Nanobioimaging and sensing of infectious diseases

Immunochromatography Lateral Flow Strip Enhancement Based on Passive Gold Nanoparticles Conjugation to Detect Schistosma haematobium Antigens in Human Serum

PURPOSE

This study aimed to develop and evaluate a lateral flow card for the detection of active Schistosoma haematobium infection.

METHODS

In order to prepare the immunochromatography lateral flow strip (ICLFS), antibodies purified from schistosomiasis were conjugated passively with gold nanoparticles using a potassium carbonate buffer.

RESULTS

The novel ICLFS was able to correctly identify 64 out of 67 samples of schistosomiasis, 6 out of 90 samples of other parasites, and 0 out of 27 control samples. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) were 95.5%, 93.3%, 90%, and 91.4% respectively. Comparatively, the sensitivity, specificity, NPV, and PPV of sandwich enzyme-linked immunosorbent assays (ELISA) conjugated with gold nanoparticles (AuNPs) were 91.1%, 88.8%, 85.9%, and 84.4% respectively. The increased sensitivity and specificity of ICLFS produced superior results to those of sandwich ELISA.

CONCLUSION

In conclusion, ICLFS is more beneficial and precise than sandwich ELISA for detection of S. haematobium infection at early stage.

Recent advances in nanomaterial-based biosensor for periodontitis detection

Periodontitis, a chronic inflammatory condition caused by bacteria, often causes gradual destruction of the components that support teeth, such as the alveolar bone, cementum, periodontal ligament, and gingiva. This ultimately results in teeth becoming loose and eventually falling out. Timely identification has a crucial role in preventing and controlling its progression. Clinical measures are used to diagnose periodontitis. However, now, there is a hunt for alternative diagnostic and monitoring methods due to the progress of technology. Various biomarkers have been assessed using multiple bodily fluids as sample sources. Furthermore, conventional periodontal categorization factors do not provide significant insights into the present disease activity, severity and amount of tissue damage, future development, and responsiveness to treatment. In recent times, there has been a growing utilization of nanoparticle (NP)-based detection strategies to create quick and efficient detection assays. Every single one of these platforms leverages the distinct characteristics of NPs to identify periodontitis. Plasmonic NPs include metal NPs, quantum dots (QDs), carbon base NPs, and nanozymes, exceptionally potent light absorbers and scatterers. These find application in labeling, surface-enhanced spectroscopy, and color-changing sensors. Fluorescent NPs function as photostable and sensitive instruments capable of labeling various biological targets. This article presents a comprehensive summary of the latest developments in the effective utilization of various NPs to detect periodontitis.

Effect of Protein Corona on the Specificity and Efficacy of Nanobioconjugates to Treat Intracellular Infections

Encapsulating drugs into functionalized nanoparticles (NPs) is an alternative to reach the specific therapeutic target with lower doses. However, when the NPs are in contact with physiological media, proteins adsorb on their surfaces, forming a protein corona (PC) biomolecular layer, acquiring a distinct biological identity that alters their interactions with cells. Itraconazole (ITZ), an antifungal agent, is encapsulated into PEGylated and/or functionalized NPs with high specificity for macrophages. It is evaluated how the PC impacts their cell uptake and antifungal effect. The minimum inhibitory concentration and colony-forming unit assays demonstrate that encapsulated ITZ into poly(ethylene glycol) (PEG) NPs improves the antifungal effect compared with NPs lacking PEGylation. The improvement can be related to the synergistic effect of the encapsulated ITZ and NPs composition and the reduction of PC formation in PEG NPs. Functionalized NPs with anti-F4/80 and anti-MARCO antibodies, or mannose without PEG and treated with PC, show an improved uptake but, in the presence of PEG, significantly reduce the endocytosis, dominating the stealth effect from PEG. Therefore, the PC plays a crucial role in the nanosystem uptake and antifungal effects, which suggests the need for in vivo model studies to evaluate the effect of PC in the specificity and biodistribution.

Recent advances in nanobiosensors for sustainable healthcare applications: A systematic literature review

The need for novel healthcare treatments and drugs has increased due to the expanding human population, detection of newer diseases, and looming pandemics. The development of nanotechnology offers a platform for cutting-edge in vivo non-invasive monitoring and point-of-care-testing (POCT) for rehabilitative disease detection and management. The advancement and uses of nanobiosensors are currently becoming more common in a variety of scientific fields, such as environmental monitoring, food safety, biomedical, clinical, and sustainable healthcare sciences, since the advent of nanotechnology. The identification and detection of biological patterns connected to any type of disease (communicable or not) have been made possible in recent years by several sensing techniques utilizing nanotechnology concerning biosensors and nanobiosensors. In this work, 2218 articles are drawn and screened from six digital databases out of which 17 were shortlisted for this review by using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) technique. As a result, this study uses a systematic methodology to review some recently developed extremely sensitive nanobiosensors, along with their biomedical, point-of-care diagnostics (POCD), or healthcare applications and their capabilities, particularly for the prediction of some fatal diseases based on a few of the most recent publications. The potential of nanobiosensors for medicinal, therapeutic, or other sustainable healthcare applications, notably for ailments diagnostics, is also recognized as a way forward in the manifestation of future trends.

Nanoform of Phospholipid Composition: Investigation of the Morphological Features by Atomic Force Microscopy

Morphological features of the nanoform of a phospholipid composition (NFPh), which can be used as an individual pharmaceutic agent or as a platform for designing drug delivery systems, have been studied using atomic force microscopy (AFM). NFPh has been developed, and its characteristics have been investigated using conventional drug analysis methods, including the determination of the mean diameter of nanosized vesicles in the emulsion via dynamic light scattering (DLS). Using DLS, the mean diameter of the vesicles was found to be ~20 nm. AFM imaging of the surface has revealed four types of objects related to NFPh: (1) compact objects; (2) layer fragments; (3) lamellar structures; and (4) combined objects containing the compact and extended parts. For type (4) objects, it has been found that the geometric ratio of the volume of the convex part to the total area of the entire object is constant. It has been proposed that these objects formed owing to fusion of vesicles of the same size (with the same surface-to-volume ratio). It has been shown that this is possible for vesicles with diameters of 20 nm. This diameter is in good coincidence with the value obtained using DLS.

