Injectable and Thermosensitive Hydrogel and PDLLA Electrospun Nanofiber Membrane Composites for Guided Spinal Fusion

Abstract

Spinal fusion is the classic treatment to achieve spinal stability for the treatment of the spinal disease. Generally, spinal fusion still has to combine a certain of bone matrix for promoting bone formation to achieve the desired fusion effect based on the surgery, including the traditional bone matrix, such as the autologous bone, allografts and xenografts. Nevertheless, some problems still existed such as the immunogenic problems, the secondary wound, and pathogenic transfer and so on. Here the injectable thermosensitive hydrogel could substitute to avoid the problems as a potential biological scaffold for tissue engineering. Once injected, they could fill in the irregular-shaped cavity and change to a gel state at physiological temperature. We wanted to design the collagen/n-HA/BMP-2@PCEC/PECE hydrogel composites based on previous work about collagen/n-HA/PECE hydrogel to exhibit better performance in guiding spinal fusion because of the addition of BMP-2@PCEC nanoparticles (PCEC, PCL-PEG-PCL). However, when the hydrogels were injected, one of the surfaces was in contact with the spine, but others were in contact with soft tissue like muscles and fascia. The release behavior was the same at the different surfaces, so the factors could be released into the soft tissue, and it may then be consumed or lead to ectopic bone formation. The hydrogel composites should be improved to adjust the direction of the releaser behavior. In consequence, we wrapped an electrostatic spinning nanofiber membrane possessing hydrophobicity around the hydrogels. In this study, we developed a system that the collagen/n-HA/BMP-2@PCEC/PECE hydrogels were wrapped with the hydrophobicity PDLLA electrospun nanofiber membrane, setting up a barrier between the hydrogels and the soft tissue. The system could exhibit biocompatibility, preventing the factors from escaping to keep their retention in the needed places of osteogenesis; the results demonstrated that it showed an excellent effect on spinal fusion.

Poly(N‐isopropylacrylamide)/mesoporous silica thermosensitive composite hydrogels for drug loading and release

“…When the temperature is lower than the LCST, the hydrophobic interactions become dominant and the volume of the hydrogel expands, causing a reversible phase change and allowing the uptake of drugs . The existence of this reversible sol–gel phase transition between 30 and 35 °C in PNIPA hydrogel is therefore key to its application in drug delivery, tissue engineering, and biological separations …”

“…17 The existence of this reversible sol-gel phase transition between 30 and 35 C in PNIPA hydrogel is therefore key to its application in drug delivery, tissue engineering, and biological separations. [18][19][20][21][22] Traditionally, PNIPA hydrogel has been synthesized by polymerization of NIPA monomer [with potassium persulfate (KPS) as the initiator], then crosslinking polymer chains with chemical crosslinking agent. 23 The use of chemical crosslinking agents is not ideal for drug delivery systems, tissue engineering, or biological separations as some crosslinking agents are toxic, such as glutaraldehyde, residual chemical crosslinking agent can negatively impact the biocompatibility of hydrogels and their phase transition behavior, limiting their usefulness.…”

Preparation of PEI nanofiber membrane based on in situ and solution crosslinking technology and their adsorption properties

“…In addition, electrospinning, as a simple and effective new process for the production of continuous long nanofibers, plays an irreplaceable role in the fields of energy, optoelectronics, catalysis, sensing, biomedicine, filtration, and protection . Electrospinning technology has the advantages of simple operation, low cost, and continuous preparation, which has been a research hotspot in the field of nanofibers …”

Inorganic polymerization: an attractive route to biocompatible hybrid hydrogels

“…Physical hydrogels result from the formation of a physical network involving weak and reversible interactions such as ionic and π-π stacking interactions, hydrogen bonds, Van der Waals forces, and hydrophobic interactions. 13,[27][28][29] The large number of these interactions counterbalances their weakness to stabilize the three-dimensional network. Because physical hydrogels do not require any chemical reaction to crosslink the network, they can be prepared more easily in a biocompatible way.…”