In addition many crosslinking agents are known to be toxic (Speer et al., 1980). Therefore the removal of the potentially toxic crosslinker is required prior hydrogel usage, which may cause additional complications.

For NFC, a triggering mechanism is not required, as it is a readily injectable hydrogel in its natural state due to its pseudoplastic and thixotropic properties. This can prove to be advantageous in the use of biomaterials as injectable hydrogels or implants, as there is no additional toxicity or interactions introduced by external activators. Interactions between therapeutic compounds and NFC would still require further investigation; however with the absence of additional activation, processing or crosslinking agent removal, the process is simplified. Additionally, the results indicate that NFC hydrogels could show potential in the VX-809 manufacturer delivery of biopharmaceuticals, where parenteral administration could address the delivery problems of protein and peptide drugs. However it is likely that the native NFC requires further modifications for more effective delivery. In this study, we have demonstrated a reliable and efficient method of 99mTc-NFC labeling. Further research conducted on NFC hydrogels

with molecular imaging can be readily Staurosporine performed with this methodology. In addition, our proposed method can help in evaluating the rate of drug release with the use of pharmacokinetic models in conjunction with molecular imaging in drug-biomaterial studies. In the field of non-invasive or minimal invasive research, NFC has very potential use as surgical adhesive, space-filling

biomaterial in addition to tissue engineering and repair. We performed our study in mind of a potential controlled release or local drug delivery hydrogel that could be easily prepared and readily injected. NFC did not disintegrate or migrate during the study despite the activity of the study animals while awake between image acquisitions. Potential local delivery or long-term controlled release treating chronic diseases, especially in easily accessible areas such as the skin, could be possible with injectable hydrogels. Removal of NFC after treatment can be performed by small surgery or potentially disintegrated into glucose by locally administering cellulose metabolizing enzymes. NFC does not require external activators or crosslinking agents; in addition to it being biocompatible and non-toxic. Further studies to improve hydrogel handling or with specific therapeutic compounds should be performed. However, we have shown the potentiality of wood pulp NFC in the biomedical field, which is complementary to the research already done with bacterial cellulose. This work has been supported by the Finnish Funding Agency for Technology and Innovation, Functional materials program and UPM-Kymmene Corporation, Finland.