Investigation of the lubrication properties and synergistic interaction of biocompatible liposome-polymer complexes applicable to artificial joints

https://doi.org/10.1016/j.colsurfb.2019.03.041Get rights and content

Highlights

  • Liposomes with increasing carbon chain length reveal excellent lubrication.

  • The bilayers weaken the stability of vesicles and exhibit increased friction.

  • Lipid complexes led to the formation of a remarkable boundary lubrication layer.

  • Lipid complexes can efficiently improve the lubrication properties of liposomes.

Abstract

Achievement of efficient biolubrication is essential for the design of artificial joints with long lifetimes. This study examines the frictional behaviors and adsorption structures of liposomes and liposome complexes with biocompatible polymers to reveal the underlying lubrication mechanisms between biomimetic bearing surfaces of polyetheretherketone (PEEK) and silicon nitride (Si3N4). The liposomes with increasing carbon chain lengths exhibit the remarkable lubrication capabilities that correlate strongly with the structural integrity of small unilamellar vesicles adsorbed on the Si3N4 surfaces, while the bilayer structures weaken the stability of vesicles against rupture and cause the increase of friction. The synergistic interaction of liposomes and biocompatible negative-charged polymer leads to the formation of a boundary–lubricating layer with high-density liposome–polymer complex structures that can efficiently improve the lubrication properties of liposomes. Our findings might have implications for future biolubrication investigations on biocompatible liposome–polymer complexes applicable to artificial joints at the specified macroscale conditions.

Introduction

In recent years, continuing efforts have been expended in the field of biotribology, including biolubrication and biomaterials for many medical applications, such as synovial joints, dental, and heart valve prostheses [1]. The synovial joints, involving the hip, knee, and elbow in mammals, consist of two interacting bones covered by a thin layer of cartilage tissue, and synovial fluid (SF) between them [1]. Many studies have been carried out to reveal the compositions of the cartilage tissue [2] and SF, as well as the load bearing and lubrication mechanisms for the treatment of joint diseases [[3], [4], [5], [6]]. Some models, such as fluid film theories [1], and boundary lubrication theories [4,5], have been proposed to explain the lubrication properties of the adsorbed or grafted layer on the joint surfaces. However, little reliable information is available about the composition and mechanism of the sliding layers that keep the joint surfaces well lubricated [1]. Recently, phosphatidylcholine (PC) liposomes and bilayers were extensively considered as efficient biological lubricants in physiological joint lubrication [[7], [8], [9], [10]]. Sorkin et al. found that liposomes have more stable and significantly efficient lubricant capabilities compared to bilayers on the surface force balance (SFB) measurements [11]. Tribological interactions between the layers of surface-attached small unilamellar vesicles (SUVs) or liposomes have also been examined showing that such layers can provide an efficient boundary lubrication [12], but also depend on the PC used and the presence of SUVs in the surrounding dispersions [8,10,13,14]. Seror et al. confirmed that the efficient hydration lubrication capability of phospholipids could aid the reduction of physiological coefficient of friction (COF) under physiological pressures, thereby suggesting a potential role for the boundary lubricant of synovial joints [1,3,7,8,15]. Some reports have also shown that the lubrication ability of the phospholipids is mainly related to the lipid stability on the biosurfaces as surface-attached molecules provide lubrication when the sliding surfaces come into contact [10]. Biocompatible polymers have already been used in biomedical applications [[16], [17], [18], [19]], owing to the considerable potential of their mechanical and biological properties [[20], [21], [22], [23]]. Many studies reported that PC lipids complexed with biopolymers, such as hyaluronic acid and lubricin, could provide efficient boundary lubrication between two biomaterial surfaces [[24], [25], [26], [27], [28]]. A complex of hyaluronan and PC lipids between mica surfaces could yield low-friction coefficients (μ ≈ 10−3) following nanotribological measurements [17]. It is thus tempting to evaluate a synergistic effect between cartilage macromolecules and complexes with PC lipids, providing efficient lubrication of synovial joints at the macroscale [1,24,25,29].

