WPI STX2-PLUS Manuale utente
WORLD
PRECISION
INSTRUMENTS
STX2-PLUS
for use with EVOM3 Epithelial Voltohmmeter
Serial No._____________________
www.wpiinc.com
INSTRUCTION MANUAL
082620
STX2-PLUS
World Precision Instruments i
Copyright © 2020 by World Precision Instruments. All rights reserved. No part of this publication may
be reproduced or translated into any language, in any form, without prior written permission of World
Precision Instruments, Inc.
CONTENTS
ABOUT THIS MANUAL ................................................................................................................... 1
INTRODUCTION .............................................................................................................................. 1
Unpacking................................................................................................................................... 2
OPERATING INSTRUCTIONS......................................................................................................... 3
Positioning Electrode in a Culture Cup................................................................................ 3
Stable Repeatable Readings ............................................................................................. 3
Ease of Use ........................................................................................................................... 3
Adjusting the Length of the Electrodes............................................................................... 4
MAINTENANCE ................................................................................................................................ 5
Cleaning/Maintaining the STX2-PLUS Electrodes.............................................................. 5
Disinfecting the STX2-PLUS Electrodes ............................................................................... 5
Sterilizing the STX2-PLUS Electrode..................................................................................... 6
Rechloriding the Electrodes ................................................................................................... 6
Storing the Electrodes ............................................................................................................. 6
Testing the STX2-PLUS Electrodes........................................................................................ 7
ACCESSORIES................................................................................................................................... 7
TROUBLESHOOTING ..................................................................................................................... 8
APPENDIX A: KCL TESTING MIXTURES....................................................................................... 9
APPENDIX B: COMPATIBLE INSERTS AND PLATES ................................................................. 9
WARRANTY .....................................................................................................................................11
Claims and Returns ................................................................................................................11
Repairs.......................................................................................................................................11
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STX2-PLUS
World Precision Instruments 1
ABOUT THIS MANUAL
The following symbols are used in this guide:
This symbol indicates a CAUTION. Cautions warn against actions that can cause
damage to equipment. Please read these carefully.
This symbol indicates a WARNING. Warnings alert you to actions that can cause
personal injury or pose a physical threat. Please read these carefully.
NOTES and TIPS contain helpful information.
Fig. 1—The STX2-PLUS electrode is designed for use with the EVOM3 meter.
INTRODUCTION
The STX2-PLUS electrode can be used with the EVOM3 and is designed to facilitate
measurements of membrane voltage and resistance (TEER) of cultured epithelia
directly in 12- and 24-well tissue culture plates. The electrode incorporates a
adjustable pair of probes, 5 mm tall, 4 mm wide and 0.7 mm in thickness. Each probe
has an outer (current) and an inner (voltage) electrode.
For 12- or 24-well measurements, the STX2-PLUS electrode is capable of making
precise measurements. The STX2-PLUS is designed primarily for 24-well inserts, and
it can be used with 24-well HTS plates (Corning 3378) and 12-well inserts (Corning
3460) with good results, as long as the placement is consistent. Consistent electrode
placement and mechanical stability are essential for consistent resistance results. Try
to keep the uid levels and uid temperatures constant. The use of a warming plate
can add to measurement items and reduce CO2out gassing during readings. CO2out
gassing can change the pH of the media and sharply increase a resistance reading.
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Unpacking
Upon receipt of this instrument, make a thorough inspection of the contents and
check for possible damage. Missing cartons or obvious damage to cartons should be
noted on the delivery receipt before signing. Concealed damage should be reported
at once to the carrier and an inspection requested. Please read the section entitled
“Claims and Returns” on page 11 of this manual. Please contact WPI Customer
Returns: Do not return any goods to WPI without obtaining prior approval (RMA
# required) and instructions from WPI’s Returns Department. Goods returned
(unauthorized) by collect freight may be refused. If a return shipment is necessary,
use the original container, if possible. If the original container is not available, use a
suitable substitute that is rigid and of adequate size. Wrap the instrument in paper or
plastic surrounded with at least 100 mm (four inches) of shock absorbing material. For
further details, please read the section entitled “Claims and Returns” on page 11 of
this manual.
STX2-PLUS
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OPERATING INSTRUCTIONS
Positioning Electrode in a Culture Cup
Proper placement of the electrode in the cell is critical to making accurate
measurements. The STX2-PLUS electrode is designed to facilitate measurements of
membrane voltage and resistance of cultured epithelia
in tissue culture wells. The lengths of the electrodes
are unequal allowing the longer (external) electrode to
touch the bottom of the dish containing the external
culture media while preventing the shorter (internal
electrode) from reaching the bottom of the tissue
culture cup or insert (see Fig. 1) below). This feature
ensures proper repeatable positioning between the
electrode and the cell layer in the cup during the trans
membrane measurement. The reproducibility of the
measurements is signicantly improved.
Fig. 2— (Right) Electrodes in solution.
Stable Repeatable Readings
This new electrode design sets the correct depth and centering of the electrode
elements. Once placed and released, movement ceases, the EVOM3 readings become
more stable, negating any need to make multiple measurements.
Ease of Use
The STX2-PLUS is designed for use with Corning 347X 24-well plates or Millipore
hanging inserts. The apical volume is 250 µL, and the basal volume is 750 to 1000 µL.
Insert the outer electrode into the basal access, center the lower adjustment ring onto
the upper edge of the insert and let the electrode stand on its own. The electrode legs
no longer need to ex or be inserted at an angle (Fig. 4). The electrode placement is
stable and repeatable.
