FAQ - General questions

What is the difference between SCHOTT NEXTERION® Glass B and D?

NEXTERION® Glass B is a borosilicate glass that is produced by the microfloat process, resulting in a top fire-polished surface; and a lower surface that has been in contact with the molten tin. On customer request SCHOTT indicates which is the top (fire polished) side of the NEXTERION® Glass B slides, and all the slides are kept in the same orientation throughout processing and packing. The refractive index of Glass B is 1.47 (nd λ = 546nm and ne λ = 588nm).

NEXTERION® Glass D is also a borosilicate glass but it is produced by a special down-draw production process that results in two fire-polished surfaces that can be used without any additional processing. The refractive index of Glass B is 1.52 (nd λ = 546nm and ne λ = 588nm).

What is the tensile strength of NEXTERION® Glass B and Glass D, how do these values compare to soda lime glass?

Young's modulus is a measure of the stiffness of an isotropic material. The measured value can vary slightly due to differences in sample composition and test method.

NEXTERION® Glass B = Borofloat 33:
Tensile strength (Young's modulus, E): 64.0 GPa

NEXTERION® Glass D = D263T:
Tensile strength (Young's modulus, E): 72.9 GPa

Corning 0211:
Tensile strength (Young's modulus, E): 75.9 GPa

Soda lime glass:
Tensile strength (Young's modulus, E): 70 - 72 GPa

What How does the hardness of Glass B and D compare to Soda lime glass?

Mechanical hardness in brittle materials is measured using the Knoop hardness test.
This is a microindentation test, and the value is calculated as the ratio of the load applied to the indenter over the unrecovered indented area.

Knoop hardness (ISO 9385:1990) kg/mm2
• BOROFLOAT® 33 (Glass B)mehr platz 480
• D263 (Glass D) 590
• Soda lime 565 - 605

Has BOROFLOAT® 33 / NEXTERION® Glass B been tested for hydrolytic resistance in accordance with the European Pharmacopeia EP 6 (2010) Chapter 3.2.1 and the United States Pharmacopeia USP 32?

Yes, BOROFLOAT® 33 / NEXTERION® Glass B is tested for hydrolytic resistance in accordance with the following Pharmacopeia standards?

European Pharmacopeia EP 6 (2010) Chapter 3.2.1
Glass containers for pharmaceutical use
B Test for hydrolytic resistance of powdered glass

United Sates Pharmacopeia USP 32
<660> Containers, Chemical resistance - glass containers
- Powdered Glass Test classified as Hydrolytic resistance: class 1

A copy of the test certificate is available here:
Analysis report according European Pharmacopeia EP 6 and United Sates Pharmacopeia USP 32

What is the average surface micro roughness (Ra) of Glass B (BOROFLOAT® 33) and D (D263)?

The typical micro roughness of the "fire polished" surface of Glass B and D is less than 3 nanometers.



NEXTERION® Glass B
Micro roughness of Nexterion Glass B

In the NEXTERION® Glass B specification, a number of spot type defects are listed under "Surface specification".
What do these terms mean?

Here are the definitions of possible glass surface defects in NEXTERION® Glass B slides:

Spot defect:
A defect that commonly looks dark against the surrounding coating, when viewed in transmission.

Open bubble:
Large bubble located on the glass surface.

Dig:
An oblong or circular abrasion to the surface of the glass. The cause is similar to that of the scratches, but digs are shorter in nature.

Chip:
A small piece of glass broken from an edge.

Dross:
Dross is formed from molten tin as a result of oxidation or reaction with other contaminants.

Drip:
A drip is produced by the condensation of alkali-borates, released from the float bath, on the glass surface.

Tos:
This is an abbreviation for "top opened seed". Seeds are tiny round or oval shaped enclosed bubbles, generally 1-2 mm wide, that may contain small particles from the powdered ingredients used in the production of the BOROFLOAT glass. There is a depression in the glass that accompanies the inclusion or seed that will be apparent when looking at it from an angle.

