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Abstract: Introduction: The direct thrombin inhibitor dabigatran interferes with thrombophilia screening and with the diagnosis of hemostasis disorders that develop during treatment with the anticoagulant. In vitro addition of idarucizumab, a humanized antibody fragment that binds dabigatran, to plasma samples containing dabigatran fully neutralizes the drug. This study was carried out to determine whether binding of dabigatran on selected insoluble commercial adsorbent material, DOAC‐STOPR, was as efficient as idarucizumab to neutralize the anticoagulant activity of the drug in vitro. Methods: Coagulation assays sensitive to dabigatran were carried out with patient and control plasma samples spiked with dabigatran and supplemented with idarucizumab or incubated with adsorbent material. Results: In samples containing upto 10 000 ng/mL dabigatran, the adsorption procedure was at least as efficient as the addition of idarucizumab to neutralize the activity of the anticoagulant drug. Neither the adsorption procedure nor the addition of idarucizumab did impair routine coagulation assays carried out with plasma devoid of dabigatran, such as the activated partial thromboplastin time, prothrombin time, fibrinogen Clauss, and the thrombophilia screening assays used to detect antiphospholipid antibodies or activated protein C resistance. In addition, the adsorption procedure did not interfere with the detection of lupus anticoagulant samples. Conclusions: Adsorption of dabigatran in plasma samples containing the drug neutralizes its activity as efficiently as the addition of idarucizumab. This method allows the evaluation of thrombophilia markers without interruption of anticoagulation therapy or the detection of hemostasis disorders in patients treated with the drug. [ABSTRACT FROM AUTHOR]

Introduction: Postinfusion ReFacto AF levels can be difficult to measure accurately due to discrepancies between one‐stage and chromogenic FVIII assays. To overcome this, the use of the ReFacto AF laboratory standard (RAFLS) is recommended, but there are discordant reports regarding its usefulness. Aim: We investigated whether calibration with RAFLS and measurement of ReFacto AF levels are influenced by the choice of reagents and patient‐specific factors in one‐stage FVIII assays. Methods: Calibration curves were generated with both the RAFLS and a plasma standard using different F8DPs and one‐stage FVIII assay reagents. This selection of reagents was then used to determine FVIII levels in the plasma of patients repeatedly treated with ReFacto AF. Results were compared with those obtained with a chromogenic assay. Results: F8DP devoid of von Willebrand factor (VWF) falsely increased the values of RAFLS pro‐coagulant activity generated using the APTT reagent. The resulting RAFLS calibration curve underestimated ReFacto AF levels to be half of their true concentration. The use of RAFLS with F8DP containing VWF reduced the discrepancy observed between the one‐stage and chromogenic FVIII assays. However, the mean difference between the two assays still varied up to 50% depending on the patient. Conclusions: The RAFLS is a suitable calibrator for one‐stage FVIII assays carried out with F8DP containing VWF. However, calibration with the RAFLS does not avoid the effect of patient‐specific variables that contribute to discrepancies between the measurements of ReFacto AF levels with one‐stage and chromogenic FVIII assays. [ABSTRACT FROM AUTHOR]

Phalangeal microgeodic syndrome is a rare but benign disorder that affects the fingers of children. This condition was originally described by Maroteaux in 1970. We present two patients who consulted a pediatrician with swelling of the digits of one or both hands. Both lacked additional clinical or biochemical signs. Radiological examination showed multiple small osteolytic areas with sclerotic lining and periostal reactions in the phalanges of the affected hands. These cases were treated with a conservative approach and spontaneous resolution occurred within weeks to months. As it is a rare disease, the clinical presentation can be misinterpreted as an infectious, inflammatory, or even malignant condition and prompts clinicians to expand the diagnostic process with radiological or nuclear imaging and even biopsy. In these patients, a timely clinical diagnosis by a physician who is aware of the disease prevented further investigations. [ABSTRACT FROM AUTHOR]

