Effect of omega-3 supplements or diets on fertility in women: A meta-analysis.

Objective: This study aimed to assess the effect of increased omega-3 consumption on fertilization rates and the probability of women getting pregnant. This study is needed because different perspectives exist regarding the use of omega-3 fatty acids in enhancing fertility among women with reproductive issues, and information for those planning a spontaneous pregnancy is limited. Methods: PubMed, Clinical Trials, CINAHL/EBSCO, Medline Complete, Cochrane Library, and Google Scholar were searched for articles published until April 2021, and the search was limited to articles in English language. The search strategy included the following key words: "in-vitro fertilization (IVF)," "intracytoplasmic sperm injection techniques (ICSI)," "pregnancy," "omega-3 fatty acid," "alpha-linolenic acid," "eicosapentaenoic acid," "docosahexaenoic acid," "n-3 polyunsaturated fatty acid," and "fish oil and seafood." Studies reporting female fertility occurring naturally or IVF/ICSI concurrent with omega-3 intake were included. Retrospective studies, studies including postmenopausal women, and unevenly matched control and study groups were excluded. To assess bias, we used the Cochrane Handbook for Systematic Reviews of Interventions, version 5.1.0. To synthesize the findings from the studies included in this review, a meta-analysis was conducted using calculated or extracted odds ratios (OR) of clinical pregnancies and fertilization rates for each group in each study. Results: We included six trials involving 1789 women who received fertility treatment, four trials involving 2607 women who conceived naturally, and three trials involving 1725 oocytes for fertility rates. Aggregated ORs for the effects of omega-3 on pregnancies were 1.74, 1.36, and 2.14 for women who received fertility treatment, those who conceived naturally, and fertilization rate, respectively. All these results were significant (p ≤ 0.01), although they had high heterogeneity I2>68 %. Conclusion: This systematic review and meta-analysis suggest that omega-3 intake significantly improves women's pregnancy and fertilization rates; however, the high heterogeneity in this review somewhat limits its interpretation. Therefore, further prospective randomized studies are necessary to better understand this relationship.

Omega-3 Intake Improves Clinical Pregnancy Rate in Polycystic Ovary Syndrome Patients: A Double-Blind, Randomized Study.

BACKGROUND: Omega-3 fatty acids promote fertility in males and females and constitute an important factor in the normal development of the fetus. OBJECTIVES: We investigated the effect of omega-3 supplements during ovulation induction treatment in women with polycystic ovary syndrome (PCOS)-related infertility. METHODS: A randomized, double-blind study was conducted for 60 treatment cycles in 34 women with PCOS-related oligo/anovulation referred to the fertility clinic at the Bikur Cholim/Shaare Zedek Medical Center in Jerusalem, who underwent ovulation induction with clomiphene citrate (50 mg). Seventeen women (mean age 33.9 ± 0.9 years) received omega-3 supplements (3 × 600 mg/day) and 17 received placebo capsules (mean age 32.7 ± 0.9 years) for a maximum of two cycles. We recorded their characteristics and data from their serial hormonal blood tests and ultrasound examinations. We also conducted both univariate and multivariate analyses. The primary endpoint was conception. RESULTS: There were clinical pregnancies in 8/30 (26.7%) treatment cycles for women receiving omega-3 supplements versus 4/30 (13.3%) cycles with placebo. Among overweight/obese women (body mass index [BMI] 25-35), there were clinical pregnancies in 8/27 cycles (29.6%) versus 1/19 (5.3%) with placebo (P < 0.04). For overweight/obese PCOS women, omega-3, lower BMI rates, and higher values of the endometrium's thickness increased the odds of becoming pregnant. No harmful side effects from the omega-3 treatment were reported. CONCLUSIONS: Omega-3 supplements demonstrated beneficial effects for fertility in women diagnosed with PCOS. Among the overweight/obese participants, the increased clinical pregnancy rate was significant.

Clinical outcome of planned oocyte cryopreservation at advanced age.

