Copper is an indispensable trace metal element in the human body, which is mainly absorbed in the stomach and small intestine and excreted into the bile. Copper is an important component and catalytic agent of many enzymes and proteins in the body, so it can influence human health through multiple mechanisms. Based on the biological functions and benefits of copper, an increasing number of researchers in the field of biomaterials have focused on developing novel copper-containing biomaterials, which exhibit unique properties in protecting the cardiovascular system, promoting bone fracture healing, and exerting antibacterial effects. Copper can also be used in promoting incisional wounds healing, killing cancer cells, Positron Emission Tomography (PET) imaging, radioimmunological tracing and radiotherapy of cancer. In the present review, the biological functions of copper in the human body are presented, along with an overview of recent progress in our understanding of the biological applications and development of copper-containing materials. Furthermore, this review also provides the prospective on the challenges of those novel biomaterials for future clinical applications.
Porous anodic aluminum oxide (AAO) templates with diverse nano/submicron/micron multiple-scale structures have been fabricated by a facile and controllable two-step anodization process. The first step anodization has been achieved by using a simple competitive growth process with high anodization voltage (U a ) in ethanol-oxalic acid mixture electrolytes. The effects of U a (300-600 V), anodization current density (J a , 100-200 A m −2 ), and the proportion of ethanol adding (0.3 M oxalic acid : ethanol = 1 : 1, 3 : 2, V/V) on the submicron/micron structures of AAO templates have been investigated in detail. The second step anodization has been conducted under relatively lower U a of 30 V and 40 V, respectively. The effects of U a , etching process, and anodization time on the nanostructures of as-fabricated porous AAO templates have been studied carefully. In addition, related intrinsic formation mechanisms have also been investigated. Based on these quantitative experimental results, the fabrication of multiple-scale porous AAO films with diverse nano/submicron/micron structures can be more controllable and designable, facilitating their practical applications in simple template synthesis of complex multiple-scale functional materials.Anodic aluminum oxide (AAO) films prepared by aluminum anodization have been investigated and used in numerous fields for more than 150 years. 1-24 In 1953, Keller et al. investigated the structural features of porous type AAO films in detail with the electron microscope and proposed a corresponding structural model. 5 Since then, porous AAO films which contain a large number of nanopores have attracted considerable attention. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] In 1995, Masuda et al. firstly proposed a pre-patterning fabrication process which contains the first anodization for forming highly ordered dimples on the aluminum surface, and the second anodization for obtaining ideally ordered porous AAO films. 12,13 At present, they have become one of the most commonly used nanoporous templates for the fabrication of diverse nanomaterials (e.g., nanowire, nanotube, and nanodot) because of their apparent advantages, such as good reproducibility, adjustable pore size, and controllable film thickness, etc. 25-35 Moreover, they can also be used as functional materials for many applications: e.g., biotechnology, photonics, sensors. [36][37][38][39][40] Nowadays, although porous AAO films can be applied in many practical fields, there are still some shortcomings which greatly limit their applications: most of the fabricated porous AAO films have a simple honeycomb-like microstructure, and their pore size is typically limited to nanoscale or submicron scale. Based on these structural features, it is difficult for their template synthesis of functional materials with micron scale or nano/submicron/micron multiple-scale structures. Over the last decade, tremendous research has been focused on the development of multiple-scale materials which have become a h...
In this paper, three types of unique anodic aluminum oxide (AAO) structure were fabricated based on patterned aluminum surface:(1) AAO with three-dimensional (3D) interconnected pores; (2) controllable self-assembled AAO nanowires; (3) supporting AAO skeleton structures. Patterned aluminum surface was obtained by using high voltage anodization processes (400-600 V) in ethanoloxalic acid electrolyte and a following AAO removing method. The voltage/current-time curves during anodization were analyzed in detail. Moreover, the AAO microstructure, film thickness, and film growth rate have been studied based on smooth and also on patterned aluminum surface. In addition, the influences of anodization and etching conditions on AAO microstructure evolutions, e.g., 3D interconnected pores, controllable self-assembled nanowires and supporting skeleton structures have also been investigated. The present fabrication methods for obtaining unique AAO structures are facile, effective, and inexpensive, facilitating practical applications of AAO in diverse related fields.
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