Tuesday, July 14, 2020

Laysan is pronounced, "LI-"sän" and it is an albatross that is found in the islands of the Pacific Ocean. It is a large, rare bird that is known to be graceful and impressive in flight.

Our Mission
We are dedicated to building a long term relationship with our customers by offering quality PEG reagents backed up with exceptional customer service and technical support.

Frequently Asked Questions

I have a question about one of your products, who do I contact?

For a question regarding an order or how to place an order, contact us at sales@laysanbio.com.  If you have a technical question about one of our reagents, please contact us at tech@laysanbio.com.  You can also reach one of our customer service representatives by phone at 888-852-9726 or 256-586-9004.

How do I place an order?

You can place an order on our products page at www.laysanbio.com/products or by clicking on the products link in the menu.  You can also fax your order to us at 256-586-9007 or email orders to sales@laysanbio.com.  You can use our order form or send us the following information...billing address, shipping address, delivery telephone number, e-mail address, item information, and a P.O. number or credit card information.  We accept VISA, MasterCard and American Express.  Please contact us at sales@laysanbio.com or at 888-852-9726 or 256-586-9004 with any questions. Laysan accepts and ships orders for national and international customers.  Laysan does not charge tax to any of our customers.

What are the storage conditions for the products?

Because PEG reagents are temperature, light, and moisture sensitive they should be stored in a -15C freezer upon receipt. Please allow PEG reagents to equal room temperature prior to opening. We recommend storing our PEG reagents as the dry, powder form only and not in any type of solution.  Each time the bottle is opened it will need to be backfilled with an inert gas (i.e. Argon, Nitrogen) before it is stored again.

If your reagent requires rebottling please follow these steps:
Allow reagent to equilibrate to room temperature
While reagent is thawing prepare glove box or another suitable area for packaging which will allow for an inert atmosphere
Flush the repackaging enclosure with an inert gas (i.e. Argon, Nitrogen)
Repackage into desire aliquots
Flush each aliquot with inert gas before closing
Store each aliquot at or below -15C until ready to use
Please note that acrylate products are light sensitive and need to keep light exposure to a minimum.

How do you ship your reagents?

We ship all of our reagents at room temperature for overnight delivery in the United States and Priority International for international orders, most international shipments arrive within 3-4 days. You will receive an email with tracking number so you can track your shipment.

Do you offer compliant (cGMP) manufacturing?

Laysan Bio has established our Quality System and is manufacturing cGMP compliant “Bulk Pharmaceutical Chemical” reagents.  We welcome all discussions regarding this service and will work with you to help our products fit your project requirements.  Call today to request a quotation or to schedule a conference call.

Do I need compliant (cGMP) products or catalog (research-grade) products?

Click here to read more about the differences between compliant and catalog grade products.

Do you offer consulting services?

Laysan now offers consulting services for your current and future PEG programs.  Laysan has extensive experience in this area and welcomes all discussions. Call today to discuss how this valuable technology can help your program progress.

How do I get the structures for your products?

If there is not a structure posted for the reagent you are interested in, please contact us at sales@laysanbio.com for structure information.

How do I get an MSDS or SDS?

These documents will be sent with your shipment.  If you need one beforehand you can find them on our MSDS Documents page or SDS Documents page.  If you do not find the one that you need, please contact us at sales@laysanbio.com to request these documents.

What is the difference between your ester reagents, SC and SCM?


Hydrolysis half-life is 0.75(minutes) at pH8, 25°C
Amide linkage
Faster conversion
Good conversion in organic; not good in aqueous 

Hydrolysis half-life is 20.4(minutes) at pH8, 25°C 

Urethane or Carbamate linkage 
Longer reaction time 
Slower hydrolysis 

Good in organic; also works in aqueous

Do you have more information on your SVA reagents?

Click here to download more information regarding our popular SVA reagents.

What is the half-life information for your ester reagents?

Click here to download information regarding the half-lives of our esters.

Which reagents are Amine reactive and what is the difference between them?

The end groups that are reactive with are listed below and they are in two different categories, permanent linkage and degradable linkage

How do I deprotect the BOC and FMOC reagents?

