In order to avoid the toxicities associated with prescription drug use today, we have explored novel methods for delivering drugs selectively to pathologic cells, thereby avoiding the collateral damage that accompanies their uptake by healthy cells. In this Account, we describe our quest for the ideal targeted therapeutic agent. This effort began with a search for ligands that would bind selectively to pathologic cells, displaying no affinity for healthy cells. After identification of an optimal targeting ligand, effort was focused on construction of linkers that would carry the attached drug to pathologic cells with receptors for the selected ligand. In the case of cancer, we exploited the well-characterized up-regulation of folate receptors on malignant cells to target folate-linked pharmaceuticals to cancer tissues in vivo. Drugs that have been linked to folic acid for tumor-selective drug delivery to date include (i) protein toxins, (ii) chemotherapeutic agents, (iii) gene therapy vectors, (iv) oligonucleotides (including small interfering RNA (siRNA)), (v) radioimaging agents, (vi) magnetic resonance imaging (MRI) contrast agents, (vii) liposomes with entrapped drugs, (viii) radiotherapeutic agents, (ix) immunotherapeutic agents, and (x) enzyme constructs for prodrug therapy. Current clinical trials of four folate-linked drugs demonstrate that folate receptor-targeting holds great promise for increasing the potency while reducing toxicity of many cancer therapies. In the course of developing folate-conjugated drugs for cancer, we discovered that folate receptors are also overexpressed on activated (but not resting or quiescent) macrophages. Recognizing that activated macrophages either cause or contribute to such diseases as rheumatoid arthritis, Crohn's disease, atherosclerosis, lupus, inflammatory osteoarthritis, diabetes, ischemia reperfusion injury, glomerulonephritis, sarcoidosis, psoriasis, Sjogren's disease, and vasculitis, we initiated studies aimed at developing folate-conjugated imaging and therapeutic agents for the diagnosis and treatment of such diseases. In very brief time, significant progress has been made towards identification of clinical candidates for targeted treatment of several inflammatory and autoimmune diseases. This Account summarizes the discovery and development of a variety of folate-targeted drugs for the diagnosis and therapy of cancers and inflammatory/autoimmune diseases.

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Context.-The clinical introduction of new oral anticoagulants (NOACs) has stimulated the development of tests to quantify the effects of these drugs and manage complications associated with their use. Until recently, the only treatment choices for the prevention of venous thromboembolism in orthopedic surgical patients, as well as for stroke and systemic embolism in patients with atrial fibrillation, were vitamin K antagonists, antiplatelet drugs, and unfractionated and low-molecular-weight heparins. With the approval of NOACs, treatment options and consequent diagnostic challenges have expanded.Objective.-To study the utility of thromboelastography (TEG) in monitoring and differentiating between 2 currently approved classes of NOACs, direct thrombin inhibitors (dabigatran) and factor Xa inhibitors (rivaroxaban and apixaban).Design.-Blood samples from healthy volunteers were spiked with each NOAC in both the presence and absence of ecarin, and the effects on TEG were evaluated.Results.-Both the kaolin test reaction time (R time) and the time to maximum rate of thrombus generation were prolonged versus control samples and demonstrated a dose response for apixaban (R time within the normal range) and dabigatran. The RapidTEG activated clotting time test allowed the creation of a dose-response curve for all 3 NOACs. In the presence of anti-Xa inhibitors, the ecarin test promoted significant shortening of kaolin R times to the hypercoagulable range, while in the presence of the direct thrombin inhibitor only small and dose-proportional R time shortening was observed.Conclusions.-The RapidTEG activated clotting time test and the kaolin test appear to be capable of detecting and monitoring NOACs. The ecarin test may be used to differentiate between Xa inhibitors and direct thrombin inhibitors. Therefore, TEG may be a valuable tool to investigate hemostasis and the effectiveness of reversal strategies for patients receiving NOACs.

Rapid identification of infectious pathogens constitutes an important step toward limiting the spread of contagious diseases. Whereas antibody-based detection strategies are often selected because of their speed, mutation of the pathogen can render such tests obsolete. In an effort to develop a rapid yet mutation-proof method for pathogen identification, we have explored the use of "immutable ligands" to capture the desired microbe on a detection device. In this "proof-of-principle" study, we immobilize pyoverdine, a siderophore that Pseudomonas aeruginosa must bind to obtain iron, onto gold-plated glass chips and then examine the siderophore's ability to capture P. aeruginosa for its subsequent identification. We demonstrate that exposure of pyoverdine-coated chips to increasing dilutions of P. aeruginosa allows detection of the bacterium down to concentrations as low as 10(2)/mL. We further demonstrate that printing of the siderophore in a periodic pattern on the detection chip enables a sensitive method of detecting the bound pathogen by a Fourier transform analysis of light scattered by the patterned chip. Because unrelated bacteria are not captured on the pyoverdine chip, we conclude that pyoverdine can be exploited for the specific binding and identification of P. aeruginosa. It follows that the utilization of other microbe-specific "immutable ligands" may allow the specific identification of their cognate pathogens.

Abstract:We describe an integrated approach for detection of diagnostic markers using in situ assembled optical diffraction gratings in combination with immunomagnetic capture. Folate receptor (FR), a serum protein indicative of various cancers, was chosen as a model system to demonstrate the potential of the method. Magnetic beads coupled to FR antibody were used to capture FR from serum. The FR-bound magnetic beads self-assembled onto microcontact-printed folate-coupled BSA (F-BSA) patterns to form diffraction gratings which served to detect FR by measuring the diffraction intensities caused by laser illumination. The FR-containing beads, upon binding to the F-BSA surface, served as intrinsic signal enhancement agents, circumventing the need for additional enzymatic signal amplification or fluorescent labeling steps. With this approach, a detection sensitivity of 700 fM (20 pg/mL) was achieved. The potential use of this approach in clinical diagnostics was demonstrated by measuring FR concentration in blood samples obtained from cancer patients.