*For 24-well HTS plates, keep the basal electrode centered in the basal access.
*For 12-well inserts, the STX2-PLUS must be hand held.
Fig. 3—Correct Fig. 4—Angle variance Fig. 5—Depth variance
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Adjusting the Length of the Electrodes
1. Firmly grasp the white adjustment nut at the end of the electrode body with one
hand. With the other hand hold the shaft of the electrode body. Rotate the nut
clockwise to shorten the electrodes. Rotate it counter-clockwise to lengthen the
electrodes.
NOTE: The ring should extend a little beyond the steel surface. This allows the
step in the ring to engage the outer edge of the insert (or the tri supports of a
hanging insert).
Fig. 6—Rotate the nut to adjust the length
of the electrodes.
Fig. 7—The electrode length is properly
adjusted.
2.
Align the electrodes with the well inserts and position the
STX2-PLUS
over the well
so that it rests securely in an upright position. (Images shown with a Corning 3470
24-well insert and plate. For greater stability, rest the cable on the tabletop. For
other plates and inserts, center the electrodes and the weight holds the electrode
in place when making measurement readings.
Fig. 8—The outer electrode reaches close to
the bottom of the well plate, and the inner
electrode does not touch the membrane.
Fig. 9—The STX2-PLUS sits securely over a
well insert.
STX2-PLUS
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MAINTENANCE
Electrodes must be properly cleaned, sterilized and stored.
CAUTION: Do not ame electrodes. Doing so will cause them to melt.
Cleaning/Maintaining the STX2-PLUS Electrodes
IMPORTANT! With the use of DMEM, the electrode surface will become coated with
protein or other foreign materials. This build-up, or contamination, will degrade the
performance of the system. After every use, rinse the STX electrodes with distilled
water and store them dry. Periodically clean your STX electrodes with Tergazyme,
Enzol or Endozyme proteolytic detergents. (These detergents are manufactured by
Alconox, Johnson & Johnson, Ruhof.)
1. Rinse with the electrodes with distilled water and dry them.
2. Make a 1% solution of Tergazyme according to the manufacturer’s instructions.
3. Suspend the tips of the electrodes in the Tergazyme solution, with the exposed
electrode surfaces fully immersed. During soaking, you can brush the surfaces
of the electrodes with a soft brush (like a toothbrush), if desired. The soaking
time varies according to your maintenance schedule and the frequency of your
cleaning.
• Soak the electrodes overnight when the electrodes have not been on a
routine maintenance cleaning schedule.
• Soak 60 minutes if you are on a weekly cleaning schedule.
• Soak 10-30 minutes if you clean your electrodes daily.
4. Rinse the electrodes well with distilled or de-ionized water. Allow them to air dry
and store the electrodes dry away from exposure to sunlight.
Disinfecting the STX2-PLUS Electrodes
The STX2-PLUS electrodes are resistant to most methods of low temperature
chemical disinfection. A solution of 5% sodium hypochlorite (undiluted household
bleach) is a good choice. Ortho-phthaladehyde (Cidex OPA or Rapicide OPA), 30/70
ethanol or 30/70 isopropyl alcohol are also acceptable.
The STX2-PLUS electrodes require a 10-15 minute soak in a solution of 5% sodium
hypochlorite (undiluted household bleach) to revitalize the electrodes.
CAUTION: NEVER leave the electrode in alcohol for more than 30 minutes at a
time. Continuously soaking the electrode in alcohol will weaken the protective
coating on the electrode and shorten its life. A damaged electrode showing
peeling of the transparent coating will expose tissues to copper. An electrode showing
signs of peeling must be replaced.
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CAUTION: Ammonia is NOT recommended, because silver chloride dissolves
in ammonia.
Sterilizing the STX2-PLUS Electrode
The STX2-PLUS electrodes are non-sterile as supplied. Acceptable low temperature steril-
ization methods for the electrodes include gamma irradiation and ethylene oxide gas (ETO).
CAUTION: Do NOT autoclave the electrode.
CAUTION: Do NOT use ionized hydrogen peroxide (H2O2).
CAUTION: Do NOT expose the electrodes to ultra-violet light, because UV light
decomposes silver/silver chloride electrodes.
CAUTION: Do not sand or abrade the electrode surfaces. A damaged
electrode will expose tissues to copper. An electrode showing deep scrateches
on the Ag-AgCl surfaces must be replaced.
CAUTION: Do not immerse the electrode head.
Rechloriding the Electrodes
The STX2-Plus electrode must be dipped into chlorine bleach (5% sodium
hypochlorite) on occasion to maintain the amount of Ag to AgCl balance. Otherwise,
the electrode will become unstable. A 10–15 minute immersion of the tips is
recommended before each daily use. (These treatments may be reduced to once
per week as experience guides). DMEM deposits cause resistance measurements to
become unstable and the coating appears as a dark crust on the electrode surfaces.
See “Appendix A: KCL testing mixtures” on page 9. A properly chlorided silver
surface will appear to be a dark silvery grey coloration.
https://www.wpiinc.com/wp-34521-endozime-enzymatic-detergent-169-oz
https://www.wpiinc.com/7363-4-enzol-enzymatic-detergent-1-gallon
CAUTION: Too much chloriding can also lead to instabilities. A short 5 minute
soak in ammonia water (3%) will convert the AgCl back to Ag. After a DI water
rinse, repeat the chloriding. Follow this with an electrode test.
Storing the Electrodes
After a daily use, wash and store the electrodes dry.
Indice
