THIS
      NOTE HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
      “SECURITIES ACT”), OR THE SECURITIES LAWS OF ANY STATE, AND MAY NOT BE OFFERED
      OR SOLD UNLESS A REGISTRATION STATEMENT UNDER THE SECURITIES ACT AND APPLICABLE
      STATE SECURITIES LAWS SHALL HAVE BECOME EFFECTIVE WITH REGARD THERETO, OR AN
      EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT AND APPLICABLE STATE
      SECURITIES LAWS IS AVAILABLE IN CONNECTION WITH SUCH OFFER OR SALE.


    


    NANOSENSORS,
      INC.

    SENIOR
      PROMISSORY NOTE

    


    
      	
              New
                York, New York 

            	
              $50,000.00

            


    

    Issue
      Date as of: December 5, 2007

    


    FOR
      VALUE RECEIVED, NANOSENSORS, INC., a
      Nevada
      corporation (the
      “Company”),
      hereby unconditionally promises to pay to the order of CUCHULAINN
      HOLDINGS INC.,
      a
      Panamanian corporation having its offices c/o Shirley y Asociados, Edificio
      ADR,
      Piso 13, Avenida Samuel Lewis, Obarrio, Panama City, Republic of Panama, or
      its
      permitted successors or assigns (the “Holder”
or
      “Cuchulainn”),
      the
      principal sum (“Principal”)
      of
FIFTY
      THOUSAND DOLLARS ($50,000.00)
      in the
      lawful money of the United States of America available in immediately available
      funds, on the date and in the amount set forth in this Senior Promissory Note
      (this “Note”),
      provided, however, that the aggregate unpaid Principal balance (the
“Principal
      Balance”)
      of
      this Note shall in all events be due and payable, on May 31, 2007, or, if
      earlier, upon the occurrence of an Event of Default (the “Maturity
      Date”).
      

    


    The
      Company also promises to pay interest (computed on the basis of a 365-day year
      for actual days elapsed) at said office in like money on the unpaid Principal
      amount of this Note from time to time outstanding at a rate of five percent
      (5%)
      per annum simple interest (“Interest”).
      Interest on this Note shall be payable on the Maturity Date, except as provided
      in Section 4(c). 

    


    The
      Company further agrees that upon and following an Event of Default (as defined
      herein) and/or after any stated or any accelerated maturity of the indebtedness
      evidenced hereby, the aggregate Principal Balance of this Note shall bear
      Interest (computed daily) at a rate equal to five percent (5%) per annum in
      excess of the rate then applicable to this Note, payable on demand
      (“Default
      Interest Rate”).
      In no
      event shall Interest payable hereunder be in excess of the maximum rate of
      interest permitted under applicable law. If any payment to be so made hereunder
      becomes due and payable on a day other than a Business Day, such payment shall
      be extended to the next succeeding Business Day, and to the extent permitted
      by
      applicable law, interest thereon shall be payable at the then applicable rate
      during such extension.

    


    All
      payments hereunder shall be made to the Holder unconditionally in full without
      set-off, counterclaim or, to the extent permitted by applicable law, other
      defense, and free and clear of, and without reduction for or on account of,
      any
      present and future taxes or withholdings, and all liabilities with respect
      thereto.

     

    
      
         

      

      
         

        
          

        

      

      
         

      

    

     

    All
      payments shall be made by wire transfer to an account or accounts designated
      by
      Holder which shall provide federal wire transfer instructions to the
      Company.

     

    The
      following additional terms shall apply to this Note:

    


    1. DEFINITIONS.

     

    “Business
      Day”
means
      any
      day
      other than a Saturday, a Sunday or a day on which the New York Stock Exchange
      is
      closed or on which banks are authorized by law to close in New York, New
      York.

    


    “Governmental
      Authority”
means
      any nation or government, any state, provincial or political subdivision thereof
      and any entity exercising executive, legislative, judicial, regulatory or
      administrative functions of or pertaining to government, including without
      limitation any stock exchange, securities market or self-regulatory
      organization.

