Empirical economic analysis shows cost-effective continuous manufacturing of cultivated chicken using animal-free medium.

Cellular agriculture aims to meet the growing demand for animal products. However, current production technologies result in low yields, leading to economic projections that prohibit cultivated meat scalability. Here we use tangential flow filtration for continuous manufacturing of cultivated meat to produce biomass of up to 130 × 106 cells per ml, corresponding to yields of 43% w/v and multiple harvests for over 20 days. Continuous manufacturing was carried out in an animal-component-free culture medium for US$0.63 l-1 that supports the long-term, high density culture of chicken cells. Using this empirical data, we conducted a techno-economic analysis for a theoretical production facility of 50,000 l, showing that the cost of cultivated chicken can drop to within the range of organic chicken at US$6.2 lb-1 by using perfusion technology. Whereas other variables would also affect actual market prices, continuous manufacturing can offer cost reductions for scaling up cultivated meat production.

Tuning of protease resistance in oligopeptides through N-alkylation.

N-Methylation of amino acids is an effective way to create protease resistance in both natural and synthetic peptides. However, alkyl substituents other than N-methyl have not been extensively studied. Here, we prepare and examine a series of N-substituted peptides in which the size and length of the alkyl group is modulated. These design insights provide a unique and modular handle for tuning proteolysis in oligopeptides.

Light-Mediated Atom Transfer Radical Polymerization of Semi-Fluorinated (Meth)acrylates: Facile Access to Functional Materials.

A highly efficient photomediated atom transfer radical polymerization protocol is reported for semi-fluorinated acrylates and methacrylates. Use of the commercially available solvent, 2-trifluoromethyl-2-propanol, optimally balances monomer, polymer, and catalyst solubility while eliminating transesterification as a detrimental side reaction. In the presence of UV irradiation and ppm concentrations of copper(II) bromide and Me6-TREN (TREN = tris(2-aminoethyl amine)), semi-fluorinated monomers with side chains containing between three and 21 fluorine atoms readily polymerize under controlled conditions. The resulting polymers exhibit narrow molar mass distributions (D ≈ 1.1) and high end group fidelity, even at conversions greater than 95%. This level of control permits the in situ generation of chain-end functional homopolymers and diblock copolymers, providing facile access to semi-fluorinated macromolecules using a single methodology with unprecedented monomer scope. The results disclosed herein should create opportunities across a variety of fields that exploit fluorine-containing polymers for tailored bulk, interfacial, and solution properties.

Gold Nanoparticle Assemblies on Surfaces: Reactivity Tuning through Capping-Layer and Cross-Linker Design.

The immobilization of metal nanoparticles (NPs) with molecular control over their organization is challenging. Herein, we report the formation of molecularly cross-linked AuNP assemblies using a layer-by-layer approach. We observed four types of assemblies: 1) small aggregates of individual AuNPs, 2) large aggregates of individual AuNPs, 3) networks of fused AuNPs, and 4) gold islands. Interestingly, these assemblies with the different cross-linkers and capping layers represent different stages in the complete fusion of AuNPs to afford islands of continuous gold. We demonstrate that the stability toward fusion of the nanoparticles of the on-surface structures can be controlled by the reactivity of the cross-linkers and the hydrophilicity/hydrophobicity of the nanoparticles.

Surface-confined core-shell structures based on gold nanoparticles and metal-organic networks.

Here we show a step-wise approach for the formation of continuous shell-structures on surface-confined gold nanoparticles. The nanoparticle-cores induce order in the shell-structure, which consists of metal-organic networks. Communication between the organic and inorganic parts is reflected in their optical properties.

Assembly of surface-confined homochiral helicates: chiral discrimination of DOPA and unidirectional charge transfer.