PURPOSE: To report outcome of planned oocyte cryopreservation (POC) in the first 8 years of this treatment in our center. METHODS: A retrospective study in a university-affiliated medical center. RESULTS: A total of 446 women underwent POC during 2011-2018. Fifty-seven (13%) women presented to use these oocytes during the study period (until June 2021). POC was performed at a mean age of 37.9 ± 2.0 (range 33-41). Age at thawing was 43.3 ± 2.1 (range 38-49). A total of 34 (60%) women transferred their oocytes for thawing at other units. Oocyte survival after thawing was significantly higher at our center than following shipping to ancillary sites (78 vs. 63%, p = 0.047). Forty-nine women completed their treatment, either depleting their cryopreserved oocytes without conceiving (36) or attaining a live birth (13)-27% live birth rate per woman. Only one of eleven women who cryopreserved oocytes aged 40 and older had a live birth using thawed oocytes. CONCLUSION: Women should be advised to complete planned oocyte cryopreservation before age 40, given low success rates in women who underwent cryopreservation at advanced reproductive age. In this study, oocyte shipping was associated with lower survival rate. These findings may be relevant for women considering POC and utilization of cryopreserved oocytes.

'Luckily, I don't believe in statistics': survey of women's understanding of chance of success with futile fertility treatments.

RESEARCH QUESTION: Why are women who face poor prognoses for success in assisted reproductive technology (ART) treatment choosing to pursue procedures using their own eggs, despite receiving information that their chances of success are very low. DESIGN: Cross-sectional study based on an anonymous questionnaire distributed to women aged between 43 and 45 years, undergoing ART using their own oocytes, at six public outpatient fertility clinics and three public in-hospital IVF units in Israel between 2015 and 2016. The main outcome measure was personal estimation of chance to achieve a live birth after the current ART treatment cycle and the cumulative estimated rate after all the treatment cycles the patient intended to undergo. RESULTS: Response rate was 70.0%, with 91 participants of mean age 43.8 ± 0.7 years. Participants estimated their delivery rates after the next ART treatment cycle at 49.0 ± 31.8% (response rate 93.4%) and their cumulative delivery rates after all the ART treatments they would undergo at 57.7 ± 36.3% (response rate 90.1%). This is significantly higher than the predicted success rates of 5% and 15%, respectively (both P < 0.001), which are based on national register data. Nearly one-half of patients rated themselves as having a better than average chance of conception (47.3%). CONCLUSION: Women do not pursue futile treatments because they lack information. Despite being informed of the low success rates of conception using ART treatments, many patients of advanced maternal age have unrealistically high expectations from ART, essentially ignoring their estimated prognosis when deciding on treatment continuation. Future work should examine the psychological reasons behind continuing futile fertility treatments.

Cancer in IVF patients treated at age 40 years and older: long term follow-up.

RESEARCH QUESTION: Current knowledge of cancer risk among women who undergo IVF is based mainly on studies of women treated in their thirties, frequently with short follow-up periods. Therefore, information about cancer risk among infertile menopausal women is limited. We aimed to evaluate the risk of cancer among IVF patients treated at age 40 years and older, followed up for an extended period. DESIGN: Historical cohort study of all IVF patients treated at the age of 40 years or older at two university-affiliated IVF units in Jerusalem, Israel, between 1994 and 2002. Data were cross-linked with the Israel National Cancer Registry to 2016. Standardized incidence ratios (SIR) and 95% confidence intervals were computed by comparing the observed number of cancer cases with the expected cancer rate in the general Israeli population adjusted for age and year of birth. In addition, Kaplan-Meier analysis was conducted to account for the length of follow-up. RESULTS: A total of 501 patients were included in the analysis, with mean follow-up of 16.7 ± 3.7 years (range 2-22 years). Mean age at first IVF cycle was 42.3 years (±2.1). Mean number of IVF cycles was 3.2 ± 2.6 (range 1-15). Thirty-six women (7.2%) developed invasive cancer, compared with 47.2 expected cases; SIR 0.76 (95% CI 0.53 to 1.06); 22 women were diagnosed with invasive breast cancer, compared with 19.84 expected; SIR 1.11 (95% CI 0.69 to 1.68). CONCLUSIONS: Older women undergoing IVF treatment were not significantly associated with an excess risk of cancer at long-term follow up. Further studies, however, are needed to confirm these findings.

Cryopreserved embryo transfer: adjacent or non-adjacent to failed fresh long GnRH-agonist protocol IVF cycle.