Protocol to Deprotect BOC
Standard BOC Amino Acid Deprotection
50% (v/v) TFA/DCM; 50 minutes at room temperature
Follow with washings with 5% (v/v) DIPEA/DCM to remove TFA

Protocol to Deprotect FMOC
Standard FMOC Amino Acid Deprotection
Place the FMOC protected product in a round bottom flask and add 20% (v/v) piperdine in DMF(approximately 10ml/gm resin)
Shake the mixture at room temperature for 30 minutes
Filter the FMOC protected product and wash it with several portions of DMF

What is PEG's solubility?

PEG in all molecular weights are soluble at concentrations less than a 50:50 w/w concentration in water and other solvents.
PEGs are readily soluble in dichloromethane, chloroform, acetonitrile and water at room temperature.
PEGs require heat to be soluble in toluene, methanol, ethanol, and isopropanol.
PEGs are not soluble in ethers, ethylene glycol, hexane, and are not soluble in most alcohols at room temperature.
If you need an organic solvent, dichloromethane and acetonitrile are two good choices.

What is the difference between Butyraldehyde and Propionaldehyde?

The propionaldehyde is a little more reactive than the butyraldehyde so the reaction with the butyraldehyde should be allowed to mix about 2 hours longer.

Both propionaldehyde and butyraldehyde will form a secondary amine when reacted and will work in the same solutions. The butyraldehyde has one more methylene between the PEG and Aldehyde functionality that the propionaldehyde.

The Maldi spectrum  of PEG-DSPE product shows PEG without DSPE peak as a major peak. Is this evidence that DSPE is not connected to the PEG in the product?

The DSPE part cleaves easily even with mild ionization techniques. It is common to see the PEG fragment as a major peak in the spectrum. This is not evidence that the DSPE is not connected to the PEG in the product. Connectivity is proven by NMR.

Determining Molecular Weight for Phospholipid Products

Laysan reports a theoretical Molecular Weight for phospholipid products. The Theoretical Molecular Weight is determined by adding the known molecular weight of the PEG plus the weight of the phospholipid. Laysan determines the Mn on the starting PEG by NMR, which is reported on the CoA, then the MW of the end groups are added which gives the Theoretical Molecular Weight. Phospholipids are harmful to the GFC columns therefore Laysan does not run GFC on any of our phospholipid products and MALDI can cleave the fatty esters from the phospholipid due to the ionization strength of the method, therefore resulting in a lower molecular weight.

How do I calculate density of PEG reagents?

This is only accurate for molecular weights below 1,000.  Take syringe and draw up 1ml then weigh product.  Density = Mass over Volume.

What is the physical distance within the PEG?

C-C is 154 pm (0.154 nm)
C-O is 143 pm (0.143 nm)

Which PEG should I use?

Reagent selection, linkage and stability (under physiological conditions) for PEGylation.

Carboxyl PEGylation (Nucleophilic PEGs)                                   Linkage Formation
MPEG-AMINE and a coupling agent                                            Amide (stable)
MPEG-ALCOHOL and a coupling agent                                      Ester (subject to hydrolysis)

Amine PEGylation (Electrophilic PEGs)
MPEG-Ester                                                                                  Amide (stable)
MPEG-Carbonate                                                                          Urethane (stable)
MPEG-Aldehyde and a reducing agent                                         Secondary amine (stable)
MPEG-Aldehyde acetal and a reducing agent                              Seoncary amine

Thiol Reagent PEGylation
MPEG-MALEIMIDE                                                                    Sulfide (stable)
MPEG-THIOL                                                                               Disulfide (can be reduced)

Protein PEGylation reaction conditions vary depending on the protein, the desired degree of PEGylation, and the PEG reagent.  Factors to consider in the choice of a PEG reagent are: (1) the desired point of attachment (amine, thiol, carboxyl, etc.)
(2) hydrolytic stability, activity, pharmacokinetics, PEG-isomers, and immunogenicity of the derivative
(3) suitability for analysis.

Additional Information can be obtained from the following source:

General Discussions: (a) "Poly(Ethylene Glycol) Chemistry:  Biotechnical and Biomedical Applications", J.M. Harris, Ed., Plenum, NY, 1992, Chap. and (b) "Poly(ethylene glycol) Chemistry and Biological Applications", J.M. Harris and S. Zalipsky, Ed., ACS Symposium Series 680, 1997.