Metallic Nanoparticles and Core-Shell Nanosystems in the Treatment, Diagnosis, and Prevention of Parasitic Diseases

The usage of nanotechnology in the fight against parasitic diseases is in the early stages of development, but it brings hopes that this new field will provide a solution to target the early stages of parasitosis, compensate for the lack of vaccines for most parasitic diseases, and also provide new treatment options for diseases in which parasites show increased resistance to current drugs. The huge physicochemical diversity of nanomaterials developed so far, mainly for antibacterial and anti-cancer therapies, requires additional studies to determine their antiparasitic potential. When designing metallic nanoparticles (MeNPs) and specific nanosystems, such as complexes of MeNPs, with the shell of attached drugs, several physicochemical properties need to be considered. The most important are: size, shape, surface charge, type of surfactants that control their dispersion, and shell molecules that should assure specific molecular interaction with targeted molecules of parasites' cells. Therefore, it can be expected that the development of antiparasitic drugs using strategies provided by nanotechnology and the use of nanomaterials for diagnostic purposes will soon provide new and effective methods of antiparasitic therapy and effective diagnostic tools that will improve the prevention and reduce the morbidity and mortality caused by these diseases.

Recent progress of emitting long-wavelength carbon dots and their merits for visualization tracking, target delivery and theranostics

As a novel strategy for in vivo visualization tracking and monitoring, carbon dots (CDs) emitting long wavelengths (LW, 600-950 nm) have received tremendous attention due to their deep tissue penetration, low photon scattering, satisfactory contrast resolution and high signal-to-background ratios. Although, the mechanism of CDs emitting LW remains controversial and what properties are best for in vivo visualization have not been specifically elucidated, it is more conducive to the in vivo application of LW-CDs through rational design and ingenious synthesis based on the appreciation of the luminescence mechanism. Therefore, this review analyzes the current tracer technologies applied in vivo and their advantages and disadvantages, with emphasis on the physical mechanism of emitting LW fluorescence for in vivo imaging. Subsequently, the general properties and merits of LW-CDs for tracking and imaging are summarized. More importantly, the factors affecting the synthesis of LW-CDs and its luminescence mechanism are highlighted. Simultaneously, the application of LW-CDs for disease diagnosis, integration of diagnosis and therapy are summarized. Finally, the bottlenecks and possible future directions of LW-CDs in visualization tracking and imaging in vivo are detailly discussed.

Integration of DNA barcoding and nanotechnology in drug delivery

In recent years' development in nanotechnology utilization of DNA barcodes with potential benefit of nanoparticulate system is a hallmark for novel advancement in healthcare, biomedical and research sector. Interplay of biological barcoding with nanodimensional system encompasses innovative technologies to offer unique advantages of ultra-sensitivity, error-free, accuracy with minimal label reagents, and less time consumption in comparison to conventional techniques like ELISA, PCR, culture media, electrophoresis. DNA barcoding systems used as universal novel tool for identification and multiplex structural detection of proteins, DNAs, toxins, allergens, and nucleic acids of humans, viruses, animals, bacteria, plants as well as personalized treatment in ovarian cancer, AIDS-related Kaposi sarcoma, breast cancer and cardiovascular diseases. Barcoding tools offer substantial attention in drug delivery, in-vivo screening, gene transport for theranostics, bioimaging, and nano-biosensors applications. This review article outlines the recent advances in nano-mediated DNA barcodes to explore various applications in detection of cancer markers, tumor cells, pathogens, allergens, as theranostics, biological sensors, and plant authentication. Furthermore, it summarizes the diverse newer technologies such as bio-barcode amplification (BBA), Profiling Relative Inhibition Simultaneously in Mixtures (PRISM) and CRISPR-Cas9 gene knockout and their applications as sensors for detections of antigens, allergens, and other specimens.

Application of nano-antibiotics in the diagnosis and treatment of infectious diseases

Infectious diseases are the leading cause of death worldwide. Thus, nanotechnology provides an excellent opportunity to treat drug-resistant microbial infections. Numerous antibiotics have been used to inhibit the growth and kill of microbes, but the development of resistance and the emergence of side effects have severely limited the use of these agents. Due to the development of the nanotechnology, nanoparticles are widely used as antimicrobials. Silver and chitosan nanoparticles have antifungal, antiviral and antibacterial properties, and many studies confirm the antifungal properties of silver nanoparticles. Nowadays, the use of nanoparticles in the diagnosis and treatment of infectious diseases has developed due to less side effects and also the help of these particles in effective drug delivery to the target tissue. Liposomes are also used as carriers of drug delivery, genes, and modeling of cell membranes in both animals and humans. The ability of these liposomes to encapsulate large amounts of drugs, minimize unwanted side effects, high effectiveness and low toxicity has attracted the interest of researchers. This review article examines recent efforts by researchers to identify and treat infectious diseases using antimicrobial nanoparticles and drug nano-carriers.

Red-Emitting Latex Nanoparticles by Stepwise Entrapment of β-Diketonate Europium Complexes

The core-shell structure of poly(St-co-MAA) nanoparticles containing β-diketonate Eu³⁺ complexes were synthesized by a step-wise process. The β-diketonate Eu³⁺ complexes of Eu (TFTB)₂(MAA)P(Oct)₃ [europium (III); 4,4,4-Trifluoro-1-(2-thienyl)-1,3-butanedione = TFTB; trioctylphosphine = (P(Oct)₃); methacrylic acid = MAA] were incorporated to poly(St-co-MAA). The poly(St-co-MAA) has highly monodispersed with a size of 300 nm, and surface charges of the poly(St-co-MAA) are near to neutral. The narrow particle size distribution was due to the constant ionic strength of the polymerization medium. The activated carboxylic acid of poly(St-co-MAA) further chelated with europium complex and polymerize between acrylic groups of poly(St-co-MAA) and Eu(TFTB)₂(MAA)P(Oct)₃. The E_m spectra of europium complexes consist of multiple bands of E_m at 585, 597, 612 and 650 nm, which are assigned to ⁵D₀→⁷F_{J (J = 0-3)} transitions of Eu³⁺, respectively. The maximum E_m peak is at 621 nm, which indicates a strong red E_m characteristic associated with the electric dipole ⁵D₀→⁷F₂ transition of Eu³⁺ complexes. The cell-specific fluorescence of Eu(TFTB)₂(MAA)P(Oct)₃@poly(St-co-MAA) indicated endocytosis of Eu(TFTB)₂(MAA)P(Oct)₃@poly(St-co-MAA). There are fewer early apoptotic, late apoptotic and necrotic cells in each sample compared with live cells, regardless of the culture period. Eu(TFTB)₂(MAA)P(Oct)₃@poly(St-co-MAA) synthesized in this work can be excited in the full UV range with a maximum E_m at 619 nm. Moreover, these particles can substitute red luminescent organic dyes for intracellular trafficking and cellular imaging agents.