The optimal time to perform cryopreserved embryo transfer (CET) after a failed oocyte retrieval-embryo transfer (OR-ET) cycle is unknown. Similar clinical pregnancy rates were recently reported in immediate and delayed CET, performed after failed fresh OR-ET, in cycles with the gonadotrophin-releasing hormone (GnRH) antagonist protocol. This study compared outcomes of CET performed adjacently (<50 days, n = 67) and non-adjacently (≥50 to 120 days, n = 62) to the last OR-day of cycles with the GnRH agonist down-regulation protocol. Additional inclusion criteria were patients' age 20-38 years, the transfer of only 1-2 cryopreserved embryos, one treatment cycle per patient and artificial preparation for CET. Significantly higher implantation, clinical pregnancy and live birth rates were found in the non-adjacent group than in the adjacent group: 30.5% versus 11.3% (P = 0.001), 41.9% versus 17.9% (P = 0.003) and 32.3% versus 13.4% (P = 0.01), respectively. These results support the postponement of CET after a failed OR-ET for at least one menstrual cycle, when a preceding long GnRH-agonist protocol is used.

How Many Embryos should be Transferred? The Relevance of Parity and Obstetric History.

BACKGROUND: Fertility treatments are responsible for the rise in high order pregnancies in recent decades and their associated complications. Reducing the number of embryos returned to the uterus will reduce the rate of high order pregnancies. OBJECTIVES: To explore whether obstetric history and parity have a role in the clinician's decision making regarding the number of embryos transferred to the uterus during in vitro fertilization (IVF). METHODS: In a retrospective study for the period August 2005 to March 2012, data of twin deliveries > 24 weeks were collected, including parity, mode of conception (IVF vs. spontaneous), gestational age at delivery, preeclampsia, birth weight, admission to the neonatal intensive care unit (NICU), and Apgar scores. RESULTS: A total of 1651 twin deliveries > 24 weeks were record- ed, of which 959 (58%) were at term (> 37 weeks). The early preterm delivery (PTD) rate (< 32 weeks) was significantly lower with increased parity (12.6%, 8.5%, and 5.6%, in women with 0, 1, and ≥ 2 previous term deliveries, respectively). Risks for PTD (< 37 weeks), preeclampsia and NICU admission were significantly higher in primiparous women compared to those who had one or more previous term deliveries. Primiparity and preeclampsia, but not IVF, were significant risk factors for PTD. CONCLUSIONS: The risk for PTD in twin pregnancies is significantly lower in women who had a previous term delivery and decreases further after two or more previous term deliveries. This finding should be considered when deciding on the number of embryos to be transferred in IV.

Delivering elsewhere between the first and second deliveries is a risk marker for obstetric complications in the second delivery.

PURPOSE: We speculate that parturients who deliver elsewhere between the first and second deliveries compose a unique clinical group, characterized by higher rates of cesarean section (CS) both in the first and second deliveries, compared with parturients who deliver both deliveries at the same hospital. METHODS: A retrospective study conducted at Shaare Zedek Medical Center in a tertiary university-affiliated hospital. The cohort included all women in the second delivery, aged ≤24 years with a singleton pregnancy who delivered their second child in our medical center during 2010-2012. Parturients who delivered both the first and second children in our medical center ("stayers") were compared with parturients who delivered their first child in a different hospital ("switchers"). Groups were compared in regard to history of CS in the first delivery and obstetric complications in the second delivery, including CS, instrumental vaginal delivery (IVD), preterm delivery (PTD), and postpartum hemorrhage (PPH). Logistic regressions were constructed to study if delivering elsewhere between the first and second deliveries was a risk for adverse pregnancy outcome, followed by multivariate analysis controlling for confounders. RESULTS: In all, 4166 parturients were included: "stayers" = 3163 and "switchers" = 1003. History of CS in the first delivery was approximately twice as prevalent in "switchers" (12 versus 6.3 %, p < 0.000). "Switchers" experienced higher rates of CS: OR = 1.8 (95 % CI 1.2-2.3); IVD: OR = 1.3 (95 % CI 0.8-2.1); and PTD (<37w): OR = 1.4 (95 % CI 1.0-1.9). CONCLUSIONS: Parturients who deliver elsewhere between the first and second childbirth are at increased risk for CS and PTD in the second delivery; hence, the decision to deliver elsewhere after the first delivery should be considered as a risk marker for obstetric complication.

Ovarian stimulation for oocyte cryopreservation for prevention of age-related fertility loss: one in five is a low responder.

