TABLE 1.

Overview of biopolymers used for bacteriophage embedding.

Envisioned application	Biopolymers and construct	Embedded phage	Relevant results				Reference
			Study type	Phage release	Protective properties	Antimicrobial effects
Intestinal phage delivery	Millimeter sized beads with sodium alginate and chitosan core/shell structure. Alginate core viscosity was increased by supplementation with honey/gelatin.	E. coli phage ZSEC5	In vitro	Complete phage release in 5 h under SIF conditions.	Resisted acidic environments (pH = 2) for 60 min and 3-min exposure to 80°C, both with a 1log10 reduction of embedded PFU.	4.5–5log10 reduction of E. coli CFU after 10 h incubation.	Abdelsattar et al., 2019
Intestinal phage delivery	Microspheres of sodium alginate and chitosan core/shell structure.	E. coli phage O157:H7	In vitro	65% of embedded phage released after 6 h under SIF conditions.	Resisted acidic environments (pH = 2) for 60 min, with a 1.5log10 reduction of embedded PFU.	After 5 h incubation a 2.5log10 CFU reduction was observed compared to control cultures.	Kim et al., 2015
Intestinal phage delivery	Beads of Sodium Alginate with either a chitosan or a polyethyleneimine (PEI) coating	E. coli phage T4	In vitro	Release plateaus after 12 h under SIF conditions. Chitosan and PEI coatings delayed phage release but reduced cumulative release as well.	Polycationic coatings increased acid resistance of embedded phage. 4log10 reduction in Alginate beads vs. 1log10 reduction in Alginate-PEI beads.	Not assessed	Moghtader et al., 2017
Preservation of meat	Sodium Alginate thin films	Pseudomonas fluorescens phage ϕIBB-PF7A	In vitro	Complete release of phage in 3 h.	PFU count was reduced by 4.2log10 after storage of 12 weeks at 4°C.	P. fluorescens CFU was reduced by 2log10 compared to control cultures.	Alves et al., 2019
Phage delivery for non-topical infections	Fibrin glue (TISSEEL®, Baxter, United States)	P. aeruginosa phage PA01	In vitro	Phage release was followed for 11 days, in which daily release was between 109 and 1010 PFU/day.	Not assessed	Significant reductions in OD600 indicate antimicrobial effects,	Rubalskii et al., 2019
Treatment of cystic fibrosis	Spray dried or lyophilized particles of a mixture of trehalose, mannitol and leucine	P. aeruginosa phage PEV2	In vitro	Phage delivery was in the order of 105 PFU per dose from an inhaler device.	Not assessed	Not assessed	Leung et al., 2016
Intestinal phage delivery	Sodium alginate and chitosan beads (±800 μm diameter)	Salmonellla phage Felix O1	In vitro	Near complete phage release (1.6⋅107 PFU) in 5 h under SIF conditions.	After 60 min in SGF (pH = 2.4) a 2.6log10 reduction in phage titer was observed. At pH = 2, no titer was observed after 30 min.	Not assessed	Ma et al., 2008
			Study type	Phage release	Protective properties	Antimicrobial effects
Intestinal phage delivery	Sodium Alginate/CaCO3– beads (±150 μm diameter)	Salmonella phages UAB_Phi20/Phi78/Phi87	In vivo	80–100% of all three phages were released after 40 min in SIF.	Titer loss after 60 min exposure to SGF approximately 2–3log10 for UAB_Phi78 and UAB_Phi87. No significant titer loss for UAB_Phi20.	Alginate/CaCO3– beads showed 1.7log10 reduction of excremental Salmonella. Effect of free phage was initially stronger but showed no significant difference with control group a week after treatment ceased.	Colom et al., 2017
Prophylactic phage delivery in an osteointegrative hydrogel	Sodium Alginate/nano-hydroxyapatite (nHAP) hydrogel	E. faecalis phages vB_EfaS_LM99	In vitro and ex vivo	97% of phage released in 24 h. No difference in phage release observed for nHAP containing hydrogels.	Phage titers in the hydrogel are stable for 7 days	Approximate 2log10 reduction of CFU after coincubation of hydrogels with bacteria. On a chicken femur ex vivo model a 3log10 reduction of CFU was observed after 48 h.	Pennone et al., 2019
Phage delivery triggered by bacteria-secreted hyaluronidase	Composite films of agarose and hyaluronan	S. aureus phage ϕK	In vitro	Phage release of 106 PFU/mL in 4 h of coincubation with hyaluronidase	Not assessed	Not assessed	Barros et al., 2020
Treatment of osteomyelitis after implant (i.e., screw) removal	Alginate hydrogel	CRISPR-Cas9 modified phage against S. aureus	In vivo	Not assessed	Not assessed	No significant difference between phage loaded alginate and empty alginate on CFU load of a bone defect. CFU reduction (0.55log10) was observed in the soft tissues surrounding the bone defect.	Cobb et al., 2019
Clinical trial: treatment of burn wound patients with P. aeruginosa monoinfections. (Phagoburn project)	Alginate wound dressing soaked in phage cocktail solution	Phage cocktail of 12 P. aeruginosa phages	Clinical trial	Phage release was assessed in vitro. Burst release of phages was observed. Data set was not published or referenced.	Not assessed	Phage loaded wound dressing performed less effectively as standard of care control (sulfadiazine silver cream). Less adverse side effects were observed in patients undergoing phage treatment.	Jault et al., 2019

Abbreviations – CFU: Colony forming unit; nHAP: nano-hydroxyapatite; OD₆₀₀: Optical density at a wavelength of 600 nm; PEI: Poly(ethylenimine); PFU: Plaque forming unit; SGF: Stimulated gastric fluid; SIF: Stimulated intestinal fluid.