Piezoelectricity, the linear relationship between stress and induced electrical charge, has attracted recent interest due to its manifestation in biological molecules such as synthetic polypeptides or amino acid crystals, including gamma (γ) glycine. It has also been demonstrated in bone, collagen, elastin and the synthetic bone mineral hydroxyapatite. Piezoelectric coefficients exhibited by these biological materials are generally low, typically in the range of 0.1-10 pm V, limiting technological applications. Guided by quantum mechanical calculations we have measured a high shear piezoelectricity (178 pm V) in the amino acid crystal beta (β) glycine, which is of similar magnitude to barium titanate or lead zirconate titanate. Our calculations show that the high piezoelectric coefficients originate from an efficient packing of the molecules along certain crystallographic planes and directions. The highest predicted piezoelectric voltage constant for β-glycine crystals is 8 V mN, which is an order of magnitude larger than the voltage generated by any currently used ceramic or polymer.

Cytochrome aa3 from Paracoccus denitrificans and cytochrome ba3 from Thermus thermophilus, two distinct members of the heme–copper oxidase superfamily, were immobilized on electrodes modified with gold nanoparticles. This procedure allowed us to achieve direct electron transfer between the enzyme and the gold nanoparticles and to obtain evidence for different electrocatalytic properties of the two enzymes. The pH dependence and thermostability reveal that the enzymes are highly adapted to their native environments. These results suggest that evolution resulted in different solutions to the common problem of electron transfer to oxygen.

Here, we present experimental evidence of the direct piezoelectric effect in the globular protein, lysozyme. Piezoelectric materials are employed in many actuating and sensing applications because they can convert mechanical energy into electrical energy and vice versa. Although originally studied in inorganic materials, several biological materials including amino acids and bone, also exhibit piezoelectricity. The exact mechanisms supporting biological piezoelectricity are not known, nor is it known whether biological piezoelectricity conforms strictly to the criteria of classical piezoelectricity. The observation of piezoelectricity in protein crystals presented here links biological piezoelectricity with the classical theory of piezoelectricity. We quantify the direct piezoelectric effect in monoclinic and tetragonal aggregate films of lysozyme using conventional techniques based on the Berlincourt Method. The largest piezoelectric effect measured in a crystalline aggregate film of lysozyme was approximately 6.5 pC N−1. These findings raise fundamental questions as to the possible physiological significance of piezoelectricity in lysozyme and the potential for technical applications.

Aldehyde dehydrogenases (ALDH) form a superfamily of dimeric or tetrameric enzymes that catalyze the oxidation of a broad range of aldehydes into their corresponding carboxylic acids with the concomitant reduction of the cofactor NAD(P) into NAD(P)H. Despite their varied polypeptide chain length and oligomerisation states, ALDHs possess a conserved architecture of three domains: the catalytic domain, NAD(P)+ binding domain, and the oligomerization domain. Here, we describe the structure and function of the ALDH from Thermus thermophilus (ALDHTt) which exhibits non-canonical features of both dimeric and tetrameric ALDH and a previously uncharacterized C-terminal arm extension forming novel interactions with the N-terminus in the quaternary structure. This unusual tail also interacts closely with the substrate entry tunnel in each monomer providing further mechanistic detail for the recent discovery of tail-mediated activity regulation in ALDH. However, due to the novel distal extension of the tail of ALDHTt and stabilizing termini-interactions, the current model of tail-mediated substrate access is not apparent in ALDHTt. The discovery of such a long tail in a deeply and early branching phylum such as Deinococcus-Thermus indicates that ALDHTt may be an ancestral or primordial metabolic model of study. This structure provides invaluable evidence of how metabolic regulation has evolved and provides a link to early enzyme regulatory adaptations.

A combination of chemotherapy with nonconventional nanoparticle based physical destruction therapy has been proposed clinically to reduce the prospect of evolution of drug resistance in cancer. Superparamagnetic nanoparticles have been actively used for synergetic cancer therapy including magnetic fluid hyperthermia (MFH) guided by magnetic resonance imaging (MRI). To explore this direction of potential applications in cancer therapy, we have functionalized superparamagnetic La 0.7 Sr 0.3 MnO 3 nanoparticles (SPMNPs) with an oleic acid-polyethylene glycol (PEG) polymeric micelle (PM) structure, and loaded it with anticancer cancer drug doxorubicin (DOX) in a high loading capacity (∼60.45%) for in vitro delivery into cancer cells. The micellar structure provided good colloidal stability and biocompatibility. Upon drug loading, the cancer cell death rate of 89% was comparable to free DOX (75%) for 24 h, and that the counterstrategy of DOX conjugated SPMNPs-induced hyperthermia resulted the cancer cell extinction up to 80% under in vitro conditions within 30 min. In addition, the preliminary effect of protein corona formation on in vitro drug release and delivery was studied. Finally, in vivo bio distribution of micellar SPMNPs is observed in mice model for 50 mg kg −1 dose of SPMNPs. Taken together, polymeric micelle SPMNPs reported here can serve as a promising candidate for effective multimodal cancer theranostics such as in the combined chemotherapy− hyperthermia cancer therapy.