Material and Method2-Chorotrityl chloride resin (100-200 Mesh, 1.44 mmol Cl/g resin) and Fmoc-Rink Amide AM PS resin (100-200 Mesh, 0.94 mmol/g resin) were purchased from Iris Biotech and stored at 4°C. Protected amino acids and HBTU were purchased from Iris Biotech, Senn Chemicals and Bachem. PEG (MW = 2000 g/mol) was purchased from Alfa Aesar. All reagents and solvents were from Alfa Aesar, Acros, Sigma-Aldrich or Merck and were used without further purification. Water sensitive reactions were carried out under an argon atmosphere with anhydrous solvents. Preparative chromatographic purification was performed using Waters HPLC 4000 instrument, equipped with a UV detector 486 and Waters Delta-Pack 40×100 mm, 100Å, 15 µm, C 18 reversed-phase column using a flow rate of 50 mL/min. Solvents employed were water/0.1% TFA and ACN/0.1% TFA. Samples for LC/MS analyses were prepared in acetonitrile/water (50:50, v/v) mixture, containing 0.1% TFA. The LC/MS system consisted of a Waters Alliance 2695 HPLC, coupled to a Water Micromass ZQ spectrometer (electrospray ionization mode, ESI+). All the analyses were carried out using a Phenomenex Onyx, 25 x 4.6 mm reversed-phase column. A flow rate of 3 mL/min and a gradient of (0-100)% B over 2.5 min were used. Eluent A: water/0.1% HCO 2 H; eluent B: acetonitrile/0.1% HCO 2 H. UV detection was performed at 214 nm. Electrospray mass spectra were acquired at a solvent flow rate of 200 µL/min. Nitrogen was used for both the nebulizing and drying gas. The data were obtained in a scan mode ranging from 100 to 1000 m/z or 250 to 1500 m/z to in 0.7 sec intervals. High Resolution Mass Spectrometric analyses were performed with a time of flight (TOF) mass spectrometer fitted with an Electrospray Ionisation source. All measurements were performed in the positive ion mode. 1 H, 13 C and 29 Si NMR spectra were recorded at room temperature in deuterated solvents on a Bruker AMX/400 spectrometer operating at 400, 101 and 79 MHz respectively. Chemical shifts (δ) are reported in parts per million using residual non-deuterated solvents as internal references (CHCl 3 in CDCl 3 , δH = 7.26 ppm; DMSO-d6, δH = 2.50 ppm). Signals are indicated as s (singlet), d (doublet), t (triplet), q (quartet), dt (double triplet), m (multiplet), br (broad)… Coupling constants are measured in Hertz.Picture of the experimental set-up for antibacterial assays. Upside-down Petri dish containing from top to bottom: hybrid PEG hydrogel, MTT stained bacteria, nitrocellulose membrane, tryptic soy agar culture medium.