Table 3.

Activity of various NO-releasing polymeric materials on planktonic and biofilm bacteria.

Macromolecular NO-Releasing Material	Concentration of NO/NO Donor Used	Stains/Test Conditions	Activity	Ref.
NO-releasing chitosan oligosaccharide (COS/NO)	0.12–3.1 µmol NO/mL	In vitro Mucoid/non-mucoid/clinical P. aeruginosa, E. coli, and S. aureus	Killing of planktonic and biofilm cells, with complete eradication of biofilms at high COS/NO concentration Reduction in bacteria adhesion Synergistic effects when used with antibiotics Non-cytotoxic to mouse fibroblast at bactericidal concentrations	[40,113,114,115]
NO-releasing chitosan gels	Variable depending on design and NO donors used. NO concentrations of ~ nmol NO/mg film or initial NO flux of ~ nmol cm−2 min−1	In vitro S. aureus, P. aeruginosa, MRSA, L. monocytogenes and E. faecalis In vivo MRSA	Reduction in bacteria viability and in biofilm cells Synergistic antimicrobial effects when used with antibiotics Improved wound healing in gels used in in vivo wound infection models	[13,116,117,118]
NO-releasing chitosan-dendrimer (CS-PAMAM/NO)	1–2.5 mg/mL chitosan dendrimer (~1.5 µmol NO/mg)	In vitro E. coli, S. aureus and MRSA In vivo MRSA	Killing of planktonic and biofilm bacteria cells, with increased killing compared to CS/PAMAM backbone Reduction in biofilm biomass Improve wound healing rate in in vivo models Not cytotoxic to NIH/3T3 cells at 1 mg/mL	[21,119]
NO-releasing alginate	~ µmol NO/mL for NONOate conjugated alginate	In vitro P. aeruginosa, S. aureus, B. cepacia complex, MRSA, S. mutans, and E. coli	Killing of planktonic and biofilm bacteria cells Lower MW NONOate conjugated alginate most effective with higher effectiveness of than tobramycin treatment AHG-SN-MSA-AgNPs not cytotoxic to Vero cells at concentrations for bacterial eradication, but cytotoxic at >20 μg/mL	[99,120]
NO-releasing cyclodextrins (NO/CD)	100–2000 µg/mL NO/CD (~ nmol NO/mL)	In vitro P. aeruginosa	Killing of planktonic and biofilm bacteria, with lower hepta-substituted CD concentration needed due to its higher NO burst More effective than tobramycin and colistin treatment Not cytotoxic against L929 cell lines at up to 2000 µg /mL	[121,122]
NO-releasing silica NPs (NO-NPs)	~ µg/mL to mg/mL NO-NPs with varying NO release kinetics and flux	In vitro P. aeruginosa, E. coli, S. aureus, S. epidermidis, S. aureus, A. actinomycetemcomitans, P. gingivalis, and S. mutans	Killing of planktonic and biofilm bacteria cells Combining NO release and QA-functionalities can increase bactericidal efficacy Smaller NO-NP size and higher aspect ratio give lower MBC Cytotoxicity towards L929 fibroblast and HGF-1 cells varies, and is influenced by concentration used, quaternary ammonium (QA) functionalization with increased cytotoxicity at longer alkyl QA chain length, and whether there is NO release	[104,123,124,125,126,127]
NO-releasing silane-based hydrogel nanoparticle platform	Steady state NO in nM range	In vitro MRSA and MSSA S. aureus In vivo MRSA	Inhibition of MRSA and MSSA strains from 312 to 2500 μg/mL Prevention of biofilm in vitro and in in vivo rat central venous catheter biofilm model Promotion of wound healing in wound infection models	[31,128]
