Internet‐of‐medical‐things integrated point‐of‐care biosensing devices for infectious diseases: Toward better preparedness for futuristic pandemics

Abstract Microbial pathogens have threatened the world due to their pathogenicity and ability to spread in communities. The conventional laboratory‐based diagnostics of microbes such as bacteria and viruses need bulky expensive experimental instruments and skilled personnel which limits their usage in resource‐limited settings. The biosensors‐based point‐of‐care (POC) diagnostics have shown huge potential to detect microbial pathogens in a faster, cost‐effective, and user‐friendly manner. The use of various transducers such as electrochemical and optical along with microfluidic integrated biosensors further enhances the sensitivity and selectivity of detection. Additionally, microfluidic‐based biosensors offer the advantages of multiplexed detection of analyte and the ability to deal with nanoliters volume of fluid in an integrated portable platform. In the present review, we discussed the design and fabrication of POCT devices for the detection of microbial pathogens which include bacteria, viruses, fungi, and parasites. The electrochemical techniques and current advances in this field in terms of integrated electrochemical platforms that include mainly microfluidic‐ based approaches and smartphone and Internet‐of‐things (IoT) and Internet‐of‐Medical‐Things (IoMT) integrated systems have been highlighted. Further, the availability of commercial biosensors for the detection of microbial pathogens will be briefed. In the end, the challenges while fabrication of POC biosensors and expected future advances in the field of biosensing have been discussed. The integrated biosensor‐based platforms with the IoT/IoMT usually collect the data to track the community spread of infectious diseases which would be beneficial in terms of better preparedness for current and futuristic pandemics and is expected to prevent social and economic losses.

and Internet-of-Medical-Things (IoMT) integrated systems have been highlighted.
Further, the availability of commercial biosensors for the detection of microbial pathogens will be briefed. In the end, the challenges while fabrication of POC biosensors and expected future advances in the field of biosensing have been discussed. The integrated biosensor-based platforms with the IoT/IoMT usually collect the data to track the community spread of infectious diseases which would be beneficial in terms of better preparedness for current and futuristic pandemics and is expected to prevent social and economic losses.

| INTRODUCTION
Any deviation from a condition of good health and well-being caused by infectious agents is called infectious disease. Infectious agents include pathogenic microorganisms such as bacteria, fungi, viruses, or parasites. 1 Infectious diseases may be spread directly or indirectly from one person to another. The spread of infectious diseases usually occurs when the infected person during their incubation period touches, coughs or sneezes near someone who is not infected or exchanges body fluids while having sexual contact. 2 The incubation period is the period during which the infected person can infect the non-infected, healthy individuals. 3 Sometimes, the infected person may not show the symptoms but can infect healthy individuals. 4 Another direct spread of infectious diseases occurs from mothers to their children either through the placenta for the unborn child or through breast milk. 5 The indirect transmission of infectious diseases occurs if the microorganism remains on physical objects such as doorknobs. When an infected person touches the object, they left germs that in contact with the healthy person can cause infection. 6 Infectious diseases are also spread indirectly via vectors, the most common vector is the mosquito. The mosquito can cause and spread the diseases such as dengue, and malaria. 7,8 Zoonotic diseases have also come under infectious diseases. Zoonotic diseases are animal diseases which when transmitted to humans can cause infectious diseases.
