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<!-- Creation Date :2023-08-07T14:35:48.1717+00:00 -->
<!-- Copyright (c) 2023 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="arct_UpfrontPaymentIncludingTaxes" name="UpfrontPaymentIncludingTaxes" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_AxceleadIncMember" name="AxceleadIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_CommitmentAndContingenciesTable" name="CommitmentAndContingenciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_GrantRevenueDisclosureTextBlock" name="GrantRevenueDisclosureTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="arct_StudySupportAgreementMember" name="StudySupportAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
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  <xsd:element id="arct_PreclinicalMilestonePaymentReceived" name="PreclinicalMilestonePaymentReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
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  <xsd:element id="arct_MaximumPotentialUpfrontPaymentAmountPayableOnTerminationOfAgreement" name="MaximumPotentialUpfrontPaymentAmountPayableOnTerminationOfAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_VallonPharmaceuticalsIncMember" name="VallonPharmaceuticalsIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
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  <xsd:element id="arct_LesseeOperatingLeaseLiabilityPaymentsDueAfterYearThree" name="LesseeOperatingLeaseLiabilityPaymentsDueAfterYearThree" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
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  <xsd:element id="arct_AcquisitionOfResearchAndDevelopmentInProcessThroughIssuanceOfCommonStock" name="AcquisitionOfResearchAndDevelopmentInProcessThroughIssuanceOfCommonStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
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  <xsd:element id="arct_TwoThousandNineteenOmnibusIncentivePlanMember" name="TwoThousandNineteenOmnibusIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
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  <xsd:element id="arct_GrantReceivableNumberOfInstallments" name="GrantReceivableNumberOfInstallments" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="arct_PrepaidExpensesAndOtherReceivables" name="PrepaidExpensesAndOtherReceivables" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
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  <xsd:element id="arct_DebtInstrumentOptionForRenewalTerm" name="DebtInstrumentOptionForRenewalTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="arct_UpfrontFeeReceived" name="UpfrontFeeReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
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  <xsd:element id="arct_WellsFargoCreditAgreementMember" name="WellsFargoCreditAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
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  <xsd:element id="arct_DisbursementAmountPayableUponAchievementOfProjectGoal" name="DisbursementAmountPayableUponAchievementOfProjectGoal" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
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  <xsd:element id="arct_MaximumSalesRequiredForLoansForgivable" name="MaximumSalesRequiredForLoansForgivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
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  <xsd:element id="arct_DisbursementPaymentUponAchievementOfRequiredManufacturingPracticesAndINDApplication" name="DisbursementPaymentUponAchievementOfRequiredManufacturingPracticesAndINDApplication" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
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  <xsd:element id="arct_ExpectedPaymentEligibleToReceiveUnderAgreement" name="ExpectedPaymentEligibleToReceiveUnderAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
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  <xsd:element id="arct_VinbiocareContractualLiabilities" name="VinbiocareContractualLiabilities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_DisbursementPeriodFourMember" name="DisbursementPeriodFourMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_UnderlyingAgreementMember" name="UnderlyingAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
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  <xsd:element id="arct_RevenueRecognitionReserveTargetExclusivityPeriod" name="RevenueRecognitionReserveTargetExclusivityPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="arct_GriBioIncMember" name="GriBioIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
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  <xsd:element id="arct_OtherCollaborationAgreementsMember" name="OtherCollaborationAgreementsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_BiomedicalAdvancedResearchAndDevelopmentAuthorityMember" name="BiomedicalAdvancedResearchAndDevelopmentAuthorityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_DevelopmentMilestonesReceivedAdvancePayment" name="DevelopmentMilestonesReceivedAdvancePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="arct_DevelopmentMilestonesAchieved" name="DevelopmentMilestonesAchieved" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="arct_QuarterlyPaymentsPayableOnTerminationsAgreement" name="QuarterlyPaymentsPayableOnTerminationsAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="arct_LiquidityPolicyPolicyTextBlock" name="LiquidityPolicyPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="arct_ReductionInNumberOfCommonStockCapitalSharesAvailableForFutureIssuance" name="ReductionInNumberOfCommonStockCapitalSharesAvailableForFutureIssuance" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="arct_ContractWithCustomerAssetDeductions" name="ContractWithCustomerAssetDeductions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_CollaborationPartnerCureVacEnteredIntoCoDevelopmentAgreementMember" name="CollaborationPartnerCureVacEnteredIntoCoDevelopmentAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_RevenueRecognitionPotentialMilestoneRevenueRecognized" name="RevenueRecognitionPotentialMilestoneRevenueRecognized" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_OtherAccruedResearchAndDevelopmentExpenses" name="OtherAccruedResearchAndDevelopmentExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_CollaborationRevenueMember" name="CollaborationRevenueMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_PercentageOfNetProfits" name="PercentageOfNetProfits" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="arct_NumberOfPerformanceObligations" name="NumberOfPerformanceObligations" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="arct_UpfrontPaymentPayable" name="UpfrontPaymentPayable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_RoyaltyPayments" name="RoyaltyPayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_PharmaceuticalCompanyMember" name="PharmaceuticalCompanyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_BusinessAcquisitionOfHoldingShare" name="BusinessAcquisitionOfHoldingShare" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="arct_MilestonePayments" name="MilestonePayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_Covid19VaccineMember" name="Covid19VaccineMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_DevelopmentMilestonesAmountReceivedForAgreement" name="DevelopmentMilestonesAmountReceivedForAgreement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="arct_ADAIRTechnologyMember" name="ADAIRTechnologyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_DisbursementPeriodOneMember" name="DisbursementPeriodOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_ReservedUpfrontPayment" name="ReservedUpfrontPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_COVIDNineteenVaccineDevelopmentMember" name="COVIDNineteenVaccineDevelopmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_MRNATechnologyMember" name="MRNATechnologyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_JanssenMember" name="JanssenMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_BillingReceivedAmountRelatedToClinicalTrial" name="BillingReceivedAmountRelatedToClinicalTrial" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="arct_AdditionalFinancialSupport" name="AdditionalFinancialSupport" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_RepyamentOfPrincipalAndInterestOnCollateralizedTermLoan" name="RepyamentOfPrincipalAndInterestOnCollateralizedTermLoan" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="arct_CslSeqirusMember" name="CslSeqirusMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_DevelopmentMilestonesAdvancePaymentIncludedInDeferredRevenue" name="DevelopmentMilestonesAdvancePaymentIncludedInDeferredRevenue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="arct_CommitmentAndContingenciesLineItems" name="CommitmentAndContingenciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_ContingentGrantsMember" name="ContingentGrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="arct_GrantRevenue" name="GrantRevenue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
</xsd:schema>