    


    “Liquidation
      Event”
means
      the (i) institution of any insolvency or bankruptcy proceedings, or any
      receivership, liquidation, reorganization or other similar proceedings in
      connection therewith, relative to the Company,
      or to
      its creditors, as such, or to its assets; or (ii) the liquidation, dissolution
      or other winding up of the Company, whether voluntary (including without
      limitation by a vote or action of the Board of Directors of the Company) or
      involuntary and whether or not involving insolvency or bankruptcy proceedings;
      (iii) any assignment for the benefit of creditors or any marshalling of the
      material assets or material liabilities of the Company;
      (iv)
      the admission, in writing, by the Company of its inability to pay its debts
      as
      such debts become due or the failure of the Company generally to pay its debts
      as they come due; or (v) the Company fails to pay the Principal or Interest
      or
      any other amounts payable under this Note when the same becomes due and
      payable.

    


    “Merger
      Agreement”
means
      the Agreement and Plan of Merger entered into as of November 27, 2007, by and
      among the Company, Cuchulainn Acquisition Inc., a Panamanian corporation and
      a
      wholly-owned subsidiary of the Company, and Cuchulainn.

    


    “Person”
means
      any individual, corporation, trust, association, company, partnership, joint
      venture, limited liability company, joint stock company, Governmental Authority
      or other entity. 

    


    All
      definitions contained in this Note are equally applicable to the singular and
      plural forms of the terms defined. The words “hereof”, “herein” and “hereunder”
and words of similar import referring to this Note refer to this Note as a
      whole
      and not to any particular provision of this Note. 

    


    2. INTEREST.
       

     

    (a) The
      Holder shall be entitled to receive Interest in cash at the annual rate of
      5.0%
      simple interest per annum payable on the Maturity Date. 

    


    (b) All
      payments made by the Company on this Note shall be applied first to the payment
      of accrued and unpaid Interest on this Note and then to the reduction of the
      unpaid Principal amount of this Note. Payments of Principal and Interest shall
      be deemed made on the date such payment is received in an account or accounts
      designated by the Holder. 

     

    
      
         

      

      
        2

        
          

        

      

      
         

      

    

     

    (c) In
      the
      event that the date for the payment of any amount payable under this Note falls
      due on a Saturday, Sunday or public holiday under the laws of the State of
      New
      York, the time for payment of such amount shall be extended to the next
      succeeding Business Day and Interest shall continue to accrue on any Principal
      amount so effected until the payment thereof on such extended due
      date.

     

    3. PREPAYMENT.
      

    


    The
      Company may prepay the Principal Balance of this Note, in whole or in part,
      at
      any time, without discount or penalty, provided that each such prepayment shall
      be accompanied by Interest accrued or the amount prepaid to and including the
      date of prepayment.

     

    4.
       EVENTS
      OF DEFAULT.

     

    (a) Events
      of Default.
      Each of
      the following events shall be deemed an “Event
      of Default”:
      

     

    (i)  The
      failure of Company to pay Principal, Interest or any other amount payable
      hereunder within five (5) days after such amount becomes due
      hereunder;

     

    (ii)  A
      Liquidation Event occurs or is publicly announced;

     

    (iii)  The
      termination of the Merger Agreement for any reason; or

     

    (iv)  The
      failure of the “Closing,” as that term is defined in the Merger Agreement, by
      January 10, 2008.

     

    (b) If
      any
      Event of Default shall occur, the Holder may, by notice to the Company, declare
      the entire unpaid Principal Balance and unpaid accrued Interest in respect
      thereof of this Note, and all other amounts payable hereunder, to be forthwith
      due and payable, whereupon all unpaid Principal Balance and unpaid accrued
      Interest under this Note and all such other amounts shall become and be
      forthwith due and payable, without presentment, demand, protest or further
      notice of any kind, all of which are hereby expressly waived by the Company,
      provided that if a Liquidation Event shall occur, this Note shall automatically
      become immediately due and payable without presentment, demand, protest or
      further notice of any kind, all of which are expressly waived by the
      Company.