Some of the zoonotic diseases include rabies, toxoplasmosis, leptospirosis, campylobacter, and swine flu. An estimation of 60% of infectious diseases is zoonotic diseases. 9,10 Pandemics caused due various infectious diseases are always a concern. In the past, bacterial pandemics have caused a lot of calamities. Cholera was one of the most concerned bacterial infections. The first cholera pandemic was caused in 1817, which was followed by the second, third, and many cholera pandemics till now. 11 The fleaborne bacteria Yersinia pestis, which caused the third plague, the Black Death, and at least three more human plague pandemics, is what causes plague (Zietz and Dunkelberg, 2004). Furthermore, a sizable section of the population is increasingly becoming concerned about their health due to the spread of various infectious diseases (such as malaria, cholera, and tuberculosis) to wide geographic areas. 11 Infectious organisms, such as Yersinia pestis, Bacillus anthracis, and the variola virus, have the potential to be employed as bioweapons and pose a threat to humanity. Contrary to this, the effects of specific fungal diseases on human health are significant and each year, there are over 220,000 new cases of cryptococcal meningitis worldwide, which cause 181,000 deaths, mostly in sub-Saharan Africa. More than 400,000 people get Pneumocystis pneumonia and pass away without receiving treatment. One of the most prevalent opportunistic fungal diseases among HIV/AIDS patients in Latin America is histoplasmosis, which causes death in about 30%. Morbidity rates associated with fungus infections are therefore a significant health concern worldwide. 12 The new coronavirus disease    13 In history, no other viral disease has caused this much threat to human beings. [14][15][16][17][18] The other pandemics that occurred in the past years include the 1918 influenza pandemic, behavior like maintaining hygiene and sanitation, using condoms, using masks, healthy diets, taking vaccines, and proper medications. [19][20][21] The infectious agents invade the healthy organism through the direct and indirect routes as described. Upon the invasion of the microbial agents, the organism's immune system fights the infection and protects the organism. There are two types of immunity that play role in human organisms, namely innate and adaptive immunity. Innate immunity is germline-encoded, so keeps invariable throughout the person's lifespan. 22 Natural killer cells are lymphoid cell that is innate and facilitates the recognition of the infection. In contrast to birth-innate immunity, adaptive immunity is generated by somatic cell line mutations and reorganizations. This type of immunity allows the generation of memory of the encounters made after birth and protects individuals throughout their life span. T and B cells are the two types of adaptive immunity-associated receptors. B cells secrets the immunoglobulins, which protect the organisms from foreign attacks. 23 The innate and adaptive responses that occur due to infection are termed cytokines. Normally, a sprinkling of cytokine is enough to protect from the infection, but when it overflows due to excessive production, can spread to the whole body. The flood of cytokines that happens upon the infection is termed a cytokine storm. Excessive production of cytokines once starts is very complex to control. It can cause disturbance of physiologic functions, can cause shock, and can even reach the stage of death. For the prevention, early diagnosis can prevent the cytokine storm. [24][25][26] A person with weaker immunity is more likely to be infected by the disease. The weaker immunity can be because of age, drugs, or some other diseases like diabetes, obesity, etc. The period between the infection and the onset of symptoms is known as the incubation period, various pathogens have different incubation periods. The symptoms may be very mild to very severe symptoms. In some cases, the disease may be asymptomatic also. 27 The diseases last until the infection lingers or the person dies. The infectious diseases can be grouped into three categories, first, the diseases which can cause a high number of deaths, second the ones which can cause a high number of individuals with disabilities, and third the severe ones which can spread rapidly and cause serious global problem. 28 Out of these controlling methods, the source of infection is the most important. The source of the infection can be controlled by early detection, early isolation of the infected from the non-infected, and early treatment. For fulfilling the above-stated demand, there is a need for rapid, accurate, sensitive, and economical detection methods. 21 The conventional techniques used for the identification and detection of various strains of pathogens mainly involve culture techniques, CT scan, ELISA, serological testing, PCR, chromatographic techniques, etc. These conventional techniques are time-consuming, required sophisticated instruments, and need trained personnel. 29 Due to the delayed diagnosis, there is a risk of the spread of infectious diseases from the infected ones to the non-infected ones. The limitations of conventional techniques need to be addressed properly. With the advent of advanced biosensing approaches the loop whole of conventional diagnostic modalities can be taken care off.
Biosensors are powerful analytical tools, having the potential for application to a wide range of analytes ranging from environmental contaminants to drug discovery, and medical diagnostics to security and defenses. The biosensor combines a bio-sensitive element also called biorecognition elements with the physicochemical transducer which is connected to a detector for the detection of specific analytes. Biosensors are economical, reliable, favorable, easy to use and portable devices with high sensitivity, and selectivity and are specific to the target analyte. [30][31][32] Based on the recent advances in microbial sensing, electrochemical, optical, and microfluidics-based techniques are gaining much attention. 33 The electrochemical techniques are an electroanalytical method of analysis that studies the electrochemical behavior of the materials used to modify the electrode conductive surface. In electrochemicalbased detection, when the specific analyte binds to the biorecognition element, it generated electrical signals, these electrical signals are then converted to quantifiable results with the help of transducers which monitor the amount of analyte present. 22,34,35 Electrochemical method of analysis includes potentiometry, amperometry, and voltammetry. 36,37 The optical method of analysis includes techniques like surface plasmon resonance, interferometers, ring-resonators, fiberoptics photonic crystals, and planar optical waveguides. Optical biosensors track and recognize analytes by the calculation of complete reflection which senses the change in the absorbance, fluorescence, polarization, luminescence, refractive index, etc. 19,38 Microfluidics technology deals with a very little volume of samples and reagents which is why most suitable for disease diagnosis. 39 A microfluidicsbased biosensor is an on-chip detection that allows the detection system to be portable, disposable, and applicable for real-time detection and can be easily integrated with any of the transducers like optical and electrochemical. 40 Microfluidics-based systems are speedy, economical, give high throughput, and are portable. 41 However, the miniaturization of these biosensing platforms is a challenging task that needs special attention. Recently, portable point-of-care testing (POCT) devices have gained much attention in monitoring infectious diseases. 42 The POCT devices enable rapid and early detection of diseases which can further help in early treatment and can save lives.
