Longitudinal Piezoelectricity in Orthorhombic Amino Acid Crystal Films

The symmetry of orthorhombic amino acid single crystals precludes the existence of a longitudinal piezoelectric response. Here we report the growth of amino acid crystal films on conductive substrates that demonstrate measurable longitudinal piezoelectricity of the same order of magnitude as large piezoelectric biopolymers. Crystal films of the nonproteinogenic amino acid hydroxyproline show a response of the same magnitude as quartz single crystals. This response is deconstructed using density functional theory single crystal predictions and cross-sectional electron microscopy. These results verify that amino acid films can serve as simple piezoelectric transducers, which could be used for a variety of energy harvesting applications

Multimodal Superparamagnetic Nanoparticles with Unusually Enhanced Specific Absorption Rate for Synergetic Cancer Therapeutics and Magnetic Resonance Imaging

Superparamagnetic nanoparticles (SPMNPs) used for magnetic resonance imaging (MRI) and magnetic fluid hyperthermia (MFH) cancer therapy frequently face trade off between a high magnetization saturation and their good colloidal stability, high specific absorption rate (SAR), and most importantly biological compatibility. This necessitates the development of new nanomaterials, as MFH and MRI are considered to be one of the most promising combined noninvasive treatments. In the present study, we investigated polyethylene glycol (PEG) functionalized La_1–<i>x</i>Sr_<i>x</i>MnO₃ (LSMO) SPMNPs for efficient cancer hyperthermia therapy and MRI application. The superparamagnetic nanomaterial revealed excellent colloidal stability and biocompatibility. A high SAR of 390 W/g was observed due to higher colloidal stability leading to an increased Brownian and Neel’s spin relaxation. Cell viability of PEG capped nanoparticles is up to 80% on different cell lines tested rigorously using different methods. PEG coating provided excellent hemocompatibility to human red blood cells as PEG functionalized SPMNPs reduced hemolysis efficiently compared to its uncoated counterpart. Magnetic fluid hyperthermia of SPMNPs resulted in cancer cell death up to 80%. Additionally, improved MRI characteristics were also observed for the PEG capped La_1–<i>x</i>Sr_<i>x</i>MnO₃ formulation in aqueous medium compared to the bare LSMO. Taken together, PEG capped SPMNPs can be useful for diagnosis, efficient magnetic fluid hyperthermia, and multimodal cancer treatment as the amphiphilicity of PEG can easily be utilized to encapsulate hydrophobic drugs

(CHI/PEC)₄/Cyt<i>c</i>O NPCs sequence of images before (Panel A) and after addition of dye (B–D).

<p>The dashed line indicates the border of one (CHI/PEC)₄/Cyt<i>c</i>O NPCs which upon addition of the dye swells and finally explodes. Scale bar is 5 µm.</p

Confocal images of NPCs in the presence of rhodamine.

<p>Forward (a, d), confocal (b, e) and merged (c, f) images of empty capsules (top) can be compared with the corresponding images of (PSS/PAH)₄/Cyt<i>c</i>O NPCs (bottom). The scale bar is equivalent to 5 µm.</p

QCM-D result showing the in situ build-up of the multilayer PAH-(PSS/PAH)₄/Cyt<i>c</i>O films at a pH 8.5.

<p>Frequency changes are recorded as a function of time for the 3^rd, 5^th and 7^th armonics.</p

Cyt<i>c</i>O redox activity measured polarographically.

<p>The O₂-consumption as a function of time for reaction mixture without Cyt<i>c</i>O, Cyt<i>c</i>O in solution, PSS/PAH)₄/Cyt<i>c</i>O NPCs and PSS/PAH)₄ NPCs. 100% indicate the initial amount of O₂ in all the different samples.</p

Surface coverage grow-up of the multilayer (PAH/PSS)₄/PAH/Cyt<i>c</i>O at pH 8.5 as a function of the number of layers, calculated with the Voigt model by QCM-D.

<p>Step number 11 correspond to surface coverage value of the multilayer after the addition of Cyt<i>c</i>O.</p

Effects of Polydopamine Functionalization on Boron Nitride Nanotube Dispersion and Cytocompatibility

Boron nitride nanotubes (BNNTs) have unique physical properties, of value in biomedical applications; however, their dispersion and functionalization represent a critical challenge in their successful employment as biomaterials. In the present study, we report a process for the efficient disentanglement of BNNTs via a dual surfactant/polydopamine (PD) process. High-resolution transmission electron microscopy (HR-TEM) indicated that individual BNNTs become coated with a uniform PD nanocoating, which significantly enhanced dispersion of BNNTs in aqueous solutions. Furthermore, the cytocompatibility of PD-coated BNNTs was assessed in vitro with cultured human osteoblasts (HOBs) at concentrations of 1, 10, and 30 μg/mL and over three time-points (24, 48, and 72 h). In this study it was demonstrated that PD-functionalized BNNTs become individually localized within the cytoplasm by endosomal escape and that concentrations of up to 30 μg/mL of PD-BNNTs were cytocompatible in HOBs cells following 72 h of exposure