Many materials, such as metal alloys, ceramic and polymers have been increasingly used for knee and hip joint replacements owing to their excellent wear and abrasion resistance [30,31]. Some ceramics, such zirconia (ZrO2) and alumina (Al2O3), have already been reported to be used as implant materials [32]. Si3N4 is an advanced ceramic material that might also play a prominent position as composite ceramics used in the artificial joints for biomedical applications. PEEK has been extensively considered as a suitable polymer material for use in the replacement of metal components in orthopaedics, trauma, and spinal implants. It is characterized by increased strength and stiffness, good fracture toughness, resistance to corrosion, and comparable elastic modulus and density to those of human tissue [33,34]. However, most studies on friction of PEEK materials focused on water, phosphate buffered solution (PBS), or calf serum (CS) as the lubricants, few of these have studied the interaction between lipids and PEEK. Therefore, in the present work, we focus on the synergistic interaction between lipid complexes and PEEK for potential applications in artificial joints and biolubrications. Moreover, the synergistic lubrications between lipids and biocompatible polymer were also studied at the macroscale.

Section snippets

Materials

The lipids used in this study were (using the notation X : Y to indicate the number of carbon in the fatty acid chains and the degree of unsaturation, respectively) [35], 1, 2-dilauroyl-sn-glycero-3-phosphocholine (DLPC 12:0, Mw = 621.8 g mol−1); 1, 2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC 14:0, Mw = 677.933 g mol−1); 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC 16:0, Mw = 734.039 g mol−1); 1, 2-distearoyl-sn-glycero-3-phosphocholine (DSPC 18:0, Mw = 790.2 g mol−1); and

Tribological behavior of PC–SUV liposomes

Fig. 1a depicts the evolution of COFs with the lubrication of five different PC liposomes, showing that all the COFs were always maintained at a stable level with time until the end of the test. The liposomes of HSPC and DSPC both exhibited the lowest COF at approximately 0.045, while DLPC exhibited the highest COF at 0.15. An obvious phenomenon was observed whereby the COFs experienced an abrupt decline and a minor decrease from a value higher than 0.15 to a value of 0.045 approximately, in

Conclusions

In summary, we have revealed that the lubrication effects of liposomes at the macroscale are determined by their carbon chain lengths. The COFs between the PEEK and Si3N4 surfaces show a decreasing tendency for liposomes with increasing carbon chain length. Friction experiments are less sensitive to sliding speed effects but are obviously dependent on normal loads. The surface topography of the adsorbed PC liposomes also demonstrated that liposomes and bilayers are significant parameters for

Acknowledgement

This work is financially supported by the National Natural Science Foundation of China (51775295, 51522504).

References (46)

  • M. Daniel

    Role of surface-active lipids in cartilage lubrication

    Adv. Planar Lipid Bilayers Liposomes

    (2012)
  • J. Serora et al.

    Boundary lubrication by macromolecular layers and its relevance to synovial joints

    Polym. Adv. Technol.

    (2014)
  • L.J. Sandell et al.
  • J. Klein

    Molecular mechanisms of synovial joint lubrication

    Proc. IME J. Eng. Tribol.

    (2006)
  • J. Klein

    Repair or replacement–a joint perspective

    Science

    (2009)
  • J. Seror et al.

    Articular cartilage proteoglycans as boundary lubricants: structure and frictional interaction of surface-attached hyaluronan and hyaluronan–aggrecan complexes

    Biomacromolecules

    (2011)
  • J. Seror et al.

    Normal and shear interactions between Hyaluronan–Aggrecan complexes mimicking possible boundary lubricants in articular cartilage in synovial joints

    Biomacromolecules

    (2012)
  • R. Goldberg et al.

    Boundary lubricants with exceptionally low friction coefficients based on 2D close-packed phosphatidylcholine liposomes

    Adv. Mater.

    (2011)
  • S. Sivan et al.

    Liposomes act as effective biolubricants for friction reduction in human synovial joints

    Langmuir

    (2010)
  • R. Sorkin et al.

    Mechanical stability and lubrication by phosphatidylcholine boundary layers in the vesicular and in the extended lamellar phases

    Langmuir

    (2014)
  • G. Anastasia et al.

    Normal and frictional interactions between liposome-bearing biomacromolecular bilayers

    Biomacromolecules

    (2016)
  • A. Gaisinskaya et al.

    Hydration lubrication: exploring a new paradigm

    Faraday Discuss.

    (2012)
  • U. Raviv et al.

    Fluidity of bound hydration layers

    Science

    (2002)
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