How can free PEG be detected?

Free PEG can be detected by SDS-PAGE using barium iodide stain.

Manfred M. KurfUrst, Analytical Biochemistry 200, 244-248 (1992).

This paper gives the recipe for the stain.  The stain can be washed out with water and then the protein stained with Coomassie Blue.

Free PEG can also be detected by SEC HPLC using an RI detector.

What are the disadvantages to the PEG-Aldehydes?  What is the advantage to the ButyrALD?

Propionaldehyde PEG reagents involve coupling challenges to proteins due to formation of undesirable side-products necessitating extensive purification to obtain pharmaceutical grade product.

ButyrALD overcomes these challenges by being more selective and stable during coupling to biological agents.  ButyrALD's increased selectivity allows preferential coupling with specific amino groups; and in particular, may lead to a greater selectivity for N-terminal amino groups on proteins and peptides.

Regarding Polydispersity (molecular weight distribution)

NOTE: All of our PEGs have a polydispersity of less than 1.07.
All of our PEG's have some variance in the number of ethylene oxide units.....this is a result of anionic polymerization.  Polydispersity (PDI) is a ratio that represents the broadness of a molecular weight distribution.  PDI is the ratio of the number average molecular weight (Mn) to the weight distribution.  PDI is the ratio of the number average molecular weight (Mn) to the weight average molecular weight (Mw) (PDI = Mw/Mn).  If the PDI is equal to 1, then Mn equals Mw and the polymer is said to be monodisperse.  In real life, polymers are not truly monodisperse (accept for natural proteins), although PEGs made anionically do have a low PDI (1.01 - 1.05).  As Mn changes with Mw, the PDI changes (It will always be greater than 1).

What are the conditions for covalently linking PEG to a silicon dioxide or quartz glass surface?

Possible candidates should have an electrophilic group (like aldehydes, active carbonates, etc.) for the surface coating of quartz and modified-quartz.  A useful reference would be Chapter 24 in the ACS Symposium Series 680 book "Poly(ethylene glycol) Chemistry and Biological Applications" edited by J. Milton Harris and S. Zalipsky.  Pages 390 and 391 (“Effect of PEG Functional Group and MW on PEG-modified Quartz”) might be more specific to the your needs.


The process of pegylation of silicon/glass surfaces with mPEG-silane can be, for example (reference:  Desai et al, Business Briefing: Medical Device Manufacturing and Technology, 2002), conducted as follows.  The silicon/glass surfaces are first cleaned by treatment with 1:1:5 ratio of 25% ammonia, 30% hydrogen peroxide, and deionized water for 15 minutes at 80 Celsius.  This is followed by treatment with 1:1:6 ratio of 50% hydrogen chloride, 30% hydrogen peroxide, and deionized water for 15 minutes at 80 Celsius.  The surfaces are then rinsed with distilled water and dried with nitrogen gas.  Alternatively, surfaces can be cleaned with acetone and isopropanol for 5 min each, then activated in concentrated HNO3 for 3 min followed by extensive rinsing with water (Biomaterials, 23(2002):893-900). The surface modification with mPEG-silane can be carried out by immersing the surface in freshly prepared solution of 2 mg/mL of mPEG-silane for 1 hour, followed by rinsing with corresponding solvent and drying with nitrogen gas.

Protocol for attaching PEG to a glass surface:
Nature, Vol 419 (October 10, 2002), page 638.

Protocol for Coating Gold Surfaces?

A useful reference would be Chapter 23 in the ACS Symposium Series 680 book, "Poly(ethylene) glycol Chemistry and Biological Applications" edited by J. Milton Harris and S. Zalipsky.  ("Using Self-Assembled Monolayers that Present Oligo(ethylene glycol) Groups to Control the Interactions of Proteins with Surfaces").

Protocol for General Coating

A useful reference would be Chapter 24 in the ACS Symposium Series 680 book, "Poly(ethylene glycol) Chemistry and Biological Applications" edited by J. Milton Harris and S. Zalipsky ("Electrokinetic Analysis of Poly(ethylene glycol) Coating Chemistry").

What are the Sulfhydrl (SH) selective PEG reagents?


These reagents have both been utilized for coupling to the free sulfhydryl group of cysteines present in proteins.

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