     

    (c) Upon
      the
      occurrence and during the continuation of an Event of Default, interest shall
      accrue on the outstanding Principal Balance of this Note at the Default Interest
      Rate until such amount is paid in full. Any interest that accrues at the Default
      Interest Rate shall be due and payable on the last day of each calendar month
      (through and including the date of payment). 

     

    (d) The
      remedies of the Holder in this Note or at law or in equity, shall be cumulative
      and concurrent, and may be pursued singly, successively or together in the
      Holder’s discretion. The Company agrees to pay all reasonable costs of
      collection with respect to amounts owing under this Note, including, without
      limitation, reasonable attorneys’ fees and disbursements of the
      Holder.

     

    
      
         

      

      
        3

        
          

        

      

      
         

      

    

     

    5. SENIORITY.

     

    This
      Note
      shall be senior in priority to the general obligations of the Company.


     

    6. MISCELLANEOUS.

     

    (a) Failure
      to Exercise Rights not Waiver.
      No
      failure or delay on the part of the Holder in the exercise of any power, right
      or privilege hereunder shall operate as a waiver thereof, nor shall any single
      or partial exercise of any such power, right or privilege preclude any other
      or
      further exercise thereof. All rights and remedies of the Holder hereunder are
      cumulative and not exclusive of any rights or remedies otherwise
      available.

     

    (b) Notices.
      Any
      notice, demand or request required or permitted to be given by the Company
      or
      the Holder pursuant to the terms of this Note shall be in writing and shall
      be
      deemed delivered (i) when delivered personally or by verifiable facsimile
      transmission, unless such delivery is made on a day that is not a Business
      Day,
      in which case such delivery will be deemed to be made on the next succeeding
      Business Day, (ii) on the next Business Day after delivery to an overnight
      courier and (iii) on
      the
      Business Day actually received if deposited
      in the U.S. mail (certified or registered mail, return receipt requested,
      postage prepaid), addressed as follows: 

    

      
        	 	
                If
                  to the Holder:

              	
                With
                  a copy to:

              
	 	 	 
	 	
                Cuchulainn
                  Holdings Inc.

              	
                Barry
                  Miller, Esq.

              
	 	
                c/o
                  Shirley y Asociados

              	
                Casa
                  9, Calle Brisa Allegre , Villa Zaita

              
	 	
                Edificio
                  ADR, Piso 13

              	
                Las
                  Cumbres, Republic of Panama

              
	 	
                Avenida
                  Samuel Lewis, Obarrio

              	 
	 	
                Panama
                  City, Republic of Panama

              	 
	 	
                T:
                  +507.269.2255

              	
                T:
                  + 248.232.8039

              
	 	
                F:
                  +507.269.1552

              	
                F:
                  +248.479.5395

              
	 	 	 
	 	
                If
                  to the Company:

              	
                With
                  a
                  copy
                  to: 

              
	 	 	 
	 	
                NanoSensors,
                  Inc.

              	
                Becker
                  & Poliakoff, LLP

              
	 	
                Attn:
                  Josh Moser

              	
                Attn:
                  Victor J. DiGioia, Esq.

              
	 	
                1475
                  Veterans Blvd.

              	
                45
                  Broadway, 11th
                  Floor

              
	 	
                Redwood
                  City, CA 94063

              	
                New
                  York, NY 10006

              
	 	
                P:
                  408.306.5956

              	
                P:
                  212.599.3322

              
	 	
                F:
                  650.618.1483

              	
                F:
                  212.557.0295

              


      

    

    


    Either
      party may from time to time designate by notice delivered in accordance with
      this Section
      6(b),
      specify
      a different address for notices, demands and requests hereunder.

     

    
      
         

      

      
        4

        
          

        

      

      
         

      

    

     

    (c)
       Amendments.
      No
      amendment, modification or other change to, or waiver of any provision of,
      this
      Note may be made unless such amendment, modification or change is set forth
      in
      writing and is signed by the Company and the Holder. 

