NOVELTY - An amphiphilic peptide and/or peptoid capable of self-assembling into three-dimensional macromolecular nano-fibrous networks, which entrap water and form a hydrogel, where the amphiphilic peptide and/or peptoid comprises an amphiphilic sequence consisting of a hydrophobic sequence stretch of aliphatic amino acids, and a hydrophilic sequence stretch linked to the hydrophobic sequence stretch and having a polar moiety which is acidic, neutral or basic, where the polar moiety comprises 1-5 adjacent hydrophilic amino acids, is new.    USE - In hydrogel for fuel cell, solar cell, electronic cell, biosensing device, medical device, implant, wound dressing, pharmaceutical composition and cosmetic composition, where composition is provided in the form of topical gel or cream, spray, powder, or sheet, patch or membrane or composition is provided in the form of injectable solution, where hydrogel is used in release of pharmaceutical active compound, medical tool kit, fuel cell, solar cell, electronic cell, tissue regeneration, tissue replacement, wound healing, skin care, stem cell therapy and gene therapy; in surgical implant or stent; in pharmaceutical and/or cosmetic composition and/or biomedical device and/or electronic device; and in kit of parts, where tissue is selected from skin tissue, nucleus pulposus in intervertebral disc, cartilage tissue, synovial fluid and submucosal connective tissue in bladder neck; in wound treatment, where wound is burn wound. The hydrogel functions as hemostatic agent or as antiinflammatory agent, which acts by scavenging extracellular nucleic acids that stimulate innate immune system (claimed).    ADVANTAGE - The peptide and/or peptoid is stable in aqueous solution at physiological conditions at ambient temperature for period of 1 day to at least 6 months, preferably to at least 8 months, especially at least 12 months. The peptide and/or peptoid is stable in aqueous solution at physiological conditions at up to 90 degrees C for at least 1 hour. The hydrogels are rigid, biocompatible and entrap up to 99.9% of water and hence are well suited for applications utilizing electronic devices. The hydrogel is stable in aqueous solution at ambient temperature for at least 7 days, preferably at least 2-4 weeks, especially at least 1-6 months. The hydrogel has storage modulus G' to loss modulus G'' ratio of greater than 2; and storage modulus G' of 100-80000 Pa at frequency of 0.02-16 Hz; has higher mechanical strength than collagen or its hydrolyzed form (gelatin). The hydrogel when used in wound treatment induces autolytic debridement. The peptide exhibits improved rigidity, favorable physiological properties and/or simplicity and reduced production costs. The peptide hydrogels are easily formed, non-toxic and have high rigidity for standard applications. The hydrogel allows stimuli-responsive gelation of peptides and hence can then be applied as minimally invasive injectable therapy or implanted as biological construct to replace damaged/missing tissue. The peptide shows remarkable stability at physiological conditions even at elevated temperatures; is stable in aqueous solution at physiological conditions at ambient temperature for 1 day to greater than or equal to 1 month; is stable in aqueous solution at physiological conditions at 90 degrees C for at least 1 hour, at least 2 hours, at least 3 hours, at least 4 hours or at least 5 hours. When used as wound dressing, hydrogel forms barrier to prevent bacteria and fungal spores from entering wound, forms physical barrier to prevent cells from leaking out of damaged blood vessels (hemostatic function), limits dehydration of tissues, protects against mechanical stress and abrasion and provides mechanical cues for cellular and tissue regeneration (biomimetic scaffold).    DETAILED DESCRIPTION - An amphiphilic peptide and/or peptoid capable of self-assembling into three-dimensional macromolecular nano-fibrous networks, which entrap water and form a hydrogel, where the amphiphilic peptide and/or peptoid comprises an amphiphilic sequence consisting of: a hydrophobic sequence stretch of n aliphatic amino acids, and a hydrophilic sequence stretch linked to the hydrophobic sequence stretch and having a polar moiety which is acidic, neutral or basic, where the polar moiety comprises m adjacent hydrophilic amino acids, is new.    n=2 to 15;    m=1-5.    INDEPENDENT CLAIMS are included for the following:    (1) a hydrogel comprising the peptide and/or peptoid;    (2) preparing hydrogel involving dissolving peptide and/or peptoid in aqueous solution;    (3) surgical implant or stent comprising peptide and/or peptoid scaffold formed by the hydrogel;    (4) pharmaceutical and/or cosmetic composition and/or biomedical device and/or electronic device comprising the peptide and/or peptoid or hydrogel;    (5) kit of parts (K1) comprising first container with peptide and/or peptoid and second container with aqueous solution;    (6) kit of parts (K2) comprising first container with aqueous solution of peptide and/or peptoid and second container with gelation enhancer;    (7) method (M1) of tissue regeneration or tissue replacement involving: a) providing hydrogel; b) exposing to cells which are to form regenerated tissue; and c) growing cells on or in hydrogel; and    (8) method (M2) of wound treatment involving: a1) providing hydrogel; and b1) exposing to wound.