To improve liquid formulation stability, formulators employ various excipients designed to stabilize protein drugs, including buffers, salts, sugars, and surfactants. One of the roles of surfactants is to protect the protein drug from surface interactions that can destabilize the protein. Protein drug products formulated with surfactants usually contain either a polysorbate or poloxamer. Even in the presence of these surfactants, protein drug stability is often insufficient, particularly because of agitation-induced aggregation. FM1000 is one of a series of surfactants containing an alkyl chain, an amino acid, and a polyetheramine. The characterization of the dynamics of FM1000 at various water/hydrophobic interfaces was compared to Polysorbate 20, Polysorbate 80, and Poloxamer 188. FM1000 stabilizes an interface 1−2 orders of magnitude faster than all three of these surfactants, even in the presence of protein. The faster dynamics leads to improved stabilization of model protein biologic drugs IgG and abatacept against agitation-induced aggregation. These results provide mechanistic understanding of the key causes and drivers of protein aggregation.

The mechanical stimuli generated as a finger interrogates the physical and chemical features of an object forms the basis of fine touch. Haptic devices, which are used to control touch,...

Biomedical electronic devices can be interfaced with the human body to measure physiological signals [1,2] or to provide electrical stimulation for treatment. [3,4] Electronic materials that can be seamlessly interfaced with human tissues or cells are, therefore, essential to study or stimulate the nervous system, or to serve as neural tissue scaffolds. But, materials challenges remain to be addressed to bridge the gap between "soft" biological tissues and "hard" electronics. The mechanical mismatch between biological tissues and electronics can lead to scar formation between the electronics and the target tissue, which significantly hampers the performance and efficacy of bioelectronic stimulation and recording. [3,5,6] Conductive hydrogels are a promising strategy for interfacing electronic materials with biological tissues. [6,7] Due to their high water content (70-99 wt%), hydrogels can be as soft and flexible as biological tissues, including skin, muscle, heart, spinal cord, and brain (E < 100 kPa). [6] To impart electrical conductivity, conductive nanoparticles, such as metal nanowires (NWs) [8,9] carbon nanotubes (CNTs), [7] and conductive polymers [5,7,10] can be incorporated inside the hydrogel. NWs and CNTs, while effective at achieving electronically conductive hydrogels, were shown to lead to heterogeneities in the network and hydrogels with a high elastic modulus; overall leading to a poor interface with biological entities. [8] Compared to these nanocomposite hydrogels, conductive hydrogels made from conducting polymers (CPs), including poly(3,4-ethylenedioxythiophene) (PEDOT), [11,12] polypyrrole (PPy), [13][14][15] or polyaniline (PANI) [15,16] offer a higher compatibility with biological systems, by virtue of their flexibility and potential for ionic-as well as electronic-conductivity.Several methods have been envisioned for the preparation of conductive hydrogels from CPs. [17,18] The conducting polyelectrolyte complex of PEDOT with poly(styrene sulfonate) (PEDOT:PSS) can be gelled directly from its aqueous solution by increasing the ionic strength with bivalent ions Mg 2þ , Ca 2þ , or multivalent ions Fe 3þ , Ce 4þ . [19,20] These conductive hydrogels, however, are only weakly crosslinked leading to poor strength and contain residual ions, which could lead to potential inflammation and cell toxicity. [21] Thus, the purification process requires a large amount of distilled water for at least a week to wash out excess ions. [20] Another method is the use of secondary dopants, including sulfuric acid and dimethyl sulfoxide, as both