Functionalization of Titanium Surfaces via Controlled Living Radical Polymerization:  From Antibacterial Surface to Surface for Osteoblast Adhesion

Abstract

Controlled surface graft polymerizations allowed a wide range of functionalities, from antibacterial effects to cell adhesion properties, to be imparted on titanium surfaces. A trichlorosilane coupling agent, containing an atom-transfer radical polymerization (ATRP) initiator, was first immobilized on the oxidized titanium (Ti−OH) surface to cater for the surface-initiated ATRP of 2-hydroxyethyl methacrylate (HEMA). The pendant hydroxyl end groups of the grafted HEMA chains were subsequently converted into carboxyl or amine groups to allow the coupling of gentamicin, penicillin, or collagen via the carbodiimide chemistry. The functionalized Ti surfaces were characterized by X-ray photoelectron spectroscopy and assayed for antibacterial activities or cell adhesion properties. The covalently immobilized antibiotics retain the antibacterial properties, as indicated by a significant reduction in the viability of contacting Staphylococcus aureus. The collagen-immobilized surfaces, on the other hand, promote fibroblast and osteoblast cells adhesion and proliferation. Thus, the present surface-initiated living radical graft polymerization technique allows the tailoring of the Ti surface with vastly different functions and is potentially useful to the design or improvement of Ti-based biomedical implants.

Controlled adhesion of Salmonella Typhimurium to poly(oligoethylene glycol methacrylate) grafts

“…[8,9] In this regard, polyacrylates, oligosaccharides, poly(sulfobetaine methacrylate)s, poly(ethylene glycol)-based polymers, and polyglycidol are well known to be effective in resisting nonspecific protein or cellular adhesion. [10] Nevertheless, hydrophilic polymers such as poly(hydroxyethyl methacrylate) [PHEMA], [8] poly(hydroxypropyl methacrylate) [PHPMA] [11] or polyglycidol [12] can be activated by proteins and antibodies in order to switch them from nonfouling to bioadhesive coatings.…”

Elucidation of Acceleration Mechanisms by a Photosensitive Onium Salt for Nitroxide-Mediated Photocontrolled/Living Radical Polymerization

“…electron donor to OASbF 6 , however this possibility is negated because OASbF 6 should be converted into MTEMPO to control the molecular weight if the electron transfer occurs from the triphenylamine to OASbF 6 . In order to verify the formation of the OAS in the excited state by the electron transfer from MTEMPO to t BuS, the acceleration by t BuS for the MTEMPO-mediated photopolymerization was explored in the presence of the triphenylamine.…”

“…The ratio of the polymer with the uncontrolled molecular weight to that with the controlled molecular weight was estimated to be 0.454/0.546 for Mn = 1,630,000/10,300 based on the area percent by the GPC analysis. The formation of the polymer with the uncontrolled molecular weight implies the generation of a free radical propagating chain end without the counter radical of the mediator, indicating the deactivation of OASbF 6 . This deactivation is considered to occur by the β-elimination of OASbF 6 by the triphenylamine (Scheme 2).…”

“…The controlled/living radical polymerization (CLRP) has been an indispensable technique to design and create highly functional and efficient materials supporting today's cutting-edge technologies in many fields, such as drug and gene deliveries [1]- [4] and anti-bacterial treatment [5] in medical care, photolithography in electronics [6]- [8], water purification in environmental engineering [9], and surface modifications of wettability in the textile and vehicle industries [10]- [12]. The significance of the CLRP is the improvement of the functions by unifying the physical properties based on strict control of the molecular weight related to the structure of the polymers.…”

Controlled Surface Initiated Polymerization of N‐Isopropylacrylamide from Polycaprolactone Substrates for Regulating Cell Attachment and Detachment

“…[15][16][17][18][19] Surface-initiated ATRP was used with great success to obtain designed surfaces exhibiting coatings with thicknesses in the nanoscale with targeted and controlled properties. [1][2][3][4] Gold and silicon were most often employed as substrates for polymerization [3][4][20][21][22][23][24][25][26][27][28] , although tissue culture polystyrene (TCPS) [29][30][31] or titanium [32][33][34][35][36] were also investigated as substrates for biomedical applications. In the specific case of polymer-based scaffolds for tissue engineering, the use of biocompatible polymer substrates, such as poly(ε-caprolactone) (PCL) or other polyester based polymers, is desirable.…”