Unlabelled: Serum procalcitonin (PCT) has been proposed as a marker to identify bacterial infection in children. For optimal management of cystic fibrosis (CF) patients, early recognition of pulmonary exacerbations is necessary, but sensitive biomarkers to do so are lacking. Our study was done to establish baseline values for PCT in children with CF and to compare these to values at onset of a pulmonary exacerbation. Serum PCT values were determined in CF children during an outpatient clinic visit and at onset of treatment with intravenous (IV) antibiotics for a pulmonary exacerbation. Serum PCT was measured using a quantitative immunoassay (BRAHMS Kryptor PCTsensitive, Henningsdorf, Germany). In 92 outpatients (mean age 10.0 years, SD 4.8 years; mean forced expiratory volume in 1 s 91%, SD 18; 9 chronically colonized with Pseudomonas aeruginosa), mean baseline PCT was 0.05 ng/ml (SD 0.07). Mean PCT on admission for IV treatment of pulmonary exacerbation was 0.07 ng/ml (SD 0.06) (n = 22) and not different from the baseline value. PCT values were markedly higher in two CF patients with an acute nonrespiratory infection (central venous catheter-associated bloodstream infection, acute gastroenteritis), demonstrating that they can mount a PCT response.Conclusion: PCT values in CF children are not different from values reported in healthy children. In CF children, PCT values do not rise significantly at the onset of a respiratory exacerbation and thus hold no promise as an early marker to identify a pulmonary exacerbation. [ABSTRACT FROM AUTHOR]

Background: Safety netting advice (SNA) can help in the management of acutely ill children., Aim: Assess the effectiveness of different SNA methods for acutely ill children on antibiotic prescription and consumption., Design and Setting: Systematic review and network meta-analysis of randomised controlled trials, non-randomised trials of interventions, and controlled before-after studies in ambulatory care., Method: We searched MEDLINE, Embase, Web-Of-Science Core Collection, and Cochrane Central Register of Controlled Trials (22 January 2024). We assessed the risk of bias (RoB) with the Cochrane Tool 2, Revised Cochrane Tool for Cluster-Randomised Trials, and ROBINS-I tool. Certainty of evidence was assessed using the CINeMA approach. We performed sensitivity analyses and network meta-regression., Results: We included 30 studies (20 interventions). Compared to usual care, paper SNA may reduce antibiotic prescribing (OR=0.66 (95%CI: 0.53-0.85), I²=92%, very low certainty; 3 studies, 35,988 participants), especially when combined with oral SNA (OR=0.40 (95%CI: 0.08-2.00), P-score: 0.86), antibiotic consumption (OR=0.39 (95%CI: 0.27-0.58), low RoB; 1 study, 509 participants), and return visits (OR=0.74 , 95%CI 0.63-0.87). Paper SNA without antibiotics may reduce antibiotic consumption compared to paper SNA and delayed antibiotics (OR=0.27 (95%CI: 0.15-0.51, some RoB; 1 study, 206 participants). Video SNA, oral SNA, read-only websites, and web-based modules may increase parental knowledge (ORs 2.23-4.52). Video SNA and web-based modules may improve parental satisfaction (ORs 1.64-4.08)., Conclusion: Paper SNA (with oral SNA) may reduce antibiotic use and return visits. Video, oral, and online SNA, may improve parental knowledge while video SNA and web-based modules may increase parental satisfaction., (Copyright © 2024, The Authors.)

