities, thus differentiating the process from commonly used pre-patterning techniques. Bilayer models supported the co-culture of human dermal fibroblasts and human epidermal keratinocytes, and the formation of stratified epithelia. Our findings provide a potential alternative method to introduce DEJ-like anatomical features into full-thickness skin tissue models.

Animal cell-cultured ingredients are entering the EU and UK pet food markets under frameworks that do not require pre-market, ingredient-level safety assessments, creating an ethical need for transparent safety disclosure. We present the first public safety dossier for this sector, describing the proprietary mouse embryonic stem cell line PE25 and its derived, non-viable cellular and conditioned media ingredient produced in food and feed-grade media. PE25 characterization confirmed Mus musculus identity, sterility, absence of mycoplasma and replication-competent retroviruses, and stable growth. Doxorubicin-induced p53 stress testing, CD44/BMI1 profiling, and soft agar assays showed no cancer-like traits and a non-tumorigenic profile; the final ingredient contains no viable cells. Independent OECD TG 471 and 487 assays confirmed non-genotoxicity. Heavy metals, biogenic amines, solvents, and chemical residues were below regulatory limits. Given process variability, we recommend case-by-case safety evaluation and propose this dossier as a model for responsible commercialization.

Manual intervention for concrete repair and replacement comes at high environmental and economic costs. Bioconcrete, which can be formed by bacteria via microbially-induced carbonate precipitation (MICP), is a sustainable method for concrete repair. Bioconcrete-forming bacteria can be incorporated into the concrete at mixing and then heal cracks where and when they occur. Bioconcrete is not intentionally made by bacteria; rather, it is a byproduct of alterations to the local environment that occur during their normal metabolic activities. Bacteria thus make bioconcrete by different metabolic mechanisms, and the environment plays a substantial role in the yield and physical properties of the bioconcrete produced by a given bacterium. The ureolytic bacterium Sporosarcina pasteurii is the most commonly used model organism for MICP, but it requires urea supplementation, which is not feasible for all applications because of nitrogenous waste. In particular, the marine environment is understudied for bioconcrete applications, yet there is a need for self-healing structures in this environment, wherein urea and nitrogenous waste would be detrimental to native biota. Here, we assessed the ability of S. pasteurii to form bioconcrete under marine-like media conditions with urea and calcium supplementation. We found that S. pasteurii generated higher bioconcrete yields in these media conditions compared to standard growth media. We then designed an enrichment protocol to isolate and characterize non-urea-requiring bioconcrete-forming bacteria from Atlantic seawater. We identified three isolates, from the Sulflitobacter, Marinobacter, and Bacillus genera, two of which yielded higher bioconcrete yields in seawater-mimicking media compared to non-ureolytic bacteria utilized in prior literature. Moreover, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy revealed distinct chemical and structural features of the bioconcrete produced by bacteria in seawater-mimicking medium and between ureolytic and non-ureolytic cultures. Overall, our work establishes a pipeline for the isolation and characterization of novel bioconcrete-forming bacteria from marine samples, with potential for application to marine self-healing materials.

The suspension culture of pluripotent stem (PS) cells in stirred bioreactors poses a delicate balance between maintaining homogeneous cell dispersion and avoiding excessive shear stress that can compromise cell viability and pluripotency. In this study, we used computational fluid dynamics (CFD) coupled with a discrete particle method (DPM) to simulate iPS cell behavior in a 5 mL delta-impeller stirred tank. Our analysis revealed that upward flow at the tank bottom and downward flow at the top are critical for maintaining a stable suspension. To optimize the stirring protocol, we applied Bayesian optimization to identify a time-dependent stirring schedule that begins with a high-speed phase for resuspension, followed by a low-speed phase for sustained suspension with minimal hydrodynamic stress. The optimized schedule demonstrated improved suspension ratio and reduced slip velocity, indicating lower mechanical stress on cells. These findings provide engineering insights into scalable bioreactor operation, contributing to the design of robust iPS cell manufacturing systems.

Vodobatinib (VBN) is a weakly basic (pKa {approx} 2.3), anticancer treatment with poor enteric solubility and low oral bioavailability. This study demonstrates how an emerging polymeric amorphization technique, slurry conversion, can yield amorphous drug-polymer salts with enhanced dissolution rates. The technique had not previously been applied to a weakly basic drug, so design rules for this class of active were unknown. Two acidic polymers, poly(styrene sulfonic acid) (PSSA) and poly(acrylic acid) (PAA), were individually evaluated for salt formation with VBN. Formulation involved blending the drug and polymer in a 1:2 (v/v) ratio of a protic liquid to solvent and a 1:9 (w/w) ratio of solid to solvent. Design rules for effective combinations of solvents and protic liquids were developed and optimized to thread the needle between dissolution of all species and acid-base interactions, both of which were required to form amorphous salts. Drug loadings of 10%, 20%, and 40% by mass were tested. X-ray photoelectron spectroscopy was employed to evaluate protonation of the quinoline nitrogen atoms on VBN, a key indicator of successful salt formation. Powder X-ray diffraction was used to confirm that the resulting slurry contained amorphous VBN, and 1H NMR spectroscopy indicated residual solvent remained after drying, which remains an area for improvement. In dissolution kinetics tests in FeSSIF, the lead drug-polymer salt formulation achieved a concentration of dissolved VBN up to 140 {micro}g/mL, an improvement of >35-fold compared to <4 {micro}g/mL (LLD) for crystalline VBN. These results demonstrate that slurry conversion is a viable polymeric amorphization technique even for weakly basic drugs. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=148 SRC="FIGDIR/small/734800v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1812ceforg.highwire.dtl.DTLVardef@1ad06dcorg.highwire.dtl.DTLVardef@9d8bb7org.highwire.dtl.DTLVardef@13fcbe8_HPS_FORMAT_FIGEXP M_FIG C_FIG

Silk proteins, including sericin and fibroin, are natural biopolymers with broad applications in tissue engineering where angiogenesis plays an essential role. However, the pro-angiogenic effects of silk proteins with varying molecular weights (MWs) remain poorly understood. Here, silk proteins with MW distributions at 40-180 kDa or less than 25 kDa were obtained through alkaline hydrolysis to evaluate their effects on angiogenesis. Structurally, reducing MW induced a conformational transition in silk proteins, accompanied by a striking morphological shift in sericin from nanofibers to nanoparticles. Functionally, high-MW sericin (SSH) suppressed, whereas low-MW sericin (SSL) and both high- and low-MW silk fibroin (SFH/SFL) directly promoted endothelial angiogenic activity. Transcriptomic analysis revealed that angiogenesis-related genes such as Id1 and Smad6/9 may underlie the angiostatic effects of SSH. Notably, both SSH and SSL enhanced angiogenesis indirectly via macrophages; however, SSH induced mixed M1/M2-like polarization, while SSL preferentially drove an M2-like phenotype. In a subcutaneous implantation model, SSH promoted angiogenesis but yielded vessels with weak integrity and increased fibrosis, whereas SSL enhanced angiogenesis with improved vascular maturity and reduced fibrotic response. These findings elucidate how the MWs of silk proteins shape angiogenic behavior and highlight the importance of MW tailoring for optimized tissue engineering applications.