There is considerable attention in the scientific community to the detection of microbial pathogens using optical, electrochemical, and microfluidic devices (Figure 1a) which is very well reflected by several published papers for biosensor-based detection of bacteria, viruses, and fungi ( Figure 1b). The commercial market of biosensor-based diagnostics for infectious agents gaining sufficient momentum (Figure 1c).
The integration of these devices with the internet-of-things (IoT), internet-of-medical-things (IoMT) and artificial intelligence (AI) can serve to monitor diseases with one click. [43][44][45] The IoT is a smart solution to disease tracking and monitoring. The IoT can enable real-time monitoring of diseases and can warn the public all around the globe. 46 The IoT-based devices can perform multiple tasks such as tracking the spread of disease, monitoring and responding to public healthcare, and can also use to implement effective preventive and curative measures. The AI-integrated devices may serve many purposes like material innovation, receptors examination, signal acquisition and its transportation, processing of the data, and also the decision system. 47 Owing to the advantages of electrochemical biosensors and their integrated platform in terms of rapid, ultra-low detection limit and cost-effectiveness, the design and construction of electrochemical and microfluidic biosensors for detecting microbial pathogens such as bacteria, viruses, fungus, and parasites are reviewed in this study. Biosensors integrated with the IoT and the IoMT---to collect data to track the spread of infectious illnesses in communities have been discussed. In the end, the difficulties encountered during the manufacture of POC biosensors were explored, as well as anticipated future improvements in the field of biosensing.

| PAST, PRESENT, AND FUTURE OF BIOSENSORS FOR INFECTIOUS DISEASES DIAGNOSTICS
Biosensors are diagnostic devices that can detect many biomolecules, they are frequently utilized for the detection of clinical pathogens like bacteria and viruses, with excellent results. 48 Clark and Lyons initially addressed the biosensor idea in 1962 when they built an oxidase enzyme electrode for glucose detection. 49 In biosensors for bacterial detection, biological recognition components such as receptors, nucleic acids, or antibodies are normally in intimate contact with an appropriate transducer. 50 Biosensors are classified into four categories based on the manner of signal transmission: optical, piezoelectric, electrochemical, and microfluidic ( Figure 2). With the discovery of different micro-organisms that are present in the environment and responsible for health issues in populations around the globe, various detection techniques and bio-sensing devices were emerging. 48,50,51 Biosensors have sparked scientific study to improve the development of biosensor technologies that can transcend traditional in vitro diagnostics for illness diagnosis and health monitoring, owing to their enormous potential in medical diagnostics. 52 A historical perspective and breakthrough discoveries in the field of development of Biosensors for the detection of microbes have been illustrated in Figure 2. In the 1980s, Conventional diagnostic techniques are well established as gold standards for the diagnosis of many infectious diseases. 53 A technique was developed which used a thin culture medium film-coated quartz crystal microbalance (QCM) sensor.
The Quartz Crystal Microbalance (QCM) is a highly sensitive mass balance that analyzes changes in mass per unit area at the nanogram to microgram level. Quartz is a piezoelectric substance that can be induced to oscillate at a certain frequency by providing a suitable voltage, often via metal electrodes. 54 This type of biosensor has a low F I G U R E 1 (a) Various microbial pathogens mediated disease diagnostic using optical, electrochemical, and microfluidic devices and their advantageous implication. (b) Several published papers for biosensor-based detection of bacteria, viruses, and fungi (Data was obtained from "Web of Science" with "Biosensor for detection of bacteria, virus, fungi" entered as "Subject" in the search box [last access date: May 4, 2022]). (c) commercial market of biosensor-based diagnostics for infectious agents. sensitivity, which prevents it from directly detecting tiny molecules.
