Bio-Rad Mini Trans-Blot Cell User Manual

Mini Trans-Blot®
Electrophoretic
Transfer Cell

Instruction Manual

Catalog numbers

170-3930
170-3935
170-3989
170-3836

Assembly and Disassembly

To insure best performance from the Mini Trans-Blot®
electrophoretic transfer cell, become fully acquainted
with these operating instructions before using the cell
to transfer samples. Bio-Rad recommends that you first
read these instructions carefully. Then assemble and
disassemble the cell completely. After these preliminary
steps, you should be ready to transfer a sample.

Wash Cell Before Use

Bio-Rad also recommends that all Mini Trans-Blot
electrophoretic transfer cell components and accessories
be cleaned with a suitable laboratory cleaner (such as
Bio-Rad Cleaning Concentrate, catalog #161-0722) and
rinsed thoroughly with distilled water before use.

Warranty

Bio-Rad Laboratories warrants the Mini Trans-Blot
electrophoretic transfer cell against defects in materials
and workmanship for 1 year. If any defects occur in
the instrument during this warranty period, Bio-Rad
Laboratories will repair or replace the defective parts free.

The following defects, however, are specifically excluded:

1. Defects caused by improper operation.

2. Repair or modification done by anyone other than
Bio-Rad Laboratories or an authorized agent.

3. Use of fittings or other spare parts supplied by anyone
other than Bio-Rad Laboratories.

4. Damage caused by accident or misuse.

5. Damage caused by disaster.

6. Corrosion due to use of improper solvent or sample.

For any inquiry or request for repair service, contact
Bio-Rad Laboratories after confirming the model and serial
number of your instrument.

Mini-Trans-Blot Electrophoretic Transfer Cell i

Table of Contents

Assembly and Disassembly .......................................... i

Wash Cell Before Use ................................................... i

Warranty ........................................................................ i

Section 1 Introduction .................................................. 1

1.1 Specifications ................................................. 3

1.2 Safety Instructions .......................................... 4

Section 2 Mini Trans-Blot Cell Assembly and

Preparation for Transfer ............................................... 5

2.1 Mini Trans-Blot Cell Description and

Assembly of Parts .......................................... 5

2.2 Preparation for Blotting .................................. 6

2.3 Acidic Transfers ............................................. 9

Section 3 Transfer Conditions ....................................10

3.1 General Guide to Transfer Buffers and

Running Conditions.......................................10

3.2 Notes on Electrophoretic Transfer

Conditions ....................................................11

3.3 Buffer Formulation ........................................13

Section 4 Strategies for Optimizing

Electrophoretic Transfer ............................................. 15

4.1 Optimizing Protein Transfer ...........................15

4.2 Optimizing DNA and RNA Transfer................ 18

Section 5 Choice of Blotting Membranes.................. 19

5.1 Protein Blotting ............................................ 19

5.2 DNA and RNA Blotting Membranes ............. 20

Section 6 Troubleshooting Guide .............................. 22

6.1 Electrophoretic Transfer ............................... 22

Section 7 References ................................................. 27

Section 8 Product Information .................................. 29

Section 1
Introduction

Blotting was first performed by Southern in 1975 with
the transfer of DNA from agarose gels to nitrocellulose
membranes.1 Since that time, blotting has been applied to

2-4

RNA

and proteins
gels. To circumvent the inefficiencies observed in
various capillary transfers, electric current has been
adopted for eluting proteins from polyacrylamide gels,
as first described by Towbin et al. in 1979.7 The use of
electrophoretic transfer has also been applied to DNA and
RNA blotting.
the topic of protein electrophoretic transfer techniques.
There have also been reviews summarizing the expanding
literature being generated on electrophoretic blotting
methodology.

The Mini Trans-Blot® tank is part of Bio-Rad’s modular
Mini-PROTEAN® Tetra system. The unique feature of this
electrophoresis system is that the electrode modules
are interchangeable. After finishing gel electrophoresis,
remove the electrode module from the buffer tank, insert
a new electrode module, add new buffer, and the next
electrophoresis application can be performed.

The Mini Trans-Blot module accommodates two cassettes
for electrophoretic transfer. The Mini Trans-Blot module is
useful for blotting either protein or nucleic acid from both
agarose and acrylamide gels. It is also capable of blotting
isoelectric focusing gels from horizontal electrophoresis
cells, or DNA and RNA gels from the Mini-Sub® submarine
electrophoresis cell. For applications where the gel is
larger than 7.5 x 10 cm, or when there are more than two
mini gels to be transferred, the larger standard Trans-Blot®
cell (catalog #170-3910 or 170-3946), Criterion™ Blotter
(catalog #170-4070, 170-4071) or the Trans-Blot® SD
semi-dry cell (catalog #170-3940) should be used.

The heart of the Mini Trans-Blot cell is its electrode
module. This module has the capacity to hold two gel
cassettes between parallel electrodes only 4 cm apart.
The driving force for blotting applications is the voltage
applied over the distance between the electrodes.

