Smartphone-based cytometric biosensors for point-of-care cellular diagnostics

Analysis on a single-cell basis is both fundamental and meaningful in biomedical research and clinical practice.Flow cytometry is one of the most popular approaches in this field with broad applications in cell sorting,counting,and identification of rare cells.However,the complicated design and bulky size of conventional flow cytometry have restricted their applications mainly in centralized laboratories.With the recent development of smartphone devices,smartphone-based cytometry has been explored and tested for single-cell analysis.Compared with traditional cytometers,smartphone-based cytometric biosensors are more suitable for point-of-care(POC)uses,such as on-site disease diagnosis and personal health monitoring.In this review article,the history of traditional flowcytometry is introduced,and advances of smartphone-enabled cytometry are summarized in detail based on different working principles.Representative POC applications of smartphone cytometers are also discussed.The achievements demonstrated so far illustrate the potential of smartphone-based cytometric devices to transform single-cell measurement in general,with a significant impact in POC diagnostics,preventive medicine,and cell biology.

Algorithm-based arterial blood sampling recognition increasing safety in point-of-care diagnostics

AIM To detect blood withdrawal for patients with arterial blood pressure monitoring to increase patient safety and provide better sample dating.METHODS Blood pressure information obtained from a patient monitor was fed as a real-time data stream to an experimental medical framework. This framework was connected to an analytical application which observes changes in systolic, diastolic and mean pressure to determine anomalies in the continuous data stream. Detection was based on an increased mean blood pressure caused by the closing of the withdrawal three-way tap and an absence of systolic and diastolic measurements during this manipulation. For evaluation of the proposed algorithm, measured data from animal studies in healthy pigs were used.RESULTS Using this novel approach for processing real-time measurement data of arterial pressure monitoring, the exact time of blood withdrawal could be successfully detected retrospectively and in real-time. The algorithm was able to detect 422 of 434(97%) blood withdrawals for blood gas analysis in the retrospective analysis of 7 study trials. Additionally, 64 sampling events for other procedures like laboratory and activated clotting time analyses were detected. The proposed algorithm achieved a sensitivity of 0.97, a precision of 0.96 and an F1 score of 0.97.CONCLUSION Arterial blood pressure monitoring data can be used toperform an accurate identification of individual blood samplings in order to reduce sample mix-ups and thereby increase patient safety.

基于point-of-care理念的手卫生设施设置现状调查

目的基于point-of-care(POC)理念调查某三级甲等综合性教学医院手卫生设施的设置现状。方法采用横断面方法调查该院各诊疗区域主要供医务人员使用的手卫生设施种类、数量、位置、设施完备程度,以及速干手消毒剂的消耗量。结果调查102个区域,1165间诊疗用房,手卫生设施配置率为96.48%,洗手池完备率为91.37%%,不同区域完备率比较,差异有统计学意义(P<0.01)。80.53%的速干手消毒剂设置符合POC理念,59.51%的普通病区病室速干手消毒剂设置符合POC理念,速干手消毒剂设置符合POC理念比例高的科室手消毒剂消耗量相对较高。结论手卫生设施的设置和改进应强化POC理念,以提高手卫生依从性和预防医院感染的发生。

Nanozymes in Point-of-Care Diagnosis:An Emerging Futuristic Approach for Biosensing