Instead, signal amplification is needed since a relatively high mass must be bound to produce a detectable change in signal. 55,56 Fiber optic (FO) biosensors are another type of biosensor that has been the subject of intense research since the early 1980s, owing to their potential sensitivity, detection speed, and flexibility to a wide range of assay conditions. 57 The field of optical fiber biosensors is fairly broad, with several applications that have been documented in the literature, mostly through the use of evanescent wave detection. 58 The exponential advancement in micro and nano-level technologies leads to a new era for pathogenic detection techniques. In the 1990s, opticalbased biosensors were advancing, one of the literature reported, that a reusable Bulk Acoustic Wave (BAW)-Impedance sensor has been created for continuous monitoring of Proteus Vulgaris development and numbers on the surface of a solid medium. 59 One of the reported sensors is based on bacteria converting electron-deficient or weakly charged substrates into highly charged end products, resulting in a change in medium conductance. 60 Optical transducers are particularly appealing for use in direct (label-free) bacterium identification. When cells connect to receptors placed on the transducer surface, these sensors may detect minute changes in refractive index or thickness. composed of (100) silicon with a 2m insulating layer of thermal oxide, and it measured a change in impedance caused by bacteria trapped on interdigitated gold electrodes.
For producing the biological sensing surface, antibodies specific to Escherichia coli (E.Coli) were adsorbed on the oxide between the electrodes. 72 Another group of researchers demonstrates that single- In past decades, microfluidic paper-based analytical devices (μ-PADs) were the new type of POC diagnostic gadget. Paper is lightweight, thin, flexible, combustible (disposable), compatible with biological samples, and chemically modifiable in the 2010s. Hydrophobic barriers establish microfluidic channels, which are patterned by infusing paper with photoresist and subjecting them to UV light. 77 Other than microfluidic-based biosensors, nucleic acid hybridization-based biosensors were also being developed for pathogens such as E. coli and Mycobacterium tuberculosis. A wide range of microorganisms has been detected using bioluminescence systems. 78 An electrochemical sensor based on graphene oxide polymers imprinted for Zika virus (ZIKV) detection was developed by one of the research groups, the biosensor was utilized to detect by monitoring changes in the electrical signal with varying viral amounts in buffer and serum. Our approach's detection limit is comparable to that of the real-time quantified reverse transcription PCR method. 79 Nowadays, infections are among the most catastrophic natural catastrophes, having a significant influence on global well-being (in terms of severe morbidity and death) as well as economics. Presently, the pursuit of smart systems such as smart implants, prosthetics, and biosensors is obtaining focus because of their role in disease management and control, rehabilitation, and other post-surgical operations. 80 The use of nano-chips, nano-sensors, and nano-robots in smart sensing and monitoring systems has the potential to monitor vital signs, drug medication, and the identification of infections linked to illnesses. 81 Chemo-metrics is essential in biosensor detection, analysis, and diagnosis. In recent years machine learning (ML) has made substantial advancements in the discipline of AI. However, innovative advanced ML approaches, particularly deep learning, which is well-known for image analysis, facial recognition, and speech recognition, have remained elusive to the biosensor community. 82 While taking potential and advances into account with AI to manage an earmarked infectious disease. Smart biosensors have the potential to aid physicians in monitoring and predicting illnesses for early intervention by sensing important parameters. 47,68,83,84 The artificial intelligence-powered biosensor takes physiological and other data from patients' wearable biosensors and uses AI or ML algorithms to identify changes in their important signal patterns. 83 IoMT-assisted sophisticated biosensors infection. 47 The combination of smartphones and nanotechnology has created smart nanosensors that might help the general population utilize a smartphone as colorimetric, fluorimetric, and electrochemical sensors. 84 Using augmented reality which is critical for the diagnosis of COVID-19, a paper-based plasmonic biosensor linked with a smartphone was constructed for the automated detection of interleukin 16. 85 The smartphones are used to identify colorimetric and fluorimetric changes, which are imaged and analyzed using a smartphone camera and a standalone android application, They can also detect electrochemical alterations, which are analyzed by using a smartphone camera and CMOS detectors for further data interpretation and communication. 85

| RECENT ADVANCES IN MICROBIAL SENSING
In the last decade, the science of biosensing has seen tremendous progress in illness diagnostics. 90 is their limited level of multiplexing, which is referred to as the total number of sequences (or strains) that can be identified in a single reaction. 96 The second issue is their inability to detect single-nucleotide polymorphisms (SNPs) or other alterations/mutations due to their low resolution and precision. However, it is possible to examine localized sequence alterations (usually 3-6 nucleotides) using allele-specific primers or fluorophore-labeled probes, however, the exact base change and the precise coordinate cannot be obtained with high confidence. 97 The limitations of these techniques can be well tackled using advanced biosensors which include electrochemical, and microfluidic-based platforms, which provide cost-effective, ultra-highly sensitive, and selective detection of target analyte within a limited time frame. The details of electrochemical, and microfluidic-based POCT for infectious disease diagnostics will be discussed in the next section.