Bos:
This is an abbreviation for "bottom opened seed". Seeds are tiny round or oval shaped enclosed bubbles, generally 1-2 mm wide, that may contain small particles from the powdered ingredients used in the production of the BOROFLOAT glass. There is a depression in the glass that accompanies the inclusion or seed that will be apparent when looking at it from an angle.
NEXTERION® Glass D
Micro Roughness of Nexterion® Glass D

Are the properties of the two Glass D (D263) surfaces identical?

Yes, NEXTERION® Glass D is produced by a special down-draw production process that results in two identical "fire-polished" surfaces, which can be used without any additional processing.

What is the "flatness" of Glass B (BOROFLOAT® 33)?

There are several ways to measure glass flatness.

1. SCHOTT NEXTERION® defines “flatness” as the accumulated overall possible thickness deviation. NEXTERION® slides have a maximum total “flatness” deviation of ≤ 25 µm for these three factors (warp, intra-slide thickness deviation, and inter-slide thickness tolerance) combined.

2. A project to measure the flatness deviation of individual Glass B Slides (75.6 x 25 mm) using Interferrometry, showed that the flatness deviation across a slide is ≤ 5 µm.

For additional information please download a presentation here.

Can SCHOTT offer any advice on the best method of bonding Glass D (D263) to Polydimethylsiloxane (PDMS)?

The three most common systems / methods used by SCHOTT customers to bond D263 to PDMS are:

  1. AutoGlow Plasma System
    http://www.glowresearch.org/applications.html

  2. March Plasma treatment system
    http://www.marchplasma.com/products.htm

    Example of a protocol: http://engineering.tufts.edu/microfab/index_files/SOP/PDMS_GlassBond_SOP.pdf

  3. Jelight UV-ozone cleaner
    "PDMS elastomer valves are formed by activating both sides of the PDMS membrane (254-ím-thick HT-6240, Bisco Silicones, Elk Grove, IL) with an UV ozone cleaner (Jelight Co. Inc., Irvine, CA) for 1.5 min to improve PDMS-glass bonding and then sandwiching the membrane between the manifold and the bonded channel wafers."
    http://www.cchem.berkeley.edu/ramgrp/alpha/people/Alumni/nick/PCR%20Anal%20Chem%202006.pdf
    http://www.jelight.com/uvo-ozone-cleaning.php
    "The valves were assembled after bonding in a manner similar to that outlined by Grover et al.27 Briefly, a PDMS membrane (254-ím-thick HT-6240, Bisco Silicones, Elk Grove, IL) was applied to the bonded channel/RTD wafer stack.glass manifold and spacer were separately cleaned in a UV-ozone cleaner (Jelight Co. Inc., Irvine, CA) and then irreversibly bonded at room temperature for 2 h."
    http://www.cchem.berkeley.edu/ramgrp/alpha/people/nick/Pathogen%20Anal%20Chem%202004.pdf
    http://www.ocf.berkeley.edu/~wgrover/monolithic_membrane_valves_and_diaphragm_pumps.pdf
    http://www.escholarship.org/uc/item/4cj37381

NEXTERION® Glass B (BOROFLOAT® 33) is produced by the microfloat process, resulting in a "fire-polished" upper surface, and a lower surface that has been in contact with molten tin. Is it possible to tell the difference between the two surfaces?

How to find tin side of Nexterion® glass slides






Yes, as all the slides are kept in the same orientation throughout processing and packing. The top (fire polished) side of the NEXTERION® Glass B slides packed in a 25-slide box is indicated in this photograph

Does SCHOTT offer alternative glass types for biological applications?

Yes, SCHOTT has a variety of different glasses (e.g. with higher refractive indexes) that might be suitable for specific biological applications. Please enquire!

What is the difference between the three levels of cleanliness of the SCHOTT NEXTERION® uncoated slides?

Please click here for an overview on the levels of cleanliness.

Uncleaned:
These slides are cleaned using deionised water and a conventional washing machine with brushes.
SCHOTT recommends uncleaned slides if the user intends to subject the slides to a thorough cleaning procedure prior the further processing.