Nanomaterial-based artificial enzymes(or nanozymes) have attracted great attention in the past few years owing to their capability not only to mimic functionality but also to overcome the inherent drawbacks of the natural enzymes.Numerous advantages of nanozymes such as diverse enzyme-mimicking activities,low cost,high stability,robustness,unique surface chemistry,and ease of surface tunability and biocompatibility have allowed their integration in a wide range of biosensing applications. Several metal,metal oxide,metal–organic framework-based nanozymes have been exploited for the development of biosensing systems,which present the potential for point-of-care analysis. To highlight recent progress in the field,in this review,more than 260 research articles are discussed systematically with suitable recent examples,elucidating the role of nanozymes to reinforce,miniaturize,and improve the performance of point-of-care diagnostics addressing the ASSURED(a ordable,sensitive,specific,user-friendly,rapid and robust,equipment-free and deliverable to the end user) criteria formulated by World Health Organization. The review reveals that many biosensing strategies such as electrochemical,colorimetric,fluorescent,and immunological sensors required to achieve the ASSURED standards can be implemented by using enzyme-mimicking activities of nanomaterials as signal producing components. However,basic system functionality is still lacking. Since the enzyme-mimicking properties of the nanomaterials are dictated by their size,shape,composition,surface charge,surface chemistry as well as external parameters such as pH or temperature,these factors play a crucial role in the design and function of nanozyme-based point-of-care diagnostics. Therefore,it requires a deliberate exertion to integrate various parameters for truly ASSURED solutions to be realized. This review also discusses possible limitations and research gaps to provide readers a brief scenario of the emerging role of nanozymes in state-of-the-art POC diagnosis system development for futuristic biosensing applications.

Microfluidics-based strategies for molecular diagnostics of infectious diseases

Traditional diagnostic strategies for infectious disease detection require benchtop instruments that are inappropriate for point-of-care testing(POCT). Emerging microfluidics, a highly miniaturized, automatic, and integrated technology,are a potential substitute for traditional methods in performing rapid, low-cost, accurate, and on-site diagnoses.Molecular diagnostics are widely used in microfluidic devices as the most effective approaches for pathogen detection.This review summarizes the latest advances in microfluidics-based molecular diagnostics for infectious diseases from academic perspectives and industrial outlooks. First, we introduce the typical on-chip nucleic acid processes,including sample preprocessing, amplification, and signal read-out. Then, four categories of microfluidic platforms are compared with respect to features, merits, and demerits. We further discuss application of the digital assay in absolute nucleic acid quantification. Both the classic and recent microfluidics-based commercial molecular diagnostic devices are summarized as proof of the current market status. Finally, we propose future directions for microfluidics-based infectious disease diagnosis.

Applications of smartphone-based near-infrared(NIR)imaging,measurement,and spectroscopy technologies to point-of-care(POC)diagnostics

The role of point-of-care(POC)diagnostics is important in public health.With the support of smartphones,POC diagnostic technologies can be greatly improved.This opportunity has arisen from not only the large number and fast spread of cell-phones across the world but also their improved imaging/diagnostic functions.As a tool,the smartphone is regarded as part of a compact,portable,and low-cost system for real-time POC,even in areas with few resources.By combining near-infrared(NIR)imaging,measurement,and spectroscopy techniques,pathogens can be detected with high sensitivity.The whole process is rapid,accurate,and low-cost,and will set the future trend for POC diagnostics.In this review,the development of smartphone-based NIR fluorescent imaging technology was described,and the quality and potential of POC applications were discussed.

Leveraging electrochemical sensors to improve efficiency of cancer detection

Electrochemical biosensors have emerged as a promising technology for cancer detection due to their high sensitivity,rapid response,low cost,and capability for non-invasive detection.Recent advances in nanomaterials like nanoparticles,graphene,and nanowires have enhanced sensor performance to allow for cancer biomarker detection,like circulating tumor cells,nucleic acids,proteins and metabolites,at ultra-low concentrations.However,several challenges need to be addressed before electrochemical biosensors can be clinically implemented.These include improving sensor selectivity in complex biological media,device miniaturization for implantable applications,integration with data analytics,handling biomarker variability,and navigating regulatory approval.This editorial critically examines the prospects of electrochemical biosensors for efficient,low-cost and minimally invasive cancer screening.We discuss recent developments in nanotechnology,microfabrication,electronics integration,multiplexing,and machine learning that can help realize the potential of these sensors.However,significant interdisciplinary efforts among researchers,clinicians,regulators and the healthcare industry are still needed to tackle limitations in selectivity,size constraints,data interpretation,biomarker validation,toxicity and commercial translation.With committed resources and pragmatic strategies,electrochemical biosensors could enable routine early cancer detection and dramatically reduce the global cancer burden.