| Electrochemical-based microbial biosensors
The detection of biomolecules via biosensors requires a chemical recognition element that captures the target analyte and the chemical energy from the biological interactions/chemical reactions would then be translated into electrical energy via a physio-chemical transducer.
Further, this signal needs to be sent to a detector for signal processing and analysis. In the case of an electrochemical biosensor, an electrochemical transducer is used on a chemically modified electrode that combines with a biological analyte for selective detection of a target analyte. 98,99 Among the numerous merits of electrochemical biosensors, the ability of high sensitivity, low detection limit, portability, high stability, ease of operation, and high-throughput diagnostics which are most demanding in recent times for POCT. Microbial diseases encompass either viruses, bacteria, parasites, or fungi which are of huge interest owing to their high mortality rate and severity.
POCT is a fundamental requirement for an early diagnosis for diseases concerning contact and non-contact-based transmissions. The screening and diagnosis of the patients need to make localized and personalized enabling better and faster management prospects. Figure 3a represents the linking between electrochemical-based POC platforms and monitoring methods that helps report disease statistics throughout an outbreak situation.   In a recent study, Lee et al. 117  aureus. The catalytic activity of nanoenzyme-based immunosensor was studied, along with its electrochemical parameter optimization for time, pH, temperature as well as different vancomycin concentrations.
The results revealed the LOD of the sensor to be six colony-forming units CFU ml À1 in the detection range of 10-7.5 Â 10 7 CFU ml À1 .
The MOF nanoenzyme-assisted detection of S. aureus is presented in used as detection probes. The aptasensor showed linear detection in the range of 1 Â 10 À3 to 10 ng ml À1 and 1 Â 10 À3 to 1 Â 10 2 ng ml À1 , and LOD of 5 Â 10 À4 ng ml À1 for ZEN and FB1, respectively. The results were validated in real maize samples as well.

| Detection of the parasite by electrochemical biosensors
Fabrication of electrochemical biosensors for detection of parasitic infection gained considerable attention due to added advantages. The diverse    high loading of bacteria even in the large volume of the samples.
Hence, it improved the sensitivity and detection limit. It was found that the proposed assay has excellent detection for E. coli, with concentrations ranging from 5 to 5000 CFU ml À1 . Furthermore, it takes minimum loading and detection time which could serve as an alternative biosensor as compared with the other time-consuming methods. 164  The more capturing of fungus enhances the sensitivity of the assay.