Measuring the refractive index and sub-nanometre surface functionalisation of nanoparticles in suspension

Direct measurements to determine the degree of surface coverage of nanoparticles by functional moieties are rare, with current strategies requiring a high level of expertise and expensive equipment. Here, a practical method to determine the ratio of the volume of the functionalisation layer to the particle volume based on measuring the refractive index of nanoparticles in suspension is proposed. As a proof of concept, this technique is applied to poly(methyl methacrylate) (PMMA) nanoparticles and semicrystalline carbon dots functionalised with different surface moieties, yielding refractive indices that are commensurate to those from previous literature and Mie theory. In doing so, it is demonstrated that this technique is able to optically detect differences in surface functionalisation or composition of nanometre-sized particles. This non-destructive and rapid method is well-suited for in situ industrial particle characterisation and biological applications.

Ultrasensitive Hypoxia Sensing at the Single-Molecule Level via Super-Resolution Quantum Dot-Linked Immunosandwich Assay

Activated hypoxia-inducible factor-1alpha (HIF-1α) plays an important role in the adaptive response of tumor cells to oxygen changes through the transcriptional activation of genes that regulate important biological processes required for tumor survival and progression. In this study, we developed an ultrasensitive hypoxia sensor based on read-out with quantum dots on a gold nanodisc (quantum dot-linked immunosandwich assay, QLISA) with excellent selectivity for HIF-1α. The immunoassay platform was established by comparing the immune response results using Qdot525 as a detection nanoprobe instead of a fluorescent dye (Alexa488) (fluorescent-linked immunosandwich assay, FLISA). In addition, using three-dimensional total internal reflection fluorescence microscopy, the platform was optically sectioned along the z-axis at 10 nm intervals to compare the height difference between the nanodisc and the nanoprobe following the QLISA and FLISA procedures and to localize the target location. Here, the super-resolution QLISA (srQLISA)-based hypoxia sensor exhibited high accuracy and precision for the detection of HIF-1α-extracted samples in cancer spheroids compared with the super-resolution FLISA (srFLISA) method. The developed nanobiosensor method demonstrated a wide dynamic linear detection range of 32.2 zM-8.0 pM with a limit of detection of 16 zM under optimal experimental conditions for HIF-1α, an approximate 10⁶-fold enhanced detection sensitivity compared with the conventional enzyme-linked immunosorbent assay method based on absorbance. The detection of HIF-1α using the newly developed srQLISA sensor allows for independently predicting tumor progression and early cancer onset increases in the microvasculature density of tumor lesions.

Small variations in reaction conditions tune carbon dot fluorescence

The development of robust and reproducible synthetic strategies for the production of carbon dots (CDs) with improved fluorescence quantum yields and distinct emission profiles is of great relevance given the vast range of applications of CDs. The fundamental understanding at a molecular level of their formation mechanism, chemical structure and how these parameters are correlated to their photoluminescence (PL) properties is thus essential. In this study, we describe the synthesis and structural characterization of a range of CDs with distinct physico-chemical properties. The materials were prepared under three minutes of microwave irradiation using the same common starting materials (D-glucosamine hydrochloride 1 and ethylenediamine 2) but modifying the stoichiometry of the reagents. We show that small variation in reaction conditions leads to changes in the fluorescent behaviour of the CDs, especially in the selective enhancement of overlapped fluorescence bands. Structural analysis of the different CD samples suggested different reaction pathways during the CD formation and surface passivation, with the latter step being key to the observed differences. Moreover, we demonstrate that these materials have distinct reversible response to pH changes, which we can be attribute to different behaviour towards protonation/deprotonation events of distinct emission domains present within each nanomaterial. Our results highlight the importance of understanding the reaction pathways that lead to the formation of this carbon-based nanomaterials and how this can be exploited to develop tailored materials towards specific applications.

COVID-19: A systematic review and update on prevention, diagnosis, and treatment

Since the rapid onset of the COVID-19 or SARS-CoV-2 pandemic in the world in 2019, extensive studies have been conducted to unveil the behavior and emission pattern of the virus in order to determine the best ways to diagnosis of virus and thereof formulate effective drugs or vaccines to combat the disease. The emergence of novel diagnostic and therapeutic techniques considering the multiplicity of reports from one side and contradictions in assessments from the other side necessitates instantaneous updates on the progress of clinical investigations. There is also growing public anxiety from time to time mutation of COVID-19, as reflected in considerable mortality and transmission, respectively, from delta and Omicron variants. We comprehensively review and summarize different aspects of prevention, diagnosis, and treatment of COVID-19. First, biological characteristics of COVID-19 were explained from diagnosis standpoint. Thereafter, the preclinical animal models of COVID-19 were discussed to frame the symptoms and clinical effects of COVID-19 from patient to patient with treatment strategies and in-silico/computational biology. Finally, the opportunities and challenges of nanoscience/nanotechnology in identification, diagnosis, and treatment of COVID-19 were discussed. This review covers almost all SARS-CoV-2-related topics extensively to deepen the understanding of the latest achievements (last updated on January 11, 2022).

Tracking SARS-CoV-2: Novel Trends and Diagnostic Strategies

The COVID-19 pandemic has had an enormous impact on economies and health systems globally, therefore a top priority is the development of increasingly better diagnostic and surveillance alternatives to slow down the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In order to establish massive testing and contact tracing policies, it is crucial to have a clear view of the diagnostic options available and their principal advantages and drawbacks. Although classical molecular methods such as RT-qPCR are broadly used, diagnostic alternatives based on technologies such as LAMP, antigen, serological testing, or the application of novel technologies such as CRISPR-Cas for diagnostics, are also discussed. The present review also discusses the most important automation strategies employed to increase testing capability. Several serological-based diagnostic kits are presented, as well as novel nanotechnology-based diagnostic methods. In summary, this review provides a clear diagnostic landscape of the most relevant tools to track COVID-19.