Real-time electrical detection of epidermal skin MoS2 biosensor for point-of-care diagnostics

Various approaches have been proposed for point-of-care diagnostics, and in particular, optical detection is preferred because it is relatively simple and fast. At the same time, field-effect transistor （FET）-based biosensors have attracted great attention because they can provide highly sensitive and label-free detection. In this work we present highly sensitive, epidermal skin-type point-of-care devices with system-level integration of flexible MOS2 FET biosensors, read-out circuits, and light-emitting diode （LEDs） that enable real-time detection of prostate cancer antigens （PSA）. Regardless of the physical forms or mechanical stress conditions, our proposed high-performance MoS2 biosensors can detect a PSA concentration of 1 pg.mL-1 without specific surface treatment for anti-PSA immobilization on the MoS2 surface on which we characterize and confirm physisorption of anti-PSA using Kelvin probe force microscopy （KPFM） and tapping-mode atomic force microscopy （tm-AFM）. Furthermore, current modulation induced by the binding process was stably maintained for longer than 2-3 min. The results indicate that flexible MoS2-based FET biosensors have great potential for point-of-care diagnostics for prostate cancer as well as other biomarkers.

Microneedle-based devices for point-of-care infectious disease diagnostics

Recent infectious disease outbreaks,such as COVID-19 and Ebola,have highlighted the need for rapid and accurate diagnosis to initiate treatment and curb transmission.Successful diagnostic strategies critically depend on the efficiency of biological sampling and timely analysis.However,current diagnostic techniques are invasive/intrusive and present a severe bottleneck by requiring specialist equipment and trained personnel.Moreover,centralised test facilities are poorly accessible and the requirement to travel may increase disease transmission.Self-administrable,point-of-care(PoC)microneedle diagnostic devices could provide a viable solution to these problems.These miniature needle arrays can detect biomarkers in/from the skin in a minimally invasive manner to provide(near-)real-time diagnosis.Few microneedle devices have been developed specifically for infectious disease diagnosis,though similar technologies are well established in other fields and generally adaptable for infectious disease diagnosis.These include microneedles for biofluid extraction,microneedle sensors and analyte-capturing microneedles,or combinations thereof.Analyte sampling/detection from both blood and dermal interstitial fluid is possible.These technologies are in their early stages of development for infectious disease diagnostics,and there is a vast scope for further development.In this review,we discuss the utility and future outlook of these microneedle technologies in infectious disease diagnosis.

Microfluidic Extreme PCR: <1 Minute DNA Amplification in a Thin Film Disposable

Point-of-care diagnostic testing using PCR requires a device that is fast, economical, and practical. Sub-minute amplification has been demonstrated using high concentrations of primers and polymerase in glass capillaries, but its platform is limited to research use. A system using heated copper blocks to clamp a microfluidic flow-through PCR card fabricated from thin film polycarbonate was modeled, fabricated, and tested. Models show that fluid flowing through a thin-film device clamped between temperature-controlled copper blocks equilibrates to a temperature change in 250 milliseconds. A 2-step, 35 cycle PCR with 1.06 second cycles specifically amplified a 69-base pair fragment from a 450-base pair synthetic DNA template of random sequence with the same performance as the glass capillary system. This system demonstrates the feasibility of <1 minute PCR in an inexpensive, disposable sample container.

