Exhibit 4.27

FOURTH AMENDMENT TO PROMISSORY NOTE

ISSUED FEBRUARY 19, 2009

THIS AMENDMENT (the Amendment) is made as of the 28th day of February, 2011 (the Effective Date), by and
between RBC Capital Markets Corporation Custodian for Leonard Samuels IRA,a Minnesota corporation, with an address of 510 Marquette Avenue, M09-Alternative Investments, Minneapolis, MN 55402RBC (Holder) and Dais Analytic
Corporation having an office at 11552 Prosperous Drive, Odessa, Florida 33556 (Maker). (Each individually referred to herein as Party and together as Parties).

WITNESSETH

WHEREAS, on February 19, 2010, Maker issued to Holder an unsecured promissory note in the principal amount of Six Hundred and
Twenty Thousand Dollars ($620,000) (Note); and

WHEREAS, the Parties amended the Note so as to cause the
Maturity Date (as defined in said Note) to be February 28, 2011; and

WHEREAS, the Parties desire to further amend
the Note to cause the Maturity Date to be April 30, 2010; and

NOW, THEREFORE, in consideration of the mutual
premises, representations, warranties, covenants and agreements contained herein, and intending to be legally bound hereby, the Parties hereto agree as follows:



|1. | The following paragraph of the Note, as amended, is hereby deleted in its entirety:
|-- | -----------------------------------------------------------------------------------

All payments under or pursuant to this Note shall be made in United States Dollars in immediately available funds to the Holder at
the address of the Holder first set forth above or at such other place as the Holder may designate from time to time in writing to the Maker or by wire transfer of funds to the Holders account, as requested by the Holder. The outstanding
principal balance of this Note, together with all accrued and unpaid interest, shall be due and payable in full on February 28, 2011 (the Maturity Date) or at such earlier time as provided herein.



|2. | The following provision is hereby inserted in place of the paragraph deleted pursuant to Section 1 of this Amendment:
|-- | ---------------------------------------------------------------------------------------------------------------------

All payments under or pursuant to this Note shall be made in United States Dollars in immediately available funds to the Holder at
the address of the Holder first set forth above or at such other place as the Holder may designate from time to time in writing to the Maker or by wire transfer of funds to the Holders account, as requested by the



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|Page 1 of 2 |  | Fourth Amendment to Promissory Note |  | RBC Capital/Dais
|            |  | Issued 2/19/10                      |  |                 



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Holder. The outstanding principal balance of this Note, together with all accrued and unpaid interest, shall be due and payable in full on April 30, 2011 (the Maturity
Date) or at such earlier time as provided herein.



|3. | Section 2.3 of the Note, as amended, is hereby deleted in its entirety and the following provision shall be inserted in place thereof:
|-- | --------------------------------------------------------------------------------------------------------------------------------------

Section 2.3. Additional Remedy Upon Non-Payment. If this Note is not paid in full on or before April 30, 2011, the
Holder shall be permitted, at its sole option and in addition to its other remedies hereunder, to convert the principal and interest outstanding under this Note into any debt, equity or equity-linked security issued by the Maker in connection with
any capital-raising issuance after the date hereof and prior to the date this Note is paid in full on the terms and conditions of such offering, if any, it being understood that nothing in this Section 2.3 shall be deemed to prohibit the Maker
from prepaying the Note pursuant to Section 1.2 hereof.



|4. | All other terms and conditions of the Note shall remain unchanged and in full force and effect.
|-- | -----------------------------------------------------------------------------------------------

IN WITNESS WHEREOF,the Parties have caused this Amendment to be executed by their duly authorized respective representatives as
of the date first written above.



|                                  |  |                                     
|--------------------------------- |  | ------------------------------------
|DAIS ANALYTIC CORPORATION        
|                                  | 
|By:                               |  | /s/ Timothy N. Tangredi             
|                                  | 
|Name:                             |  | Timothy N. Tangredi                 
|                                  | 
|Title:                            |  | President and Chief Executive Office
|                                 
|RBC CAPITAL MARKETS CORPORATION  
|CUSTODIAN FOR LEONARD SAMUELS IRA
|                                  | 
|By:                               |  | /s/ Lisa Van Zee                    
|                                  | 
|Name:                             |  | Lisa Van Zee                        



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|Page 2 of 2 |  | Fourth Amendment to Promissory Note |  | RBC Capital/Dais
|            |  | Issued 2/19/10                      |  |