One of the main challenges in modern tissue engineering is to design biocompatible scaffolds with finely tuned porous architecture and capacity to load bioactive molecules that guide the growth and differentiation of the cells during tissue reconstruction. This work proposes a strategy to design porous alginate scaffolds (PAS) with well-tuned architecture by leaching of sacrificial vaterite CaCO 3 microspheres packed in alginate. Pore size and interconnectivity depend on CaCO 3 sphere dimensions and packing as well as alginate concentration. Varying of these parameters, almost hundred percent pore interconnectivity (or, by contrast, a zero pore interconnectivity) can be achieved. Junctions between interconnected pores are about 50-70% of the pore dimensions that provides molecular transport through the PASs potentially ensuring diffusion of nutrition, oxygen and metabolic products when cell seeding. An opportunity to fabricate a multifunctional scaffold is demonstrated by encapsulation of desired macromolecules into the individual pores of a scaffold (is illustrated by dextran loading). Mechanical properties of PASs are found typical for soft and hydrated structures (Young's modulus of 19 ± 15 kPa) which is appropriate for cell seeding. The three cell lines (HeLa, HEK293, and L929) are cultured on different alginate scaffolds to examine cell viability and adhesiveness.

A statistical mechanical theory of nonionic (single-component) micelles, well suited for applications, is developed by a simple extension of Hill's theory of solutions. An expression for the Gibbs potential of a dilute micellar solution is derived which involves the micelle size distribution and certain effective micelle partition functions. Using this Gibbs potential, both micelle thermodynamics and micelle structure and size distribution can be simply and directly treated. The thermodynamics obtained agrees with Hall and Pethica's small system thermodynamics treatment within the approximations (ideality, monodispersity, neglect of solvent composition changes) made by these authors. The micelle size distribution is found to obey Tanford's law of mass action type relation with a size dependent free energy. An approximate but detailed consideration of the effective micelle partition function leads to the local packing condition for micelles recently introduced by Israelachvili, Mitchell, and Ninham. Interactions between micelles can be included in the present statistical theory by an expansion in powers of micelle molalities; a rough, excluded volume type estimate indicates that these interactions only become important for the micelle properties when the total amphiphile molality (moles of amphiphile per mole of solvent) is greater than about I. IntroductionA statistical mechanical theory of nonionic micelles1 is developed in this paper. The treatment amounts to a straightforward generalization of Hill's theory of solutions2 which is based on a statistical ensemble first extensively used by S t~c k m a y e r .~ An expression for the Gibbs potential of a micellar solution is derived; it involves the distribution of micelle aggregation numbers and also certain effective micelle partition functions. From this Gibbs potential the small system thermodynamics of Hall and Pethica4 for (single-component) nonionic micelles can be derived very simply. We note, however, that except in the monodisperse limit the micellar enthalpy and volume differences defined by Hall and Pethica are not identical with the quantities measured in a dilution experiment.Tanfords has introduced a theory, based on the law of mass action, which relates micelle sizes and the critical micelle concentration to a size dependent free energy of micellization. Israelachvili, Mitchell, and Ninham6i7 modified Tanford's theory by introducing a local packing criterion which imposes certain geometrical constraints on the allowed micelle structures. We indicate how contact between these theories and the present statistical theory is made by means of suitable approximations to evaluate the effective micelle partition functions. In particular, an approximate derivation of the local packing condition of ref 6 mentioned above is given. This packing condition appears to be of considerable importance. It links together

To implement a specific function, cells recognize multiple physical and chemical cues and display molecular responses at their interfaces - boundary regions between cell lipid-based membrane and surrounding extracellular matrix...