Semiconducting nanowires have the potential to function as highly sensitive and selective sensors for the label-free detection of low concentrations of pathogenic microorganisms. Successful solution-phase nanowire sensing has been demonstrated for ions, small molecules, proteins, DNA and viruses; however, 'bottom-up' nanowires (or similarly configured carbon nanotubes) used for these demonstrations require hybrid fabrication schemes, which result in severe integration issues that have hindered widespread application. Alternative 'top-down' fabrication methods of nanowire-like devices produce disappointing performance because of process-induced material and device degradation. Here we report an approach that uses complementary metal oxide semiconductor (CMOS) field effect transistor compatible technology and hence demonstrate the specific label-free detection of below 100 femtomolar concentrations of antibodies as well as real-time monitoring of the cellular immune response. This approach eliminates the need for hybrid methods and enables system-scale integration of these sensors with signal processing and information systems. Additionally, the ability to monitor antibody binding and sense the cellular immune response in real time with readily available technology should facilitate widespread diagnostic applications.

Nanowire field effect transistors (NW-FETs) can serve as ultrasensitive detectors for label-free reagents. The NW-FET sensing mechanism assumes a controlled modification in the local channel electric field created by the binding of charged molecules to the nanowire surface. Careful control of the solution Debye length is critical for unambiguous selective detection of macromolecules. Here we show the appropriate conditions under which the selective binding of macromolecules is accurately sensed with NW-FET sensors.The ability to rapidly sense minute concentrations of specific macromolecules such as DNA sequences is critical for clinical diagnostics, 1,2 genomics, 3,4 and drug discovery 3,4 and useful for applications in defense and homeland security. 5 Most current systems for macromolecular sensing rely on labels, such as radiolabeled tags or fluorophores. 6-8 Techniques that could distinguish these without the need for labels, i.e., label-free sensing, are of great interest because they would not only significantly decrease the cost and time needed for sample preparation but would also eliminate issues related to modification of target molecules. 9,10One of the most promising platforms for unlabeled sensing is the nanowire field effect transistor (NW-FET). 9-11 These devices operate similarly to conventional chemical FETs, sensing the presence of bound species by their intrinsic charge, with the advantage of enhanced sensitivity due to the nanoscale channel confinement. 11,12 By binding a receptor protein or a singlestranded DNA (ssDNA) oligomer to the NW-FET surface, the binding of the specific ligand or complementary ssDNA modifies the electric field surrounding the device, enabling direct electronic detection. [13][14][15][16] The integration issues faced by traditional, as-grown NWs have been overcome with the advent of NW-like devices patterned by "top-down" microlithography. 14-18 Although early devices suffered from low signal-to-noise ratios, a "top-down" method producing high-quality nanosensors capable of detecting specific antibodies at «10 fM concentrations have recently The charge of solution-based molecules and macromolecules is screened by dissolved solution counterions: a negative species such as streptavidin or DNA will be surrounded by positively charged ions due to electrostatic interactions. On a certain length scale, termed the Debye length (λ D ), the number of net positive charges approaches the number of negative charges on the protein or DNA. The result is a screening effect such that the electrostatic potential arising from charges on the protein or DNA decays exponentially toward zero with distance. 19 For aqueous solutions at room temperature, this length is given by NIH Public Access( 1) where l B is the Bjerrum length = 0.7 nm, ∑ i is the sum over all ion species, and ρ i and z i are the density and valence, respectively, of ion species i (ref 19). Thus, for optimal sensing, the Debye length must be carefully selected for NW-FET measurements because molecules binding to t...

The tumour microenvironment thwarts conventional immunotherapy through multiple immunologic mechanisms, such as the secretion of the transforming growth factor-β (TGF-β), which stunts local tumour immune responses. Therefore, high doses of interleukin-2 (IL-2), a conventional cytokine for metastatic melanoma, induces only limited responses. To overcome the immunoinhibitory nature of the tumour microenvironment, we developed nanoscale liposomal polymeric gels (nanolipogels; nLGs) of drug-complexed cyclodextrins and cytokine-encapsulating biodegradable polymers that can deliver small hydrophobic molecular inhibitors and water-soluble protein cytokines in a sustained fashion to the tumour microenvironment. nLGs releasing TGF-β inhibitor and IL-2 significantly delayed tumour growth, increased survival of tumour-bearing mice, and increased the activity of natural killer cells and of intratumoral-activated CD8+ T-cell infiltration. We demonstrate that the efficacy of nLGs in tumour immunotherapy results from a crucial mechanism involving activation of both innate and adaptive immune responses.

Label-free nanosensors can detect disease markers to provide point-of-care diagnosis that is low-cost, rapid, specific and sensitive.1-13 However, detecting these biomarkers in physiological fluid samples is difficult because of problems like biofouling and nonspecific binding, and the resulting need to use purified buffers greatly reduces the clinical relevance of these sensors. Here, we overcome this limitation by using distinct components within the sensor to perform purification and detection. A microfluidic purification chip captures multiple biomarkers simultaneously from blood samples and releases them, after washing, into purified buffer for sensing by a silicon nanoribbon detector. This two-stage approach isolates the detector from the complex environment of whole blood, and reduces its minimum required sensitivity by effectively pre-concentrating the biomarkers. We show specific and quantitative detection of two model cancer antigens from a 10 uL sample of whole blood in less than 20 minutes. This study marks the first use of label-free nanosensors with physiologic solutions, positioning this technology for rapid translation to clinical settings.