From:  Functional lignin hydrogels for biosensors and biomedical therapy

 Applications of lignin-based hydrogel as a drug delivery carrier

MaterialDrug usedMethodPropertiesApplicationReference
Cellulose/lignin hydrogel (95:05 ratio)ParacetamolMixture of cellulose and lignin in NaOH/urea, freeze-thaw, addition of epichlorohydrin as crosslinker, freeze-dryPore size:100–160 µm, swelling dec slightly. Diffusion: 1.1 × 10–4 cm2/s. Mechanical strength: high compressive. Modulus (~11 kPa) achievedEnhance release of paracetamol (~50%) than pure cellulose hydrogel[100]
Lignin/β-cyclodextrin (LCD) matrixKetoconazole (K) & Piroxicam (P)β-Cyclodextrin crosslinked with lignin using epichlorohydrin, followed by loading of drugs into the matrixIn vitro release studies (Korsmeyer-Peppas model) revealed that the LepCD-based materials released medicines at a slower rate (k = 1.117–1.789) compared to LCD-based materials with a constant release rate (k = 2.210–4.824)Used as drug carrier[101]
Gelatin/lignin hydrogel using EDC as cross linkerRibavirinLignin + NaOH solution, to which gelatin is added. Magnetically stirred & left overnight at 80°C to obtain an aqueous solution. EDC is used to crosslink the gelatin/lignin sampleHigher lignin concentration (3%) in gelatin/lignin hydrogels resulted in greater cumulative ribavirin release i.e., 68% higher as compared with gelatin hydrogel after 270 minFor antiviral drug delivery[102]
Lignocellulose nanofibril-poly(vinyl alcohol) hydrogelTetracycline hydrochlorideCrosslinkinghigh compression modulus (3.92 MPa) and significant sustained-release effect with a release rate of 80.73% after 336 hPotential for controlled drug delivery system[103]
M-HPMC/M-SLS hydrogel (methacrylate hydroxypropyl methylcellulose (M-HPMC) and methacrylate lignin (M-SLS) hydrogel)Alpha-pinene (α-pinene)Preparation of nanostructured lipid carriers (NLCs) and loading of α-pinene into NLCs. α-pinene-loaded NLCs (0, 18, 38, and 50 wt%) were encapsulated in M-HPMC/M-SLS hydrogelControlled α-pinene release for up to 96 h, shows significant antioxidant activity. Increased adhesive strength (113.5 ± 7.5 kPa) to bovine buccal mucosaBuccal mucoadhesive hydrogel for the potential application in the treatment of oral ulcers[104]
Cotton stalk lignin hydrogelCurcumin, naringenin, α-lactalbuminLignin + HEC polymerization in the Prescence of PEG400 (2–4%) & 1–3% glycerol. Addition of actives by mixing at 50–80°C at 2,000 rpm to form hydrogelPore size: 283 nm (ocular). Swelling ratio: high (about 385%). Mechanical strength: tensile strength: 0.63 MPa. Elasticity modulus: 0.52 MPaFor topical ocular treatment of diabetic retinopathy[105]
CP loaded lignin based PVA hydrogelCiprofloxacinCumulative drug release found to be 88.2 ± 3.2% after 10 h. CP-loaded hydrogel exhibits antibacterial activity towards Staphylococcus aureus, Bacillus subtilis, Acinetobacter baumannii, Pseudomonas aeruginosaCan be used as pharmaceutical carrier. Useful for sustained release applications[106]