Table 5.

Recent trends on biomolecule immobilization strategies onto natural fibers.

Natural Fiber	Cleaning	Pre-treatment	Immobilization Strategies	Functional Groups	Biomolecule	Main chemical Reactions	References
Flax	Non-ionic detergent 80 °C 30 min, DW 70 °C 30 min, 100 °C 10 min	-	Dip–pad–dry method to deposit pegylated silver NPs, drying 100 °C 20 min, water, drying 100 °C 6 min In situ NP synthesis by sol-gel method: immersion in Zn(CH3COO)2.2H2O 50 °C 1 h stirring, NaOH, drying 100 °C 6 h	-OH	Silver NPs and Zinc oxide NPs (inorganic NPs)	Metal–ligand binding with Ag+ and Zn2+ ions from NPs	[201]
Linen (flax family)	-	-	Dip–pad–dry–cure method: immersion in CA, NaPO2H2 and chitosan, padding, drying 100 °C 3 min, curing 140 °C 5 min In situ NP synthesis by sol-gel method: immersion in Ce(SO4)2 solution 45 min, NaOH 50 °C 30 min under ultrasound irradiation, cold water, drying	-OH	Chitosan (Polysaccharide) and Cerium oxide NPs inorganic NPs)	Esterification of linen with -COOH of CA; electrostatic interaction of CA with -NH2 of chitosan; Metal-ligand binding with Ce3+ ions	[99]
	-	-	Dip–pad–dry–cure method with chitosan, BTCA and NaPO2H2, dried 80 °C 4 min and cured 140 °C 4 min In situ NP synthesis by sol-gel method: immersion in AgNO3 20 min, then in mordant TSCE 60 min under ultrasound irradiation, cold water, drying	-OH	Silver NPs (Inorganic NPs), Chitosan (Polysaccharide), Tamarindus indica L. seed coat extract (TSCE, plant extract)	Esterification with -COOH of BTCA; electrostatic interaction of BTCA with -NH2 of chitosan, and of -COOH, NH2 and -OH groups with silver nitrate; Metal–ligand binding between phenol groups of tannings of TSCE and Ag+ ions	[84]
Kenaf	-	-	Casting of a resin mixture (polyester resin with NP filler loadings and MEKP as catalyst) onto the fibers using hand layup process, cure cold press 24 h, polymerization 105 °C	-OH	Bamboo NPs (organic NPs)	Hydrogen bonding between NPs, fiber and matrix	[101]
Cotton		-	In situ NP synthesis by sol-gel process: immersion in Zn(NO3)2.6H2O and CH3C3H3N2H solutions in CH3OH 24h, DIW with ultrasound irradiation 10 min, drying 80 °C 2 h Immersion in THF solution with PDMS and curing agent stir 5 min, drying 80 °C 2 h	-OH	Metal–organic framework (zeolitic imidazolate framework-8, ZIF-8) (inorganic NPs)	Metal–ligand binding with Zn2+ ions	[95]
	-	Esterification through the dip–pad–cure–dry method: immersion in CMCS solution 15 min, pad-roll, cure 180 °C 5 min, DW, drying 100 °C 1 h. Same for Cys adsorption	In situ NP synthesis by sol-gel process: immersion in AgNO3 10 min, drying 100 °C 1 h, immersion in NaBH4 10 min, DW, drying 100 °C 1 h	-SH	Silver NPs (inorganic NPs)	Metal–ligand binding with Ag+ ions	[13]
	Ultrasound treatment in DIW, drying	Silanization: drying 55 °C 24 h, immersion in OTS and MTS in C7H8 sealed 10 min, drying	Immersion in silver NP dispersion for 10 min	-OH	Silver NPs (inorganic NPs)	Metal–ligand binding with Ag+ ions	[202]
	-	-	Ultrasound treatment: immersion into a hot dispersion of loaded FF peptide nanotubes in an ice bath, DW, freeze-drying	Unspecific	Curcumin (plant extract)	Physical adsorption after sonication process: based on the point melting of the substrate and carbonization of the fibers at the points of their contact with the silver nuclei due to the high rate and temperature of the nanotubes thrown to the solid surface by sonochemical microjets	[110]