A Molecular Communications System for the Detection of Inflammatory Levels Related to COVID-19 Disease

A recent and extensive research activity highlighted the process behind the attack and spread of COVID-19 in the human body. What emerged is that the SARS-CoV-2 virus makes use of both the ACE2 receptor, expressed by pneumocytes in the ephitelial alveolar lining, and by the endothelium to spread the disease and to replicate itself. Since the endothelium is an extended tissue lying in the circulatory system, this may lead to a large state of diffuse endothelial inflammation with serious clinical consequences. This situation may be further compromised by the immune system, that may generate pro-inflammatory cytokines (IL-6) as a consequence of the infection. In this paper we propose and analyze a molecular communication system, designed for the detection of excessive IL-6 level, that allows monitoring its evolution in the blood vessels. The proposed analysis was performed by using the BiNS2 simulator, which is suitable for the numerical analysis of flow-based molecular communications in blood vessels, as well as Markov models of the endothelium.

Targeted Delivery of Drugs and Genes Using Polymer Nanocarriers for Cancer Therapy

Cancer is one of the primary causes of worldwide human deaths. Most cancer patients receive chemotherapy and radiotherapy, but these treatments are usually only partially efficacious and lead to a variety of serious side effects. Therefore, it is necessary to develop new therapeutic strategies. The emergence of nanotechnology has had a profound impact on general clinical treatment. The application of nanotechnology has facilitated the development of nano-drug delivery systems (NDDSs) that are highly tumor selective and allow for the slow release of active anticancer drugs. In recent years, vehicles such as liposomes, dendrimers and polymer nanomaterials have been considered promising carriers for tumor-specific drug delivery, reducing toxicity and improving biocompatibility. Among them, polymer nanoparticles (NPs) are one of the most innovative methods of non-invasive drug delivery. Here, we review the application of polymer NPs in drug delivery, gene therapy, and early diagnostics for cancer therapy.

Nanotechnology based solutions to combat zoonotic viruses with special attention to SARS, MERS, and COVID 19: Detection, protection and medication

Zoonotic viruses originate from birds or animal sources and responsible for disease transmission from animals to people through zoonotic spill over and presents a significant global health concern due to lack of rapid diagnostics and therapeutics. The Corona viruses (CoV) were known to be transmitted in mammals. Early this year, SARS-CoV-2, a novel strain of corona virus, was identified as the causative pathogen of an outbreak of viral pneumonia in Wuhan, China. The disease later named corona virus disease 2019 (COVID-19), subsequently spread across the globe rapidly. Nano-particles and viruses are comparable in size, which serves to be a major advantage of using nano-material in clinical strategy to combat viruses. Nanotechnology provides novel solutions against zoonotic viruses by providing cheap and efficient detection methods, novel, and new effective rapid diagnostics and therapeutics. The prospective of nanotechnology in COVID 19 is exceptionally high due to their small size, large surface-to-volume ratio, susceptibility to modification, intrinsic viricidal activity. The nano-based strategies address the COVID 19 by extending their role in i) designing nano-materials for drug/vaccine delivery, ii) developing nano-based diagnostic approaches like nano-sensors iii) novel nano-based personal protection equipment to be used in prevention strategies.This review aims to bring attention to the significant contribution of nanotechnology to mitigate against zoonotic viral pandemics by prevention, faster diagnosis and medication point of view.

Nanotechnology-based Colorimetric Approaches for Pathogenic Virus Sensing: A review

Fast and inexpensive virus identification protocols are paramount to hinder the further extent of pandemic diseases, minimize economic and social damages, and expedite proper clinical rehabilitation. Until now, various biosensors have been fabricated for the identification of pathogenic particles. But, they offer many difficulties. Nanotechnology resolves these difficulties and offers direct identification of pathogenic species in real-time. Among them, nanomaterial based-colorimetric sensing approach of pathogenic viruses by the naked eye has attracted much awareness because of their simplicity, speed, and low cost. In this review, the latest tendencies and advancements are overviewed in detecting pathogenic viruses using colorimetric concepts. We focus on and reconsider the use of distinctive nanomaterials such as metal nanoparticles, carbon nanotubes, graphene oxide, and conducting polymer to form colorimetric pathogenic virus sensors.

Microbe-Mediated Biosynthesis of Nanoparticles: Applications and Future Prospects

Nanotechnology is the science of nano-sized particles/structures (~100 nm) having a high surface-to-volume ratio that can modulate the physical, chemical and biological properties of the chemical compositions. In last few decades, nanoscience has attracted the attention of the scientific community worldwide due to its potential uses in the pharmacy, medical diagnostics and disease treatment, energy, electronics, agriculture, chemical and space industries. The properties of nanoparticles (NPs) are size and shape dependent. These characteristic features of nanoparticles can be explored for various other applications such as computer transistors, chemical sensors, electrometers, memory schemes, reusable catalysts, biosensing, antimicrobial activity, nanocomposites, medical imaging, tumor detection and drug delivery. Therefore, synthesizing nanoparticles of desired size, structure, monodispersity and morphology is crucial for the aforementioned applications. Recent advancements in nanotechnology aim at the synthesis of nanoparticles/materials using reliable, innoxious and novel ecofriendly techniques. In contrast to the traditional methods, the biosynthesis of nanoparticles of a desired nature and structure using the microbial machinery is not only quicker and safer but more environmentally friendly. Various microbes, including bacteria, actinobacteria, fungi, yeast, microalgae and viruses, have recently been explored for the synthesis of metal, metal oxide and other important NPs through intracellular and extracellular processes. Some bacteria and microalgae possess specific potential to fabricate distinctive nanomaterials such as exopolysaccharides, nanocellulose, nanoplates and nanowires. Moreover, their ability to synthesize nanoparticles can be enhanced using genetic engineering approaches. Thus, the use of microorganisms for synthesis of nanoparticles is unique and has a promising future. The present review provides explicit information on different strategies for the synthesis of nanoparticles using microbial cells; their applications in bioremediation, agriculture, medicine and diagnostics; and their future prospects.

An Insight into Nanomedicinal Approaches to Combat Viral Zoonoses

BACKGROUND

Emerging viral zoonotic diseases are one of the major obstacles to secure the "One Health" concept under the current scenario. Current prophylactic, diagnostic and therapeutic approaches often associated with certain limitations and thus proved to be insufficient for customizing rapid and efficient combating strategy against the highly transmissible pathogenic infectious agents leading to the disastrous socio-economic outcome. Moreover, most of the viral zoonoses originate from the wildlife and poor knowledge about the global virome database renders it difficult to predict future outbreaks. Thus, alternative management strategy in terms of improved prophylactic vaccines and their delivery systems; rapid and efficient diagnostics and effective targeted therapeutics are the need of the hour.

METHODS

Structured literature search has been performed with specific keywords in bibliographic databases for the accumulation of information regarding current nanomedicine interventions along with standard books for basic virology inputs.