     

    (d)
       Transfer
      of Note.
      The
      Holder may sell, transfer or otherwise dispose of all or any part of this Note
      (including without limitation pursuant to a pledge) to any person or entity
      as
      long as such sale, transfer or disposition is the subject of an effective
      registration statement under the Securities Act of 1933, as amended, and
      applicable state securities laws, or is exempt from registration thereunder.
      From and after the date of any such sale, transfer or disposition, the
      transferee hereof shall be deemed to be the holder of a Note in the Principal
      amount acquired by such transferee, and the Company shall, as promptly as
      practicable, issue and deliver to such transferee a new note identical in all
      respects to this Note, in the name of such transferee. The Company shall be
      entitled to treat the original Holder as the holder of this entire Note unless
      and until it receives written notice of the sale, transfer or disposition
      hereof.

     

    (e)
       Lost
      or Stolen Note.
      Upon
      receipt by the Company of evidence of the loss, theft, destruction or mutilation
      of this Note, and (in the case of loss, theft or destruction) of indemnity
      or
      security reasonably satisfactory to the Company, and upon surrender and
      cancellation of the Note, if mutilated, the Company shall execute and deliver
      to
      the Holder a new Note identical in all respects to this Note.

     

    (f)
       Governing
      Law; Waiver of Jury Trial.
      This
      Note shall be governed by and construed in accordance with the laws of the
      State
      of New York applicable
      to contracts made and to be performed entirely within the State of New York,
      without regard to conflicts of law principles that would require the application
      of the laws of another jurisdiction. The Company agrees that any suit for the
      enforcement of this Note may be brought in the courts of New York sitting in
      New
      York County or any Federal court sitting therein and consents to the
      nonexclusive jurisdiction of such court and service of process in any such
      suit
      being made upon the Company by mail at the address set forth in the first
      paragraph of this Note. The Company hereby waives any objection that it may
      now
      or hereafter have to the venue of any such suit or any such court or that such
      suit is brought in an inconvenient forum.WAIVER
      OF JURY TRIAL. EACH OF THE PARTIES WAIVES THE RIGHT TO A JURY IN ANY TRIAL
      OF
      ANY CASE OR CONTROVERSY WHICH CASE OR CONTROVERSY ARISES OUT OF OR IS IN RESPECT
      OF ANY DEALINGS AMONG THEM OR ANY ONE OF THEM RELATING TO THE SUBJECT MATTER
      OF
      THIS NOTE.

     

    (g) Successors
      and Assigns.
      The
      terms and conditions of this Note shall inure to the benefit of and be binding
      upon the respective successors (whether by merger or otherwise) and permitted
      assigns of the Company and the Holder. The Company may not assign its rights
      or
      obligations under this Note except as specifically required or permitted
      pursuant to the terms hereof.

    


    (h) Usury.
      This
      Note
      is subject to the express condition that at no time shall the Company be
      obligated or required to pay interest hereunder at a rate which could subject
      the Holder to either civil or criminal liability as a result of being in excess
      of the maximum interest rate which the Company is permitted by applicable law
      to
      contract or agree to pay.  If by the terms of this Note, the Company is at
      any time required or obligated to pay interest hereunder at a rate in excess
      of
      such maximum rate, the rate of interest under this Note shall be deemed to
      be
      immediately reduced to such maximum rate and the interest payable shall be
      computed at such maximum rate and all prior interest payments in excess of
      such
      maximum rate shall be applied and shall be deemed to have been payments in
      reduction of the principal balance of this Note.

     

    
      
         

      

      
        5

        
          

        

      

      
         

      

    

     

     
      

    IN
      WITNESS WHEREOF,
      the
      Company has caused this Note to be signed in its name by its duly authorized
      officer on the date first above written.

    


    NANOSENSORS,
      INC. 

    


    


    By:           
      /s/ Robert
      Baron                                                   


    Name:
      Robert Baron 

    Title:
      Interim Chief Executive Officer

    


    


    
      
         

      

      
        6