Table 2.

Characteristics of air-liquid interface exposure chambers for in vitro cell cultures

	VITROCELL® 6/6, 12/12, OR 24/24	VITROCELL® Cloud 6, 12, OR 24	Cultex® RFS OR RFS COMPACT	University of Bern NACIVT
What level of throughput can be achieved?	VITROCELL® 6/6	VITROCELL® Cloud 6	Cultex® RFS	NACIVT
	• 6-well inserts (can use adaptors to adapt to 12 or 24-well-sized)	• 6-well inserts	• 6, 12, or 24-well inserts	• 6-well inserts
	• compartments for exposing 6 cell culture inserts	• compartments for exposing 6 cell culture inserts: 6 inserts at one exposure; no clean air control	• compartments for exposing 3 cell culture inserts - all exposed to the same substance	• compartments for exposing 24 cell culture inserts – allexposed to the same substance.
	• allows for separate clean air exposure in one module:	• 1 well can be used for the (optional) microbalance.	• would have to purchase 2 modules for clean air control	• would have to purchase 2 modules for clean air control
	o 3 replicates clean air control
	o 3 replicates of one dose (or 2 replicates plus optional 1 well for microbalance)
	VITROCELL® 12/12	VITROCELL® Cloud 12	Cultex® RFS Compact
	• 12-well inserts (can use adaptors to adapt to 24-well-sized)	• 12-well inserts	• 12 or 24-well inserts
	• compartments for exposing 12 cell culture inserts	• compartments for exposing 12 cell culture inserts	• compartments for exposing 6 cell culture inserts
	• allows for separate clean air exposure in one module:	• allows for separate clean air exposure in one module:	• allows for separate clean air exposure in one module
	o 3 replicates clean air control	o 3 replicates for clean air control
	o 3 dose dilutions with 3 replicates per dilution (or 2 replicates plus optional 1 well for microbalance)	o 9 inserts at one exposure (1 well can be used for the optional microbalance)
	VITROCELL® 24/24	VITROCELL® Cloud 24
	• 24-well inserts	• 24-well inserts
	• compartments for exposing 24 cell culture inserts	• compartments for exposing 24 cell culture inserts; 24 inserts at one exposure (1 well can be used for the optional microbalance)
	• allows for separate clean air exposure in one module:	• would have to purchase 2 modules for clean air control
	o 4 replicates clean air control
	o 5 dose dilutions with 4 replicates per dilution (or 3 replicates plus optional 1 well for microbalance)
Commercially available?	Yes	Yes	Yes	No
Deposited-dose determination	• The microbalance is capable of measuring the deposition in the module at a resolution of 10 ng/cm2.	1 well can be used for the microbalance (optional).	Gravimetric methods, using the precision balance.	One of the wells is designed to carry a transmission electron microscope (TEM) grid to monitor exposure. Also has an electrometer.
	• For the 6/6 and 12/12, a built-in microbalance option is available. A microbalance sensor would occupy one compartment; therefore, the module should have at least 4 compartments in order to allow 3 replicates for exposure.
	• For the 24/24, the purchase of a separate, standalone 12/1 CF module to use a microbalance would be needed.
Exposure Method	The VITROCELL® 6/6 is compatible with electrostatic deposition.	Not compatible with electrostatic deposition, but due to high deposition efficiency of NMs in the Cloud, electrostatic deposition is not needed (Cloud is equipped with a nebulizer that generates liquid aerosols).	Compatible with electrostatic deposition (both RFS and RFS compact).	Compatible with electrostatic deposition.
	The 12/12 and 24/24 are not, but in those cases, the VITROCELL® 6/6 modules can be used with adaptors for 12 or 24-well inserts.
Exposure time duration	Maximum 6 h possible	Approximately 3–4 min	Up to 1 h reported	Up to 2 h reported
Ability to utilize multiple aerosol generating techniques?	May be used with a wide range of aerosol generators.	Compatible only with the aerosol generator, which is part of the delivery (vibrating mesh type for liquid aerosols).	May be used with a wide range of aerosol generators; One option is the Cultex® dust generator, which is a Mitchell or screw mill type.	May be used with a wide range of aerosol generators; Can be placed close to the workplace or aside a busy street.