Objectives: Although cycling is a healthy, ecological and practical way of transportation, it is not without risk. The effect of bicycle helmets to prevent head injuries on crashing has been extensively investigated. Nonetheless, the overall use of helmets by adolescents remains low. While various interventions to increase helmet use have been adopted, adolescents' perspectives on these interventions have not been extensively explored. In our study, we aim to understand the facilitators and barriers to bicycle helmet use by adolescents and their perspectives on injury prevention campaigns., Methods: A qualitative methodology was selected. A convenience sample of three schools in Belgium was selected for participation. 12 focus groups were conducted with a total of 84 adolescents aged 12-17 years in the second, third or fourth year of secondary school., Results: Four key themes regarding adolescents' views on safe cycling practices emerged from the analysis: external motivation, internal motivation, factors specific to the helmet and the cycling environment. The main barriers to bicycle helmet use identified by adolescents were peer pressure, appearance and discomfort. The perceived risks of cycling without a helmet among adolescents were low. Mandatory bicycle helmet laws and non-legislative programmes were considered to be an effective strategy by the study participants. Parental strategies, including strict parental rules and parental helmet use, further contributed to wear a bicycle helmet., Conclusion: The results of this qualitative study add to the literature by expanding the understanding of motivation for bicycle helmet use and should be considered when designing interventions to promote bicycle helmet use., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Social media have become integral in adolescents' lives, presenting both opportunities and risks, especially concerning psychiatric issues like eating disorders, prevalent in this vulnerable age group., Methods: This qualitative study employed semi-structured interviews with seven adolescent girls (aged 15-17) diagnosed with eating disorders. Interviews covered seven predefined topics, recorded and transcribed for thematic analysis., Results: Participants identified four key themes: exposure to selective content, biased interpretation, behavioural adaptation, and evolving perspectives during recovery. They highlighted social media's role in exacerbating body dissatisfaction and altering behaviours related to eating disorders., Conclusions: This research underscores the critical need for awareness and guidance in adolescents' social media use to mitigate negative impacts, emphasizing the potential link between exposure to specific content and cognitive-behavioural changes in those with eating disorders. Further investigation is warranted to deepen our comprehension of these dynamics.