5, 6

in both agarose and polyacrylamide

8–14

Numerous publications have dealt with

27–29

15–26

Mini-Trans-Blot Electrophoretic Transfer Cell 1

This short 4 cm electrode distance allows generation of
higher driving forces to produce efficient protein transfers.
A second feature of the electrode module is that it is
offset to accommodate a blue cooling unit. The cooling
unit, which is completely contained within the Mini
Trans-Blot cell, absorbs the Joule heat generated during
rapid electrophoretic transfers. The advantages of having
an internal cooling unit include elimination of an expensive
external cooling bath and avoidance of cumbersome
cooling tubing. Other features of the Mini Trans-Blot cell
include gel holder cassette latches for easy handling, color
coordinated cassettes and electrodes to insure proper
orientation of the gel during transfer, and an efficient
design which simplifies insertion and removal of the
cassettes from the electrode assembly. These features
result in an electrophoretic transfer system which is easy
to use and produces excellent blotting results.

2 Mini-Trans-Blot Electrophoretic Transfer Cell

1.1 Specifications

Construction

Electrode module Molded polysulfone

Gel holder cassettes Molded polycarbonate

Electrodes Platinum wire 0.254 mm

diameter

Buffer chamber and lid Molded polycarbonate

Cooling unit Polyethylene

Overall dimensions

Mini Trans-Blot cell 16 (L) x 12 (W) x 18 (H) cm

Gel holder dimensions 10 x 11 cm

Maximum gel size 7.5 x 10 cm

Buffer capacity

With cooling unit 950 ml

Without cooling unit 1,150 ml

Cleaning Use mild soap and warm

water to clean the electrodes,
cassettes, and buffer tank.
Use special care when
cleaning the electrode cards.
Avoid stretching or breaking
the platinum wires. Do not
use abrasives or strong
detergents. Rinse the fiber
pads under hot water and
then in distilled, deionized
water.

Chemical compatibility The Mini Trans-Blot cell

components are not
compatible with chlorinated
hydrocarbons (e.g.,
chloroform), aromatic
hydrocarbons (e.g., toluene,
benzene), or acetone. Use of

organic solvents voids all
warranties.

Mini-Trans-Blot Electrophoretic Transfer Cell 3

1.2 Safety Instructions

!

Power to the Mini Trans-Blot cell is supplied by
an external DC voltage power supply. This power
supply must be ground isolated in such a way that
the DC voltage output floats with respect to ground.
All of Bio-Rad’s power supplies meet this important
safety requirement. Regardless of which power
supply is used, the maximum specified operating
parameters for the cell are:

400 VDC Maximum voltage limit

500 W Maximum power limit

40°C Maximum ambient temperature limit

Current to the cell, provided from the external power
supply, enters the unit through the lid assembly,
providing a safety interlock to the user. Current to
the cell is broken when the lid is removed. Do not
attempt to circumvent this safety interlock, and
always turn the power supply off before removing
the lid, or when working with the cell in any way.

Important: This Bio-Rad instrument is designed and certified to
meet IEC61010-1 and EN61010-1* safety standards. Certified
products are safe to use when operated in accordance with the
instruction manual. This instrument should not be modified or
altered in any way. Alteration of this instrument will:

• Void the manufacturer’s warranty

• Void the IEC61010-1 and EN61010-1 safety certification

• Create a potential safety hazard

Bio-Rad is not responsible for any injury or damage caused by
the use of this instrument for purposes other than for which it is
intended or by modifications of the instrument not performed by
Bio-Rad or an authorized agent.

* IEC61010-1 and EN61010-1 are internationally accepted electrical safety standard
for laboratory instruments.

4 Mini-Trans-Blot Electrophoretic Transfer Cell

Section 2
Mini Trans-Blot® Cell Assembly and
Preparation for Transfer

2.1 Mini Trans-Blot Cell Description and Assembly of
Parts

Lid

Fiber pad

Filter paper
Membrane

Gel
Filter paper

Fiber pad

Gel holder
cassette

Electrode
module

Blue cooling
(keep frozen at
–20°C)

Buffer tank

Mini-Trans-Blot Electrophoretic Transfer Cell 5

2.2 Preparation for Blotting

Store the blue cooling unit in your laboratory freezer at
–20°C until ready to use. After use, rinse the outside
container with water and return the cooling unit to the
freezer for storage.

1. Prepare the transfer buffer. (See Section 3.3 for buffer

formulation. Using buffer chilled to 4°C will improve
heat dissipation.)

2. Cut the membrane and the filter paper to the

dimensions of the gel or use precut membranes
and filter paper. Always wear gloves when handling
membranes to prevent contamination. Equilibrate the
gel and soak the membrane, filter paper, and fiber
pads in transfer buffer (15–20 min depending on gel
thickness).

3. Prepare the gel sandwich.

a. Place the cassette, with the gray side down,
on a clean surface.

b. Place one prewetted fiber pad on the gray
side of the cassette.

c. Place a sheet of filter paper on the fiber pad.
d. Place the equilibrated gel on the filter paper.*
e. Place the prewetted membrane on the gel.*
f. Complete the sandwich by placing a piece of

filter paper on the membrane.*
g. Add the last fiber pad.

6 Mini-Trans-Blot Electrophoretic Transfer Cell