WORKFLOW KIT · ANTIBODY DISCOVERY

Controllable Surface Antigen

Expression Kit

Express any antigen on any cell surface in hours, no stable cell line generation required.

Kits include: Custom cargoes · Optimized protocols · Portal reagents · Delivery cartridges · Suggested readouts

Upgrade Your Workflow

Gateway™ mechanoporation opens each cell with a brief mechanical squeeze, so RNA encoding your antigen or receptor diffuses into the cytosol and the cell reseals. The cell translates it and traffics it to the surface within hours, at a dose-controlled level, in primary cells and cell lines alike. Staining and screening happen the same day, without building a stable cell line.

The Current Workflow is Broken

Antigen discovery usually starts by building a stable cell line that expresses your target. That takes weeks of cloning, transfection, and selection for each antigen. It works only in cell lines that transfect well, and it locks each antigen to a single expression level. Every additional antigen, or combination, adds more of the same wait.

01

Design construct

02

Generate stable cell line

03

Wait weeks

04

Run assay

Dead End

Portal has the Solution

01

Prepare

Cells of choice, no stable cell line

02

Mix

Cells + custom antigen/receptor RNA

03

Boost

Gateway™ mechanoporation

04

Express

Surface antigen within hours

05

Assay

Binding or discovery assay

Antigens expressed in hours

Hours

Surface antigen expressed, no stable cell line to build

Any cell type

Primary cells and cell lines, not only the ones that transfect well

Tunable

RNA dose sets the surface expression level

What's in the Kit

The cargo and protocols below make this kit specific. The core consumables, settings, and support ship with every Portal kit.

Available Cargoes

Custom antigen/receptor RNA: Single antigens, Antigen combinations
Example targets: CD19, BCMA, HER, Combinations, e.g. CD19 + CD3

Don't see your cargo? Ask us about custom configurations

Reagents & Consumables

Delivery tracer
MicroBooster™
Portal reagents

Protocol & Settings

Single-antigen dose-range protocol
Multi-antigen matrix protocol
Recommended cell concentrations
Suggested readouts

Support

Antigen and assay design with a Portal scientist
Optional: hands-on implementation visit

Available Cargoes

Custom antigen/receptor RNA: Single antigens, Antigen combinations
Example targets: CD19, BCMA, HER, Combinations, e.g. CD19 + CD3

Don't see your cargo? Ask us about custom configurations

Reagents & Consumables

Delivery tracer
MicroBooster™
Portal reagents

Protocol & Settings

Single-antigen dose-range protocol
Multi-antigen matrix protocol
Recommended cell concentrations
Suggested readouts

Support

Antigen and assay design with a Portal scientist
Optional: hands-on implementation visit

Proof Points

Surface Antigen Level Scales With RNA Dose

We titrated antigen-encoding RNA from a low to a high dose and read the surface antigen by flow cytometry. Mean surface signal rose about 5-fold from the lowest dose to the highest, a clean step at each concentration, so you set the expression level by dose. Viability held across every dose, similar to the untreated control.

Expression in Any Cell Type, Including Primary Immune Cells

Because mechanoporation delivers cargo by physically opening the cell rather than by transfection, it works even in cells that do not transfect easily. We delivered RNA into a mixed primary PBMC prep and saw expression in all four subtypes at once — T cells, B cells, NK cells, and monocytes — rather than in a single engineered cell line. The same boost can carry antigen and receptor RNA into primary cells and cell lines alike.

Broad Compatibility

Portal’s platform supports delivery to a diverse range of cell types and cargoes

Delivery materials

Validated cell types

mRNA, siRNA, saRNA

Proteins & Peptides

CRISPR RNPs

Small Molecules

Polymers

Nanoparticles

Antibodies

Virus

PBMCs

T cells

B cells

NK cells

iPSCs

Monocytes

RBCs

HSCs

Delivery materials

mRNA, siRNA, saRNA

Proteins & Peptides

CRISPR RNPs

Small Molecules

Polymers

Nanoparticles

Antibodies

Virus

Validated cell types

PBMCs

T cells

B cells

NK cells

iPSCs

Monocytes

RBCs

HSCs

Check out our other kits

Validated live-cell workflows for target engagement, compound profiling, and beyond.