Purpose: Adolescence is a period of growing independence and maturity, within the period of legal minority. As parents or guardians are socially and legally responsible for adolescents' medical decisions, shared decision-making in adolescent healthcare could be ethically challenging. This review aims to identify and map the ethical tensions in shared decision-making in adolescent healthcare., Methods: We systematically searched the literature following the PRISMA guidelines to identify relevant articles, which were analyzed using the review of reasons methodology Strech and Sofaer (J Med Ethics 38(2):121-6, 2012)., Results: We included 38 articles which involved adolescents, healthcare professionals and parents as being the main stakeholders. Shared decision-making was influenced not only by individual stakeholders' characteristics, but by tensions between stakeholder dyads. Most studies supported the involvement of the adolescent in decision-making, depending on their life experience, decision-making capacity and clinical condition., Conclusions: Shared decision-making in adolescent health is receiving increasing attention. However, questions remain on what this concept entails, the roles and involvement of stakeholders and its practical implementation., What Is Known: • Although adolescents wish to be involved in health decisions, shared decision-making in adolescents is underexplored • Adolescent shared decision-making is different from pediatric and adult shared decision-making, and is ethically complex due to the adolescent's growing autonomy What is new: • Adolescent SDM involves three-way interactions between the adolescent, healthcare professional and parents • In adolescent shared decision-making, involving or excluding a stakeholder and sharing or withholding information are ethically value-laden steps • Research is needed to further understand the roles of adolescents' personal value systems, extended or reconstituted families and decision aids in shared decision-making., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: It is crucial to understand the trends in paediatric antibiotic prescribing and serious and nonserious infections to improve antibiotic prescribing practices for children in ambulatory care., Objectives: Assessing trends in paediatric antibiotic prescribing and infection incidence in general practice from 2002 to 2022., Methods: In this retrospective cohort study using INTEGO network data from 162 507 patients in Flanders (Belgium), we calculated antibiotic prescribing rates and proportions alongside incidence rates of serious and nonserious infections, stratified by age (0-1, 2-6, 7-12 years) and municipality. We performed autoregressive moving average time-series analyses and seasonality analyses., Results: From 2002 to 2022, antibiotic prescribing rate decreased significantly: 584/1000 person-years (PY) (95% CI 571-597) to 484/1000PY (95% CI 478-491); so did antibiotic overall prescribing proportion: 46.3% (95% CI 45.1-47.6) to 23.3% (95% CI 22.9-23.7) (59.3% amoxicillin and 17.8% broad spectrum). Prescribing proportions dropped significantly for nonserious (45.6% to 20.9%) and increased for serious infections (64.1% to 69.8%). Proportions significantly dropped for acute suppurative otitis media (74.7% to 64.1%), upper respiratory tract infections (44.9% to 16.6%), bronchitis/bronchiolitis (73.6% to 44.1%) and acute tonsillopharyngitis (59.5% to 21.7%), while significantly increasing for pneumonia (65.2% to 80.2%). Nonserious and serious infection incidence rates increased from 785/1000PY and 34.2/1000PY to 1223/1000PY and 64.1/1000PY, respectively. Blood and CRP testing proportions increased significantly., Conclusions: Antibiotic prescribing in general practice for children declined from 2002 to 2022. Further targeted antibiotic stewardship initiatives are needed to reduce the use of broad-spectrum antibiotics and antibiotic prescribing for conditions such as otitis media and bronchitis/bronchiolitis., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Society for Antimicrobial Chemotherapy. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: The aim of this study was to investigate the link between parenting and parents' perspectives on health-related decision making for adolescents. During adolescence, there is a gradual increase in responsibility and autonomy, which influences parenting behavior and child development. Understanding how parenting is associated with parents' views on medical decision making is crucial in the context of the parent-child-physician triad. This study was the first to explore parenting and parents' views on adolescent health care decision making. We compare Belgian and Dutch parents-two countries selected for their different legal frameworks on medical adolescent decision making., Method: An online questionnaire surveyed 984 Belgian and 992 Dutch parents (ages 35-55) with at least one child. Analytical methods included t tests, structural equation modeling, and latent profile analysis., Results: Parents considered adolescents to be competent decision makers at 16.7 years old. Dutch parents granted autonomy at younger ages than Belgian parents. Parents with high behavioral expectations granted autonomy to adolescents at higher ages, while those high in autonomy support and punishment granted autonomy at lower ages. When classifying parents into profiles, we distinguished four types: highly permissive, moderately permissive, moderately restrictive, and highly restrictive groups. The majority of the sample was classified into moderately and highly restrictive profiles., Conclusion: The study highlighted the importance of providing parents with education and support on adolescent development and autonomy. Parenting practices that encourage autonomy and support open communication between parents and adolescents may contribute to a more trusting and supportive parent-child context for adolescent medical decision making. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Background: Vitamin D deficiency is the most frequent cause of impaired skeletal growth, and can lead to the development of nutritional rickets. The aim of this study was to evaluate the vitamin D status in a large group of children aged 0-18 years. Methods: We collected laboratory data on vitamin D levels from children who underwent blood sampling between 2014 and 2021. Results: We included 14,887 samples. In this group, 17.7% were vitamin D severely deficient (<12 ng/mL), 25.2% were insufficient (12-20 ng/mL), and another large proportion (28.3%) was borderline (20-30 ng/mL). Sufficient levels (>30 ng/mL) were met in 28.8% of children. We observed no association between gender and vitamin D status ( p = 0.132). Adolescents aged 13-18 years ( n = 3342) had the highest prevalence of severe vitamin D deficiency (24.9%). Vitamin D levels were higher in summer/autumn compared to winter/spring. Conclusions: Vitamin D deficiency/insufficiency has a high prevalence in children, mostly in children above 7 years of age. Many of these children (over 80%) do not meet the 30 ng/mL sufficiency threshold. It is essential that Belgian Health Authorities are aware of this high prevalence, as the current Belgian recommendation suggests ceasing vitamin D supplementation at the age of six. Additional research is required to investigate the consequences of our findings, and what specific approach is needed to achieve normal vitamin D levels in children aged 0 to 18 years., Competing Interests: The authors declare no conflicts of interest.

Objective: Develop a consensus on the content and form of safety netting advice (SNA) for parents of acutely ill children., Design: Four-round modified e-Delphi using online questionnaires and feedback among clinical and research experts., Setting: Ambulatory care in high-income countries., Participants: Forty-one experts from 13 countries: 3 emergency physicians, 15 general practitioners, 4 nurses and 19 paediatricians., Results: The experts defined the content of SNA as advice on the normal, expected disease course of the provisional diagnosis, diagnostic uncertainty, alarm signs that indicate the need for medical help and information on where and how to find such help. Regarding the form of the SNA, the experts agree that a reliable source should give SNA verbally with paper or digital written or video/image resources at every appropriate healthcare encounter in a short and simple empowering fashion, specific to the child's situation and seek confirmatory feedback from parents., Conclusions: SNA needs to contain advice on the expected disease course, alarm signs and where and how to find help. It should be given verbally with written resources by a reliable healthcare professional or digital platform. Short, simple and specific, SNA needs to empower the parent whose understanding of the advice should be checked. The effectiveness of SNA resources coproduced by parents and experts should be assessed in different settings and those providing SNA require up-to-date and reliable training., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