The proposed assay is cost-effective, portable, equipment-free, and required minimal process to perform the detection as compared with conventional methods. 168 In another report, Bras et al. estimated the elevated level of three acids such as salicylic acid, azelaic acid, and jasmonic acid against two fungal pathogens, Botrytis cinerea and Erysiphe necator on a microfluidic device within 7 min in grape and their other products. Since, salicylic acid, azelaic acid, and jasmonic acid are produced in plants against fungal diseases in response to protect them or to fight against the disease. So, the estimation of these acids is the key indicator to knowing about the specific fungal disease. Herein, these three acids were detected using different strategies. Firstly, salicylic acid is detected by the analysis of the shifting of absorbance, when salicylic acid binds to amine-functionalized-TiO 2 . Table 2     The developed model can help identification and monitoring infected individuals or suspect before the spread of infectious disease, as well as analysis of diseases in specific geographical area and countries. 178 This will enable an early containment and prevention system based on disease outbreaks. The prediction of infectious agent transmission and spread as well as early warning systems for diseases, which provides comprehensive information on pathogen emergence that reflects national and international features could pave the way toward prevention of futuristic pandemics.  187 Aside from the psychological strain of the examination, the patient must be assured that the results will not be accessible to third parties. Indeed, a data security breach might result in a significant rise in the expense of health care and life insurance, as well as job discrimination. As a result, it is evident that to successfully undertake a large-scale illness detection program, a strong socioeconomic foundation is required, which can be fulfilled by using additive manufacturing. 188,189 Chemists and chemical biologists can contribute significantly to the development of biosensing devices against infectious agents which include bacteria, viruses, fungi, and parasites. We still have a lot to learn about the microbial population, their genetics, biochemical pathways, and the mode of interactions with receptors of biological cells. Researchers can use chemical knowledge to link microbial activity to genes and enzymes. At the signaling pathway level, small molecule probes are being produced and utilized to explore microbiota-immune system interactions. Researchers can use chemical knowledge to link microbial activity to genes and enzymes and hence use it to discover particular microbial components that impact infections or the host immune system.

| OUTLOOK, CHALLENGES, AND PROSPECTS
To fully grasp the potential of biosensing techniques for treating and preventing infectious illnesses, we must solve the significant obstacles of changing the makeup and function of these complex communities. Chemists can assist in the development of nextgeneration biosensing strategies via novel material design, which possesses enhanced chemical functionality, high electroconductivity, enhanced surface area, and other tunable physicochemical properties.
In addition to their utility as tools, such chemicals may have therapeutic promise. Overall, our increased understanding of the processes underlying the host-pathogen interaction, along with new technologies for the fabrication of multiplexed, miniaturized, high throughput biosensing tools holds promises to enable innovative strategies to combat infectious disease, a major worldwide health burden.

| CONCLUSION
We must address the major challenges of manipulating the integrated systems and function of these complex devices to fully realize the potential of multiplexed, miniaturized biosensing POC strategies for preventing infectious diseases. Chemists can help develop next-generation approaches for nano-material manipulation for the fabrication and development of advanced biosensors, with enhanced sensitivity up to attomolar level and good reproducibility. Such nanomaterials may be the potential for medicinal development in addition to functioning as diagnostic systems. Overall, our growing understanding of the mechanisms behind microbial interaction with human receptors connections, together with emerging tools with the advent of sample manipulation, promises to disclose and enable novel interventions to combat infectious disease, which is a major global health problem. Another unanswered question is how the demand and supply of medical POC diagnostic systems can be fulfilled.
The additive manufacturing-based 3D bioprinting of POC devices has potential in this regard. It will be crucial to figure out if POCT diagnostics play a role in identifying pathogenic versus nonpathogenic bacteria in the environment. There is still a lot to learn about the process of infection mechanism spread and the role of POCT in germ detection and bacterial defense. We attempted to unify different seemingly unrelated biosensing systems which include electrochemical and microfluidic POCT platforms in this review. The underlying concept, which requires the obstruction of an aperture through which a current is traveling by the analyte species, is the unifying aspect.
While the review started with a traditional and commercially available device, it quickly moved on to two fairly recent expressions of the POC sensing paradigm: electrochemical platforms for the detection of viruses, bacteria, fungi, and parasites. The relative benefits and drawbacks of different sensing techniques are worth considering. The capacity to detect an analyte signature via detecting single molecules as they move in and out of the POC system, as well as the ability to use protein engineering to construct a diversity of analyte binding sites in microfluidic channels, are two significant features of the microfluidic integrated approaches.
Furthermore, the advancement in nanomaterial synthetic sciences, on the other hand, has a crucial advantage in the fabrication of mechanically, thermally, and physically stable devices. Additionally, the interior core of the nanomaterial, as well as the chemical environment within the device, can be adjusted at a whim. It seems logical to assume that these two paradigms may be blended to provide a practical sensor that incorporates the best aspects of both. The future of stochastic sensing could be sensor elements that combine the benefits of nanomaterials and BREs into a single entity. Alternatively, functional groups or covalently bonded adapters could be used more efficiently. While these prospects are intriguing, protein engineering's versatility and precision are likely to continue to dominate the field for some time.