Ultrasonically cleaned:
SCHOTT offers as standard uncoated slides that are ultrasonically cleaned. These slides are cleaned ultrasonically under alkaline conditions to remove all particles, debris, and surface contaminants. The slides are also subjected to a 100% QC process (the same standard process used for NEXTERION® coated slides) to validate dimensional tolerances and ensure a particle-free surface on every slide produced.
SCHOTT recommends ultrasonically cleaned slides if a basic cleaning procedure is used prior the further processing.

Cleanroom cleaned:
SCHOTT’s highest grade of uncoated slide is cleaned ultrasonically and quality controlled, as detailed in the Ultrasonically cleaned section above. In addition, the slide storage boxes used to transport the slides are sealed in protective foil pouches under inert atmosphere in a class 100 cleanroom environment. The slides can be used immediately from the sealed boxes without subjecting them to a cleaning process.
Cleanroom cleaned slides are recommended if users intend to coat the slides without carrying out any cleaning steps.


Can you certify that NEXTERION® Glass B / BOROFLOAT® 33 does not contain any toxic heavy metals?

Yes, we can certiy that NEXTERION® Glass B / BOROFLOAT® 33 is free of any toxic heavy metals, such as Lead, Cadmium, Mercury or Hexavalent Chromium.
Download manufacturer's declaration to that effect.


We are using NEXTERION® Glass B / BOROFLOAT® 33 in a diagnostic product / medical device. Can you certify that the glass does not contain any animal derived material?

NEXTERION® Glass B / BOROFLOAT® 33 is manufactured from inorganic materials, and does not contain any raw materials produced from or substances derived of animal origin. Moreover these products are not derived from specific-risk materials as defined in European Commission Decision 97/534/EC. Due to the high temperature processing, the glass is free from Transmissible Spongiform Encephalopathy (TSE) and Bovine Spongiform Encephalopathy (BSE).
Download the http://www.schott.com/d/nexterion/d73f2694-26d0-4d17-b352-dd6d2cf5d0d0/usp_32_ph_eur_6_0.pdf to that effect.

What barcode options can SCHOTT offer?

The standard barcode is a special laser bonded foil barcode, but also a label barcode is available. The barcodes are fully compatible with commercial automated hybridization stations, and are robust enough to withstand standard hybridization and washing procedures. The barcodes conform to Code 128, and are readable with all commonly available microarray scanners and hand-held barcode readers.
In addition SCHOTT can offer customers the opportunity to customise their slides and glass substrates with graphics, logos, company names, barcodes, reference marks, or 2-D matrix codes. These markings may be added at any location on, or within the glass surface, and may feature a combination of items, for example a company logo with a sequential barcode. Please contact us to discuss your requirements.
Different logos and barcodes at SCHOTT Nexterion glass substrates
Different barcodes and logos at NEXTERION® glass substrates

Can SCHOTT Microarray Solutions offer custom logos?

Yes, SCHOTT can offer customers the opportunity to customise their slides and glass substrates with graphics, logos, company names, barcodes, reference marks, or 2-D matrix codes.
Please look at the section above.

How are the NEXTERION® microarray subtrates packaged?

The NEXTERION® substrates are packed in 5, 25 or 30-slide containers. The boxes are made of a specially developed plastic material to minimise out-gassing, and maintain the slide properties.
NEXTERION® coated slides and cleanroom cleaned uncoated substrates are additional sealed in tough protective laminated foil pouches under an inert atmosphere.
The specially developed packaging protects the slides from damage due to breakage and external contamination. It also offers protection from the adverse effects of light and humidity during transportation and long-term storage.
Packaging of Nexterion Glass Substrates, Plastic Boxes
Packaging of NEXTERION® Glass Substrates / Plastic Boxes
Package of Nexterion coated Slides/Foil Pouch
Packaging of NEXTERION® Glass Substrates / Foil Pouch

How firmly are the SCHOTT NEXTERION® coatings attached to the glass?