The major focus of this research is the level of awareness among Dutch parents of general patient rights in relation to minors' patient rights. Moreover, this study is intended to highlight the most effective strategies to increase the awareness of general and minor patient rights in the Netherlands. A survey was conducted among 1010 Dutch parents aged between 35 and 55 years who had at least one child. In this study, we described the relationship between the knowledge among parents of general patient rights and their understanding of the patient rights of minors. A significant connection was found between the knowledge levels of general patient rights and the knowledge levels of the patient rights of minors ( p < 0.05 [95% CI: 0.019-0.183]). While age and sex (male/female) did not appear to be significant confounders in this association, the educational background of the participants may have played a role. This study provides comprehensive insights into the association between the knowledge of general patient rights and the patient rights of minors among Dutch parents. Furthermore, this study points out that there is a need for focused educational interventions to address specific areas of misunderstanding or uncertainty.

Thanks to its non-invasive nature and high-resolution imaging capabilities, magnetic resonance imaging (MRI) is a valuable diagnostic tool for pediatric patients. However, the fear and anxiety experienced by young children during MRI scans often result in suboptimal image quality and the need for sedation/anesthesia. This study aimed to evaluate the effect of a smartphone application called COSMO@home to prepare children for MRI scans to reduce the need for sedation or general anesthesia. The COSMO@home app was developed incorporating mini-games and an engaging storyline to prepare children for learning goals related to the MRI procedure. A multicenter study was conducted involving four hospitals in Belgium. Eligible children aged 4-10 years were prepared with the COSMO@home app at home. Baseline, pre-scan, and post-scan questionnaires measured anxiety evolution in two age groups (4-6 years and 7-10 years). Eighty-two children participated in the study, with 95% obtaining high-quality MRI images. The app was well-received by children and parents, with minimal technical difficulties reported. In the 4-6-year-old group (N = 33), there was a significant difference between baseline and pre-scan parent-reported anxiety scores, indicating an increase in anxiety levels prior to the scan. In the 7-10-year-old group (N = 49), no significant differences were observed between baseline and pre-scan parent-reported anxiety scores. Overall, the COSMO@home app proved to be useful in preparing children for MRI scans, with high satisfaction rates and successful image outcomes across different hospitals. The app, combined with minimal face-to-face guidance on the day of the scan, showed the potential to replace or assist traditional face-to-face training methods. This innovative approach has the potential to reduce the need for sedation or general anesthesia during pediatric MRI scans and its associated risks and improve patient experience.

Severe bacterial infections in children need prompt, appropriate antibiotic treatment. We report challenges observed within a prospective, cohort study on antibiotic efficacy in non-typhi Salmonella bloodstream infection (NCT04850677) in Kisantu district hospital (Democratic Republic of Congo). Children (aged > 28 days to < 5 years) admitted with suspected bloodstream infection (August 1, 2021 through July 31, 2022) were enrolled and followed until day 3 or discharge for non-typhi Salmonella patients. Antibiotics were administered to 98.4% (1,838/1,867) of children, accounting for 2,296 antibiotic regimens (95.7% intravenous, 4.3% oral). Only 78.3% and 61.8% of children were, respectively, prescribed and administered antibiotics on the admission day. At least one dose was not administered in 3.6% of children, mostly because of mismatch of the four times daily cefotaxime schedule with the twice-daily administration rounds. Inappropriate intravenous administration practices included multidose use, air-venting, and direct injection instead of perfusion. There was inaccurate aliquoting in 18.0% (32/178) of intravenous ciprofloxacin regimens, and thus administered doses were > 16% below the intended dose. Dosing accuracy of oral suspensions was impaired by lack of instructions for reconstitution, volume indicators, and/or dosing devices. Adult-dose tablets were split without/beyond scoring lines in 84.4% (27/32) of tablets. Poor availability and affordability of age-appropriate oral formulations contributed to low proportions of intravenous-to-oral switch (33.3% (79/237) of non-typhi Salmonella patients). Other quality issues included poor packaging, nonhomogeneous suspensions, and unsafe water for reconstitution. In conclusion, poor antibiotic products (no age-appropriate formulations, poor quality and access), processes (delayed prescription/administration, missed doses), and practices (inaccurate doses, [bio]safety risks) must be urgently addressed to improve pediatric antibiotic treatment.