Every kit includes: Cargoes · Optimized protocols · MicroBooster™ cartridges · Suggested readouts · Reagents

Impermeable Candidate Validation in Live Cells

Solves: Permeability engineering as a prerequisite for testing cellular activity
Cargo: Your impermeable drug candidate
Validate and test your candidates in live cells, regardless of permeability
e.g. small molecules, macrocycles, peptides

Live-Cell Protein Detection

Solves: Live-cell context lost to lysis, and target labeling that requires cell engineering.
Cargo: Intracellular antibodies (primary & secondary)
Measure endogenous intracellular proteins in live cells
e.g. p-BTK, p-ERK, p-AKT, p-STAT3, p-MET Compatible with LgBiT/HgBiT reagents

Live-Cell Target Engagement

Solves: Live-cell context lost to lysis and detergents, and the need to create cell-permeable tracers
Cargoes: Your tracers (e.g. NanoBRET) and compounds
Enables live-cell target engagement without lysis; supports impermeable tracers
e.g. kinase inhibitor profiling, degrader engagement

Intracellular DEL Screening

Solves: DEL screens can't be done in live human cells
Cargo: Your DEL library
Screen intracellular targets with no library bias
e.g. iPSCs, HeLa, PBMCs - any cell type

Direct-to-Assay

Solves: The stable-line bottleneck: infeasible in primary cells, slow and laborious elsewhere
Cargo: Custom RNA encoding tagged POI
Run NanoBRET or LgBiT/HgBiT without stable lines
e.g. VHL-NanoLuc, HgBiT-tagged POI, HA-tagged POI

What is the Surface Antigen Expression Kit?The Surface Antigen Expression Kit is a Portal Bio workflow kit that displays a custom antigen or receptor on the surface of live cells from the mRNA or circRNA that encodes it, without building a stable cell line. Gateway™ mechanoporation opens each cell with a brief mechanical squeeze so antigen-encoding RNA enters the cytosol; the cell translates it and traffics the protein to its surface within hours. The kit ships custom antigen or receptor RNA for single antigens or combinations, a delivery tracer, MicroBooster™ cartridges, Portal reagents, single-antigen dose-range and multi-antigen matrix protocols, and suggested readouts. It is built for antibody discovery and other binding assays, where you need the target on the cell surface fast and at a level you control.

How do you express a surface antigen without a stable cell line?You deliver the RNA that encodes the antigen straight into the cell instead of engineering the genome to make it. With this kit, Gateway™ mechanoporation opens each cell with a brief mechanical squeeze, so antigen or receptor RNA diffuses into the cytosol before the membrane reseals. The cell's own machinery then translates the RNA and presents the antigen on its surface within hours. Because nothing is cloned, transfected, or selected, the antigen is on the cells the same day, and the expression is transient rather than a permanent cell line you have to maintain.

Can you control the level of surface antigen expression?Yes. Surface expression scales with the amount of antigen-encoding RNA you boost in, so raising or lowering the RNA dose sets how much antigen is displayed on the surface, read out by flow cytometry. That lets you match a physiological expression level, profile a target across a range of densities, or hold different antigens at comparable levels in the same experiment. Viability stays similar to the untreated control across the dose range, so the cells stay healthy at every level.

How quickly does the antigen appear on the cell surface?Within hours of the boost. The RNA lands directly in the cytosol, so translation and surface trafficking begin right away rather than after the days or weeks it takes to build and expand a stable cell line. In practice you boost in the morning and have antigen-displaying cells ready to stain or screen the same day, which is what makes it practical to run several antigens, or several expression levels, side by side.

Which cell types can display antigens with this kit?Because mechanoporation is a physical delivery route, it does not depend on a cell being easy to transfect, so it works in primary cells and cell lines alike. Portal has expressed delivered RNA in primary human immune cells across subtypes, including T cells, B cells, NK cells, and monocytes, as well as in common cell lines. That means you can express your antigen in the cell type that matters for the assay, instead of defaulting to whichever cell line tolerates a stable transfection.

Can you express more than one antigen at a time?Yes. A single boost can carry one antigen-encoding RNA or several together, so you can co-display a combination of antigens on the same cell or build a multi-antigen matrix across a plate. Portal has co-delivered multiple RNA cargoes in one boost and seen the constructs co-expressed in the same cells, which is the basis for screening antigen pairs without making a separate stable cell line for each combination.

Ready to run the Controllable Surface Antigen Expression Kit?

Request the kit and a Portal scientist will spec it for your cells, cargo, and readout.