A novel low molecular weight nanocomposite hydrogel formulation for intra- tumoural delivery of anti-cancer drugs Ivana Štaka a,b,c ; Ana Cadete a ; Bhanu Teja Surikutchi c ; Haneen Abuzaid b ; Tracey D. Bradshaw b ; Maria J Alonso a* ; Maria Marlow c* a CIMUS Research University, University of Santiago de Compostela, 15706 Campus Vida, Spain; b Centre 5 for Biomolecular Sciences, University of Nottingham, NG7 2RD, UK; c Boots Science Building, School of Pharmacy, University of Nottingham, NG7 2RD, UK. *Corresponding authors: maria.marlow@nottingham.ac.uk and mariaj.alonso@usc.es Keywords: gel-nanocomposite; polymeric nanocapsules; low molecular weight gelators; local delivery 10 Herein, an injectable formulation composed of a low molecular weight gelator (LMWG) based hydrogel and drug-loaded polymeric nanocapsules (NCs) is described. The NCs, made of hyaluronic acid and polyglutamic acid and loaded with C14-Gemcitabine (GEM C14), showed a size of 40 and 80 nm and a encapsulation efficiency > 90%. These NCs exhibited a capacity to control the release of the encapsulated drug for more than 1 month. GEM C14-loaded NCs showed activity against various cancer cell lines in 15 vitro; cell growth inhibition by 50% (GI50) values of 15 ± 6, 10 ± 9, 13 ± 3 and 410 ± 463 nM were obtained in HCT 116, MIA PaCa-2, Panc-1 and Panc-1 GEM resistant cell lines respectively. Nanocomposite hydrogels were prepared using the LMWG - N4-octanoyl-2ʹ-deoxycytidine and loaded for the first time with polymeric NCs. 2% and 4% w/v nanocapsule concentrations as compared to 8% w/v NC concentrations with 2 % and 3% w/v gelator concentrations gave mechanically stronger gels as determined by oscillatory 20 rheology. Most importantly, the nanocomposite formulation reformed instantly into a gel after injection through a needle. Based on these properties, the nanocomposite gel formulation has potential for the intratumoural delivery of anticancer drugs. 1 Abbreviations: low molecular weight gelator (LMWG); nanocapsules (NCs); N4-myristoyl gemcitabine (GEM C14); low molecular weight (LMW); hexadecyltrimethylammonium bromide (CTAB); Sodium 25 hyaluronate (HA); poly-L-glutamic acid (PGA); GEM hydrochloride (GEM-HCl); 9-Diethylamino-5H- benzo[a]phenoxazine-5-one - Nile Red (NR); Linear visco-elastic (LVE) region; GEM resistant cell line (GEM R Panc-1).