Alternative family configurations are becoming more prevalent, yet current legislative statutory does not support stepparents in medical decisions for their stepchildren. We investigate opinions of Belgian and Dutch adults regarding inclusion of stepparents in medical decision-making in minors. We make two observations. First, participants wanted stepparents to be involved in cases when medical information had to be shared or informed consent signed. Second, when stepparents object against previously approved medical interventions by a biological parent, respondents were less likely to support stepparents. Participants with stepchildren were likely to favour inclusion of stepparents in decision-making. Overall, our findings indicate that Belgian and Dutch adults view stepparents as potential executive actors in medical decision-making for minors, but not as primary decision-makers. This study is a first step in showing to what extent stepparents could be included in medical information and decision-making regarding stepchildren. We reflect on these findings in light of implications for medical practice and legislative shortcomings., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Child abuse and neglect is a common, underreported, and worldwide problem. Health care providers play an important role in detecting and reporting this problem. This study examined the knowledge on the clinical signs and mimickers of child abuse among Belgian trainees in family medicine and pediatrics. Participants filled out an anonymous online survey of 15 fictional but realistic cases with either suspicious or non-suspicious signs of abuse or neglect in the context of primary or emergency care. The overall score on all cases, the number of correct answers per case, and the median score were calculated, and the association of the participant's demographic characteristics with their score was examined using regression analysis. A total of 70 participants completed the survey. The overall median score was 73.3% (IQR 20.0%). The suspicious cases were solved more correctly than the non-suspicious cases (median: 85.7% versus 62.5%, p < 0.001). Regression analysis could not reveal a significant association of type and level of education with the performance on the survey. Knowledge of the clinical signs of child maltreatment among pediatricians and general practitioners in training is good, but there is still room for improvement.

Background: Parents are often confronted with a difficult decision when their child falls ill: should they go to the general practitioner (GP) or not? This study aims to describe this process comprehensively in order to allow clinicians to assess the extent to which parents can recognise clinical warning signs and act accordingly. The purpose of this study is to describe parents' decision-making processes when deciding whether or not to consult a GP for their sick child., Methods: We used a qualitative study design based on semistructured interviews to investigate the decision-making process of 25 parents. Four case scenarios describing a developing illness in a child were presented., Results: Parents' reasons for seeking medical attention could be divided into two main categories. First, non-specific fears lead parents to consult a doctor. Parents were alarmed by the persistence and progression of symptoms, the combination of symptoms or changes in their child's behaviour or they needed reassurance. Second, several specific fears were identified. Sometimes, parents fear a specific disease, while at other times, they are concerned about warning signs. Some parents, however, would not seek medical attention at any decision point even though their child could be in a potentially life-threatening situation., Conclusions: Although parents make carefully considered decisions on whether or not to consult a doctor, many appear to miss red flags, including more experienced parents. Conversely, some become overly concerned with certain specific symptoms such as fever, and few parents are familiar with self-management strategies., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

The biomedical use of nanoparticles (NPs) has been the focus of intense research for over a decade. As most NPs are explored as carriers to alter the biodistribution, pharmacokinetics and bioavailability of associated drugs, the delivery of these NPs to the tissues of interest remains an important topic. To date, the majority of NP delivery studies have used tumor models as their tool of interest, and the limitations concerning tumor targeting of systemically administered NPs have been well studied. In recent years, the focus has also shifted to other organs, each presenting their own unique delivery challenges to overcome. In this review, we discuss the recent advances in leveraging NPs to overcome four major biological barriers including the lung mucus, the gastrointestinal mucus, the placental barrier, and the blood-brain barrier. We define the specific properties of these biological barriers, discuss the challenges related to NP transport across them, and provide an overview of recent advances in the field. We discuss the strengths and shortcomings of different strategies to facilitate NP transport across the barriers and highlight some key findings that can stimulate further advances in this field.