RESULTS

Multi-arrayed applications of nanomedicine have proved to be an effective alternative in all the aspects regarding the prevention, diagnosis, and control of zoonotic viral diseases. The current review is focused to outline the applications of nanomaterials as anti-viral vaccines or vaccine/drug delivery systems, diagnostics and directly acting therapeutic agents in combating the important zoonotic viral diseases in the recent scenario along with their potential benefits, challenges and prospects to design successful control strategies.

CONCLUSION

This review provides significant introspection towards the multi-arrayed applications of nanomedicine to combat several important zoonotic viral diseases.

FEAST of biosensors: Food, environmental and agricultural sensing technologies (FEAST) in North America

We review the challenges and opportunities for biosensor research in North America aimed to accelerate translational research. We call for platform approaches based on: i) tools that can support interoperability between food, environment and agriculture, ii) open-source tools for analytics, iii) algorithms used for data and information arbitrage, and iv) use-inspired sensor design. We summarize select mobile devices and phone-based biosensors that couple analytical systems with biosensors for improving decision support. Over 100 biosensors developed by labs in North America were analyzed, including lab-based and portable devices. The results of this literature review show that nearly one quarter of the manuscripts focused on fundamental platform development or material characterization. Among the biosensors analyzed for food (post-harvest) or environmental applications, most devices were based on optical transduction (whether a lab assay or portable device). Most biosensors for agricultural applications were based on electrochemical transduction and few utilized a mobile platform. Presently, the FEAST of biosensors has produced a wealth of opportunity but faces a famine of actionable information without a platform for analytics.

A bio-inspired fluorescent nano-injectable hydrogel as a synergistic drug delivery system

A nano-injectable hydrogel with fluorescence properties and controlled sequential release of dual drugs.

Promising Roles of Alternative Medicine and Plant-Based Nanotechnology as Remedies for Urinary Tract Infections

Urinary tract infections (UTIs) are considered to be the most common infections worldwide, having an incidence rate of 40-60% in women. Moreover, the prevalence of this disorder in adult women is 30 times more than in men. UTIs are usually found in many hospitals and clinical practice; as disorders, they are complicated and uncomplicated; in uncomplicated cases, there is no structural or functional abnormality in the urogenital tract. However, obstruction, retention of urine flow and use of catheters increase the complexity. There are several bacteria (e.g., E. coli, Klebsiella pneumoniae, Proteus vulgaris, etc.) successfully residing in the tract. The diagnosis must not only be accurate but rapid, so early detection is an important step in the control of UTIs caused by uropathogens. The treatment of UTIs includes appropriate antimicrobial therapy to control the infection and kill the causal microbes inside the body. A long-time usage of antibiotics has resulted in multidrug resistance causing an impediment in treatment. Thus, alternative, combinatorial medication approaches have given some hope. Available treatments considered Homeopathic, Ayurvedic, Unani, and other herbal-based drugs. There are new upcoming roles of nanoparticles in combating UTIs which needs further validation. The role of medicinal plant-based nanotechnology approaches has shown promising results. Therefore, there must be active research in phyto-based therapies of UTIs, such as Ayurvedic Biology.

Nanodiagnostics in leishmaniasis: A new frontiers for early elimination

Visceral leishmaniasis (VL) is still a major public health concern in developing countries having the highest outbreak and mortality potential. While the treatment of VL has greatly improved in recent times, the current diagnostic tools are limited for use in the post-elimination setting. Although conventional serological methods of detection are rapid, they can only differentiate between active disease in strict combination with clinical criteria, and thus are not sufficient enough to diagnose relapse patients. Therefore, there is a dire need for a portable, authentic, and reliable assay that does not require large space, specialized instrument facilities, or highly trained laboratory personnel and can be carried out in primary health care settings. Advances in the nanodiagnostic approaches have led to the expansion of new frontiers in the concerned area. The nanosized particles are blessed with an ability to interact one-on-one with the biomolecules because of their unique optical and physicochemical properties and high surface area to volume ratio. Biomolecular detection systems based on nanoparticles (NPs) are cost-effective, rapid, nongel, non-PCR, and nonculture based that provide fast, one-step, and reliable results with acceptable sensitivity and specificity. In this review, we discuss different NPs that are being used for the identification of molecular markers and other biomarkers, such as toxins and antigens associated with leishmaniasis. The most promising diagnostic approaches have been included in the article, and the ability of biomolecular recognition, advantages, and disadvantages have been discussed in detail to showcase the enormous potential of nanodiagnostics in human and veterinary medicine. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Diagnostic Tools > Biosensing.

Rapid Antibody-Based COVID-19 Mass Surveillance: Relevance, Challenges, and Prospects in a Pandemic and Post-Pandemic World

The aggressive outbreak of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) as COVID-19 (coronavirus disease-2019) pandemic demands rapid and simplified testing tools for its effective management. Increased mass testing and surveillance are crucial for controlling the disease spread, obtaining better pandemic statistics, and developing realistic epidemiological models. Despite the advantages of nucleic acid- and antigen-based tests such as accuracy, specificity, and non-invasive approaches of sample collection, they can only detect active infections. Antibodies (immunoglobulins) are produced by the host immune system within a few days after infection and persist in the blood for at least several weeks after infection resolution. Antibody-based tests have provided a substitute and effective method of ultra-rapid detection for multiple contagious disease outbreaks in the past, including viral diseases such as SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome). Thus, although not highly suitable for early diagnosis, antibody-based methods can be utilized to detect past infections hidden in the population, including asymptomatic ones. In an active community spread scenario of a disease that can provide a bigger window for mass detections and a practical approach for continuous surveillance. These factors encouraged researchers to investigate means of improving antibody-based rapid tests and employ them as reliable, reproducible, sensitive, specific, and economic tools for COVID-19 mass testing and surveillance. The development and integration of such immunoglobulin-based tests can transform the pandemic diagnosis by moving the same out of the clinics and laboratories into community testing sites and homes. This review discusses the principle, technology, and strategies being used in antibody-based testing at present. It also underlines the immense prospect of immunoglobulin-based testing and the efficacy of repeated planned deployment in pandemic management and post-pandemic sustainable screenings globally.