Novel screening test for celiac disease using peptide functionalised gold nanoparticles

AIM To develop a screening test for celiac disease based on the coating of gold nanoparticles with a peptide sequence derived from gliadin, the protein that triggers celiac disease.METHODS20 nm gold nanoparticles were first coated with NeutrAvidin. A long chain Polyethylene glycol(PEG) linker containing Maleimide at the Ω-end and Biotin group at the α-end was used to ensure peptide coating to the gold nanoparticles. The maleimide group with the thiol(-SH) side chain reacted with the cysteine amino acid in the peptide sequence and the biotinylated and PEGylated peptide was added to the NeutrAvidin coated gold nanoparticles. The peptide coated gold nanoparticles were then converted into a serological assay. We used the peptide functionalised gold nanoparticle-based assay on thirty patient serum samples in a blinded assessment and compared our results with the previously run serologicaland pathological tests on these patients.RESULTS A stable colloidal suspension of peptide coated gold nanoparticles was obtained without any aggregation. An absorbance peak shift as well as color change was caused by the aggregation of gold nanoparticles following the addition of anti-gliadin antibody to peptide coated nanoparticles at levels associated with celiac disease. The developed assay has been shown to detect anti-gliadin antibody not only in quantitatively spiked samples but also in a small-scale study on real non-hemolytic celiac disease patient's samples.CONCLUSION The study demonstrates the potential of gold nanoparticlepeptide based approach to be adapted for developing a screening assay for celiac disease diagnosis. The assay could be a part of an exclusion based diagnostic strategy and prove particularly useful for testing high celiac disease risk populations.

A smartphone-based calibration-free portable urinalysis device

As one of the most common medical diagnosis methods, urinalysis is a highly demanded technique for screening tests or daily monitoring of various diseases. With the rapid development of POC(point-of-care) systems, a convenient house-using urinalysis device is widely needed. However, considering the difference of onboard systems and multiple test indicators in urinalysis, the design of such an intelligent device is still challenging. In this paper, a smartphone-based portable urinalysis system has been developed and applied for the colorimetric analysis of routine urine examination indices using an Android app. By integrating the test paper sensor in the portable device for urinalysis,our system significantly improves the instability of conventional dipstick-based manual colorimetry, and the smartphone application used for color discrimination enhances the accuracy of the visual assessment of sample strips. Using a simple operation approach that takes ~ 2 min per test, our system can be applied as rapid urinalysis for routine check-ups.

RhIr@MoS2 nanohybrids based disposable microsensor for the point-of-care testing of NADH in real human serum

Dihydronicotinamide adenine dinucleotide(NADH)is an important enzyme in all living cells,which is found to be abnormally expressed in cancer cells.Since it is redox-active,an electrochemical detection method would be suitable for monitoring its concentration in biological fluids.Here we present a strategy for specific determination of NADH in real human serum by using RhIr@MoS2 nanohybrids based microsensor.To implement the protocol,RhIr nanocrysrals are in-situ grown onto MoS2 interlayers forming a nanohybrid structure(RhIr@MoS2).After being locally deposited on an electrochemical microsensor,it could be used for the analysis of NADH.The developed RhIr@MoS2 nanohybrids based microsensor possesses the ability for analyzing NADH at the applied potential of 0.07 V(much lower than most reported values).The detection limit is evaluated as low as 1 nmol/L even in bovine serum albumin(BSA)media.In addition,the sampling analysis of human serum from cancer patients and health controls shows that the microsensor displays good diagnostic sensitivity and specificity,illustrating that this developed detection technique is a relatively accurate method for measuring NADH in biological fluids.The proposed electrochemical microsensor assay also owns the benefits of convenience,disposable and easy processing,which make it a great possibility for future point-of-care cancer diagnosis.

Scalable Methods for Device Patterning as an Outstanding Challenge in Translating Paper-Based Microfluidics from the Academic Benchtop to the Point-of-Care

Paper-based microfluidic devices offer unparalleled adaptability for the development of low-cost,point-of-care analytical tests.The potential for these devices to drastically improve access to healthcare around the globe is obvious,but very few tests have found success in clinical environments.Here,we identify manufacturing-specifically,methods to pattern paper devices at large scales-as a major barrier to translating prototype paper-based devices from the academic benchtop to the field.We introduce current methods used to pattern papers and discuss their utility as means to prototype and manufacture paper-based devices.