Oocyte cryopreservation for age-related fertility loss is gaining interest considering the tendency to postpone motherhood in many societies. Little is currently known about the actual efficiency of this approach. We aimed to explore ovarian response of presumably fertile women undergoing in vitro fertilization for this indication. A total of 105 women underwent 151 stimulation cycles at mean age 37.7 ± 2.4. None had known infertility. Mean daily starting FSH dose was 371 ± 110 (225-600). Mean number of mature oocytes cryopreserved at the first completed cycle was 9.7 ± 7.5 (0-43). However, 21% of started cycles were either cancelled before egg retrieval or resulted in 0-3 mature oocytes retrieved. Therefore, women considering oocyte cryopreservation for prevention of age-related fertility decline should be encouraged to perform this procedure at younger age than, preferably before 35.

Preconception screening for cytomegalovirus: an effective preventive approach.

Congenital cytomegalovirus (CMV) is the leading infectious cause of sensorineural hearing loss and delayed psychomotor development. Viral transmission to the fetus is far more likely to occur following a primary than a secondary maternal infection. Primary prevention seems to be the best means to reduce the burden of congenital CMV due to the lack of treatment options during pregnancy. We evaluated this approach on a cohort of 500 women planning pregnancy who attended our fertility clinic. Of the 444 who underwent CMV screening, 18 (4.1%) had positive IgM serology for CMV; of these, IgG avidity was high in 12 (remote infection) and low in 6 (recent infection). The latter were advised to delay pregnancy. All women who were seroimmune for CMV (366/444, 82.4%), including the 12 with remote infection, continued fertility treatment. The remaining patients (72/444, 16.2%), who were not immune to CMV at the initial screen, were advised to minimize CMV exposure by improving personal hygiene and to continue fertility treatment. None of the 69/72 (95.8%) women who were followed for one year were infected with CMV. Cytomegalovirus testing and counselling at preconception seemed effective in reducing CMV exposure in pregnancy.

Ketoconazole inhibits ovulation as a result of arrest of follicular steroidogenesis in the rat ovary.

OBJECTIVE: Ketoconazole (KCZ) is a known inhibitor of steroidogenic P450 enzymes in the adrenal cortex and the gonads. Previous studies examined the potential clinical use of KCZ for attenuation of ovarian response to gonadotropin treatments. This study aimed to use the superovuating rat model to explore the effect of KCZ on ovarian steroidogenesis, follicular function, and development toward ovulation. METHODS: Prepubertal rats were treated with equine chorionic gonadotropin (eCG)/human CG (hCG) resulting in multiple follicular development and ovulation. The effect of KCZ on this model was examined by administration of KCZ-gel formula and subsequent analyses of ovarian steroidogenesis, rate of ovulation, morphometric assessments of follicular parameters, and cell-specific steroidogenic maturation of the treated ovaries. RESULTS: When applied shortly before gonadotropin stimulation, KCZ markedly reduced ovarian progesterone, androstenedione, and estradiol levels down to 18.7, 36.5, and 19.0%, respectively (P < 0.001). A single KCZ-gel administration of 6, 12, and 24 mg/rat resulted in reduction of ovulated ova/ovary down to 8.6 ± 4.9, 5.1 ± 4.3, and 2.4 ± 3.2, respectively, as compared to 13.6 ± 4.4 ova found in the oviduct of control-gel-injected animals (P < 0.001). An alternative protocol made use of small KCZ doses injected in non-gel formula (5 mg/dose/8 hours), commenced with the eCG administration and terminated 24 hours later; this treatment readily inhibited the ovulation rates to 6.6 ± 6.6 as compared to 16.5 ± 4.1 ova/ovary in the control group (P < 0.01). By contrast, KCZ failed to inhibit ovulation if administered 24 hours after eCG injection. Anovulation by KCZ resulted from arrest of follicular development at the stage of 800-840 µm Graafian follicles as compared to 920 µm of peri-ovulatory follicles (OFs) observed in the control group, P = 0.029. In addition, absence of CYP11A1 expression was evident in the granulosa cell layers of the growth-arrested follicles, which also lacked mucified mature cumulus cell complexes. CONCLUSION: These results suggest that KCZ-mediated inhibition of follicular maturation probably results from impaired steroidogenesis at early phase of follicular development toward ovulation. Hence, attenuation of folliculogenesis by KCZ may be harnessed to modulate gonadotropin-ovarian stimulation in fertility treatments.

Selective inhibition of steroidogenic enzymes by ketoconazole in rat ovary cells.