A Spellbinding Interplay Between Biological Barcoding and Nanotechnology

Great scientific research with improved potential in probing biological locales has remained a giant stride. The use of bio-barcodes with the potential use of nanotechnology is a hallmark being developed among recent advanced techniques. Biobarcoding is a novel method used for screening biomolecules to identify and divulge ragbag biodiversity. It establishes successful barcoding projects in the field of nanomedical technology for massively testing disease diagnosis and treatment. Biobarcoding and nanotechnology are recently developed technologies that provide unique opportunities and challenges for multiplex detection such as DNAs, proteins and nucleic acids of animals, plants, viruses, and various other species. These technologies also clump drug delivery, gene delivery, and DNA sequencing. Bio-barcode amplification assay (BCA) is used at large for the detection and identification of proteins and DNAs. DNA barcoding combined with nanotechnology has been proven highly sensitive rendering fast uniplex and multiplex detection of pathogens in food, blood, and other specimens. This review takes a panoramic view of current advances in nano bio-barcodes which have been summarized to explore additional applications such as detection of cytokines, neurotransmitters, cancer markers, prostate-specific antigens, and allergens. In the future, it will also be possible to detect some fungi, algae, protozoa, and other pollutants in food, agriculture, and clinical samples. Using these technologies, specific and efficient sensors would possibly be developed that can perform swift detections of antigens, allergens, and other specimens.

Cell-Membrane-Mimicking Nanodecoys against Infectious Diseases

Infectious diseases are a leading cause of mortality worldwide, with viruses and bacteria in particular having enormous impacts on global healthcare. One major challenge in combatting such diseases is a lack of effective drugs or specific treatments. In addition, drug resistance to currently available therapeutics and adverse effects caused by long-term overuse are both serious public health issues. A promising treatment strategy is to employ cell-membrane mimics as decoys to trap and to detain the pathogens. In this Perspective, we briefly review the infection mechanisms adopted by different pathogens at the cellular membrane interface and highlight the applications of cell-membrane-mimicking nanodecoys for systemic protection against infectious diseases. We also discuss the implication of nanodecoy-pathogen complexes in the development of vaccines. We anticipate this Perspective will provide new insights on design and development of advanced materials against emerging infectious diseases.

Nanomaterials and nanocomposite applications in veterinary medicine

Nowadays, nanotechnology has made huge, significant advancements in biotechnology and biomedicine related to human and animal science, including increasing health safety, production, and the elevation of national income. There are various fields of nanomaterial applications in veterinary medicine such as efficient diagnostic and therapeutic tools, drug delivery, animal nutrition, breeding and reproduction, and valuable additives. Additional benefits include the detection of pathogens, protein, biological molecules, antimicrobial agents, feeding additives, nutrient delivery, and reproductive aids. There are many nanomaterials and nanocomposites that can be used in nanomedicine such as metal nanoparticles, liposomes, carbon nanotubes, and quantum dots. In the near future, nanotechnology research will have the ability to produce novel tools for improving animal health and production. Therefore, this chapter was undertaken to spotlight novel methods created by nanotechnology for application in the improvement of animal health and production. In addition, the toxicity of nanomaterials is fully discussed to avoid the suspected health hazards of toxicity for animal health safety.

Current Trends of Nanobiosensors for Point-of-Care Diagnostics

In order to provide better-quality health care, it is very important that high standards of health care management are achieved by making timely decisions based on rapid diagnostics, smart data analysis, and informatics analysis. Point-of-care testing ensures fast detection of analytes near to the patients facilitating a better disease diagnosis, monitoring, and management. It also enables quick medical decisions since the diseases can be diagnosed at an early stage which leads to improved health outcomes for the patients enabling them to start early treatment. In the recent past, various potential point-of-care devices have been developed and they are paving the way to next-generation point-of-care testing. Biosensors are very critical components of point-of-care devices since they are directly responsible for the bioanalytical performance of an essay. As such, they have been explored for their prospective point-of-care applications necessary for personalized health care management since they usually estimate the levels of biological markers or any chemical reaction by producing signals mainly associated with the concentration of an analyte and hence can detect disease causing markers such as body fluids. Their high selectivity and sensitivity have allowed for early diagnosis and management of targeted diseases; hence, facilitating timely therapy decisions and combination with nanotechnology can improve assessment of the disease onset and its progression and help to plan for treatment of many diseases. In this review, we explore how nanotechnology has been utilized in the development of nanosensors and the current trends of these nanosensors for point-of-care diagnosis of various diseases.

Microfluidic smartphone quantitation of Escherichia coli in synthetic urine

In spite of the clinical need, there is a major gap in rapid diagnostics for identification and quantitation of E. coli and other pathogens, also regarded as the biggest bottleneck in the fight against the spread of antimicrobial resistant bacterial strains. This study reports for the first time an optical, smartphone-based microfluidic fluorescence sandwich immunoassay capable of quantifying E. coli in buffer and synthetic urine in less than 25 min without sample preparation nor concentration. A limit of detection (LoD) up to 240 CFU/mL, comensurate with cut-off for UTIs (10³-10⁵ CFUs/mL) was achieved. Replicas of full response curves performed with 10⁰-10⁷ CFUs/mL of E. coli K12 in synthetic urine yielded recovery values in the range 80-120%, assay reproducibility below 30% and precision below 20%, therefore similar to high-performance automated immunoassays. The unrivalled LoD was mainly linked to the 'open fluidics' nature of the 10-bore microfluidic strips used that enabled passing a large volume of sample through the microcapillaries coated with capture antibody. The new smartphone based test has the potential of being as a rapid, point-of-care test for rule-in of E. coli infections that are responsible for around 80% of UTIs, helping to stop the over-prescription of antibiotics and the monitoring of patients with other symptomatic communicable diseases caused by E. coli at global scale.

Hydrothermal synthesis of carbon nanodots from bovine gelatin and PHM3 microalgae strain for anticancer and bioimaging applications

Semi-conductor quantum dots (QDs) are favorite candidates for many applications especially for potential use as optical bioimaging agents. But the major issue of QDs is toxicity. In the present study, carbon nanodots were synthesized using a green hydrothermal approach from gelatin protein using a previously established protocol. However, the PL properties and applications of the as-synthesized CG (bovine gelatin) nanodots were remarkably different from those of previously reported gelatin carbon dots. CG (bovine gelatin) nanodots had sizes greater than the Bohr exciton radius but still had QD like fluorescence characteristics. Furthermore, the results from fluorescence spectroscopy demonstrated a tunable PL emission profile at various excitation wavelengths. Second, carbon nanodots were also synthesized from algal biomass of Pectinodesmus sp. via a green hydrothermal approach, denoted as CA (PHM3 algae) nanodots. A study of the PL properties and surface chemical composition of CG (bovine gelatin) and CA (PHM3 algae) nanodots suggested that the surface chemical composition significantly alters the surface states which directly influence their PL properties. CG (bovine gelatin) nanodots were used for imaging of plant and bacterial cells with good imaging sensitivity comparable to toxic semiconductor quantum dots. Moreover, the results from in vitro studies suggested good anticancer properties of CA (PHM3 algae) and CG (bovine gelatin) nanodots with minimum GI50 values of 0.316 ± 0.447 ng ml^-1 (n = 2) and 8.156 ± 6.596 ng ml^-1 (n = 2) for HCC 1954 (breast cancer) and 0.542 ± 0.715 ng ml^-1 (n = 2) and 23.860 ± 14.524 ng ml^-1 (n = 2) for HCT 116 (colorectal cancer) cell lines, respectively.