An integrative review on the applications of 3D printing in the field of in vitro diagnostics

Biomedicine is one of the fastest growing areas of additive manufacturing.Especially,in the field of in vitro diagnostics(IVD),contributions of 3D printing include i)rapid prototyping and iterative IVD proof-of-concept designing ranging from materials,devices to system integration;ii)conceptual design simpli-fication and improved practicality of IVD products;iii)shifting the IVD applications from centralized labs to point-of-care testing(POCT).In this review,the latest developments of 3D printing and its advantages in IVD applications are summarized.A series of 3D-printed objects for IVD applications,including single-function modules,multi-function devices which integrate several single-function modules for specific an-alytical applications such as sample pre-treatment and chemo-/bio-sensing,and all-in-one systems which integrate multi-function devices and the instrument operating them,are analyzed from the perspective of functional integration.The current and potential commercial applications of 3D-printed objects in the IVD field are highlighted.The features of 3D printing,especially rapid prototyping and low start-up,en-able the easy fabrication of bespoke modules,devices and systems for a range of analytical applications,and broadens the commercial IVD prospects.

Literature Review of the Use of Zinc and Zinc Compounds in Paper-Based Microfluidic Devices

Zinc and its compounds, alloys and composites play an important role in the modern day world and find application in almost every aspect that can improve the quality of our lives. This ranges from supplements and pharmaceuticals that are meant to improve our health and wellbeing to additives meant to guard or reduce corrosion in metals. However, over the past several years, a new area of technology has been garnering a great deal of attention and has made use of zinc and its compounds. This is with reference to paper-based microfluidic technology that offers several advantages and that keeps expanding in the amount of applications it covers. In this paper, a review is offered for the applications that have used zinc or zinc compounds in paper-based microfluidic devices.

A scoping review on the field validation and implementation of rapid diagnostic tests for vector-borne and other infectious diseases of poverty in urban areas

Background:Health personnel face challenges in diagnosing vector-borne and other diseases of poverty in urban settings.There is a need to know what rapid diagnostic technologies are available,have been properly assessed,and are being implemented to improve control of these diseases in the urban context.This paper characterizes evidence on the field validation and implementation in urban areas of rapid diagnostics for vector-borne diseases and other diseases of poverty.Main body:A scoping review was conducted.Peer-reviewed and grey literature were searched using terms describing the targeted infectious diseases,diagnostics evaluations,rapid tests,and urban setting.The review was limited to studies published between 2000 and 2016 in English,Spanish,French,and Portuguese.Inclusion and exclusion criteria were refined post hoc to identify relevant literature regardless of study design and geography.A total of 179 documents of the 7806 initially screened were included in the analysis.Malaria(n=100)and tuberculosis(n=47)accounted for the majority of studies that reported diagnostics performance,impact,and implementation outcomes.Fewer studies,assessing mainly performance,were identified for visceral leishmaniasis(n=9),filariasis and leptospirosis(each n=5),enteric fever and schistosomiasis(each n=3),dengue and leprosy(each n=2),and Chagas disease,human African trypanosomiasis,and cholera(each n=1).Reported sensitivity of rapid tests was variable depending on several factors.Overall,specificities were high(>80%),except for schistosomiasis and cholera.Impact and implementation outcomes,mainly acceptability and cost,followed by adoption,feasibility,and sustainability of rapid tests are being evaluated in the field.Challenges to implementing rapid tests range from cultural to technical and administrative issues.Conclusions:Rapid diagnostic tests for vector-borne and other diseases of poverty are being used in the urban context with demonstrated impact on case detection.However,most evidence comes from malaria rapid diagnostics,with variable results.While rapid tests for tuberculosis and visceral leishmaniasis require further implementation studies,more evidence on performance of current tests or development of new alternatives is needed for dengue,Chagas disease,filariasis,leptospirosis,enteric fever,human African trypanosomiasis,schistosomiasis and cholera.