Surface-confined double-helical polymers are generated by dynamic covalent assembly with preservation of chirality, metal coordination environment, and oxidation state of the precursor complexes. This one-step procedure involves both in solution and solution-to-surface assembly and resulted in chiral interfaces where pairs of ligands are wrapped around arrays of metal ions. In-plane XRD experiments revealed the formation of a highly ordered structure along the substrate surface. The chirality of the surfaces is expressed by the selective recognition of 3,4-dihydroxyphenylalanine (DOPA). The CD measurements show a response of the Δ-polymer-modified quartz substrates toward D-DOPA, whereas no change was observed after treatment with L-DOPA. These coordination-based interfaces assembled on metal-oxide substrates in combination with a redox-probe, [Os(bpy)3](PF6)2, in solution can resemble the behavior of a rectifier.

Molecule and electron transfer through coordination-based molecular assemblies.

This study provides insight into the internal structure of surface-confined molecular assemblies. The permeability of the layer-by-layer grown thin films can be controlled systematically by varying their composition and the structure of their molecular components. Moreover, the thickness can be used to control molecule permeation versus electron transfer.

Halogen-bonding mediated stepwise assembly of gold nanoparticles onto planar surfaces.

In this study halogen bonding (XB) is used as the driving force for the noncovalent assembly of gold nanoparticles (AuNPs) on silicon and quartz substrates functionalized with organic monolayers. The AuNPs are functionalized with XB-donor ligands, whereas the monolayers have pyridine groups as XB-acceptors. The surface-confined systems are formed by iteratively exposing the monolayers to solutions of organic cross-linkers having 2-4 pyridine groups and functionalized AuNPs. UV-vis spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) reveal how the structure of the resulting surface-bound assemblies are controlled by (i) the properties of the monolayers, (ii) the molecular structure and the number of XB binding sites of the organic cross-linker, and (iii) the number of functionalized AuNP and cross-linker deposition steps. Moreover, these structures exhibit surface-enhanced Raman scattering and significant changes are observed in the morphology of some of the surface-bound assemblies upon aging.

Synergism in multicomponent self-propagating molecular assemblies.

Multicomponent self-propagating molecular assemblies (SPMAs) have been generated from an organic chromophore, a redox-active polypyridyl complex, and PdCl(2). The structure of the multicomponent SPMA is not a linear combination of two assemblies generated with a single molecular constituent. Surface-confined assemblies formed from only the organic chromophore and PdCl(2) are known to follow linear growth, whereas the combination of polypyridyl complexes and PdCl(2) results in exponential growth. The present study demonstrates that an iterative deposition of both molecular building blocks with PdCl(2) results in an exponentially growing assembly. The nature of the assembly mechanism is dictated by the polypyridyl complex and overrides the linear growth process of the organic component. Relatively smooth, multicomponent SPMAs have been obtained with a thickness of ∼20 nm on silicon, glass, and indium-tin oxide (ITO) coated glass. Detailed information of the structure and of the surface-assembly chemistry were obtained using transmission optical (UV/Vis) spectroscopy, ellipsometry, atomic force microscopy (AFM), synchrotron X-ray reflectivity (XRR), and electrochemistry.

Stepwise assembly of coordination-based metal-organic networks.

Metal-organic networks (MONs) were created by a stepwise solution deposition approach from vinylpyridine-based building blocks and PdCl(2). The combined experimental and computational study demonstrates the formation of saturated, structurally organized systems on solid supports. The rigid nature and geometry of the components are well-suited to form honeycomb and parallelogram structures, as predicted by a computational study. Detailed structural information of the new MONs was obtained by optical (UV/vis) spectroscopy, ellipsometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and synchrotron X-ray reflectivity (XRR). Notably, the XPS elemental composition indicates the formation of a palladium coordination-based network.

Linear vs exponential formation of molecular-based assemblies.

Here we present the critical role of the molecular structure and reaction parameters on the nature of thin-film growth, using a versatile two-step assembly method with organic and metal-organic chromophores cross-linked with palladium. It was found that the polypyridyl complexes exhibit exponential growth, whereas, under identical conditions, the organic systems exhibit linear behavior. The internal film morphology plays a pivotal role in the storage and usage of the palladium, where a more porous structure results in exponential growth. Interestingly, through proper tuning of the reaction conditions, the growth of the molecular assemblies can be controlled, resulting in a changeover from exponential to linear growth. These findings unequivocally demonstrate the importance of both the internal film structure and deposition conditions on the assembly of molecular-based films.