NO-releasing P(OEGMA) containing polymeric nanoparticles	Variable, dependent on design (see activity for more details)	In vitro P. aeruginosa	Gentamicin-NONOate NPs block copolymer NP Synergistic when co-delivered with antibiotics with gentamicin Induction of biofilm dispersal at lower concentration (5 mM) and biofilm cell death at higher concentrations (10–50 mM)	[54]
			Spherical (S-NO) and worm-like NO-NPs (W-NO) NO release dependent on morphology Biofilm dispersal and eradication	[129]
			NO releasing polydopamine (PDA)-coated iron oxide NPs Biofilm reduction at low NO concentration (0.375 µM NO)	[105]
			Core cross-Linked star polymers Biofilm reduction with 57–400 μg/mL NO star polymer (NO release of 886 nM/h/mg/mL; Rapid release within the first hour and sustained release over 70 h)	[23]
NO-releasing polymeric nanoparticles, microparticles, and liposomes	NPs and MPs used in mg/mL range	In vitro S. aureus, MRSA	Planktonic and biofilm cell eradication Biofilm dispersal	[130,131]
			Targeted delivery of NO possible via conjugation of antibodies or with charge switchable designs	[132,133]
Photo-activated NO-releasing polymeric materials	Variable, dependent on design (see activity for more details)	In vitro P. aeruginosa, S. aureus, MRSA, E. coli In vivo S. aureus, MRSA	Self-assembled micellar NPs with hydrophobic antibiotic in core ~110 μM NO released from 0.1 g/L micellar NP NO release dependent on irradiation time and intensities Biofilm reduction concentration and irradiation dependent Synergistic effect with antibiotic treatment Some cytotoxicity to HeLa and NHLF when used at 0.4 g/L	[22]
			Surface charge switchable, GSH activated α-CD-Ce6-NO-DA NO release dependent on GSH levels α-CD-Ce6-NO-DA (~10 μg/mL Ce6 and ~20 μg/mL NO) bactericidal with low laser irradiation More rapid wound healing with α-CD-Ce6-NO-DA	[134]
			Phototherapeutic nanoplatform AI-MPDA AI-MPDA + NIR irradiation (45 °C) (4.0 μM NO, 0.2 mg/mL AI-MPDA) bactericidal and decreased biofilm Enhanced bacteria killing and wound healing in vivo Limited cytotoxicity against NIH-3T3 fibroblasts with 0.05–0.5 mg/mL AI-MPDA with no toxicity observed in vivo	[135]
			Electrospun nanocomposite membrane (UCNP@PCN@LA-PVDF) Enhanced killing of bacteria with PDT and NO treatment Decreased bacteria and complete wound healing by day 7 in vivo No cytotoxicity against L929 fibroblasts and in vivo	[136]
			PDT-driven NO controllable generation system (Ce6@Arg-ADP) Enhanced killing of planktonic bacteria (8 µg/mL Ce6@Arg-ADP + laser) MRSA biofilm eradication with 1 mg/mL Ce6@Arg-ADP + laser Eradication of all bacteria in subcutaneous abscess with 1 mg/mL Ce6@Arg-ADP + laser treatment in vivo with no biotoxicity	[137]
NO-releasing dendrimers	Variable, dependent on design. ~0.69 to 1 µmol NO/mg dendrimer released over 2–4 h in PBS, pH 7.4, 37 °C with max. flux of 2400–15,000 ppb/mg	In vitro P. aeruginosa, S. mutans, S. aureus, S. sanguinis, A. acetinomycetemcomitans, and P. gingivali	Reduction in planktonic and biofilm cell viability at µg/mL dendrimer corresponding to nmol/mL NO dendrimer) NO releasing dendrimers may be more or less cytotoxic than dendrimer scaffolds depending on design	[100,102,138,139]
NO-releasing hyperbranched dendrimers	NO storage and NO release ~µmol/mg with half-life ranging from 28 to 80 min depending on design and modifications	In vitro P. gingivalis, A. acetinomycetemcomitans, S. mutansm, S. viscosus, and ex vivo multispecies subgingival biofilms	Eradication of planktonic and biofilm cells Reduction in biofilm metabolic activity Antimicrobial activity dependent on aeration condition, with less activity under anaerobic conditions	[41,140]
