Antimicrobial quaternary ammonium organosilane cross-linked nanofibrous collagen scaffolds for tissue engineering

Abstract

Introduction

In search for cross-linkers with multifunctional characteristics, the present work investigated the utility of quaternary ammonium organosilane (QOS) as a potential cross-linker for electrospun collagen nanofibers. We hypothesized that the quaternary ammonium ions improve the electrospinnability by reducing the surface tension and confer antimicrobial properties, while the formation of siloxane after alkaline hydrolysis could cross-link collagen and stimulate cell proliferation.

Materials and methods

QOS collagen nanofibers were electrospun by incorporating various concentrations of QOS (0.1%–10% w/w) and were cross-linked in situ after exposure to ammonium carbonate. The QOS cross-linked scaffolds were characterized and their biological properties were evaluated in terms of their biocompatibility, cellular adhesion and metabolic activity for primary human dermal fibroblasts and human fetal osteoblasts.

Results and discussion

The study revealed that 1) QOS cross-linking increased the flexibility of otherwise rigid collagen nanofibers and improved the thermal stability; 2) QOS cross-linked mats displayed potent antibacterial activity and 3) the biocompatibility of the composite mats depended on the amount of QOS present in dope solution – at low QOS concentrations (0.1% w/w), the mats promoted mammalian cell proliferation and growth, whereas at higher QOS concentrations, cytotoxic effect was observed.

Conclusion

This study demonstrates that QOS cross-linked mats possess anti-infective properties and confer niches for cellular growth and proliferation, thus offering a useful approach, which is important for hard and soft tissue engineering and regenerative medicine.

Keywords:

• anti-infective wound dressing
• cyto-compatible nanofibre
• electrospinning
• cost-effective cross-linker
• tissue regeneration
• antimicrobial

Supplementary materials

Figure S1 FE-SEM micrograph of (A) Coll_5%QOS, (B) Coll_10%QOS, (C) Coll_5%QOS_XL and (D) Coll_10%QOS_XL.

Notes: Scale bar = 1 μm. Yellow arrows indicate the area with inter-fiber adhesion/binding.

Abbreviations: SEM, scanning electron microscopy; QOS, quaternary ammonium organosilane.

Figure S2 Standard (cell number vs absorbance) calibration curves plotted for (A) hDF and (B) hFOb using MTS assay.

Abbreviations: hFOb, human fetal osteoblast; hDFs, human dermal fibroblasts; MTS, 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium.

Acknowledgments

The authors thank the Translational and Clinical Research Flagship Program of the Singapore National Research Foundation (NMRC/TCR/008-SERI/2013), administered by the National Medical Research Council of the Singapore Ministry of Health. This work was supported by Cooperative Basic Research Grant from the Singapore National Medical Research Council (NMRC/CBRG/0048/2013) and SNEC Ophthalmic Technologies Incubator Program grant (project no R1181/83/2014) awarded to RL. This research is supported by the Singapore Ministry of Health’s National Medical Research Council under its Centre Grant Programme-Optimization of core platform Technologies for Ocular Research (INCEPTOR)-NMRC/CG/M010/2017_SERI. NKV acknowledges funding support from Lee Kong Chian School of Medicine, Nanyang Technological University Singapore Start-Up Grants (L0412130 and L0412290) and the Ministry of Education Singapore AcRF-Tier I Grant (2015-T1-001-082).

Disclosure

The authors report no conflicts of interest in this work.