Molecular diagnostics are an increasingly important part of biotechnology. The ability to detect small quantities of genomic, proteomic, and other biological materials enables sensitive clinical tests to be performed, as well as enabling laboratory research that affects drug development and functional biology. Molecular sensing modalities include radioactivity, mass spectroscopy, and electrical and optical techniques. The worldwide market for molecular biomarkers, diagnostics, and related services exceeded $6 billion in 2003 and is predicted to reach a value of more than $92 billion by 2016. Molecular diagnostics or the analysis of DNA and RNA at the molecular level is a fast-growing market.
Steven M. Ebstein, president of Lexitek Inc (Wellesley, MA), has created a laser-processed substrate for molecular diagnostics. The substrate when used in Surface Enhanced Raman Scattering (SERS) and related modalities offers greatly enhanced sensitivity and selectivity for detection of molecular species through the excitation of plasmon modes and their coupling to molecular vibrational modes. It is also cheaper to manufacture the substrate using lasers than processes using nanolithography.
The invention is an apparatus for use in performing a diagnostic assay of an analyte. The apparatus consists of a base that has been structured using laser processing so as to provide at least one patterned surface by melting and resolidification of the base, wherein the patterned surface is characterized by structures ranging in scale from 10 to 2000 nanometers. The pattern is stochastic in all three spatial dimensions; and a metal is applied to the at least one patterned surface so as to provide at least one metalized patterned surface.
One of the chief obstacles to widespread application is the availability of suitable nanostructured materials that exhibit strong enhancement of Raman scattering. Ebstein has created materials that are inexpensive to fabricate, and are reproducible. He describes nanostructured surfaces for SERS and other photonic sensing that use semiconductor and metal surfaces fabricated using femtosecond laser processing in U.S. Patent Application 20090279085.
A noble metal film (e.g., silver or gold) is evaporated onto the resulting nanostructured surfaces for use as a substrate for SERS. These surfaces are inexpensive to produce and can have their statistical properties precisely tailored by varying the laser processing. Surfaces can be readily micropatterned and both stochastic and self-organized structures can be fabricated. This material has application to a variety of genomic, proteomic, and biosensing applications including label free applications including binding detection. Using this material, monolithic or arrayed substrates can be designed. Substrates for cell culture and microlabs incorporating microfluidics and electrochemical processing can be fabricated as well. Laser processing can be used to form channels in the substrate or a material sandwiched onto it in order to introduce reagents and drive chemical reactions. The substrate can be fabricated so application of an electric potential enables separation of materials by electrophoresis or electro-osmosis.
A performance goal of interest to the pharmaceutical industry is 100,000 measurements per instrument per day. This parameter is a familiar benchmark to pharmaceutical industry personnel doing lead discovery. For a nominal ten second measurement per array position, this benchmark would require 12 detection channels in parallel, assuming no time for the robotic motion. Ebstein believes his device can meet this goal. “It can be achieved by using multiple fibers, and the corresponding instruments can take advantage of numerous optical components that have been developed for telecom applications that can handle multiple fiber inputs and outputs and do so with very regular positioning so no alignment is required.”
Ebstein’s approach is low cost while still retaining great flexibility to co-manufacture microarrays, microfluidic, and electrochemical features. Ebstein’s approach also has much greater control, through the laser pulse energy and polarization, than a controlled evaporation apparatus or a photolithography and etching process can economically achieve. The ability to do laser machining of the substrates adds a dimension that enhances the capabilities of my arrayed substrates. While photonic crystals offer good reproducibility and potential for microarrays similar to his approach, they are more expensive to manufacture. Moreover, the reproducibility relies on controlling a photolithography and etching process. Many manufacturers of MEMS devices have found that this can be costly to achieve in practice.
In a contrasting molecular diagnostics market estimate, Illumina CEO Jay Flatley at the JPMorgan Healthcare Conference in San Francisco January 2009 conference estimated that the molecular diagnostics market will grow from $3 billion to $5 billion by 2011and the genome sequencing market will grow from $1.1 billion to $1.5 billion during that period. This year Illumina made an $18 million investment into UK-based startup Oxford Nanopore Technologies. Oxford's nanopore sequencing technology "holds tremendous promise to be one of the first technologies to reach the sub-$1,000 genome and become the cheapest and fastest way to sequence DNA, according to Flatley.
The molecular diagnostics market was predicted to grow from a 2006 level of approximately $17.9 billion to over $92.1 billion by 2016 with an average annual growth rate of 41.5 per cent, by Dr Kenneth Krul, in a 2007 report from, entitled "Molecular Diagnostics: Major World Markets" from Kalorama Information.
The growth in the pharmacogenetic market is expected to dwarf that of other sectors with annual growth predicted at a rate of 184 per cent, with the segment expected to reach over $60 billion by 2016. The expected growth is based on the new understanding of the relationship between the genetic signatures of neuropsychiatric disorders and optimal treatment procedures, advances in the viral infection market and advances in cancer therapy.
The use of molecular diagnostics in oncology is predicted to be the second fastest growth application sector, expected to grow at a rate of over 68 per cent per year, reaching $9.8bn by 2016. The growth in this area is expected to be fuelled by the use of molecular diagnostics to assess cancer susceptibility, diagnosis and management, according to Krul’s report