Development of Label-Free Colorimetric Assay for MERS-CoV Using Gold Nanoparticles

Worldwide outbreaks of infectious diseases necessitate the development of rapid and accurate diagnostic methods. Colorimetric assays are a representative tool to simply identify the target molecules in specimens through color changes of an indicator (e.g., nanosized metallic particle, and dye molecules). The detection method is used to confirm the presence of biomarkers visually and measure absorbance of the colored compounds at a specific wavelength. In this study, we propose a colorimetric assay based on an extended form of double-stranded DNA (dsDNA) self-assembly shielded gold nanoparticles (AuNPs) under positive electrolyte (e.g., 0.1 M MgCl2) for detection of Middle East respiratory syndrome coronavirus (MERS-CoV). This platform is able to verify the existence of viral molecules through a localized surface plasmon resonance (LSPR) shift and color changes of AuNPs in the UV-vis wavelength range. We designed a pair of thiol-modified probes at either the 5' end or 3' end to organize complementary base pairs with upstream of the E protein gene (upE) and open reading frames (ORF) 1a on MERS-CoV. The dsDNA of the target and probes forms a disulfide-induced long self-assembled complex, which protects AuNPs from salt-induced aggregation and transition of optical properties. This colorimetric assay could discriminate down to 1 pmol/μL of 30 bp MERS-CoV and further be adapted for convenient on-site detection of other infectious diseases, especially in resource-limited settings.

Emerging vistas in theranostic medicine

Recent years have witnessed a paradigm shift in the focus of healthcare towards development of customized therapies which cater to the unmet needs in a myriad of disease areas such as cancer, infections, cardiovascular diseases, neurodegenerative disorders and inflammatory disorders. The term 'theranostic' refers to such multifunctional systems which combine the features of diagnosis and treatment in a single platform for superior control of the disease. Theranostic systems enable detection of disease, treatment and real time monitoring of the diseased tissue. Theranostic nanocarriers endowed with multiple features of imaging, targeting, and providing on-demand delivery of therapeutic agents have been designed for enhancement of therapeutic outcomes. Fabrication of theranostics involves utilization of materials having distinct properties for imaging, targeting, and programming drug release spatially and temporally. Although the field of theranostics has been widely researched and explored so far for treatment of different types of cancer, there have been considerable efforts in the past few years to extend its scope to other areas such as infections, neurodegenerative disorders and cardiovascular diseases. This review showcases the potential applications of theranostics in disease areas other than cancer. It also highlights the cardinal issues which need to be addressed for successful clinical translation of these theranostic tools.

Practical Three-Minute Synthesis of Acid-Coated Fluorescent Carbon Dots with Tuneable Core Structure

We report a one-pot, three-minute synthesis of carboxylic acid-decorated fluorescent carbon dots (COOH-FCDs) with tuneable core morphology dependent on the surface passivating agent. Mechanism investigations highlighted the presence of key pyrazine and polyhydroxyl aromatic motifs, which are formed from the degradation of glucosamine in the presence of a bifunctional linker bearing acid and amine groups. The novel COOH-FCDs are selective Fe3+ and hemin sensors. Furthermore, the FCDs are shown to be non-toxic, fluorescent bioimaging agents for cancer cells.

PMIDA-Modified Fe3O4 Magnetic Nanoparticles: Synthesis and Application for Liver MRI

The surface modification of Fe₃O₄-based magnetic nanoparticles (MNPs) with N-(phosphonomethyl)iminodiacetic acid (PMIDA) was studied, and the possibility of their use as magnetic resonance imaging contrast agents was shown. The effect of the added PMIDA amount, the reaction temperature and time on the degree of immobilization of this reagent on MNPs, and the hydrodynamic characteristics of their aqueous colloidal solutions have been systematically investigated for the first time. It has been shown that the optimum condition for the modification of MNPs is the reaction at 40 °C with an equimolar amount of PMIDA for 3.5 h. The modified MNPs were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric, and CHN elemental analyses. The dependence of the hydrodynamic characteristics of the MNP colloidal solutions on the concentration and pH of the medium was studied by the dynamic light scattering method. On the basis of the obtained data, we can assume that the PMIDA molecules are fixed on the surface of the MNPs as a monomolecular layer. The modified MNPs had good colloidal stability and high magnetic properties. The calculated relaxivities r₂ and r₁ were 341 and 102 mmol^-1 s^-1, respectively. The possibility of using colloidal solutions of PMIDA-modified MNPs as a T₂ contrast agent for liver studies in vivo (at a dose of 0.6 mg kg^-1) was demonstrated for the first time.

Co-reductive fabrication of carbon nanodots with high quantum yield for bioimaging of bacteria

A simple and straightforward synthetic approach for carbon nanodots (C-dots) is proposed. The strategy is based on a one-step hydrothermal chemical reduction with thiourea and urea, leading to high quantum yield C-dots. The obtained C-dots are well-dispersed with a uniform size and a graphite-like structure. A synergistic reduction mechanism was investigated using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The findings show that using both thiourea and urea during the one-pot synthesis enhances the luminescence of the generated C-dots. Moreover, the prepared C-dots have a high distribution of functional groups on their surface. In this work, C-dots proved to be a suitable nanomaterial for imaging of bacteria and exhibit potential for application in bioimaging thanks to their low cytotoxicity.