	NaOH and C58H118O24 at 70 °C 20 min	Silanization: immersion in KH-580 solution 2 min, cure 120 °C 5 min	Thiol-maleimide click chemistry: immersion in CH3C(O)CH2CH3 with N-phenyl-male-imide and C6H15N 60 °C 30 min while stirring, drying 70 °C 10 min	-SH	N-phenyl-male-imide (organic compound)	Thiol-maleimide click chemistry	[203]
	NaOCl, DW, drying 60 °C 48 h	-	Immersion in amoxicillin solutions 10 min, drying 72 h fume hood Solvent casting technique: pouring of PLA solution in CHCl3 until submersion, solvent evaporation 72 h vacuum	-OH	Amoxicillin (antibiotic)	Hydrogen bonding and electrostatic interaction with cationic groups of amoxicillin like -NH2	[14]
	-	-	Deposition by extraction method		Poly(propylenimine) dendrimers from first and third generations modified with 1,8-naphthalimide units and their Zn(II) complexes (dendrimers)		[204]
	-	-	UV-photo-grafting method of alginate-Ca2+/PNIPAA hydrogel: PAAm, SA and other additives, UV 30 min, CaCl2 24 h, DW	-OH	MB as model drug	Covalent bond with radical initiators that subtracted H atoms to cotton	[205]
	Acetone, DIW	Functionalization by immersion in dopamine solution at pH 8.5, DW, drying vacuum	In situ NP synthesis by sol-gel process: immersion in Zn(CH3COO)2 into CH3OH and NaOH 20 min, pad-rolled, dried in vacuum. Then, immersion into Zn(NO3)2.6H2O) and HMTA solutions 90 °C 5 h, DW, drying	Cathecol	Zinc oxide NPs (inorganic NPs)	Metal-ligand binding with Zn2+ ions	[206]
	Ultrasound treatment: C12H25NaO3S 30 min, ethanol 2 h, DIW 30 min 3 times	Dip–pad–dry–cure method: immersion in Cys30 min, pad, drying 3 min 80 °C, cure 180 °C 3 min, DW (3 times), drying 100 °C 1 h	In situ NP synthesis by sol-gel method: immersion in CuSO4 and CA 50 °C 30 min, NaBH4 40 °C 1h, DW twice, drying 4 h	-SH	Copper NPs (inorganic NPs)	Metal–ligand binding between Cys on cotton and Cu2+ ions	[207]
	-	-	Pad–dry–cure process: immersion in chitosan-silver zeolite composites (previously obtained by ionic gelation method with TPP) at pH 5.5, drying 90 °C 3 min, crosslinked with CA 140 °C 2 min, water, drying	-OH	Silver zeolites	Esterification with -COOH of CA that also lead to chemical reaction with -NH2 of chitosan	[94]
	-	-	Pad–dry–cure technique: immersion in aqueous solution of ethanol extract liquid of propolis with glyoxal and Al2(SO4)3, padding, drying 80 °C 3 min, cure 140 °C 5 min, warm water 15 min, drying	-OH	Propolis (plant extract)	Covalent bond of -COH of glyoxal with -OH of propolis and fabric, hydrogen bonding, physical entrapment	[106]
	Turbo Break detergent (NaOH), Silex Emulsion detergent (fatty alcohol ethoxylates, NaOH), and Ozonit Performance detergent (CH3COOH, H2O2, CH3CO3H), Finale Liquid detergent (HCOOH)	-	Immersion in Ag3C6H5O7, C4H6O4Cu as precursors in water Immersion in mixed solution with C4H6O4Cu and Ag3C6H5O7, reduction with NaBH4, stabilizer PVP	-OH	Ag+/Cu2+ and Silver NPs/Cu2+ (inorganic ions, inorganic NPs)	Metal–ligand binding with Ag+/Cu2+ ions	[86]
Milkweed	Soxhlet extraction in acetone 24 h, vacuum-drying	Carding together with core-shell PE-coated PP fibers 80–120 °C Dielectric Barrier Discharge plasma treatment at atmospheric pressure	Immersion under stirring in EDC solution in MES buffer 30 min, MES buffer twice, RGD-TAMRA HEPES solution pH 7.4) 3 h, TWEEN-20 five times, DIW three times	-COOH	RGD (peptide)	Peptide covalent bond with NH2 with RGD peptide	[11]