Diagnostic assays for COVID-19:a narrative review

Coronavirus disease 2019(COVID-19)is a newly emerged infectious disease caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).The number of COVID-19 cases is continuously increasing and no effective drugs or vaccines are currently available.Accurate and efficient diagnostic testing methods are desperately needed for the detection of SARS-CoV-2 and antiviral antibodies in infected individuals.Various assay techniques,including nucleic acid tests[eg,polymerase chain reaction(PCR),reverse transcription-PCR,real-time loop-mediated isothermal amplification,and CRISPR-Cas-based detection],serological tests[eg,immunoglobulin(Ig)A,IgM/G],imaging tests(eg,computed tomography and positron-emission tomography),and nanoparticle-based detections have been reported for COVID-19 diagnosis.This review aims to present the current diagnostic tools for SARS-CoV-2 and their performance characteristics to inform the appropriate selection of diagnostic and surveillance technologies at optimal testing times.We also describe the advantages of detection using combined nucleic acid and imaging tests,or serological testing and point-of-care diagnostics.Developing reliable protein biomarkers targeting the conserved proteins of SARS-CoV-2 rather than IgA,IgM,or IgG would be useful to manage SARS-CoV-2.

Ultrafast photonic PCR

Nucleic acid amplification and quantification via polymerase chain reaction(PCR)is one of the most sensitive and powerful tools for clinical laboratories,precision medicine,personalized medicine,agricultural science,forensic science and environmental science.Ultrafast multiplex PCR,characterized by low power consumption,compact size and simple operation,is ideal for timely diagnosis at the point-of-care(POC).Although several fast/ultrafast PCR methods have been proposed,the use of a simple and robust PCR thermal cycler remains challenging for POC testing.Here,we present an ultrafast photonic PCR method using plasmonic photothermal light-to-heat conversion via photon–electron–phonon coupling.We demonstrate an efficient photonic heat converter using a thin gold(Au)film due to its plasmon-assisted high optical absorption(approximately 65%at 450 nm,the peak wavelength of heat source light-emitting diodes(LEDs)).The plasmon-excited Au film is capable of rapidly heating the surrounding solution to over 150℃ within 3 min.Using this method,ultrafast thermal cycling(30 cycles;heating and cooling rate of 12.7960.93℃ s^(-1) and 6.660.29℃ s^(-1),respectively)from 55℃(temperature of annealing)to 95℃(temperature of denaturation)is accomplished within 5 min.Using photonic PCR thermal cycles,we demonstrate here successful nucleic acid(λ-DNA)amplification.Our simple,robust and low cost approach to ultrafast PCR using an efficient photonic-based heating procedure could be generally integrated into a variety of devices or procedures,including on-chip thermal lysis and heating for isothermal amplifications.

High-fidelity replication of thermoplastic microneedles with open microfluidic channels

Development of microneedles for unskilled and painless collection of blood or drug delivery addresses the quality of healthcare through early intervention at point-of-care.Microneedles with submicron to millimeter features have been fabricated from materials such as metals,silicon,and polymers by subtractive machining or etching.However,to date,large-scale manufacture of hollow microneedles has been limited by the cost and complexity of microfabrication techniques.This paper reports a novel manufacturing method that may overcome the complexity of hollow microneedle fabrication.Prototype microneedles with open microfluidic channels are fabricated by laser stereolithography.Thermoplastic replicas are manufactured from these templates by soft-embossing with high fidelity at submicron resolution.The manufacturing advantages are(a)direct printing from computeraided design(CAD)drawing without the constraints imposed by subtractive machining or etching processes,(b)high-fidelity replication of prototype geometries with multiple reuses of elastomeric molds,(c)shorter manufacturing time compared to three-dimensional stereolithography,and(d)integration of microneedles with open-channel microfluidics.Future work will address development of open-channel microfluidics for drug delivery,fluid sampling and analysis.