The NEXTERION® silane coatings are generally resistant to most aqueous buffer systems, and many organic solvents, (such as DMSO, alcohols like iso-propanol, ethanol, methanol, and ketones like acetone or toluene), but obviously SCHOTT has not been able to test all possible solvents. The NEXTERION® silane coatings will remain attached to the glass in solutions with pHs of between 2 and 10. Delamination of the silane coating is only observed after a prolonged treatment under highly alkaline conditions (over pH 11). SCHOTT coatings remain stable under a large range of temperature as well: For the slide E, AL, A+ and AStar coatings - temperatures of -20°C up to 100°C will not affect the coating. However, please note that these statements refer to the silane bonds to the glass surface. The active groups of the coatings may well be adversely affected by some of these treatments.

What is the density of functional groups on the slide surface?

The density of functional groups has been measured experimentally by two independent methods, fluorescence and UV Vis based for slide A+, E and AL. Typical values are shown in the table below.
Coating Dye Used FLOSS Result
molecules/cm2
UV-Vis Result
molecules/cm2
A+
Aminosilane
L1908
(Sulfonyl Chloride)
(1.0 +/- 0.3)
x1012
Below detection limit
<8.4 x 1011
E
Epoxysilane
D2371
(-NH2 modified)
(5.6 +/- 0.3)
x1012
3.7 x1012
AL
Aldehydesilane
D2371
(-NH2 modified)
(4.8 +/- 0.3)
x1012
2.7 x1012
For additional information, please consult this publication:

Yangjun Xing, and Eric Borguet
Specificity and Sensitivity of Fluorescence Labeling of Surface Species
Langmuir, 2007, 23 (2), 684-688
DOI: 10.1021/la060994s

http://www.temple.edu/borguet/Publication/Documents/pdf_files/2007-2.pdf

What factors should be considered when selecting dyes?

Dyes can be purchased from Molecular Probes, Inc., (Alexa), Atto Tec, Siegen, Germany (ATTO 550 and ATTO 647) or Amersham (Cy 3 and Cy 5). Dyes of course differentiate in their quantum efficiency, stability against oxidation and bleaching, reactivity and quality. Ideally one will use dyes that have a comparable signal yield for two colour experiments. We personally have good experiences with ATTO dyes in this regard.
Crucial for the quality in labeling experiments is the purity and the activation degree (NHS-ester) of the dyes. Both factors influence the background and signal intensity. Important is to store the dyes in water free solvents. Amino groups are far more reactive with the NHS ester than water (more than 1000fold). That’s why the labeling can be done in buffered solutions.

How can I increase the cDNA labeling efficiency when using the aminoallyl-method?

For most applications the optimal labeling level is about one dye molecule per 12 to 18. If the dye/base ratio is higher, hybridization efficiency may drop (due to steric hindrance by the dyes) and dye to dye fluorescence quenching may occur. The labeling efficiency is influenced by the reaction time/temperature, dye concentration, template purity, template concentration, type of dye etc. Free amines like Tris-buffer, ammonium acetate, hydroxylamine or proteins will interfere with the dye coupling and should be avoided. Make sure the pH (7,5-9) to guarantee optimal reactivity. Additionally, succinimidyl ester dyes hydrolyze spontaneously in the presence of moisture. It is important to keep the dyes anhydrous and dissolve it only in an anhydrous solvent (usually DMSO). Protect dyes from light (cover tubes with aluminum foil) and oxidation.

What is the optimal labeling ratio for proteins?

The optimal labeling ratio for proteins depends on the stability, size and activity of the related protein. The ratio is normally between 1 – 5 dyes per molecule.

What factors affect Cy3/Cy5 relation?

You should not expect a constant Cy3/Cy5 ratio over a wide signal range. The Cy3 and Cy5 dyes have different molar extinction coefficients and quantum efficiencies. Fluorescence intensities of the concentration of spots from each tend to produce a sigmoidal shaped curve. However, the sigmoidal shape is not identical for each dye and is more importantly influenced by environmental factors as - pH, oxygen content, temperature, buffer strength, quenching, solvatization, etc. If any of these variables change, the intensity of fluorescence changes differently for the two complexes. Therefore it is essential to keep the same conditions for each experiment.
Additionally the reactivity from boths dyes to DNA is differently. The AT content has been shown to affect uptake rate differently between Cy3 and Cy5. Moreover, some scanners (e.g. Tecan LS400) have different laser powers for the red and green channel.

