Current treatments for wound healing engage in passive healing processes and rarely participate in stimulating skin cell behaviors for active wound healing Electric potential difference-derived electrical fields (EFs) are known to modulate skin cell behaviors Here, a piezoelectric dermal patch is developed that can be applied on skin wound site and EF is generated to promote wound healing The one-directionally aligned zinc oxide nanorod-based piezoelectric patch generates piezoelectric potential upon mechanical deformations induced by animal motion, and induces EF at the wound bed In vitro and in vivo data demonstrate that the piezoelectric patch promotes the wound healing process through enhanced cellular metabolism, migration, and protein synthesis This modality may lead to a clinically relevant piezoelectric dermal patch therapy for active wound healing

Zinc Oxide Nanorod-Based Piezoelectric Dermal Patch for Wound Healing

This work characterizes the nucleation and growth kinetics of zinc oxide (ZnO) precipitated from aqueous hexamethylenetetramine (HMTA) zinc nitrate (Zn(NO3)2) solutions observed by in situ and ex situ transmission electron microscopy. Quantitative comparisons between in situ beam-induced precipitation, in situ thermally activated precipitation, ex situ thermally activated precipitation, and ex situ electrochemistry provide insights into the rate limiting mechanism and the chemistry governing the reactions. All experiments indicate that isotropic ZnO precipitates directly from solution. These particles begin to aggregate and grow anisotropically shortly after nucleation. The conversion to anisotropic growth does not rely on coalescence despite the fact that the two are often observed to occur in concert. The results indicate that the reaction pathway for in situ beam-induced growth more closely mimics ex situ electrochemistry than ex situ chemistry. In situ and ex situ thermally activated growth processes ...

Growth Kinetics and Morphological Evolution of ZnO Precipitated from Solution

We have studied the anion ratio effect of acetate and nitrate ions on the formation of different morphologies of ZnO crystals in the presence of NaOH and HMTA. We have varied the concentration of zinc salt precursors as well as adopted three different methods of synthesis (chemical, ultrasonic and hydrothermal) to study their effects on the size/shape of the formed ZnO nanostructures. We found that these anions which spontaneously get introduced along with zinc salt can modify the structure depending on their ratio. The photocatalytic properties of the as obtained ZnO nanostructures (nanoflower, nanospindle and nanorod) were tested towards anionic dye methyl orange. The results show that rod like ZnO nanostructures are catalytically more reactive than nanoflowers and nanospindles. Based on these results we propose that selection of appropriate zinc salt is important to rationally design experiments for a particular morphology. Furthermore, it is also suggested that the role of other precursor salts in synergy will lead to the formation of various nanostructures and this can be extended to other metal oxides of interest for modification.

Morphogenesis of ZnO nanostructures: role of acetate (COOH−) and nitrate (NO3−) ligand donors from zinc salt precursors in synthesis and morphology dependent photocatalytic properties

Growth process, crystal size and alignment of ZnO nanorods synthesized under neutral and acid conditions

The laser-assisted hydrothermal growth kinetics of a cluster of ZnO nanowires are studied based on optical in situ growth monitoring. The growth yields are orders of magnitude higher than those of conventional hydrothermal methods that use bulk heating. This remarkable improvement is attributed to suppression of precursor depletion occurring by homogeneous growth reactions, as well as to enhanced mass transport. The obtained in situ data show gradually decaying growth kinetics even with negligible precursor consumption. It is revealed that the growth deceleration is caused by thermal deactivation resulting from heat dissipation through the growing nanowires. Finally, it is demonstrated that the tailored temporal modulation of the input power enables sustained growth to extended dimensions. These results provide a key to highly efficient use of growth precursors that has been pursued for industrial use of this functional metal oxide semiconductor.

In situ monitoring of laser-assisted hydrothermal growth of ZnO nanowires: thermally deactivating growth kinetics.

Highly uniform mono-dispersed ZnO sub-microrods were synthesized under the condition of a limited injection of Zn divalent ions into an aqueous solution of hexamethylenetetramine at 85 °C. The mechanisms governing the initial seed formation and growth of the ZnO sub-microrods were revealed as an oriented aggregation and classical growth, respectively, from an analytic observation with a high-resolution transmission electron microscope. To demonstrate the capability and possibility of forming uniform microrods for electronic applications, a monolayer of thermally annealed rods was produced on a flexible substrate.

Sung Woo Shon

Papers

Kinetically controlled way to create highly uniform mono-dispersed ZnO sub-microrods for electronics