Helical rosette nanotubes: An investigation towards its application in orthopaedics
Abstract
Success in joint replacements has resulted in a huge demand amongst patients. Younger patients are demanding longer life expectancy from devices and this has led to new formulations of high performance nanomaterials (materials with basic structural units of 1-100 nm). Nanotubes have shown great promise because they: (1) have sizes that approach biological structures and (2) can display chemistries relevant to living systems at high densities and well-controlled spatial distribution. Helical rosette nanotubes (HRN) are novel soft organic nanomaterials composed of a guanine-cytosine building block that self-assembles in aqueous environments into stable nanotubes (inner diameter: ∼1.1 nm) decorated with chemical functionalities on the periphery. The work herein represents the first investigation of HRN for orthopaedic implant applications. It was shown that: (1) osteoblasts (bone forming cells; OB) attached more strongly and in greater numbers on surfaces coated with HRN than the corresponding bare substrates. (2) A heated (+T) sample of HRN-K1 formed denser nanotube networks than an unheated (-T) sample. (3) Following OB adhesion experiments, proteins were seen to be important only for +T HRN-K1. This was attributed to the nanotube aggregation states and surface coverage differences between +T and -T HRN-K1. (4) When OB were cultured in the absence of proteins, HRN were seen to act like some protein(s); an indication that HRN are favorable to both proteins and OB. (5) Adherent OB formed numerous long filopodia which appeared to integrate favorably with HRN; a striking new observation on a nanotube architecture. (6) Lysine moieties on HRN may play an electrostatic role in OB attachment on HRN-coated surfaces. (7) HRN displayed a dose-dependent toxicity on a monolayer of OB with an IC50 = ∼ 0.01 mg/mL after 1 day. A greater and more rapid toxic effect (with apoptotic and necrotic characteristics) was observed on a suspension of OB when exposed to the same concentration of HRN. These studies were important (1) for initial biocompatibility screening, (2) understanding the characteristics of HRN that are important for cell attachment, (3) for product development considerations and (4) for addressing some concerns surrounding the use of engineered nanomaterials in living systems.
Degree
Ph.D.
Advisors
Fenniri, Purdue University.
Subject Area
Cellular biology|Biomedical research
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