Kapok	Filter, wash, drying	Functionalization by immersion in dopamine solution at pH 8 24 h	In situ NP synthesis by sol-gel method: immersion in AgNO3 UV irradiation under stirring 30 min, DW, drying vacuum	Catechol	Silver NPs (inorganic NPs)	Metal–ligand binding with Ag+ ions	[208]
Durian skin	Washing, chopping, grinding, drying and sieving	Solvent casting method: drying PLA and durian skin fiber, dissolution in ChCl3 while stirring, EPO, 24 h	Cinnamon oil addition to the previously formed composite	-OH	Cinnamon (essential oil)	Hydrogen and covalent bonding between the PLA/durian skin fiber and aldehydes in cinnamon oil	[15]
Bamboo	Ultrasound treatment: acetone, ethanol and DW, 15 min	Functionalization by immersion in dopamine solution at pH 8.5	In situ NP synthesis by sol-gel method: immersion in Ag3C6H5O7, microwave irradiation, rinse in DW, drying	Catechol	Silver NPs (inorganic NPs)	Metal–ligand binding with Ag+ ions	[209]
	Ultrasound treatment: water, detergent and Na2CO3, 1 h 60 °C	Air plasma treatment	Exhaustion bath with loaded microcapsules, Mikracat B crosslinking agent and Sapamine softener 1 h pH 7, padding, crosslinking 1 h 130 °C, drying	-COOH, -OH, -COH	Lavender oil (essential oil)	Covalent bonding between loaded microcapsules and fabric	[210]
	Water 70 °C 3 min, DW	-	In situ NP synthesis by sol-gel method: Immersion in HAuCl4, 15 min RT, 80 °C 60 min in oscillating water bath, DW, drying; or Immersion in AgNO3, 15 min RT, 80 °C 60 min in oscillating water bath, NaOH for pH 10, 80 °C 60 min, DW, drying	-OH	Gold and silver NPs (inorganic NPs)	Metal–ligand binding with Au3+/Ag+ ions	[211]
Silk	Water 50 °C, DW	-	In situ NP synthesis by sol-gel method: Immersion in H2PtCL6 at pH 5 10 min, 90 °C 60 min in shaking water bath, DW, drying. NaOH or CH3COOH to adjust pH to 6	-SH	Platinum NPs (inorganic NPs)	Metal–ligand binding between Cys on silk and Pt+ ions	[100]
	Warm water 5 min, DIW	-	In situ NP synthesis by sol-gel method: Immersion in HAuCl4 pH 3 20 min, 90 °C 60 min in shaking water bath, DIW, drying 70 °C; or Immersion in AgNO3 pH 10 20 min, 90 °C 60 min in shaking water bath, DIW, drying 70 °C	-SH	Gold and silver NPs (inorganic NPs)	Metal–ligand binding with Au3+/Ag+ ions	[212]
	-	-	Dip dyeing process: immersion dye solution pH 3 90 °C 60 min Mordant treatment with FeSO4, Fe2(SO4)3 and TiOSO4 60 °C 30 min, tap water, drying	-SH	Tea stem extract (plant extract)	Electrostatic interaction with polyphenol groups of the extract	[213]
	3 times Na2CO3 boiling point 30 min, DW, drying		Exhaustion method: immersion in silver NP dispersion (previously reduced by SA) in shaking bath pH 4 40 °C 40 min, drying	- NH2	Silver NPs (inorganic NPs)	Electrostatic interaction with -COOH from SA	[214]
	--		In situ NP synthesis by sol-gel method: Immersion in AgNO3 90 °C 3 °C /min from 30 °C, CfA, 90 °C 30 min with agitation, DIW, drying	-SH	Silver NPs (inorganic NPs)	Meta–ligand binding with Ag+ ions	[215]
	Three times Na2CO3 98 °C 30 min, DW, drying	Layer-by-layer self-assembly: alternate immersion in PAH and PAA 3 °C 100 rpm 30 min followed by rinsing DW 1 min 3 times (outermost layer: PAH), drying 24 h	Immersion in heparin 4 °C 24h, PBS and DW under ultrasonic irradiation 10 min	-NH2	Heparin (polysaccharide)	Electrostatic interaction with sulfate groups of heparin	[216]
Wool	Non-ionic soap at 80 °C 20 min	-	Exhaustion method: in rota dyer, mordant treatment with TSCE 90 °C 60 min, squeeze, dyed with natural dye KFE 90 °C 60 min, cold water, dried	-CONH -OH	Kapok flower extract (plant extract) and Tamarind seed coat extract (TSCE, plant extract)	Bonding with phenol groups of tannings of TSCE and amide -CONH groups of wool; hydrogen bonding between mordanted wool and KFE	[217]