What is the refractive index of the glass used to manufacture the NEXTERION® Glass B slides?

The NEXTERION® Glass B slides are manufactured from 1.0 mm thick BOROFLOAT 33. The refractive indices at the standard measurement wavelengths are as follows:
Measured at air pressure: 1013.25 hPa / temperature: 22.0 °C

What is the refractive index of the glass used to manufacture the NEXTERION® Glass D slides?

The NEXTERION® Glass D slides are manufactured from 1.0 mm thick D263. The refractive indices at the standard measurement wavelengths are as follows:
Spectral line Measurement wavelength (nm) Refractive index
g line 435.8 1.5354
n F´ 479.9 1.5305
F line 486.1 1.5300
e line 546.1 1.5255 ± 0.0015
e line 587.6 1.5231
n D 589.3 1.5230
n C´ 643.9 1.5209
C line 656.3 1.5204
Measured at air pressure: 1013.25 hPa / temperature: 22.0 °C


What is the transmission / absorbance spectrum of Glass B (BOROFLOAT® 33)?

The actual transmission / absorbance spectrum is partly dependant on glass thickness.
SCHOTT has measured the transmission / absorbance of 1.1 - 25.4 mm BOROFLOAT® 33 for wavelengths from 200 to 6000 nm. The results are available in the following download:

Will the NEXTERION® slides fit into standard microarray equipment?

Yes. The outer dimensions (75.6 mm x 25.0 mm x 1.0 mm) of the standard NEXTERION® slides will fit all commercially available microarray equipment. There is no need for special settings during the printing and scanning process.

Which excitation and emission wavelengths has the Glass B and D been tested with for auto-fluorescence?

The glass slides have been tested by SCHOTT at the Cy3 (excitation 555 nm, emission 570 nm) and Cy5 (excitation 649 nm, emission 670 nm) wavelengths.

The autofluorescence of Glass B (Borofloat 33) has also been tested by the Department of Chemistry, at University of Cincinnati:

Lab Chip, 2005, 5, 1348 - 1354,
DOI: 10.1039/b508288a
The autofluorescence of plastic materials and chips measured under laser irradiation
Aigars Piruska, Irena Nikcevic, Se Hwan Lee, Chong Ahn, William R. Heineman, Patrick A. Limbach and Carl J. Seliskar

http://www.rsc.org/publishing/journals/LC/article.asp?doi=b508288a

http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b508288a&JournalCode=LC

What is the shelf life of the NEXTERION® coated and uncoated slides? What are the recommended storage conditions for the slides?

Here are the shelf lives of the NEXTERION® products when stored in the original packaging under the recommended conditions.

Coated substrates
  • NEXTERION® Slide A and other aminosilane coated substrates 12 months
    (Store at 20 to 25°C)
  • NEXTERION® Slide AStar and other aminosilane coated substrates 12 months
    (Store at 20 to 25°C)
  • NEXTERION® Slide A+ and other aminosilane coated substrates 6 months
    (Store at 20 to 25°C)
  • NEXTERION® Slide AL and other aldehydesilane coated substrates 9 months
    (Store at 20 to 25°C)
  • NEXTERION® Slide E and other epoxysilane coated substrates 12 months
    (Store at 20 to 25ºC)
  • NEXTERION® Slide H and other H-coated substrates 12 months
    (Store frozen at -20°C)
  • NEXTERION® Slide P and other P-coated substrates 12 months
    (Store frozen at -20°C)
  • NEXTERION® Slide NC-C/N and other nitrocellulose coated substrates 12 months
    (Store at 20 to 25°C)
Uncoated slides
  • NEXTERION® Glass B (clean room cleaned) 24 months (Store at 20 to 25°C)
  • NEXTERION® Glass D (clean room cleaned) 24 months (Store at 20 to 25°C)

Will you fax or e-mail me an article from your bibliography?

We may be able to provide you with some publications, however, certain copyright restrictions may prevent us from doing so. Please contact us at "coatedsubstrates@schott.com" for further information.