Capillary-scale direct measurement of hemoglobin concentration of erythrocytes using photothermal angular light scattering

Fast and sensitive smartphone colorimetric detection of whole blood samples on a paper-based analytical device

BACKGROUND

Methods based on paper-based analytical devices (PAD) and smartphone photographic colorimetric detection have become representative instrument-independent point-of-care testing (POCT) platforms due to their low cost and simplicity. However, the detection of target components from whole blood sample still presents challenges in terms of field preparation of small amounts of blood sample and detection sensitivity. This paper presents a rapid online processing method for whole blood samples on PAD based on plasma separation membrane (PSM), and combined with electrokinetic stacking and selective chromatic reaction. Real-time smartphone-based colorimetric detection of free hemoglobin (FHb) and human serum albumin (HSA) was successfully demonstrated.

RESULTS

With the proposed method, both detections for low and high concentration analytes could be implemented. The limits of detection of 16.6 mg L-1 for FHb and 0.67 g L-1 for HSA were obtained, respectively, with RSD below 8 %. The reliability of the method was verified by the recovery test and desktop spectrophotometric method. The detection results for real blood samples were in agreement with that by clinical methods.

SIGNIFICANCE AND NOVELTY

The PAD method is inexpensive, simple and fast, and detection of a whole blood sample of 5 μL can be finished in 5 min. This work shows that POCT of biomarkers from whole blood with PAD is possible without using any desktop facilities.

Nanomaterials for Fluorescent Detection of Hemoglobin

Hemoglobin plays a vital role in a series of biological activities. Abnormal levels of hemoglobin in blood are associated with many clinical diseases. Therefore, development of simple and accurate methods for sensing hemoglobin is of considerable significance. The blowout advancement in nanotechnology has urged the use of different types of fluorescent nanomaterials for hemoglobin assay. The past decades have witnessed the rapid progress of fluorescent nanosensors for hemoglobin assay. In the review, the sensing principles of fluorescent nanomaterials for sensing hemoglobin were briefly discussed. The advances of fluorescent nanosensors for detection of hemoglobin were further highlighted. And the sensing performance of fluorescent nanosensors versus traditional detection approaches was compared. Finally, the challenges and future directions of fluorescent nanomaterials for detection of hemoglobin are discussed. The review will arouse much more attention to the construction of hemoglobin sensors and facilitate rapid development of fluorescent nanosensors of hemoglobin.

Hemoglobin Nanocrystals for Drugs Free, Synergistic Theranostics of Colon Tumor

The conventional approach in cancer nanomedicine involves advanced drug nanocarriers delivering preloaded therapeutics to targeted tumor sites to maximize drug efficiency. However, both cancer drugs and nanocarriers inevitably produce side effects and systemic toxicity. Herein, hemoglobin nanocrystals (HbC) as drug-free theranostic nanoformulations with the tumor microenvironment (TME) activated diagnostic and therapeutic abilities towards colon tumors are introduced. HbC can release Fe²⁺ oxidized to Fe³⁺ in the Fenton reaction with tumor endogenous H₂ O₂ , concurrently with the generation of cytotoxic hydroxyl radicals (•OH) that allow for chemodynamic therapy (CDT). Furthermore, in situ-produced Fe³⁺ reacts with colon tumor-abundant H₂ S, resulting in the production of Fe_{1- x} S, which provides magnetic resonance imaging (MRI) contrast and allows for NIR light-inducible photothermal therapy (PTT). In vitro and in vivo studies revealed that HbC produced CDT towards 4T1 tumors, and MRI-guided, synergistically enhanced combination of CDT and PTT against H₂ S abundant colon tumors (CT26), with negligible toxicity towards normal tissues, enlightening HbC as highly efficient and biocompatible TME activated theranostic nanoplatform specific against colon cancer without any traditional drugs and drug carriers.

Point-of-care testing of plasma free hemoglobin and hematocrit for mechanical circulatory support

Hematological analysis is essential for patients who are supported by a mechanical circulatory support (MCS). The laboratory methods used to analyze blood components are conventional and accurate, but they require a mandatory turn-around-time for laboratory results, and because of toxic substances, can also be hazardous to analysis workers. Here, a simple and rapid point-of-care device is developed for the measurement of plasma free hemoglobin (PFHb) and hematocrit (Hct), based on colorimetry. The device consists of camera module, minimized centrifuge system, and the custom software that includes the motor control algorithm for the centrifuge system, and the image processing algorithm for measuring the color components of blood from the images. We show that our device measured PFHb with a detection limit of 0.75 mg/dL in the range of (0–100) mg/dL, and Hct with a detection limit of 2.14% in the range of (20–50)%. Our device had a high correlation with the measurement method generally used in clinical laboratories (PFHb R = 0.999, Hct R = 0.739), and the quantitative analysis resulted in precision of 1.44 mg/dL for PFHb value of 14.5 mg/dL, 1.36 mg/dL for PFHb value of 53 mg/dL, and 1.24% for Hct 30%. Also, the device can be measured without any pre-processing when compared to the clinical laboratory method, so results can be obtained within 5 min (about an 1 h for the clinical laboratory method). Therefore, we conclude that the device can be used for point-of-care measurement of PFHb and Hct for MCS.

A Portable Smartphone-linked Device for Direct, Rapid and Chemical-Free Hemoglobin Assay

We describe the development and clinical evaluation of an automated smartphone-linked sensor capable of chemical-free, quantitative measurement of hemoglobin concentration ([Hb]) in whole blood samples. We have demonstrated that our sensor could analyze an unprocessed blood specimen with a mean processing time of <8 s and provided the [Hb] results with ~99% accuracy against a reference hematology analyzer with coefficient of variation (CV) of 1.21% measured at [Hb] = 11.2 g/dL. Its diagnostic capability for anemia was evaluated by measuring [Hb] of 142 clinical blood specimens and comparing the results with those from an automated hematology analyzer (ADVIA 2120i, Siemens AG, Germany) and a portable hemoglobinomteter (Hb201+, Hemocue, Sweden). The sensor yielded comparable sensitivities and specificities of 87.50% and 100.00% for males, and 94.44% and 100.00% for females, respectively, for anemic detection. The results suggested that our optical sensor based on the intrinsic photothermal response of Hb molecules and advances in consumer electronics, particularly smartphone capabilities, enables a direct, chemical-free [Hb] assay accessible to people in both developed and developing countries.

A Rapid and Chemical-free Hemoglobin Assay with Photothermal Angular Light Scattering

Photo-thermal angular light scattering (PT-AS) is a novel optical method for measuring the hemoglobin concentration ([Hb]) of blood samples. On the basis of the intrinsic photothermal response of hemoglobin molecules, the sensor enables high-sensitivity, chemical-free measurement of [Hb]. [Hb] detection capability with a limit of 0.12 g/dl over the range of 0.35 - 17.9 g/dl has been demonstrated previously. The method can be readily implemented using inexpensive consumer electronic devices such as a laser pointer and a webcam. The use of a micro-capillary tube as a blood container also enables the hemoglobin assay with a nanoliter-scale blood volume and a low operating cost. Here, detailed instructions for the PT-AS optical setup and signal processing procedures are presented. Experimental protocols and representative results for blood samples in anemic conditions ([Hb] = 5.3, 7.5, and 9.9 g/dl) are also provided, and the measurements are compared with those from a hematology analyzer. Its simplicity in implementation and operation should enable its wide adoption in clinical laboratories and resource-limited settings.