Novel gold nanoparticle aggregates and their applications

Abstract

The invention is drawn to a method of using nanoparticle aggregates to form sensors and optical filters. Properly sized (60 and 200 nm) nanoparticle aggregates with cores having a sulfur-oxygen molecular species and a shell with a surface in contact with the core are obtained. Those nanoparticle aggregates have a first resonance profile to wavelengths between 350 nm and 1075 nm. A modified resonance profile for those nanoparticle aggregates is determined. The nanoparticle aggregates are then selectively sized by irradiating them with electromagnetic energy at sufficient intensity and spectral content to modify the first resonance profile towards the modified resonance profile. The resulting nanoparticle aggregates can be used as sensors or optical filters at a selected wavelength.

We claim: 
     
         1 . A method for detecting an analyte in a sample using a chemical sensor, the method comprising the steps of:
 i) providing a sample;   ii) providing a linker molecule (LM)   iii) conjugating the analyte in the sample with the LM, thereby producing an analyte-LM conjugate;   iv) providing a chemical sensor fabricated by the steps of:
 (A) providing an electromagnetic radiation source having a wavelength between 350 nm and 1075 nm; 
 (B) providing a plurality of nanoparticle aggregates, wherein each of the nanoparticle aggregates comprise a diameter between 60 nm and 200 nm, a metallic molecular core, a sulfur-oxygen shell having a surface in contact with the core; 
 (C) providing a notch filter, the notch filter having an electromagnetic wavelength absorption profile of between 650 nm and 950 nm; 
 (D) selectively sizing by irradiating the plurality of nanoparticle aggregates provided in step B with the electromagnetic radiation source of step A through the notch filter provided in step C and irradiating them with electromagnetic energy, the irradiating resulting in narrowing the optical absorption of the nanoparticle aggregates towards a selected surface plasmon resonance wavelength; the step resulting in selectively-sized nanoparticle aggregates; whereby the steps result in forming a chemical sensor; 
   v) incubating the analyte-LM conjugate with the chemical sensor for a predetermined time period; and   vi) measuring the extent of binding between the analyte-LM-SQD conjugate and the chemical sensor; thereby detecting the analyte in the sample.   
     
     
         2 . The method of  claim 1  wherein the analyte is an ovarian cancer marker antibody. 
     
     
         3 . The method of  claim 1  wherein the detecting molecule in the chemical sensor is an antigen that binds to an ovarian cancer marker antibody with an affinity (K a ) of at least 10 6  l/mole. 
     
     
         4 . An optical filter fabricated by the steps of:
 (A) providing an electromagnetic radiation source having a wavelength between 350 nm and 1075 nm;   (B) providing a plurality of nanoparticle aggregates, wherein each of the nanoparticle aggregates comprise a diameter between 60 nm and 200 nm, a metallic molecular core, a sulfur-oxygen shell having a surface in contact with the core;   (C) providing a notch filter, the notch filter having an electromagnetic wavelength absorption profile of between 650 nm and 950 nm; and   (D) selectively sizing by irradiating the plurality of nanoparticle aggregates provided in step B with the electromagnetic radiation source of step A through the notch filter provided in step C and irradiating them with electromagnetic energy, the irradiating resulting in narrowing the optical absorption of the nanoparticle aggregates towards a selected surface plasmon resonance wavelength; the step resulting in selectively-sized nanoparticle aggregates; whereby the steps result in forming an optical filter.