OBJECTIVE: Ketoconazole (KCZ) is an anti-fungal agent extensively used for clinical applications related to its inhibitory effects on adrenal and testicular steroidogenesis. Much less information is available on the effects of KCZ on synthesis of steroid hormones in the ovary. The present study aimed to characterize the in situ effects of KCZ on steroidogenic enzymes in primary rat ovary cells. METHODS: Following the induction of folliculogenesis in gonadotropin treated rats, freshly prepared ovarian cells were incubated in suspension for up to four hours while radiolabeled steroid substrates were added and time dependent generation of their metabolic products was analyzed by thin layer chromatography (TLC). RESULTS: KCZ inhibits the P450 steroidogenic enzymes in a selective and dose dependent manner, including cholesterol side-chain cleavage cytochrome P450 (CYP11A1/P450scc), the 17α-hydroxylase activity of CYP17A1/P450c17, and CYP19A1/P450arom, with IC50 values of 0.3, 1.8, and 0.3 µg/mL (0.56, 3.36, and 0.56 µM), respectively. Unaffected by KCZ, at 10 µg/mL, were the 17,20 lyase activity of CYP17A1, as well as five non-cytochrome steroidogenic enzymes including 3ß-hydroxysteroid dehydrogenase-Δ(5-4) isomerase type 1 (3ßHSD1), 5α-reductase, 20α-hydroxysteroid dehydrogenase (20α-HSD), 3α-hydroxysteroid dehydrogenase (3α-HSD), and 17ß-hydroxysteroid dehydrogenase type 1 (17HSD1). CONCLUSION: These findings map the effects of KCZ on the ovarian pathways of progestin, androgen, and estrogen synthesis. Hence, the drug may have a potential use as an acute and reversible modulator of ovarian steroidogenesis in pathological circumstances.

The dynamics of serum anti-Mullerian-hormone levels during controlled ovarian hyperstimulation with GnRH-antagonist short protocol in polycystic ovary syndrome and low responders.

OBJECTIVE: To determine whether the decrease in AMH levels during ovarian hyperstimulation for IVF occurs in patients with polycystic ovary syndrome (PCOS) and patients with low ovarian reserve (LOR), as in normal cycling women. STUDY DESIGN: A cohort of 22 infertile patients treated in a single tertiary center with a GnRH-antagonist short protocol for IVF were prospectively included and divided into three groups: PCOS with hyperandrogenism (n=7), LOR (n=8) and control (n=7). Serum AMH levels were measured before and during FSH treatment, on the day of HCG administration, at the mid-luteal phase, and 14 days after embryo transfer. The three groups were compared using an ANOVA model in the case of continuous data and with Fisher's exact test when the data were discrete. RESULTS: In the PCOS group, AMH levels increased at the beginning of the stimulation, but later decreased, until the mid-luteal stage. In the other two groups, AMH levels decreased throughout ovarian stimulation until the mid-luteal stage. In all groups, AMH levels returned to baseline levels two weeks after HCG administration, regardless of treatment outcome (pregnancy or not). CONCLUSIONS: AMH levels decline during controlled ovarian hyperstimulation with a GnRH-antagonist short protocol in women with low and normal ovarian reserves. In contrast, in women with PCOS, an increase in AMH levels precedes this decline. These findings may support the hypothesis that androgens may play a role in AMH regulation in women.

Expression and roles of steroidogenic acute regulatory (StAR) protein in 'non-classical', extra-adrenal and extra-gonadal cells and tissues.

The activity of the steroidogenic acute regulatory (StAR) protein is indispensable and rate limiting for high output synthesis of steroid hormones in the adrenal cortex and the gonads, known as the 'classical' steroidogenic organs (StAR is not expressed in the human placenta). In addition, studies of recent years have shown that StAR is also expressed in many tissues that produce steroid hormones for local use, potentially conferring some functional advantage by acting via intracrine, autocrine or paracrine fashion. Others hypothesized that StAR might also function in non-steroidogenic roles in specific tissues. This review highlights the evidence for the presence of StAR in 17 extra-adrenal and extra-gonadal organs, cell types and malignancies. Provided is the physiological context and the rationale for searching for the presence of StAR in such cells. Since in many of the tissues the overall level of StAR is relatively low, we also reviewed the methods used for StAR detection. The gathered information suggests that a comprehensive understanding of StAR activity in 'non-classical' tissues will require the use of experimental approaches that are able to analyze StAR presence at single-cell resolution.

DHEA supplementation may improve IVF outcome in poor responders: a proposed mechanism.

