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The use of polymer particles as organic templates for producing inorganic materials is an intriguing approach, because it offers the synthetic feasibility of organic–inorganic hybrid materials which may promise a variety of interesting applications. Here, inspired by mussel-adhesion phenomena in nature, we combined the use of the active surface of polydopamine (PDA) with biomimetic mineralization of hydroxyapatite (HAP) to synthesize a novel HAP-based, organic–inorganic hybrid material. Monodisperse micro-sized polystyrene (PS) particles were first prepared as inert polymer templates via dispersion polymerization, which, subsequently, were coated with PDA through the self-polymerization of dopamine in a weakly alkaline aqueous environment (pH = 8.5). This chemical modification activated the inert surface of PS particles to become bioactive. Thus, these synthesized PS/PDA composite particles were ideal templates for the biomimetic mineralization of HAP when they were incubated in a simulated body fluid (SBF) solution in aid of the biocompatible PDA layer. During the PDA-assisted biomimetic mineralization, the PDA layer interacted with the mineral ions introduced, and anchored the mineralization of HAP exclusively onto the surfaces of the composite particles. The detailed structures and morphologies of HAP-based hybrid materials (PS/PDA/HAP hybrid materials) were characterized. These HAP-based hybrid materials did not show a significant in vitro cytotoxicity against HeLa cells, indicating their potential biocapacity for drug delivery, protein and gene transfer, and as coating materials for bioimplants or as the injectable scaffold materials in bone tissue engineering for defect filling and regeneration.

A facile approach was proposed to decorate silver nanoparticles on sulfonated polystyrene microspheres (denoted as SPS@Ag composite microspheres), in which polyvinylpyrrolidone (PVP) served both as the reductant and stabilizer. In this approach, first, sulfonated polystyrene (SPS) microspheres were synthesized via the sulfonation of monodisperse polystyrene (PS) microspheres in the concentrated sulfuric acid, which were used as the active template cores. Upon the electrostatic attraction between the negatively charged –SO3H groups and the positively charged [Ag(NH3)2]+ ions, silver precursor-[Ag(NH3)2]+ ions were easily adsorbed onto the surfaces of sulfonated polystyrene microspheres. These [Ag(NH3)2]+ ions were in situ reduced to metallic Ag nanoparticles and simultaneously protected by PVP, forming the stable SPS@Ag composite microspheres. During the reaction, neither additional reducing agents nor stabilizers were needed. Moreover, by simply adjusting the concentration of [Ag(NH3)2]+ ions, the size of Ag nanoparticles and the surface coverage of SPS with Ag nanoparticles can be easily tailored. Finally, it has been proven that these as-synthesized SPS@Ag composite microspheres were the ideal active substrates for the surface-enhanced Raman spectroscopy (SERS) for the trace detection trace of the antibiotics (i.e., penicillin G sodium and chloramphenicol), and showed an enhanced antibacterial activity against both Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria) as well.

This paper describes a straightforward approach for the decoration of Ag nanoparticles onto the surface of mesoporous silica nanorods (denoted as SiO2@Ag nanocomposite rods), in which polyvinylpyrrolidone (PVP) serves as both a reductant and stabilizer. In this approach, mesoporous silica nanorods are initially synthesized through a binary surfactant template method by using CTAB and F127 in a basic aqueous solution. Subsequently, through the electrostatic attraction between the negatively charged silanol groups and the positively charged [Ag(NH3)2]+ ions, the silver precursor-[Ag(NH3)2]+ ions can be adsorbed onto the surfaces of mesoporous silica nanorods. Then, those [Ag(NH3)2]+ are in situ reduced to metallic Ag nanoparticles and stay there with the protection of PVP, consequently, SiO2@Ag nanocomposite rods are formed. By adjusting the concentration of [Ag(NH3)2]+ ions, the size of Ag nanoparticles and the surface coverage of mesoporous silica nanorods by Ag nanoparticles can be easily tailored. During the synthesis, neither additional reductants nor surface modifications are necessary. These as-synthesized SiO2@Ag nanocomposite rods show excellent catalytic activity for the reduction of organic dyes, which may be useful for wastewater treatment. Furthermore, these SiO2@Ag nanocomposite rods are ideal candidates as surface-enhanced Raman spectroscopy (SERS) active substrates for the trace detection of antibiotics, i.e., penicillin G sodium and chloramphenicol. This SERS feature may be applicable for organic residue detection in food.