TABLE 2.

Summary of microneedles used in wound healing

Microneedles	Characteristics	In vitro/vivo models	Outcomes	Ref.
PVA matrix loaded with zeolitic‐imidazolate‐frameworks‐derived porphyrin‐like metal centers nanoparticles	808 nm NIR laser‐triggered Liquid band‐aid	In vitro: S. aureus In vivo: S. aureus‐infected mouse model	Disrupt bacterial membrane by local hyperthermia and peroxidase‐like activity of PMCS Antibacterial rate (92.9%) and wound healing ratio (86.6%) A mass of fibroblasts and blood vessels	[ 182 ]
Hollow microneedles fabricated by multimaterial FDM 3D printing with hard resin as needles and flexible polymeric resin as the base	Individualized bandage for chronic diabetic wounds Programmable drug delivery platform with peristaltic micropumps Integration of reusable electronics	In vitro: crust and necrotic tissue covering the viable tissue In vivo: full‐thickness diabetic wound model	Increase healthy cells’ drug bioavailability and average wound closure rate (95%) New hair growth Reduce MMP9 (an enzyme involved in the extracellular matrix degradation) expression	[ 183 ]
NHGs embedded in porous PEGDA‐microneedles (NHGs: N‐diazeniumdiolates‐loaded copper‐benzene‐1,3,5‐tricarboxylate metal‐organic framework (MOF) is encapsulated with graphene oxide)	NO gas: facilitate angiogenesis and vasodilation Photothermally responsive release of NO Deeper and more precise release of NO Reduction of toxicity of copper ions through 4‐MAP modified‐MOF	In vitro compatibility test: NIH/3T3 cells In vivo: type I diabetic rat model	Excellent compatibility of porous NHG‐microneedles Reduction in wound area (NHG‐MN+NIR group: reduce to 1.0 ± 0.3%) Promotion of re‐epithelialization (NHG‐MN+NIR group: granulation tissue thickness reached 1.39 ± 0.02 mm)	[ 184 ]
Magnesium organic frameworks (Mg‐MOFs) mixed with poly(γ‐glutamic acid) (γ‐PGA) hydrogel as needles with γ‐PGA hydrogel and graphene oxide‐silver nanocomposites mixture as the base	Multifunctional platform including anti‐inflammation and antibacterial effect, promote angiogenesis and tissue repair	In vitro antibacterial test: S. aureus, E. coli, and P. aeruginosa In vitro cell migration test: Human umbilical vein endothelial cells In vivo: living diabetic mice with round cutaneous wounds on the back	73% inhibition rate of DPPH free radicals at a Mg‐MOF concentration of 60 µg mL–1 Significant decrease in wound area and granulation tissue width 73% inhibition rate of DPPH free radicals at a Mg‐MOF concentration of 60 µg mL–1	[ 185 ]
Zeolitic imidazolate frameworks‐8 (ZIF‐8) encapsulated photo‐crosslinked methacrylated hyaluronic acid (MeHA) based hydrogel microneedles	Zn‐MOF: nanoporous materials with anti‐bacterial property MeHA: biodegradable and ductile	In vitro antibacterial test: E. coli and S. aureus In vivo: full‐thickness infected cutaneous defect rat model	Maximum granulation tissue thickness (1.93 ± 0.06 mm) Significant decrease in IL‐6 expression Massive collagen deposition	[ 186 ]
Polydopamine‐gelatin mixture as base and PEGDA‐sodium alginate as tips with polymyxin loaded both	Suction‐cup‐structured concave chambers surrounded Excellent wet/dry adhesion; polymyxin Broad‐spectrum antimicrobial property Self‐healing ability	In vitro antibacterial test: E. coli In vivo model: knee osteoarthritis rat model	Excellent flexibility and adhesion ability (withstand weights in excess of 240 times microneedles’ mass) High E. coli killing rate Significant recovery of joint lesions after glucocorticoid‐loaded microneedles treatment	[ 187 ]
Chitosan microneedles loaded with VEGF encapsulated poly(N‐isopropylacrylamide) (pNIPAM) hydrogel	Chitosan: porous structure, excellent antimicrobial, and wound healing properties pNIPAM hydrogel: temperature‐responsive Smart drug release	In vitro antibacterial test: E. coli and S. aureus In vivo: severely infected wound model	Bacterial mortality up to 99% Enhanced airflow between internal and external environments Optimal regeneration levels brought by increased temperature induced by inflammatory reaction	[ 188 ]