As filed with the Securities and Exchange Commission on June 30, 2016

Registration No. 333-207461

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1 TO FORM S-3 REGISTRATION STATEMENT NO. 333-207461

UNDER THE SECURITIES ACT OF 1933

NANOSPHERE, INC.

(Exact name of registrant as specified in its charter)

Richard W. Rew, II

Vice President and Corporate Secretary

4088 Commercial Avenue

Northbrook, Illinois 60062

(847) 400-9000

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Jonathan M. Minnen, Esq.

M. Timothy Elder, Esq.

Smith, Gambrell & Russell LLP

1230 Peachtree Street NE, Suite 3100

Atlanta, Georgia 30309-3592

404-815-3500

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box. ¨

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities being offered only in connection with dividend or interest reinvestment plans, check the following box. ¨

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ¨

If delivery of the prospectus is expected to be made pursuant to Rule 434, please check the following box. ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See definitions of “large accelerated filer”, “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

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EXPLANATORY NOTE

Deregistration of Securities

This Post-Effective Amendment to the Registration Statement on Form S-3 (No. 333-207461), as amended (the “Registration Statement”), is being filed to remove from registration all unsold securities of Nanosphere, Inc. (the “Company”) registered under the Registration Statement.

On May 15, 2016, the Company, Luminex Corporation, a Delaware corporation (“Luminex”), and Commodore Acquisition, Inc., a Delaware corporation and a wholly-owned subsidiary of Luminex (“Purchaser”), entered into an Agreement and Plan of Merger (the “Agreement”). The Agreement contemplated that Purchaser would be merged with and into the Company (the “Merger”) and that the Company would survive the Merger as a wholly owned subsidiary of Luminex. The Merger became effective on June 30, 2016 (the “Effective Date”) as a result of filing a Certificate of Merger with the Secretary of State of the State of Delaware.

As of the Effective Date, each share of common stock of the Company issued and outstanding immediately prior to the Merger (other than each share owned by the Company’s stockholders who are entitled to and who properly exercised appraisal rights under Section 262 of the Delaware General Corporation Law with respect to such share) was cancelled and converted into the right to receive $1.70 in cash, without interest thereon and less any required withholding taxes.

As a result of the Merger, the Company has terminated all offerings of its securities pursuant to its existing registration statements, including the Registration Statement. In accordance with an undertaking made by the Company in the Registration Statement to remove from registration by means of a post–effective amendment any securities registered under the Registration Statement which remain unsold at the termination of the offering, the Company hereby removes from registration any securities registered under the Registration Statement which remained unsold as of the Effective Date.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant certifies that it has reasonable grounds to believe that it meets all the requirements for filing on Form S-3 and has duly caused this Post-Effective Amendment to the Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Austin, State of Texas, on June 30, 2016.

Note: No other person is required to sign this Post-Effective Amendment to the Registration Statement on Form S-3 in reliance upon Rule 478 under the Securities Act of 1933, as amended.

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