Liquid‐phase laser process for simple and area‐specific calcium phosphate coating

Abstract

Simple, mild, and area-specific calcium phosphate (CaP) coating techniques are useful for the production and surface modification of biomaterials. In this study, an area-specific CaP coating technique for polymer substrates was successfully developed using a liquid-phase laser process. In the proposed method, Nd-YAG laser light (355 nm, 30 Hz, and 1-3 W) irradiated an ethylene-vinyl alcohol copolymer (EVOH) substrate immersed in a supersaturated CaP solution for various periods of time (up to 30 min). The CaP-forming ability increased with an increase in the laser power and irradiation period. At the optimal laser power (3 W), a continuous CaP layer formed within 30 min on the laser-irradiated surface of the EVOH substrate. The formation of CaP was attributed to laser absorption by the EVOH substrate, which promoted the surface modification of EVOH and an increase in the temperature of the solution near the surface of the substrate. The resulting CaP coating showed better cell adhesion property than the naked EVOH substrate. The proposed CaP coating technique is simple (quick and single step) and area specific. Furthermore, the present process is carried out under mild conditions, that is, at normal pressures and temperatures in a safe aqueous medium. These are significant advantages of the proposed CaP coating technique.

Calcium orthophosphate deposits: Preparation, properties and biomedical applications

“…This occurred due to formation of small CaPO 4 crystals during irradiation, which further facilitated the growth of thicker deposits on the irradiated area of the substrates [632]. Similar results were also obtained for both polymeric [633,634] and HA [635] …”

Physicochemical fabrication of calcium phosphate-based thin layers and nanospheres using laser processing in solutions

“…Conventionally, CaP-based thin layers and nanoparticles have been fabricated by either physical or chemical process (this will be described in more detail later). Recently, we developed a new physicochemical process for the fabrication of CaP-based thin layers [38][39][40][41][42] and nanospheres 43,44 by combining a physical laser process and a chemical precipitation process. In this process, pulsed laser irradiation is performed without focusing to a metastable or labile supersaturated CaP solution to induce lightmaterial interactions at a laser-irradiated substrate surface (for thin layer fabrication) or in the entire solution (for sphere fabrication) ( Fig.…”

“…[50][51][52][53][54] Such two-step CaP coating techniques are described in Section 2.2. Recently, these twostep techniques have been refined, and one-step CaP coating was achieved using a laser-assisted biomimetic (LAB) process; [38][39][40][41][42] this process is described in detail in Section 2.3.…”

“…In the two-step techniques described in Section 2.2, the overall processing time including the immersion period in the second step is longer than 24 h. Recently, we developed a rapid (o30 min) and onestep CaP coating technique for the EVOH substrates by simplifying Lee's two-step process. 38 In this new process (referred to as a laser-assisted biomimetic (LAB) process), unfocused pulsed UV (l = 355 nm) laser light with a slightly higher fluence (200 mJ per pulse per cm 2 ) and frequency (30 Hz) than those used in Lee's process was used to irradiate the EVOH substrate immersed in the CP solution maintained at 25 1C by a water bath (Fig. 3a).…”

Synthesis of calcium phosphate coatings and nanoparticles using supersaturated solutions for biomedical applications

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