	-	-	Immersion in Cu(NO3)2 and C6H3(COOH)3 solution 85 °C, wash with DMF, drying	-SH -OH	Metal–organic framework-199 (HKUST-1, inorganic NPs)	Hydrogen bonding and Metal-ligand binding with Cu2+ ions	[218]
	Ultrasound treatment: acetone 3 h, drying 50 °C	-	Exhaustion method: immersion in LRM extract, warm water, cold rinse, drying 60 °C 15 min. Mordant treatment with FeSO4 and Fe2(SO4)3 60 °C 30 min, rinse, drying	-OH	Lycium ruthenicum Murray extract (LRM, plant extract)	Hydrogen bonding and van der Waals forces with anthocyanin of the extract	[219]
	Soaking in water	Mordanting with KAl(SO4)2, FeSO4 and SnCl2 91–93 °C 1 h under stirring, tap water	Immersion in natural dye solution 91–93 °C 1h manual agitation, non-ionic detergent Safewash, tap water, drying	-CONH	Pomegranate peel extract (plant extract)	Electrostatic interaction with phenolic compounds of dye	[220]
	Na2CO3 bath pH 8.5 60 °C 30 min and non-ionic detergent Nekanil 907, DW, drying	-	Exhaustion method: immersion in AMP solution 40 °C 1–3 h while stirring, 5-cycle washing with WOB detergent 40 °C 60 min, drying 37 °C 4 h	-COOH	Cecropin-B and [Ala5]-Tritrp7 (AMPs)	Electrostatic interaction with terminal -NH2 of peptides	[12]
	Non-ionic detergent Lotensol 60 °C 20 min	-	Exhaustion-dyeing process: immersion in dendrimer derivative dye 30 °C pH 5-5.5, 100 °C within 25 min + 60 min, non-ionic detergent 50 °C 20 min	-NH2	Poly(amidoamine) dendrimer (dendrimers)	Electrostatic interaction with terminal -COOH of dye molecules	[221]

Abbreviations: Ag₃C₆H₅O₇: silver citrate; AgNO₃: silver nitrate; Al₂(SO₄)₃: aluminum sulfate; AMP: antimicrobial peptide; BTCA: 1,2,3,4-Butanetetracarboxylic acid; CHCl₃: chloroform; CH₃C(O)CH₂CH₃: butanone; CH₃CO₃H: peracetic acid; C₄H₆O₄Cu: copper (II) acetate; C₆H₃(COOH)₃: trimesic acid; C₆H₁₅N: triethylamine; C₇H₈: toluene; C₁₂H₂₅NaO₃S: sodium 1-dodecanesulfonate; C₅₈H₁₁₈O₂₄: polyoxyethylene lauryl ether; CA: citric acid; Ce(SO₄)₂; CfA: caffeic acid; CH₃C₃H₃N₂H: 2-methylimidazole; CH₃OH: methanol; CMCS: carboxymethyl-chitosan; Cu(NO₃)₂: copper nitrate; CuSO₄: copper sulfate; Cys: L-cysteine; DIW: dionized water; DMF: dimethylformamide; DW: distilled water; EDC: 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride; EPO: epoxidized palm oil; FF: diphenylalanine; Fe₂(SO₄)₂: ferric sulfate; FeSO₄: ferrous sulfate; HAuCl₄: tetrachloroauric acid; HCOOH: formic acid; H₂PtCl₆: chloroplatinic acid; HMTA: hexamethylenetetramine; ITX: 2-isopropylthioxanthone; KAl(SO₄)₂: potash alum; KH-580: silane coupling agent; MB: methylene blue; MEKP: methyl ethyl ketone peroxide; MES: 2-(N-Morpholino)ethanesulfonic acid; NIPAAm: N-isopropylacrylamide; NP: nanoparticle; Na₂CO₃: sodium carbonate; NaBH₄: sodium borohydride; NaPO₂H₂: sodium hydrophosphite; NaOCl: sodium hypochlorite; NaOH: sodium hydroxide; OTS and MTS: long and short silanes; PDMS: polydimethylsiloxane; PE: polyethylene; PLA: polylactic acid; PP: polypropylene; PVP: polyvinylpyrrolidone; RGD: arginylglycylaspartic acid; SA: sodium alginic acid; SnCl₂: stannous chloride; TAMRA: carboxylic acid of tetramethylrhodamine THF: tetrahydrofuran; TiOSO₄: titanium sulfate; TPP: sodium tripolyphosphate; Zn(CH₃COO)₂.2H₂O: zinc acetate dihydrate; Zn(NO₃)₂.6H₂O: zinc nitrate hexahydrate.