OBJECTIVE: Dehydroepiandrosterone (DHEA) supplementation for poor responders may improve ovarian response and IVF treatment outcome. This study aimed to determine the mechanism of action of DHEA, and specifically, the stage of folliculogenesis influenced by DHEA. STUDY DESIGN: This is a prospective, self-controlled study of poor responders to IVF treatment, comparing day 3 biochemical (anti-Mullerian hormone (AMH), inhibin B and FSH) and ultrasound (antral follicle count (AFC)) ovarian reserve markers and IVF treatment outcome before and after DHEA supplementation of at least 3 months duration. RESULTS: Thirty-two women were included. Following DHEA, there was a significant increase in AFC (P=0.0003) without significant changes in the baseline biochemical parameters AMH, inhibin B, or FSH. The enhanced response comprised increased peak estradiol levels (P=0.0005), number of follicles >15 mm, oocytes, MII oocytes and embryos (P=0.004, P=0.00001, P=0.0004 and P=0.0006, respectively) and oocytes number/total FSH dose (P=0.0009). The proportion of cancelled cycles due to very poor response decreased significantly (P=0.02). CONCLUSIONS: DHEA does not appear to exert influence via recruitment of pre-antral or very small antral follicles (no change in AMH and inhibin B) but rather by rescue from atresia of small antral follicles (increased AFC).

Substrate independent assembly of optical structures guided by biomolecular interactions.

The chip-scale integration of optical components is crucial for technologies as diverse as optical communications, optoelectronics displays, and photovoltaics. However, the realization of integrated optical devices from discrete components is often hampered by the lack of a universal substrate for achieving monolithic integration and by incompatibilities between materials. Emergent technologies such as chip-scale biophotonics, organic optoelectronics, and optofluidics present a host of new challenges for optical device integration, which cannot be solved with existing bonding techniques. Here, we report a new method for substrate independent integration of dissimilar optical components by way of biological recognition-directed assembly. Bonding in this scheme is achieved by locally modifying the substrate with a protein receptor and the optical component with a biomolecular ligand or vice versa. The key features of this new technology include substrate independent assembly, cross-platform vertical scale integration, and selective registration of components based on complementary biomolecular interactions.

Ovarian hemorrhage after transvaginal ultrasonographically guided oocyte aspiration: a potentially catastrophic and not so rare complication among lean patients with polycystic ovary syndrome.

OBJECTIVE: To report the first case series of ovarian hemorrhage after transvaginal ultrasonographically guided oocyte aspiration (TVOA). DESIGN: Retrospective analysis. SETTING: In vitro fertilization unit of a tertiary university hospital. PATIENT(S): Patients who underwent TVOA during a 6-year period. INTERVENTION(S): Surgical intervention due to active bleeding from the ovary. MAIN OUTCOME MEASURE(S): Prevalence and risk factors. RESULT(S): Among 3,241 patients undergoing TVOA, 7 were diagnosed as having ovarian hemorrhage afterward. All patients were thin, with a body mass index of 19-21 kg/m(2), and 4 had polycystic ovary syndrome (PCOS). The prevalence of ovarian bleeding among lean patients with PCOS was 4.5%. The odds ratio for bleeding in lean patients with PCOS vs. all other patients was 50 (95% confidence interval 11-250). The interval between the TVOA and surgical intervention ranged from 5 to 18 hours (mean +/- SD, 11.4 +/- 5 hours). The Delta decrease in hemoglobin levels was 3.2-9 g/dL (mean 6.1 +/- 1.8). In 6 of the 7 patients, laparoscopically guided electrocoagulation was sufficient to achieve hemorrhagic control. CONCLUSION(S): Although acute hemorrhage is a rare event after TVOA, lean patients with PCOS specifically are at much higher risk for this complication.

Smart tissue culture: in situ monitoring of the activity of protease enzymes secreted from live cells using nanostructured photonic crystals.

Monitoring enzyme secretion in tissue culture has proved challenging because to date the activity cannot be continuously measured in situ. In this Letter, we present a solution using biopolymer loaded photonic crystals of anodized silicon. Shifts in the optical response by proteolytic degradation of the biopolymer provide label-free sensing with unprecedented low detection limits (1 pg) and calculation of kinetic parameters. The enhancement in sensitivity relative to previous photonic crystal sensors constitutes a change in the sensing paradigm because here the entire pore space is responsive to the secreted enzyme rather than just the pore walls. In situ monitoring is demonstrated by detecting secretion of matrix metalloprotease 9 from stimulated human macrophages.