Application of nanodiagnostics in point-of-care tests for infectious diseases

Although tremendous efforts have been put into the treatment of infectious diseases to prevent epidemics and mortality, it is still one of the major health care issues that have a profound impact on humankind. Therefore, the development of specific, sensitive, accurate, rapid, low-cost, and easy-to-use diagnostic tools is still in urgent demand. Nanodiagnostics, defined as the application of nanotechnology to medical diagnostics, can offer many unique opportunities for more successful and efficient diagnosis and treatment for infectious diseases. In this review, we provide an overview of the nanodiagnostics for infectious diseases from nanoparticle-based, nanodevice-based, and point-of-care test (POCT) platforms. Most importantly, emphasis focused on the recent trends in the nanotechnology-based POCT system. The current state-of-the-art and most promising point-of-care nanodiagnostic technologies, including miniaturized diagnostic magnetic resonance platform, magnetic barcode assay system, cell phone-based polarized light microscopy platform, cell phone-based dongle platform, and paper-based POCT platform, for infectious diseases were fully examined. The limitations, challenges, and future trends of the nanodiagnostics in POCTs for infectious diseases are also discussed.

Gentamicin-gold nanoparticles conjugate: a contrast agent for X-ray imaging of infectious foci due to Staphylococcus aureus

There is no optimal imaging method for the detection of unknown infectious foci in some diseases. This study introduces a novel method in X-ray imaging of infection foci due to Staphylococcus aureus by developing a contrast agent based on gold nanoparticles (GNPs). GNPs in spherical shape were synthesised by the reduction of tetrachloroauric acid with sodium citrate. Then gentamicin was bound directly to citrate functionalised GNPs and the complex was stabilised by polyethylene glycol. The interaction of gentamicin with GNPs was confirmed by ultraviolet-visible and Fourier transform infrared spectroscopies. The stability of complex was studied in human blood up to 6 h. The stability of conjugate was found to be high in human blood with no aggregation. The biodistribution study showed localisation of gentamicin-GNPs conjugate at the site of Staphylococcal infection. The infection site was properly visualised in X-ray images in mouse model using the gentamicin-GNPs conjugate as a contrast agent. The results demonstrated that one may consider the potential of new nanodrug as a contrast agent for X-ray imaging of infection foci in human beings which needs more investigations.

Improving health-care delivery in low-resource settings with nanotechnology: Challenges in multiple dimensions

In the two decades after 1990, the rates of child and maternal mortality dropped by over 40% and 47%, respectively. Despite these improvements, which are in part due to increased access to medical technologies, profound health disparities exist. In 2015, a child born in a developing region is nearly eight times as likely to die before the age of 5 than one born in a developed region and developing regions accounted for nearly 99% of the maternal deaths. Recent developments in nanotechnology, however, have great potential to ameliorate these and other health disparities by providing new cost-effective solutions for diagnosis or treatment of a variety of medical conditions. Affordability is only one of the several challenges that will need to be met to translate new ideas into a medical product that addresses a global health need. This article aims to describe some of the other challenges that will be faced by nanotechnologists who seek to make an impact in low-resource settings across the globe.

Nanocomposite biosensors for point-of-care—evaluation of food quality and safety

Nanosensors have wide applications in the food industry. Nanosensors based on quantum dots for heavy metal and organophosphate pesticides detection, and nanocomposites as indicators for shelf life of fish/meat products, have served as important tools for food quality and safety assessment. Luminescent labels consisting of NPs conjugated to aptamers have been popular for rapid detection of infectious and foodborne pathogens. Various detection technologies, including microelectromechanical systems for gas analytes, microarrays for genetically modified foods, and label-free nanosensors using nanowires, microcantilevers, and resonators are being applied extensively in the food industry. An interesting aspect of nanosensors has also been in the development of the electronic nose and electronic tongue for assessing organoleptic qualities, such as, odor and taste of food products. Real-time monitoring of food products for rapid screening, counterfeiting, and tracking has boosted ingenious, intelligent, and innovative packaging of food products. This chapter will give an overview of the contribution of nanotechnology-based biosensors in the food industry, ongoing research, technology advancements, regulatory guidelines, future challenges, and industrial outlook.

A comparison of nanoparticle-antibody conjugation strategies in sandwich immunoassays

Point-of-care (POC) diagnostics such as lateral flow and dipstick immunoassays use gold nanoparticle (NP)-antibody conjugates for visual readout. We investigated the effects of NP conjugation, surface chemistries, and antibody immobilization methods on dipstick performance. We compared orientational, covalent conjugation, electrostatic adsorption, and a commercial conjugation kit for dipstick assays to detect dengue virus NS1 protein. Assay performance depended significantly on their conjugate properties. We also tested arrangements of multiple test lines within strips. Results show that orientational, covalent conjugation with PEG shield could improve NS1 detection. These approaches can be used to optimize immunochromatographic detection for a range of biomarkers.

Recent trends on hydrogel based drug delivery systems for infectious diseases

Since centuries, the rapid spread and cure of infectious diseases have been a major concern to the progress and survival of humans. These diseases are a global burden and the prominent cause for worldwide deaths and disabilities. Nanomedicine has emerged as the most excellent tool to eradicate and halt their spread. Various nanoformulations (NFs) using advanced nanotechnology are in demand. Recently, hydrogel and nanogel based drug delivery devices have posed new prospects to simulate the natural intelligence of various biological systems. Owing to their unique porous interpenetrating network design, hydrophobic drug incorporation and stimulus sensitivity hydrogels owe excellent potential as targeted drug delivery systems. The present review is an attempt to highlight the recent trends of hydrogel based drug delivery systems for the delivery of therapeutic agents and diagnostics for major infectious diseases including acquired immune deficiency syndrome (AIDS), malaria, tuberculosis, influenza and ebola. Future prospects and challenges are also described.

An investigation of the interactions between an E. coli bacterial quorum sensing biosensor and chitosan-based nanocapsules

We examined the interaction between chitosan-based nanocapsules (NC), with average hydrodynamic diameter ∼114-155nm, polydispersity ∼0.127, and ζ-potential ∼+50mV, and an E. coli bacterial quorum sensing reporter strain. Dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA) allowed full characterization and assessment of the absolute concentration of NC per unit volume in suspension. By centrifugation, DLS, and NTA, we determined experimentally a "stoichiometric" ratio of ∼80 NC/bacterium. By SEM it was possible to image the aggregation between NC and bacteria. Moreover, we developed a custom in silico platform to simulate the behavior of particles with diameters of 150nm and ζ-potential of +50mV on the bacterial surface. We computed the detailed force interactions between NC-NC and NC-bacteria and found that a maximum number of 145 particles might interact at the bacterial surface. Additionally, we found that the "stoichiometric" ratio of NC and bacteria has a strong influence on the bacterial behavior and influences the quorum sensing response, particularly due to the aggregation driven by NC.