NO-releasing xerogels and polymer coatings	Variable, dependent on pH, coating, and media (see activity for more details)	In vitro P. aeruginosa	Super-hydrophobic NO-releasing xerogels with fluorinated silane/silica composite topcoat NO flux 60–53 pmol/cm2/s (6–24 layers of coating), with NO release duration extended from 59 h (no coating) to 105 h (12 layers) Reduction in bacteria surface adhesion and biofilm formation	[141]
			NO-releasing (poly)acrylonitrile (PAN/NO) polymer In PBS, initial NO burst of 3.2 nmols/min/mg; 24 h steady state NO ~ 17 pmol/min/mg and cumulative NO over 6 h at 25 nmol/mL Reduction in bacteria CFU with 3–10% w/v PAN/NO in PBS, but limited activity in TSB (7.5 nmol/mL cumulative NO over 6 h) Reduction in biofilm formation with 0.1–3% PAN/NO in TSB over 24 h Dispersal of biofilm with 1–3% w/v PAN/NO in PBS Synergistic effects when used with antimicrobials	[142]
			NO-releasing coatings on PET and silicone elastomer Reduction in viable bacteria	[143]
SNAP-containing Carbosil 2080A polymer (Carbosil-SNAP) with different top coats		In vitro P. aeruginosa, P. mirabilis, S. aureus, E. coli	Reduction in bacteria surface adhesion with following designs: 20 wt% Carbosil-SNAP with hydrophobic CarboSil topcoat (NO release >0.5 nmol/cm2/min for 3 weeks (physiological conditions)) Hydrophilic SP60D60 polymer topcoat on Carbosil-SNAP Antifouling PTFE immobilized on PDA anchor layer atop 10 wt% Carbosil-SNAP (NO surface flux of 0.05 nmol/cm2/ min over 5 days) Reduction in platelet adhesion in 3	[144,145,146]
SNAP-impregnated silicone catheters	NO release ~0.04 nmol/cm2/mL over 60 days or ~ >0.07 nmol/min/cm2 over a month	In vitro P. aeruginosa, P. mirabilis, S. aureus, S. epidermidis	Reduced bacteria adhesion and biofilm formation over 24 h–14 days	[147,148]
Other NO-releasing surfaces	NO flux in µM range (PBS, pH 7.4, 37 °C)	In vitro P. aeruginosa S. aureus	NO-releasing polydopamine (PDA) coating with PEG grafted onto PDA Reduction in bacteria adhesion with more PDA coatings and PEG grafting further inhibiting biofilm formation	[149]
			NO-releasing titanium surfaces Reduced bacteria adherence to AHAP/NO and AUTES/NO surfaces No cytotoxicity observed against human primary osteoblasts	[150]
			Thiol-functionalized coatings Improved NO loading with higher film thickness with corresponding improvement in inhibition of bacterial attachment to the surface	[151]
	NO release sustained over 15 days at levels >1 nmol/cm2/min and a maximum flux of ~ 3 nmol/cm2/min within <15 min	In vitro S. aureus, S. epidermis, E. faecalis, P. aeruginosa, K. pneumoniae, A. baumannii, and E. coli and relevant MDR isolates, In vivo (Murine subcutaneous infection model) P. aeruginosa, A. baumannii; (Porcine central venous catheterization model) N/A	Precision-structured diblock copolymer brush (H(N)-b-S) Surface antifouling block (S) and subsurface NO-releasing bactericidal block (H(N)) H(N)-b-S coating effective in inhibition of Gram-positive and Gram-negative in vitro and in vivo No toxicities against multiple cell lines, with H(N)-b-S coatings additionally showing no thrombus formation, low lymphocyte activation, and low protein fouling in vitro and biocompatibility in vivo	[24]